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</file_summary>
<directory_structure>
benches/
cell_benchmark.rs
diff_benchmark.rs
examples/
smoke_test.rs
streaming_demo.rs
include/
flywheel.h
src/
actor/
engine.rs
input.rs
messages.rs
mod.rs
renderer.rs
buffer/
buffer.rs
cell.rs
diff.rs
mod.rs
layout/
mod.rs
rect.rs
region.rs
terminal/
mod.rs
output.rs
widget/
mod.rs
scroll_buffer.rs
stream.rs
ffi.rs
lib.rs
.gitignore
ARCHITECTURE.md
Cargo.toml
cbindgen.toml
README.md
rustfmt.toml
TRACKER.md
</directory_structure>
<files>
This section contains the contents of the repository's files.
<file path="benches/cell_benchmark.rs">
//! Cell benchmark: Measure Cell comparison performance.
//!
//! Target: < 1ns per comparison
use criterion::{black_box, criterion_group, criterion_main, Criterion};
use flywheel::{Cell, Modifiers, Rgb};
fn cell_equality_same(c: &mut Criterion) {
let cell_a = Cell::new('A')
.with_fg(Rgb::new(255, 128, 64))
.with_bg(Rgb::new(32, 32, 32))
.with_modifiers(Modifiers::BOLD);
let cell_b = cell_a;
c.bench_function("cell_eq_same", |b| {
b.iter(|| black_box(&cell_a) == black_box(&cell_b))
});
}
fn cell_equality_different_grapheme(c: &mut Criterion) {
let cell_a = Cell::new('A');
let cell_b = Cell::new('B');
c.bench_function("cell_eq_diff_grapheme", |b| {
b.iter(|| black_box(&cell_a) == black_box(&cell_b))
});
}
fn cell_equality_different_color(c: &mut Criterion) {
let cell_a = Cell::new('A').with_fg(Rgb::new(255, 0, 0));
let cell_b = Cell::new('A').with_fg(Rgb::new(0, 255, 0));
c.bench_function("cell_eq_diff_color", |b| {
b.iter(|| black_box(&cell_a) == black_box(&cell_b))
});
}
fn cell_from_char(c: &mut Criterion) {
c.bench_function("cell_from_char_ascii", |b| {
b.iter(|| Cell::from_char(black_box('A')))
});
c.bench_function("cell_from_char_cjk", |b| {
b.iter(|| Cell::from_char(black_box('日')))
});
}
criterion_group!(
benches,
cell_equality_same,
cell_equality_different_grapheme,
cell_equality_different_color,
cell_from_char,
);
criterion_main!(benches);
</file>
<file path="benches/diff_benchmark.rs">
//! Diffing engine benchmark: Measure buffer diff performance.
//!
//! Target: < 500µs for 200×50 buffer
use criterion::{black_box, criterion_group, criterion_main, Criterion, BenchmarkId};
use flywheel::{Buffer, Cell, Rgb};
use flywheel::buffer::diff::{render_full_diff, render_full, DiffState};
/// Create a buffer with random-ish content for benchmarking.
fn create_test_buffer(width: u16, height: u16, seed: u8) -> Buffer {
let mut buffer = Buffer::new(width, height);
for y in 0..height {
for x in 0..width {
let c = ((x + y + seed as u16) % 26 + 65) as u8 as char; // A-Z
let cell = Cell::new(c)
.with_fg(Rgb::new(
((x * 3 + seed as u16) % 256) as u8,
((y * 7 + seed as u16) % 256) as u8,
((x + y + seed as u16) % 256) as u8,
))
.with_bg(Rgb::new(20, 20, 30));
buffer.set(x, y, cell);
}
}
buffer
}
fn diff_identical_buffers(c: &mut Criterion) {
let buffer = create_test_buffer(200, 50, 0);
let buffer_clone = buffer.clone();
c.bench_function("diff_200x50_identical", |b| {
b.iter(|| {
let mut output = Vec::with_capacity(4096);
let mut state = DiffState::new();
render_full_diff(
black_box(&buffer),
black_box(&buffer_clone),
&mut output,
&mut state,
)
})
});
}
fn diff_single_cell_change(c: &mut Criterion) {
let buffer_a = create_test_buffer(200, 50, 0);
let mut buffer_b = buffer_a.clone();
// Change a single cell in the middle
buffer_b.set(100, 25, Cell::new('X').with_fg(Rgb::new(255, 0, 0)));
c.bench_function("diff_200x50_single_change", |b| {
b.iter(|| {
let mut output = Vec::with_capacity(4096);
let mut state = DiffState::new();
render_full_diff(
black_box(&buffer_a),
black_box(&buffer_b),
&mut output,
&mut state,
)
})
});
}
fn diff_many_changes(c: &mut Criterion) {
let buffer_a = create_test_buffer(200, 50, 0);
let buffer_b = create_test_buffer(200, 50, 1); // Different seed = different content
c.bench_function("diff_200x50_full_change", |b| {
b.iter(|| {
let mut output = Vec::with_capacity(65536);
let mut state = DiffState::new();
render_full_diff(
black_box(&buffer_a),
black_box(&buffer_b),
&mut output,
&mut state,
)
})
});
}
fn diff_line_change(c: &mut Criterion) {
let buffer_a = create_test_buffer(200, 50, 0);
let mut buffer_b = buffer_a.clone();
// Change one full line
for x in 0..200 {
buffer_b.set(x, 25, Cell::new('*').with_fg(Rgb::new(255, 255, 0)));
}
c.bench_function("diff_200x50_line_change", |b| {
b.iter(|| {
let mut output = Vec::with_capacity(4096);
let mut state = DiffState::new();
render_full_diff(
black_box(&buffer_a),
black_box(&buffer_b),
&mut output,
&mut state,
)
})
});
}
fn full_render(c: &mut Criterion) {
let buffer = create_test_buffer(200, 50, 0);
c.bench_function("render_full_200x50", |b| {
b.iter(|| {
let mut output = Vec::with_capacity(65536);
render_full(black_box(&buffer), &mut output)
})
});
}
fn diff_various_sizes(c: &mut Criterion) {
let mut group = c.benchmark_group("diff_by_size");
for (width, height) in [(80, 24), (120, 40), (200, 50), (300, 80)] {
let buffer_a = create_test_buffer(width, height, 0);
let buffer_b = create_test_buffer(width, height, 1);
group.bench_with_input(
BenchmarkId::new("full_change", format!("{}x{}", width, height)),
&(buffer_a, buffer_b),
|b, (a, bb)| {
b.iter(|| {
let mut output = Vec::with_capacity(65536);
let mut state = DiffState::new();
render_full_diff(black_box(a), black_box(bb), &mut output, &mut state)
})
},
);
}
group.finish();
}
criterion_group!(
benches,
diff_identical_buffers,
diff_single_cell_change,
diff_many_changes,
diff_line_change,
full_render,
diff_various_sizes,
);
criterion_main!(benches);
</file>
<file path="examples/smoke_test.rs">
//! Smoke test: Verify the actor model with non-blocking input.
//!
//! This example demonstrates:
//! - Engine initialization with raw mode and alternate screen
//! - Non-blocking input polling
//! - Frame-based rendering
//! - Graceful shutdown on 'q' or Escape
use flywheel::{Cell, Engine, InputEvent, KeyCode, Rgb};
use std::time::Duration;
fn main() -> std::io::Result<()> {
println!("Starting Flywheel Smoke Test...");
println!("Press 'q' or Escape to quit");
println!("Type any key to see it echoed");
std::thread::sleep(Duration::from_secs(1));
// Create the engine
let mut engine = Engine::new()?;
// Draw initial UI
let width = engine.width();
let height = engine.height();
// Title bar
let title = "Flywheel Smoke Test - Press 'q' to quit";
let bg_title = Rgb::new(40, 80, 120);
for x in 0..width {
engine.set_cell(x, 0, Cell::new(' ').with_bg(bg_title));
}
engine.draw_text(2, 0, title, Rgb::WHITE, bg_title);
// Info text
let info_y = 2;
engine.draw_text(2, info_y, &format!("Terminal size: {}x{}", width, height), Rgb::new(180, 180, 180), Rgb::DEFAULT_BG);
engine.draw_text(2, info_y + 1, "Frame: 0", Rgb::new(180, 180, 180), Rgb::DEFAULT_BG);
engine.draw_text(2, info_y + 2, "Last key: (none)", Rgb::new(180, 180, 180), Rgb::DEFAULT_BG);
// Instructions
engine.draw_text(2, info_y + 4, "Type to see characters appear below:", Rgb::new(150, 200, 150), Rgb::DEFAULT_BG);
// Request initial draw
engine.request_redraw();
// Typing area
let mut typed = String::new();
let type_y = info_y + 5;
// Main loop
while engine.is_running() {
engine.begin_frame();
// Process all pending input events
while let Some(event) = engine.poll_input() {
match event {
InputEvent::Key { code, modifiers } => {
match code {
KeyCode::Char('q') | KeyCode::Esc => {
engine.stop();
}
KeyCode::Char('c') if modifiers.control => {
engine.stop();
}
KeyCode::Char(c) => {
typed.push(c);
if typed.len() > (width - 4) as usize {
typed.clear();
}
// Update typed text
engine.buffer_mut().clear_rect(2, type_y, width - 4, 1);
engine.draw_text(2, type_y, &typed, Rgb::new(100, 255, 100), Rgb::DEFAULT_BG);
}
KeyCode::Backspace => {
typed.pop();
engine.buffer_mut().clear_rect(2, type_y, width - 4, 1);
engine.draw_text(2, type_y, &typed, Rgb::new(100, 255, 100), Rgb::DEFAULT_BG);
}
KeyCode::Enter => {
typed.clear();
engine.buffer_mut().clear_rect(2, type_y, width - 4, 1);
}
_ => {}
}
// Update last key display
let key_str = format!("Last key: {:?} (modifiers: {:?})", code, modifiers);
engine.buffer_mut().clear_rect(2, info_y + 2, width - 4, 1);
engine.draw_text(2, info_y + 2, &key_str, Rgb::new(255, 200, 100), Rgb::DEFAULT_BG);
}
InputEvent::Resize { width: w, height: h } => {
engine.handle_resize(w, h);
// Update size display
let size_str = format!("Terminal size: {}x{}", w, h);
engine.buffer_mut().clear_rect(2, info_y, width - 4, 1);
engine.draw_text(2, info_y, &size_str, Rgb::new(180, 180, 180), Rgb::DEFAULT_BG);
}
InputEvent::Error(e) => {
eprintln!("Input error: {}", e);
}
InputEvent::Shutdown => {
engine.stop();
}
_ => {}
}
}
// Update frame counter
let frame_str = format!("Frame: {}", engine.frame_count());
engine.buffer_mut().clear_rect(2, info_y + 1, 30, 1);
engine.draw_text(2, info_y + 1, &frame_str, Rgb::new(180, 180, 180), Rgb::DEFAULT_BG);
engine.end_frame();
}
Ok(())
}
</file>
<file path="examples/streaming_demo.rs">
//! Matrix Streaming Demo: High-speed infinite generation with input.
#![allow(clippy::cast_precision_loss)]
#![allow(clippy::cast_sign_loss)]
#![allow(clippy::cast_possible_truncation)]
#![allow(clippy::many_single_char_names)]
#![allow(clippy::too_many_lines)]
#![allow(clippy::missing_const_for_fn)]
//!
//! Demonstrates:
//! - Infinite scrolling with high throughput
//! - Zero-flicker rendering at max FPS
//! - Responsive input handling during heavy load
//! - Per-character color attribute updates
use flywheel::{
Cell, Engine, InputEvent, KeyCode, Rect, Rgb, StreamWidget,
};
use std::time::{Duration, Instant};
use sysinfo::{CpuRefreshKind, MemoryRefreshKind, RefreshKind, System};
use crossbeam_channel::RecvTimeoutError;
/// Simple LCG for deterministic randomness without dependencies.
struct Rng {
state: u64,
}
impl Rng {
const fn new(seed: u64) -> Self {
Self { state: seed }
}
const fn next_u32(&mut self) -> u32 {
self.state = self.state.wrapping_mul(6_364_136_223_846_793_005).wrapping_add(1);
(self.state >> 32) as u32
}
fn next_float(&mut self) -> f32 {
(self.next_u32() as f32) / (u32::MAX as f32)
}
fn next_char(&mut self) -> char {
// Printable ASCII: 33-126
let val = (self.next_u32() % 94) + 33;
val as u8 as char
}
fn next_color(&mut self) -> Rgb {
// High saturation colors
let hue = self.next_float() * 6.0;
let x = (1.0 - (hue % 2.0 - 1.0).abs()) * 255.0;
let c = 255.0;
let (r, g, b) = match hue as i32 {
0 => (c, x, 0.0),
1 => (x, c, 0.0),
2 => (0.0, c, x),
3 => (0.0, x, c),
4 => (x, 0.0, c),
_ => (c, 0.0, x),
};
Rgb::new(r as u8, g as u8, b as u8)
}
}
fn main() -> std::io::Result<()> {
println!("Flywheel Matrix Streaming Demo");
println!("==============================");
println!("Simulating high-speed infinite generation.");
println!("Type in the input box to test responsiveness.");
println!("Press Escape to quit (or Ctrl+C).\n");
std::thread::sleep(Duration::from_secs(1));
let mut engine = Engine::new()?;
let mut width = engine.width();
let mut height = engine.height();
// Layout
let header_height = 0u16;
let footer_height = 2u16;
let footer_bg = Rgb::new(30, 30, 30);
let content_height = height.saturating_sub(header_height + footer_height);
let mut stream = StreamWidget::new(Rect::new(0, header_height, width, content_height));
// Initial colors
engine.request_redraw();
// State
let mut rng = Rng::new(12345);
let mut token_count = 0u64;
let mut frame_count = 0u64;
let start_time = Instant::now();
let mut user_input = String::new();
// Resource monitoring
let mut sys = System::new_with_specifics(
RefreshKind::new()
.with_cpu(CpuRefreshKind::everything())
.with_memory(MemoryRefreshKind::everything())
);
// Initial render
engine.begin_frame();
draw_demo_footer(&mut engine, width, height, &user_input, "Initializing...", footer_bg, 0);
engine.request_update();
engine.end_frame();
// Event Loop
let target_frame_time = Duration::from_micros(16_666); // ~60 FPS
let mut last_tick = Instant::now();
let mut status_line = String::from("Starting...");
while engine.is_running() {
let now = Instant::now();
let time_since_tick = now.duration_since(last_tick);
// If we missed the window, poll immediately (timeout 0)
let timeout = target_frame_time.checked_sub(time_since_tick).unwrap_or(Duration::ZERO);
match engine.input_receiver().recv_timeout(timeout) {
Ok(event) => {
// --- FAST PATH: Input Event (Instant Echo) ---
match event {
InputEvent::Key { code, modifiers } => match code {
KeyCode::Esc => engine.stop(),
KeyCode::Char('c') if modifiers.control => engine.stop(),
KeyCode::Char('r') if modifiers.control => {
// Reset
stream.clear();
token_count = 0;
user_input.clear();
}
KeyCode::Char(c) => {
if !modifiers.control && !modifiers.alt {
user_input.push(c);
}
},
KeyCode::Backspace => { user_input.pop(); }
KeyCode::Enter => { user_input.clear(); },
_ => {
// Pass nav keys to widget
// Mapping simplified for demo
match code {
KeyCode::Up => stream.scroll_up(1),
KeyCode::Down => stream.scroll_down(1),
KeyCode::PageUp => stream.scroll_up(10),
KeyCode::PageDown => stream.scroll_down(10),
_ => {}
}
}
},
InputEvent::MouseScroll { delta, .. } => {
if delta > 0 { stream.scroll_up(1); }
else { stream.scroll_down(1); }
},
InputEvent::Resize { width: w, height: h } => {
width = w;
height = h;
engine.handle_resize(w, h);
let new_h = h.saturating_sub(header_height + footer_height);
stream.set_bounds(Rect::new(0, header_height, w, new_h));
}
InputEvent::Shutdown => engine.stop(),
_ => {}
}
// Redraw Footer immediately
draw_demo_footer(
&mut engine,
width,
height,
&user_input,
&status_line,
footer_bg,
frame_count
);
engine.request_update();
}
Err(RecvTimeoutError::Timeout) => {
// --- TICK PATH: Matrix Generation (60Hz) ---
last_tick = Instant::now();
let mut buffer_dirty = false;
// 1. Generate Matrix Text (Fast Path - Bypass Buffer)
let mut fast_output: Vec<u8> = Vec::with_capacity(4096);
for _ in 0..50 {
token_count += 1;
let color = rng.next_color();
stream.set_fg(color);
let c = rng.next_char();
let mut buf = [0u8; 4];
let s_char = c.encode_utf8(&mut buf);
if stream.append_fast_into(s_char, &mut fast_output) {
// All good, handled by RawOutput
} else {
// Slow path hit (wrap or scroll)
buffer_dirty = true;
}
}
if !fast_output.is_empty() {
engine.write_raw(fast_output);
}
// 2. Update Stats (Throttle)
frame_count += 1;
if frame_count % 30 == 0 {
sys.refresh_cpu();
sys.refresh_memory();
let elapsed = start_time.elapsed().as_secs_f32();
let fps = if elapsed > 0.0 { frame_count as f32 / elapsed } else { 0.0 };
let mem_mb = sys.used_memory() as f32 / 1024.0 / 1024.0;
let cpu = sys.global_cpu_info().cpu_usage();
status_line = format!(
"Chars: {token_count} | FPS: {fps:.1} | CPU: {cpu:.1}% | Mem: {mem_mb:.1}MB"
);
buffer_dirty = true;
}
// 3. Blink Cursor or Handle Slow Path redrawing
if frame_count % 15 == 0 || stream.needs_redraw() || buffer_dirty {
draw_demo_footer(
&mut engine,
width,
height,
&user_input,
&status_line,
footer_bg,
frame_count
);
if stream.needs_redraw() || frame_count % 60 == 0 {
stream.render(engine.buffer_mut());
}
engine.request_update();
}
}
Err(_) => break, // Disconnected or other error
}
}
Ok(())
}
/// Helper to draw consistent UI.
fn draw_demo_footer(
engine: &mut Engine,
width: u16,
height: u16,
user_input: &str,
status: &str,
bg: Rgb,
frame_count: u64,
) {
let y = height.saturating_sub(1);
// Clear line
for x in 0..width {
engine.set_cell(x, y, Cell::new(' ').with_bg(bg));
}
// Input left
engine.draw_text(2, y, "> ", Rgb::new(0, 255, 255), bg);
engine.draw_text(4, y, user_input, Rgb::WHITE, bg);
// Cursor
let input_len = u16::try_from(user_input.len()).unwrap_or(0);
let cx = 4 + input_len;
if cx < width && (frame_count % 30 < 15 || input_len > 0) {
// Blink except when typing
engine.set_cell(cx, y, Cell::new('█').with_fg(Rgb::new(0, 255, 255)).with_bg(bg));
}
// Status right
if !status.is_empty() {
let status_len = u16::try_from(status.len()).unwrap_or(0);
let stat_x = width.saturating_sub(status_len + 2);
if stat_x > cx + 2 {
engine.draw_text(stat_x, y, status, Rgb::new(150, 150, 150), bg);
}
}
}
</file>
<file path="include/flywheel.h">
/**
* @file flywheel.h
* @brief Flywheel - Zero-flicker terminal compositor for Agentic CLIs
*
* This header provides the C API for Flywheel, enabling high-frequency
* token streaming (100+ tokens/s) without flickering.
*
* @version 0.1.0
* @date 2026-01-29
*/
#ifndef FLYWHEEL_H
#define FLYWHEEL_H
#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
#ifdef __cplusplus
extern "C" {
#endif
/* Version information */
#define FLYWHEEL_VERSION "0.1.0"
#define FLYWHEEL_VERSION_MAJOR 0
#define FLYWHEEL_VERSION_MINOR 1
#define FLYWHEEL_VERSION_PATCH 0
/* ============================================================================
* Opaque Handle Types
* ============================================================================ */
/** Opaque handle to a Flywheel engine. */
typedef struct FlywheelEngine FlywheelEngine;
/** Opaque handle to a stream widget. */
typedef struct FlywheelStream FlywheelStream;
/* ============================================================================
* Enums and Constants
* ============================================================================ */
/** Result codes for FFI functions. */
typedef enum FlywheelResult {
FLYWHEEL_RESULT_OK = 0,
FLYWHEEL_RESULT_NULL_POINTER = 1,
FLYWHEEL_RESULT_INVALID_UTF8 = 2,
FLYWHEEL_RESULT_IO_ERROR = 3,
FLYWHEEL_RESULT_OUT_OF_BOUNDS = 4,
FLYWHEEL_RESULT_NOT_RUNNING = 5,
} FlywheelResult;
/** Input event type from polling. */
typedef enum FlywheelEventType {
FLYWHEEL_EVENT_NONE = 0,
FLYWHEEL_EVENT_KEY = 1,
FLYWHEEL_EVENT_RESIZE = 2,
FLYWHEEL_EVENT_ERROR = 3,
FLYWHEEL_EVENT_SHUTDOWN = 4,
} FlywheelEventType;
/* Key code constants */
#define FLYWHEEL_KEY_NONE 0
#define FLYWHEEL_KEY_ENTER 1
#define FLYWHEEL_KEY_ESCAPE 2
#define FLYWHEEL_KEY_BACKSPACE 3
#define FLYWHEEL_KEY_TAB 4
#define FLYWHEEL_KEY_LEFT 5
#define FLYWHEEL_KEY_RIGHT 6
#define FLYWHEEL_KEY_UP 7
#define FLYWHEEL_KEY_DOWN 8
#define FLYWHEEL_KEY_HOME 9
#define FLYWHEEL_KEY_END 10
#define FLYWHEEL_KEY_PAGE_UP 11
#define FLYWHEEL_KEY_PAGE_DOWN 12
#define FLYWHEEL_KEY_DELETE 13
/* Modifier flags */
#define FLYWHEEL_MOD_SHIFT 1
#define FLYWHEEL_MOD_CTRL 2
#define FLYWHEEL_MOD_ALT 4
#define FLYWHEEL_MOD_SUPER 8
/* ============================================================================
* Event Structures
* ============================================================================ */
/** Key event data. */
typedef struct FlywheelKeyEvent {
uint32_t char_code; /**< Character code (for printable keys), or 0. */
int key_code; /**< Special key code (FLYWHEEL_KEY_*). */
unsigned int modifiers; /**< Modifier flags (FLYWHEEL_MOD_*). */
} FlywheelKeyEvent;
/** Resize event data. */
typedef struct FlywheelResizeEvent {
uint16_t width; /**< New terminal width. */
uint16_t height; /**< New terminal height. */
} FlywheelResizeEvent;
/** Polled event structure. */
typedef struct FlywheelEvent {
FlywheelEventType event_type; /**< Type of event. */
FlywheelKeyEvent key; /**< Key event data (if event_type == KEY). */
FlywheelResizeEvent resize; /**< Resize event data (if event_type == RESIZE). */
} FlywheelEvent;
/* ============================================================================
* Engine Functions
* ============================================================================ */
/**
* Create a new Flywheel engine with default configuration.
*
* The engine initializes the terminal in raw mode with alternate screen.
*
* @return Handle to the engine, or NULL on failure.
*/
FlywheelEngine* flywheel_engine_new(void);
/**
* Destroy a Flywheel engine and restore terminal state.
*
* @param engine Engine handle (NULL is a no-op).
*/
void flywheel_engine_destroy(FlywheelEngine* engine);
/**
* Get the terminal width in columns.
*
* @param engine Engine handle.
* @return Terminal width, or 0 if engine is NULL.
*/
uint16_t flywheel_engine_width(const FlywheelEngine* engine);
/**
* Get the terminal height in rows.
*
* @param engine Engine handle.
* @return Terminal height, or 0 if engine is NULL.
*/
uint16_t flywheel_engine_height(const FlywheelEngine* engine);
/**
* Check if the engine is still running.
*
* @param engine Engine handle.
* @return true if running, false otherwise.
*/
bool flywheel_engine_is_running(const FlywheelEngine* engine);
/**
* Stop the engine.
*
* @param engine Engine handle.
*/
void flywheel_engine_stop(FlywheelEngine* engine);
/**
* Poll for the next input event (non-blocking).
*
* @param engine Engine handle.
* @param event_out Pointer to event structure to populate.
* @return Event type.
*/
FlywheelEventType flywheel_engine_poll_event(const FlywheelEngine* engine, FlywheelEvent* event_out);
/**
* Handle a terminal resize event.
*
* @param engine Engine handle.
* @param width New width.
* @param height New height.
*/
void flywheel_engine_handle_resize(FlywheelEngine* engine, uint16_t width, uint16_t height);
/**
* Request a full screen redraw.
*
* @param engine Engine handle.
*/
void flywheel_engine_request_redraw(const FlywheelEngine* engine);
/**
* Request a diff-based screen update.
*
* @param engine Engine handle.
*/
void flywheel_engine_request_update(const FlywheelEngine* engine);
/**
* Begin a new frame. Call at the start of your render loop.
*
* @param engine Engine handle.
*/
void flywheel_engine_begin_frame(FlywheelEngine* engine);
/**
* End a frame and request update. Handles frame rate limiting.
*
* @param engine Engine handle.
*/
void flywheel_engine_end_frame(FlywheelEngine* engine);
/**
* Set a single cell at the given position.
*
* @param engine Engine handle.
* @param x Column (0-indexed).
* @param y Row (0-indexed).
* @param c ASCII character.
* @param fg Foreground color (0xRRGGBB).
* @param bg Background color (0xRRGGBB).
*/
void flywheel_engine_set_cell(FlywheelEngine* engine, uint16_t x, uint16_t y,
char c, uint32_t fg, uint32_t bg);
/**
* Draw text at the given position.
*
* @param engine Engine handle.
* @param x Starting column (0-indexed).
* @param y Row (0-indexed).
* @param text UTF-8 null-terminated string.
* @param fg Foreground color (0xRRGGBB).
* @param bg Background color (0xRRGGBB).
* @return Number of columns used.
*/
uint16_t flywheel_engine_draw_text(FlywheelEngine* engine, uint16_t x, uint16_t y,
const char* text, uint32_t fg, uint32_t bg);
/**
* Clear the entire buffer to default (black background, empty cells).
*
* @param engine Engine handle.
*/
void flywheel_engine_clear(FlywheelEngine* engine);
/**
* Fill a rectangle with a character.
*
* @param engine Engine handle.
* @param x Starting column.
* @param y Starting row.
* @param width Rectangle width.
* @param height Rectangle height.
* @param c Fill character.
* @param fg Foreground color.
* @param bg Background color.
*/
void flywheel_engine_fill_rect(FlywheelEngine* engine, uint16_t x, uint16_t y,
uint16_t width, uint16_t height,
char c, uint32_t fg, uint32_t bg);
/* ============================================================================
* Stream Widget Functions
* ============================================================================ */
/**
* Create a new stream widget for high-frequency text streaming.
*
* @param x Widget X position.
* @param y Widget Y position.
* @param width Widget width.
* @param height Widget height.
* @return Handle to the stream widget.
*/
FlywheelStream* flywheel_stream_new(uint16_t x, uint16_t y, uint16_t width, uint16_t height);
/**
* Destroy a stream widget.
*
* @param stream Stream widget handle (NULL is a no-op).
*/
void flywheel_stream_destroy(FlywheelStream* stream);
/**
* Append text to the stream widget.
*
* Uses fast path when possible (no newlines, fits on line).
*
* @param stream Stream widget handle.
* @param text UTF-8 null-terminated string.
* @return 1 if fast path was used, 0 if slow path, -1 on error.
*/
int flywheel_stream_append(FlywheelStream* stream, const char* text);
/**
* Render the stream widget to the engine's buffer.
*
* @param stream Stream widget handle.
* @param engine Engine handle.
*/
void flywheel_stream_render(FlywheelStream* stream, FlywheelEngine* engine);
/**
* Clear all content in the stream widget.
*
* @param stream Stream widget handle.
*/
void flywheel_stream_clear(FlywheelStream* stream);
/**
* Set the foreground color for subsequent text.
*
* @param stream Stream widget handle.
* @param color Color (0xRRGGBB).
*/
void flywheel_stream_set_fg(FlywheelStream* stream, uint32_t color);
/**
* Set the background color for subsequent text.
*
* @param stream Stream widget handle.
* @param color Color (0xRRGGBB).
*/
void flywheel_stream_set_bg(FlywheelStream* stream, uint32_t color);
/**
* Scroll the stream widget up by the given number of lines.
*
* @param stream Stream widget handle.
* @param lines Number of lines to scroll.
*/
void flywheel_stream_scroll_up(FlywheelStream* stream, size_t lines);
/**
* Scroll the stream widget down by the given number of lines.
*
* @param stream Stream widget handle.
* @param lines Number of lines to scroll.
*/
void flywheel_stream_scroll_down(FlywheelStream* stream, size_t lines);
/* ============================================================================
* Utility Functions
* ============================================================================ */
/**
* Create an RGB color value from components.
*
* @param r Red component (0-255).
* @param g Green component (0-255).
* @param b Blue component (0-255).
* @return 24-bit color value (0xRRGGBB).
*/
uint32_t flywheel_rgb(uint8_t r, uint8_t g, uint8_t b);
/**
* Get the Flywheel version string.
*
* @return Static version string (do not free).
*/
const char* flywheel_version(void);
#ifdef __cplusplus
}
#endif
#endif /* FLYWHEEL_H */
</file>
<file path="src/actor/engine.rs">
//! Engine: Main coordinator that ties actors together.
//!
//! The Engine is the entry point for applications using Flywheel.
//! It manages the terminal, spawns actors, and provides the main
//! event loop.
use super::messages::{InputEvent, RenderCommand};
use super::{InputActor, RendererActor};
use crate::buffer::{Buffer, Cell, Rgb};
use crate::layout::Rect;
use crossbeam_channel::{bounded, Receiver, Sender, TryRecvError};
use crossterm::{
cursor,
event::EnableMouseCapture,
execute,
terminal::{self, EnterAlternateScreen, LeaveAlternateScreen},
};
use std::io::{self};
use std::time::{Duration, Instant};
/// Configuration for the Engine.
#[derive(Debug, Clone)]
pub struct EngineConfig {
/// Target frames per second.
pub target_fps: u32,
/// Input poll timeout.
pub input_poll_timeout: Duration,
/// Whether to enable mouse capture.
pub enable_mouse: bool,
/// Whether to use alternate screen buffer.
pub alternate_screen: bool,
}
impl Default for EngineConfig {
fn default() -> Self {
Self {
target_fps: 60,
input_poll_timeout: Duration::from_millis(10),
enable_mouse: false,
alternate_screen: true,
}
}
}
/// The main Flywheel engine.
///
/// This coordinates between the input and render actors, providing
/// a simple interface for applications.
pub struct Engine {
/// Configuration.
config: EngineConfig,
/// Input event receiver.
input_rx: Receiver<InputEvent>,
/// Render command sender.
render_tx: Sender<RenderCommand>,
/// Input actor handle.
input_actor: Option<InputActor>,
/// Renderer actor handle.
#[allow(dead_code)]
renderer_actor: Option<RendererActor>,
/// Application buffer (for modifications).
buffer: Buffer,
/// Terminal width.
width: u16,
/// Terminal height.
height: u16,
/// Frame timing.
frame_start: Instant,
frame_duration: Duration,
frame_count: u64,
/// Whether the engine is running.
running: bool,
}
impl Engine {
/// Create a new engine with default configuration.
///
/// # Errors
///
/// Returns an error if terminal setup fails (raw mode, alternate screen, etc.).
pub fn new() -> io::Result<Self> {
Self::with_config(EngineConfig::default())
}
/// Create a new engine with custom configuration.
///
/// # Errors
///
/// Returns an error if terminal setup fails.
pub fn with_config(config: EngineConfig) -> io::Result<Self> {
// Get terminal size
let (width, height) = terminal::size()?;
// Enter raw mode and alternate screen
terminal::enable_raw_mode()?;
let mut stdout = io::stdout();
if config.alternate_screen {
execute!(stdout, EnterAlternateScreen)?;
}
if config.enable_mouse {
execute!(stdout, EnableMouseCapture)?;
}
execute!(stdout, cursor::Hide)?;
// Create channels
let (input_tx, input_rx) = bounded::<InputEvent>(64);
let (render_tx, render_rx) = bounded::<RenderCommand>(16);
// Spawn actors
let input_actor = InputActor::spawn(input_tx, config.input_poll_timeout);
let renderer_actor = RendererActor::spawn(render_rx, width, height);
let frame_duration = Duration::from_secs(1) / config.target_fps;
Ok(Self {
config,
input_rx,
render_tx,
input_actor: Some(input_actor),
renderer_actor: Some(renderer_actor),
buffer: Buffer::new(width, height),
width,
height,
frame_start: Instant::now(),
frame_duration,
frame_count: 0,
running: true,
})
}
/// Get the terminal width.
pub const fn width(&self) -> u16 {
self.width
}
/// Get the terminal height.
pub const fn height(&self) -> u16 {
self.height
}
/// Get a reference to the buffer.
pub const fn buffer(&self) -> &Buffer {
&self.buffer
}
/// Get a mutable reference to the buffer.
pub const fn buffer_mut(&mut self) -> &mut Buffer {
&mut self.buffer
}
/// Get the input receiver for event-driven loops.
pub const fn input_receiver(&self) -> &Receiver<InputEvent> {
&self.input_rx
}
/// Check if the engine is still running.
pub const fn is_running(&self) -> bool {
self.running
}
/// Stop the engine.
pub const fn stop(&mut self) {
self.running = false;
}
/// Poll for the next input event (non-blocking).
///
/// Returns `None` if no event is available.
pub fn poll_input(&self) -> Option<InputEvent> {
match self.input_rx.try_recv() {
Ok(event) => Some(event),
Err(TryRecvError::Empty) => None,
Err(TryRecvError::Disconnected) => {
Some(InputEvent::Error("Input channel disconnected".to_string()))
}
}
}
/// Wait for the next input event (blocking with timeout).
pub fn wait_input(&self, timeout: Duration) -> Option<InputEvent> {
self.input_rx.recv_timeout(timeout).ok()
}
/// Drain all pending input events.
pub fn drain_input(&self) -> Vec<InputEvent> {
let mut events = Vec::new();
while let Ok(event) = self.input_rx.try_recv() {
events.push(event);
}
events
}
/// Request a full redraw.
pub fn request_redraw(&self) {
let _ = self.render_tx.send(RenderCommand::FullRedraw(Box::new(self.buffer.clone())));
}
/// Request a diff-based update.
pub fn request_update(&self) {
let _ = self.render_tx.send(RenderCommand::Update(Box::new(self.buffer.clone())));
}
/// Set the cursor position (or hide it).
pub fn set_cursor(&self, x: Option<u16>, y: u16) {
let _ = self.render_tx.send(RenderCommand::SetCursor { x, y });
}
/// Write raw bytes to the output (Fast Path).
pub fn write_raw(&self, bytes: Vec<u8>) {
let _ = self.render_tx.send(RenderCommand::RawOutput { bytes });
}
/// Handle a resize event.
pub fn handle_resize(&mut self, width: u16, height: u16) {
self.width = width;
self.height = height;
self.buffer.resize(width, height);
let _ = self.render_tx.send(RenderCommand::Resize { width, height });
}
/// Begin a new frame.
///
/// Call this at the start of your render loop.
pub fn begin_frame(&mut self) {
self.frame_start = Instant::now();
}
/// End a frame and request update.
///
/// This will sleep if necessary to maintain the target FPS.
pub fn end_frame(&mut self) {
self.frame_count += 1;
// Request render
self.request_update();
// Frame rate limiting
let elapsed = self.frame_start.elapsed();
if elapsed < self.frame_duration {
std::thread::sleep(self.frame_duration - elapsed);
}
}
/// Get the current frame count.
pub const fn frame_count(&self) -> u64 {
self.frame_count
}
/// Convenience: Set a cell in the buffer.
pub fn set_cell(&mut self, x: u16, y: u16, cell: Cell) {
self.buffer.set(x, y, cell);
}
/// Convenience: Set a grapheme in the buffer.
pub fn set_grapheme(&mut self, x: u16, y: u16, grapheme: &str, fg: Rgb, bg: Rgb) -> u8 {
self.buffer.set_grapheme(x, y, grapheme, fg, bg)
}
/// Convenience: Clear the buffer.
pub fn clear(&mut self) {
self.buffer.clear();
}
/// Convenience: Fill a rectangle.
pub fn fill_rect(&mut self, rect: Rect, cell: Cell) {
self.buffer.fill_rect(rect.x, rect.y, rect.width, rect.height, cell);
}
/// Draw text at a position.
///
/// Returns the number of columns used.
pub fn draw_text(&mut self, x: u16, y: u16, text: &str, fg: Rgb, bg: Rgb) -> u16 {
let mut col = x;
for grapheme in unicode_segmentation::UnicodeSegmentation::graphemes(text, true) {
if col >= self.width {
break;
}
let width = self.buffer.set_grapheme(col, y, grapheme, fg, bg);
col += u16::from(width);
}
col - x
}
}
impl Drop for Engine {
fn drop(&mut self) {
// Stop actors
if let Some(actor) = self.input_actor.take() {
actor.join();
}
let _ = self.render_tx.send(RenderCommand::Shutdown);
// Restore terminal state
let mut stdout = io::stdout();
let _ = execute!(stdout, cursor::Show);
if self.config.enable_mouse {
let _ = execute!(stdout, crossterm::event::DisableMouseCapture);
}
if self.config.alternate_screen {
let _ = execute!(stdout, LeaveAlternateScreen);
}
let _ = terminal::disable_raw_mode();
}
}
</file>
<file path="src/actor/input.rs">
//! Input Actor: Dedicated thread for polling terminal events.
//!
//! This actor runs in its own thread and uses crossterm's event polling
//! to capture keyboard, mouse, and resize events without blocking the
//! main application.
use super::messages::{InputEvent, KeyCode, KeyModifiers, MouseButton, MouseEvent};
use crossbeam_channel::Sender;
use crossterm::event::{self, Event, KeyEventKind};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::thread::{self, JoinHandle};
use std::time::Duration;
/// Input actor that polls terminal events.
pub struct InputActor {
/// Handle to the input thread.
handle: Option<JoinHandle<()>>,
/// Flag to signal shutdown.
shutdown: Arc<AtomicBool>,
}
impl InputActor {
/// Spawn the input actor thread.
///
/// # Arguments
///
/// * `sender` - Channel to send input events to the main loop.
/// * `poll_timeout` - How long to wait for events before checking shutdown.
///
/// # Returns
///
/// The input actor handle.
#[allow(clippy::missing_panics_doc)]
pub fn spawn(sender: Sender<InputEvent>, poll_timeout: Duration) -> Self {
let shutdown = Arc::new(AtomicBool::new(false));
let shutdown_clone = shutdown.clone();
let handle = thread::Builder::new()
.name("flywheel-input".to_string())
.spawn(move || {
Self::run_loop(&sender, &shutdown_clone, poll_timeout);
})
.expect("Failed to spawn input thread");
Self {
handle: Some(handle),
shutdown,
}
}
/// Signal the input thread to shutdown.
pub fn shutdown(&self) {
self.shutdown.store(true, Ordering::Relaxed);
}
/// Wait for the input thread to finish.
pub fn join(mut self) {
self.shutdown();
if let Some(handle) = self.handle.take() {
let _ = handle.join();
}
}
/// Main input polling loop.
#[allow(clippy::collapsible_if)]
fn run_loop(sender: &Sender<InputEvent>, shutdown: &Arc<AtomicBool>, poll_timeout: Duration) {
loop {
// Check for shutdown
if shutdown.load(Ordering::Relaxed) {
let _ = sender.send(InputEvent::Shutdown);
break;
}
// Poll for events with timeout
match event::poll(poll_timeout) {
Ok(true) => {
// Event available, read it
match event::read() {
Ok(event) => {
if let Some(input_event) = Self::convert_event(event) {
if sender.send(input_event).is_err() {
// Receiver dropped, exit
break;
}
}
}
Err(e) => {
let _ = sender.send(InputEvent::Error(e.to_string()));
}
}
}
Ok(false) => {
// No event, continue loop (will check shutdown)
}
Err(e) => {
let _ = sender.send(InputEvent::Error(e.to_string()));
}
}
}
}
/// Convert a crossterm event to our `InputEvent`.
fn convert_event(event: Event) -> Option<InputEvent> {
match event {
Event::Key(key_event) => {
// Only process key press events (not release or repeat)
if key_event.kind != KeyEventKind::Press {
return None;
}
let code = Self::convert_key_code(key_event.code)?;
let modifiers = Self::convert_modifiers(key_event.modifiers);
Some(InputEvent::Key { code, modifiers })
}
Event::Mouse(mouse_event) => Self::convert_mouse_event(mouse_event),
Event::Resize(width, height) => Some(InputEvent::Resize { width, height }),
Event::FocusGained => Some(InputEvent::FocusGained),
Event::FocusLost => Some(InputEvent::FocusLost),
Event::Paste(text) => Some(InputEvent::Paste(text)),
}
}
/// Convert crossterm `KeyCode` to our `KeyCode`.
const fn convert_key_code(code: event::KeyCode) -> Option<KeyCode> {
Some(match code {
event::KeyCode::Char(c) => KeyCode::Char(c),
event::KeyCode::F(n) => KeyCode::F(n),
event::KeyCode::Backspace => KeyCode::Backspace,
event::KeyCode::Enter => KeyCode::Enter,
event::KeyCode::Left => KeyCode::Left,
event::KeyCode::Right => KeyCode::Right,
event::KeyCode::Up => KeyCode::Up,
event::KeyCode::Down => KeyCode::Down,
event::KeyCode::Home => KeyCode::Home,
event::KeyCode::End => KeyCode::End,
event::KeyCode::PageUp => KeyCode::PageUp,
event::KeyCode::PageDown => KeyCode::PageDown,
event::KeyCode::Tab => KeyCode::Tab,
event::KeyCode::BackTab => KeyCode::BackTab,
event::KeyCode::Delete => KeyCode::Delete,
event::KeyCode::Insert => KeyCode::Insert,
event::KeyCode::Esc => KeyCode::Esc,
event::KeyCode::Null => KeyCode::Null,
_ => return None, // Ignore other key codes
})
}
/// Convert crossterm `KeyModifiers` to our `KeyModifiers`.
const fn convert_modifiers(mods: event::KeyModifiers) -> KeyModifiers {
KeyModifiers {
shift: mods.contains(event::KeyModifiers::SHIFT),
control: mods.contains(event::KeyModifiers::CONTROL),
alt: mods.contains(event::KeyModifiers::ALT),
super_key: mods.contains(event::KeyModifiers::SUPER),
}
}
/// Convert crossterm `MouseEvent` to our `InputEvent`.
const fn convert_mouse_event(mouse: event::MouseEvent) -> Option<InputEvent> {
let modifiers = Self::convert_modifiers(mouse.modifiers);
match mouse.kind {
event::MouseEventKind::Down(button) => {
let button = Self::convert_mouse_button(button);
Some(InputEvent::MouseDown(MouseEvent {
x: mouse.column,
y: mouse.row,
button: Some(button),
modifiers,
}))
}
event::MouseEventKind::Up(button) => {
let button = Self::convert_mouse_button(button);
Some(InputEvent::MouseUp(MouseEvent {
x: mouse.column,
y: mouse.row,
button: Some(button),
modifiers,
}))
}
event::MouseEventKind::Moved => Some(InputEvent::MouseMove(MouseEvent {
x: mouse.column,
y: mouse.row,
button: None,
modifiers,
})),
event::MouseEventKind::Drag(button) => {
let button = Self::convert_mouse_button(button);
Some(InputEvent::MouseMove(MouseEvent {
x: mouse.column,
y: mouse.row,
button: Some(button),
modifiers,
}))
}
event::MouseEventKind::ScrollUp => Some(InputEvent::MouseScroll {
x: mouse.column,
y: mouse.row,
delta: 1,
}),
event::MouseEventKind::ScrollDown => Some(InputEvent::MouseScroll {
x: mouse.column,
y: mouse.row,
delta: -1,
}),
_ => None,
}
}
/// Convert crossterm `MouseButton` to our `MouseButton`.
const fn convert_mouse_button(button: event::MouseButton) -> MouseButton {
match button {
event::MouseButton::Left => MouseButton::Left,
event::MouseButton::Right => MouseButton::Right,
event::MouseButton::Middle => MouseButton::Middle,
}
}
}
impl Drop for InputActor {
fn drop(&mut self) {
self.shutdown();
}
}
</file>
<file path="src/actor/messages.rs">
//! Message types for actor communication.
//!
//! These enums define the protocol between actors in the system.
use std::time::Instant;
use crate::buffer::Buffer;
/// Key codes for keyboard input.
///
/// This is a simplified subset of crossterm's `KeyCode`, designed
/// for the needs of agentic CLIs.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum KeyCode {
/// A printable character.
Char(char),
/// Function key (F1-F12).
F(u8),
/// Backspace key.
Backspace,
/// Enter/Return key.
Enter,
/// Left arrow.
Left,
/// Right arrow.
Right,
/// Up arrow.
Up,
/// Down arrow.
Down,
/// Home key.
Home,
/// End key.
End,
/// Page Up.
PageUp,
/// Page Down.
PageDown,
/// Tab key.
Tab,
/// Backtab (Shift+Tab).
BackTab,
/// Delete key.
Delete,
/// Insert key.
Insert,
/// Escape key.
Esc,
/// Null (Ctrl+Space on some terminals).
Null,
}
/// Key modifiers.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
#[allow(clippy::struct_excessive_bools)]
pub struct KeyModifiers {
/// Shift key held.
pub shift: bool,
/// Control key held.
pub control: bool,
/// Alt/Option key held.
pub alt: bool,
/// Super/Command/Windows key held.
pub super_key: bool,
}
impl KeyModifiers {
/// No modifiers.
pub const NONE: Self = Self {
shift: false,
control: false,
alt: false,
super_key: false,
};
/// Check if any modifier is active.
pub const fn any(&self) -> bool {
self.shift || self.control || self.alt || self.super_key
}
}
/// Mouse button.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum MouseButton {
/// Left mouse button.
Left,
/// Right mouse button.
Right,
/// Middle mouse button.
Middle,
}
/// Mouse event details.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct MouseEvent {
/// X coordinate (column).
pub x: u16,
/// Y coordinate (row).
pub y: u16,
/// Mouse button involved (if any).
pub button: Option<MouseButton>,
/// Key modifiers held during mouse event.
pub modifiers: KeyModifiers,
}
/// Events from the input thread.
///
/// These are sent from the input actor to the main loop.
#[derive(Debug, Clone)]
pub enum InputEvent {
/// A key was pressed.
Key {
/// The key code.
code: KeyCode,
/// Modifiers held during keypress.
modifiers: KeyModifiers,
},
/// Mouse button pressed.
MouseDown(MouseEvent),
/// Mouse button released.
MouseUp(MouseEvent),
/// Mouse moved (only if tracking enabled).
MouseMove(MouseEvent),
/// Mouse scroll.
MouseScroll {
/// X coordinate.
x: u16,
/// Y coordinate.
y: u16,
/// Scroll delta (positive = up, negative = down).
delta: i16,
},
/// Terminal was resized.
Resize {
/// New width in columns.
width: u16,
/// New height in rows.
height: u16,
},
/// Focus gained.
FocusGained,
/// Focus lost.
FocusLost,
/// Paste event (bracketed paste).
Paste(String),
/// Input thread encountered an error.
Error(String),
/// Input thread is shutting down.
Shutdown,
}
/// Commands sent to the render thread.
#[derive(Debug)]
pub enum RenderCommand {
/// Request a full redraw with new buffer content.
FullRedraw(Box<Buffer>),
/// Request a diff-based update.
/// Request a diff-based update with new buffer content.
Update(Box<Buffer>),
/// Resize the buffers.
Resize {
/// New width.
width: u16,
/// New height.
height: u16,
},
/// Set the cursor position and visibility.
SetCursor {
/// X position (None = hide cursor).
x: Option<u16>,
/// Y position.
y: u16,
},
/// Write raw bytes directly to the terminal output.
///
/// This is used for the "Fast Path" optimization: directly writing generated
/// ANSI sequences without going through the diffing engine.
///
/// **Warning**: The caller is responsible for ensuring these bytes do not
/// corrupt the terminal state or contradict the buffer state.
RawOutput {
/// The raw bytes to write.
bytes: Vec<u8>,
},
/// Shutdown the render thread.
Shutdown,
}
/// Events from agent/network threads.
///
/// These represent async data arriving from external sources.
#[derive(Debug, Clone)]
pub enum AgentEvent {
/// Token(s) received from agent stream.
Tokens {
/// The text content.
content: String,
/// Source identifier (for multi-agent scenarios).
source_id: u32,
/// Whether this is the final chunk.
is_final: bool,
},
/// Agent started a new response.
ResponseStart {
/// Source identifier.
source_id: u32,
},
/// Agent finished responding.
ResponseEnd {
/// Source identifier.
source_id: u32,
},
/// Agent encountered an error.
Error {
/// Error message.
message: String,
/// Source identifier.
source_id: u32,
},
/// Connection status changed.
ConnectionStatus {
/// Whether connected.
connected: bool,
/// Source identifier.
source_id: u32,
},
}
/// Frame timing information.
#[derive(Debug, Clone)]
#[allow(dead_code)]
pub struct FrameInfo {
/// Frame number since engine start.
pub frame_number: u64,
/// Time when this frame started.
pub frame_start: Instant,
/// Duration of the previous frame's render.
pub last_render_time: std::time::Duration,
/// Current FPS (smoothed).
pub fps: f32,
}
impl Default for FrameInfo {
fn default() -> Self {
Self {
frame_number: 0,
frame_start: Instant::now(),
last_render_time: std::time::Duration::ZERO,
fps: 0.0,
}
}
}
</file>
<file path="src/actor/mod.rs">
//! Actor Model: Message-passing concurrency for the TUI engine.
//!
//! This module implements a simple actor system using crossbeam channels:
//! - **Input Actor**: Polls terminal events, forwards to main loop
//! - **Render Actor**: Receives render commands, diffs and flushes
//! - **Main Loop**: Coordinates between actors, handles application logic
//!
//! # Architecture
//!
//! ```text
//! ┌──────────────┐ InputEvent ┌──────────────┐
//! │ Input Thread │ ─────────────────▶ │ │
//! └──────────────┘ │ Main Loop │
//! │ │
//! ┌──────────────┐ RenderCommand │ │
//! │Render Thread │ ◀───────────────── │ │
//! └──────────────┘ └──────────────┘
//! │
//! │ AgentEvent
//! ▼
//! ┌──────────────┐
//! │ Agent/Network│
//! └──────────────┘
//! ```
mod messages;
mod input;
mod renderer;
mod engine;
pub use messages::{InputEvent, RenderCommand, AgentEvent, KeyCode, KeyModifiers, MouseButton, MouseEvent};
pub use input::InputActor;
pub use renderer::RendererActor;
pub use engine::{Engine, EngineConfig};
</file>
<file path="src/actor/renderer.rs">
//! Renderer Actor: Dedicated thread for rendering to the terminal.
//!
//! This actor owns the terminal and double buffers. It receives render
//! commands from the main loop and performs the actual diffing and
//! output flushing.
use super::messages::RenderCommand;
use crate::buffer::diff::{render_diff, render_full, DiffState};
use crate::buffer::Buffer;
use crate::layout::Rect;
use crossbeam_channel::Receiver;
use std::io::{self, Stdout, Write};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;
use std::thread::{self, JoinHandle};
use std::time::{Duration, Instant};
/// Renderer actor that handles terminal output.
pub struct RendererActor {
/// Handle to the render thread.
handle: Option<JoinHandle<()>>,
/// Flag to signal shutdown.
shutdown: Arc<AtomicBool>,
}
/// Render statistics for debugging/profiling.
#[derive(Debug, Clone, Default)]
pub struct RenderStats {
/// Total frames rendered.
pub frames: u64,
/// Total cells changed across all frames.
#[allow(dead_code)]
pub cells_changed: u64,
/// Total bytes written to terminal.
pub bytes_written: u64,
/// Average render time in microseconds.
pub avg_render_us: u64,
/// Last render time in microseconds.
pub last_render_us: u64,
}
/// Internal renderer state.
struct Renderer {
/// Current (visible) buffer.
current: Buffer,
/// Next (being drawn) buffer.
next: Buffer,
/// Diff state for cursor/color tracking.
diff_state: DiffState,
/// Pre-allocated output buffer.
output: Vec<u8>,
/// Terminal stdout handle.
stdout: Stdout,
/// Render statistics.
stats: RenderStats,
/// Dirty rectangles for next render.
dirty_rects: Vec<Rect>,
/// Whether a full redraw is needed.
needs_full_redraw: bool,
/// Cursor position (None = hidden).
cursor_x: Option<u16>,
cursor_y: u16,
}
impl Renderer {
/// Create a new renderer with the given dimensions.
fn new(width: u16, height: u16) -> Self {
let current = Buffer::new(width, height);
let next = Buffer::new(width, height);
Self {
current,
next,
diff_state: DiffState::new(),
output: Vec::with_capacity(65536),
stdout: io::stdout(),
stats: RenderStats::default(),
dirty_rects: Vec::new(),
needs_full_redraw: true,
cursor_x: None,
cursor_y: 0,
}
}
/// Get a mutable reference to the next buffer.
#[allow(dead_code)]
pub const fn buffer_mut(&mut self) -> &mut Buffer {
&mut self.next
}
/// Mark the entire screen as dirty.
const fn mark_full_dirty(&mut self) {
self.needs_full_redraw = true;
}
/// Add a dirty rectangle.
#[allow(dead_code)]
fn mark_dirty(&mut self, rect: Rect) {
self.dirty_rects.push(rect);
}
/// Perform a render cycle.
fn render(&mut self) -> io::Result<()> {
let start = Instant::now();
self.output.clear();
if self.needs_full_redraw {
// Full redraw
render_full(&self.next, &mut self.output);
self.needs_full_redraw = false;
self.diff_state.reset();
} else {
// Diff-based update
let _result = render_diff(
&self.current,
&self.next,
&self.dirty_rects,
&mut self.output,
&mut self.diff_state,
);
}
self.dirty_rects.clear();
// Handle cursor position
if let Some(x) = self.cursor_x {
// Show cursor at position
let _ = write!(
&mut self.output,
"\x1b[{};{}H\x1b[?25h",
self.cursor_y + 1,
x + 1
);
} else {
// Hide cursor
self.output.extend_from_slice(b"\x1b[?25l");
}
// Flush to terminal in a single write
if !self.output.is_empty() {
self.stdout.write_all(&self.output)?;
self.stdout.flush()?;
}
// Swap buffers
self.current.copy_from(&self.next);
// Update stats
let elapsed = start.elapsed();
self.stats.frames += 1;
self.stats.bytes_written += self.output.len() as u64;
self.stats.last_render_us = u64::try_from(elapsed.as_micros()).unwrap_or(u64::MAX);
// Smoothed average
if self.stats.avg_render_us == 0 {
self.stats.avg_render_us = self.stats.last_render_us;
} else {
self.stats.avg_render_us =
(self.stats.avg_render_us * 15 + self.stats.last_render_us) / 16;
}
Ok(())
}
/// Write raw bytes directly to the terminal.
fn write_raw(&mut self, bytes: &[u8]) -> io::Result<()> {
self.stdout.write_all(bytes)?;
self.stdout.flush()?;
self.stats.bytes_written += bytes.len() as u64;
// Invalidate ALL state (cursor, colors) since raw writes change them
self.diff_state.reset();
Ok(())
}
/// Resize buffers.
fn resize(&mut self, width: u16, height: u16) {
self.current.resize(width, height);
self.next.resize(width, height);
self.mark_full_dirty();
}
/// Set cursor position.
const fn set_cursor(&mut self, x: Option<u16>, y: u16) {
self.cursor_x = x;
self.cursor_y = y;
}
}
impl RendererActor {
/// Spawn the renderer actor thread.
///
/// # Arguments
///
/// * `receiver` - Channel to receive render commands from.
/// * `width` - Initial terminal width.
/// * `height` - Initial terminal height.
///
/// # Returns
///
/// The renderer actor handle.
#[allow(clippy::missing_panics_doc)]
pub fn spawn(receiver: Receiver<RenderCommand>, width: u16, height: u16) -> Self {
let shutdown = Arc::new(AtomicBool::new(false));
let shutdown_clone = shutdown.clone();
let handle = thread::Builder::new()
.name("flywheel-render".to_string())
.spawn(move || {
if let Err(e) = Self::run_loop(&receiver, &shutdown_clone, width, height) {
eprintln!("Render thread error: {e}");
}
})
.expect("Failed to spawn render thread");
Self {
handle: Some(handle),
shutdown,
}
}
/// Signal the render thread to shutdown.
pub fn shutdown(&self) {
self.shutdown.store(true, Ordering::Relaxed);
}
/// Wait for the render thread to finish.
pub fn join(mut self) {
if let Some(handle) = self.handle.take() {
let _ = handle.join();
}
}
/// Main render loop.
fn run_loop(
receiver: &Receiver<RenderCommand>,
shutdown: &Arc<AtomicBool>,
width: u16,
height: u16,
) -> io::Result<()> {
let mut renderer = Renderer::new(width, height);
loop {
// Check for shutdown
if shutdown.load(Ordering::Relaxed) {
break;
}
// Wait for command with timeout
if let Ok(command) = receiver.recv_timeout(Duration::from_millis(16)) {
match command {
RenderCommand::FullRedraw(buffer) => {
renderer.next = *buffer;
renderer.mark_full_dirty();
renderer.render()?;
}
RenderCommand::Update(buffer) => {
renderer.next = *buffer;
renderer.render()?;
}
RenderCommand::Resize { width, height } => {
renderer.resize(width, height);
}
RenderCommand::SetCursor { x, y } => {
renderer.set_cursor(x, y);
}
RenderCommand::RawOutput { bytes } => {
renderer.write_raw(&bytes)?;
}
RenderCommand::Shutdown => {
break;
}
}
} else {
// Timeout: loop again to check shutdown or run idle tasks
// (e.g. continuous animation if we had it, but here just wait)
}
}
Ok(())
}
}
</file>
<file path="src/buffer/buffer.rs">
//! Buffer: A grid of cells representing the terminal screen.
//!
//! The buffer uses contiguous memory allocation for cache efficiency.
//! Cells are stored in row-major order.
use super::cell::{Cell, CellFlags, Rgb};
use std::collections::HashMap;
/// A grid of cells representing the terminal screen.
///
/// The buffer stores cells in a contiguous `Vec` for cache efficiency.
/// Access is in row-major order: `index = y * width + x`.
///
/// # Overflow Storage
///
/// Complex graphemes (> 4 bytes) are stored in a separate `HashMap`.
/// The cell contains an index into this overflow storage when the
/// `OVERFLOW` flag is set.
#[derive(Clone)]
pub struct Buffer {
/// Contiguous cell storage (row-major order).
cells: Vec<Cell>,
/// Terminal width in columns.
width: u16,
/// Terminal height in rows.
height: u16,
/// Overflow storage for complex graphemes.
overflow: HashMap<u32, String>,
/// Next overflow index to assign.
next_overflow_index: u32,
}
impl Buffer {
/// Create a new buffer with the given dimensions.
///
/// All cells are initialized to empty (space with default colors).
///
/// # Panics
/// Panics if width or height is 0.
pub fn new(width: u16, height: u16) -> Self {
assert!(width > 0 && height > 0, "Buffer dimensions must be non-zero");
let size = (width as usize) * (height as usize);
Self {
cells: vec![Cell::EMPTY; size],
width,
height,
overflow: HashMap::new(),
next_overflow_index: 0,
}
}
/// Get the buffer width.
#[inline]
pub const fn width(&self) -> u16 {
self.width
}
/// Get the buffer height.
#[inline]
pub const fn height(&self) -> u16 {
self.height
}
/// Get the total number of cells.
#[inline]
pub const fn len(&self) -> usize {
self.cells.len()
}
/// Check if the buffer is empty (should never be true after construction).
#[inline]
pub const fn is_empty(&self) -> bool {
self.cells.is_empty()
}
/// Get a reference to the underlying cell slice.
#[inline]
pub fn cells(&self) -> &[Cell] {
&self.cells
}
/// Get a mutable reference to the underlying cell slice.
#[inline]
pub fn cells_mut(&mut self) -> &mut [Cell] {
&mut self.cells
}
/// Convert (x, y) coordinates to a linear index.
///
/// Returns `None` if coordinates are out of bounds.
#[inline]
pub const fn index_of(&self, x: u16, y: u16) -> Option<usize> {
if x < self.width && y < self.height {
Some((y as usize) * (self.width as usize) + (x as usize))
} else {
None
}
}
/// Convert a linear index to (x, y) coordinates.
#[inline]
#[allow(clippy::cast_possible_truncation)]
pub const fn coords_of(&self, index: usize) -> Option<(u16, u16)> {
if index < self.cells.len() {
let x = (index % (self.width as usize)) as u16;
let y = (index / (self.width as usize)) as u16;
Some((x, y))
} else {
None
}
}
/// Get a reference to a cell at (x, y).
///
/// Returns `None` if coordinates are out of bounds.
#[inline]
pub fn get(&self, x: u16, y: u16) -> Option<&Cell> {
self.index_of(x, y).map(|i| &self.cells[i])
}
/// Get a mutable reference to a cell at (x, y).
///
/// Returns `None` if coordinates are out of bounds.
#[inline]
pub fn get_mut(&mut self, x: u16, y: u16) -> Option<&mut Cell> {
self.index_of(x, y).map(|i| &mut self.cells[i])
}
/// Set a cell at (x, y).
///
/// Returns `false` if coordinates are out of bounds.
#[inline]
pub fn set(&mut self, x: u16, y: u16, cell: Cell) -> bool {
if let Some(idx) = self.index_of(x, y) {
self.cells[idx] = cell;
true
} else {
false
}
}
/// Set a grapheme at (x, y), handling overflow automatically.
///
/// For wide characters (CJK), this also sets a continuation cell
/// at (x+1, y).
///
/// Returns the display width of the grapheme, or 0 if out of bounds.
pub fn set_grapheme(&mut self, x: u16, y: u16, grapheme: &str, fg: Rgb, bg: Rgb) -> u8 {
let Some(idx) = self.index_of(x, y) else {
return 0;
};
let width = u8::try_from(unicode_width::UnicodeWidthStr::width(grapheme)).unwrap_or(1);
// Try to create an inline cell
let cell = if let Some(mut cell) = Cell::from_grapheme(grapheme) {
cell.set_fg(fg).set_bg(bg);
cell
} else {
// Overflow: store in HashMap
let overflow_idx = self.next_overflow_index;
self.next_overflow_index += 1;
self.overflow.insert(overflow_idx, grapheme.to_string());
Cell::overflow(overflow_idx, width).with_fg(fg).with_bg(bg)
};
self.cells[idx] = cell;
// Handle wide characters (CJK)
if width == 2
&& let Some(next_idx) = self.index_of(x + 1, y) {
self.cells[next_idx] = Cell::wide_continuation().with_bg(bg);
}
width
}
/// Get the grapheme at (x, y), including overflow lookup.
///
/// Returns `None` if out of bounds or if it's a continuation cell.
pub fn get_grapheme(&self, x: u16, y: u16) -> Option<&str> {
let cell = self.get(x, y)?;
if cell.is_wide_continuation() {
return None;
}
if cell.flags().contains(CellFlags::OVERFLOW) {
let idx = cell.overflow_index()?;
self.overflow.get(&idx).map(String::as_str)
} else {
cell.grapheme()
}
}
/// Get an overflow grapheme by its index.
///
/// This is used by the diffing engine when rendering overflow cells.
#[inline]
pub fn get_overflow(&self, index: u32) -> Option<&str> {
self.overflow.get(&index).map(String::as_str)
}
/// Fill a rectangular region with a cell.
pub fn fill_rect(&mut self, x: u16, y: u16, width: u16, height: u16, cell: Cell) {
for row in y..(y + height).min(self.height) {
for col in x..(x + width).min(self.width) {
if let Some(idx) = self.index_of(col, row) {
self.cells[idx] = cell;
}
}
}
}
/// Clear the entire buffer (fill with empty cells).
pub fn clear(&mut self) {
self.cells.fill(Cell::EMPTY);
self.overflow.clear();
self.next_overflow_index = 0;
}
/// Clear a rectangular region.
pub fn clear_rect(&mut self, x: u16, y: u16, width: u16, height: u16) {
self.fill_rect(x, y, width, height, Cell::EMPTY);
}
/// Resize the buffer, preserving content where possible.
///
/// New cells are initialized to empty.
pub fn resize(&mut self, new_width: u16, new_height: u16) {
if new_width == self.width && new_height == self.height {
return;
}
let new_size = (new_width as usize) * (new_height as usize);
let mut new_cells = vec![Cell::EMPTY; new_size];
// Copy existing content
let copy_width = self.width.min(new_width) as usize;
let copy_height = self.height.min(new_height) as usize;
for y in 0..copy_height {
let old_start = y * (self.width as usize);
let new_start = y * (new_width as usize);
new_cells[new_start..new_start + copy_width]
.copy_from_slice(&self.cells[old_start..old_start + copy_width]);
}
self.cells = new_cells;
self.width = new_width;
self.height = new_height;
}
/// Copy content from another buffer.
///
/// The buffers must have the same dimensions.
pub fn copy_from(&mut self, other: &Self) {
debug_assert_eq!(self.width, other.width);
debug_assert_eq!(self.height, other.height);
self.cells.copy_from_slice(&other.cells);
self.overflow.clone_from(&other.overflow);
self.next_overflow_index = other.next_overflow_index;
}
/// Swap the contents of two buffers.
///
/// This is O(1) - just pointer swaps.
pub const fn swap(&mut self, other: &mut Self) {
std::mem::swap(&mut self.cells, &mut other.cells);
std::mem::swap(&mut self.width, &mut other.width);
std::mem::swap(&mut self.height, &mut other.height);
std::mem::swap(&mut self.overflow, &mut other.overflow);
std::mem::swap(&mut self.next_overflow_index, &mut other.next_overflow_index);
}
/// Get an iterator over rows.
pub fn rows(&self) -> impl Iterator<Item = &[Cell]> {
self.cells.chunks(self.width as usize)
}
/// Get a mutable iterator over rows.
pub fn rows_mut(&mut self) -> impl Iterator<Item = &mut [Cell]> {
self.cells.chunks_mut(self.width as usize)
}
/// Get memory usage in bytes (approximate).
pub fn memory_usage(&self) -> usize {
let cells_size = self.cells.len() * std::mem::size_of::<Cell>();
let overflow_size: usize = self.overflow.values().map(|s| s.len() + 32).sum();
cells_size + overflow_size + std::mem::size_of::<Self>()
}
}
impl std::fmt::Debug for Buffer {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
f.debug_struct("Buffer")
.field("width", &self.width)
.field("height", &self.height)
.field("overflow_count", &self.overflow.len())
.field("memory_bytes", &self.memory_usage())
.finish_non_exhaustive()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_buffer_new() {
let buffer = Buffer::new(80, 24);
assert_eq!(buffer.width(), 80);
assert_eq!(buffer.height(), 24);
assert_eq!(buffer.len(), 80 * 24);
}
#[test]
#[should_panic]
fn test_buffer_zero_width() {
Buffer::new(0, 24);
}
#[test]
fn test_buffer_get_set() {
let mut buffer = Buffer::new(80, 24);
let cell = Cell::new('X');
assert!(buffer.set(5, 10, cell));
assert_eq!(buffer.get(5, 10).unwrap().grapheme(), Some("X"));
}
#[test]
fn test_buffer_bounds() {
let buffer = Buffer::new(80, 24);
assert!(buffer.get(79, 23).is_some());
assert!(buffer.get(80, 23).is_none());
assert!(buffer.get(79, 24).is_none());
}
#[test]
fn test_buffer_index_coords() {
let buffer = Buffer::new(80, 24);
assert_eq!(buffer.index_of(5, 10), Some(10 * 80 + 5));
assert_eq!(buffer.coords_of(10 * 80 + 5), Some((5, 10)));
}
#[test]
fn test_buffer_set_grapheme() {
let mut buffer = Buffer::new(80, 24);
// ASCII
let width = buffer.set_grapheme(0, 0, "A", Rgb::WHITE, Rgb::BLACK);
assert_eq!(width, 1);
assert_eq!(buffer.get_grapheme(0, 0), Some("A"));
// CJK (wide character)
let width = buffer.set_grapheme(5, 0, "日", Rgb::WHITE, Rgb::BLACK);
assert_eq!(width, 2);
assert_eq!(buffer.get_grapheme(5, 0), Some("日"));
// Continuation cell should return None
assert!(buffer.get(6, 0).unwrap().is_wide_continuation());
}
#[test]
fn test_buffer_overflow() {
let mut buffer = Buffer::new(80, 24);
// Complex emoji (> 4 bytes UTF-8)
let emoji = "👨👩👧👦";
let width = buffer.set_grapheme(0, 0, emoji, Rgb::WHITE, Rgb::BLACK);
assert!(width > 0);
assert!(buffer.get(0, 0).unwrap().is_overflow());
assert_eq!(buffer.get_grapheme(0, 0), Some(emoji));
}
#[test]
fn test_buffer_fill_rect() {
let mut buffer = Buffer::new(80, 24);
let cell = Cell::new('X');
buffer.fill_rect(10, 5, 3, 2, cell);
assert_eq!(buffer.get(10, 5).unwrap().grapheme(), Some("X"));
assert_eq!(buffer.get(11, 5).unwrap().grapheme(), Some("X"));
assert_eq!(buffer.get(12, 5).unwrap().grapheme(), Some("X"));
assert_eq!(buffer.get(10, 6).unwrap().grapheme(), Some("X"));
assert_eq!(buffer.get(9, 5).unwrap().grapheme(), Some(" ")); // Outside rect
}
#[test]
fn test_buffer_clear() {
let mut buffer = Buffer::new(80, 24);
buffer.set(5, 5, Cell::new('X'));
buffer.clear();
assert_eq!(buffer.get(5, 5), Some(&Cell::EMPTY));
}
#[test]
fn test_buffer_resize() {
let mut buffer = Buffer::new(80, 24);
buffer.set(5, 5, Cell::new('X'));
buffer.resize(100, 30);
assert_eq!(buffer.width(), 100);
assert_eq!(buffer.height(), 30);
assert_eq!(buffer.get(5, 5).unwrap().grapheme(), Some("X")); // Preserved
buffer.resize(10, 10);
assert_eq!(buffer.get(5, 5).unwrap().grapheme(), Some("X")); // Still preserved
assert!(buffer.get(15, 15).is_none()); // Out of bounds now
}
#[test]
fn test_buffer_swap() {
let mut a = Buffer::new(80, 24);
let mut b = Buffer::new(80, 24);
a.set(0, 0, Cell::new('A'));
b.set(0, 0, Cell::new('B'));
a.swap(&mut b);
assert_eq!(a.get(0, 0).unwrap().grapheme(), Some("B"));
assert_eq!(b.get(0, 0).unwrap().grapheme(), Some("A"));
}
#[test]
fn test_buffer_memory_usage() {
let buffer = Buffer::new(200, 50);
let usage = buffer.memory_usage();
// 200 * 50 * 16 = 160,000 bytes for cells, plus overhead
assert!(usage >= 160_000);
assert!(usage < 200_000); // Shouldn't be too much more
}
}
</file>
<file path="src/buffer/cell.rs">
//! Cell: The atomic unit of terminal display.
//!
//! # Memory Layout
//!
//! The `Cell` struct is carefully designed for cache efficiency:
//! - 16 bytes total, allowing 4 cells per cache line (64 bytes)
//! - Inline grapheme storage covers 99%+ of real-world characters
//! - Complex graphemes (emoji ZWJ sequences) spill to an external `HashMap`
//!
//! ```text
//! ┌───────────────────────────────────────────────────────────────────────────┐
//! │ Cell Layout (16 bytes) │
//! ├─────────────┬─────────────┬───────────┬───────────┬─────┬───────┬─────────┤
//! │ grapheme │ len + width│ fg │ bg │ mod │ flags │ padding │
//! │ [u8; 4] │ u8 + u8 │ [u8; 3] │ [u8; 3] │ u8 │ u8 │ [u8; 2] │
//! │ 4 bytes │ 2 bytes │ 3 bytes │ 3 bytes │ 1b │ 1b │ 2 b │
//! └─────────────┴─────────────┴───────────┴───────────┴─────┴───────┴─────────┘
//! ```
use bitflags::bitflags;
use std::hash::{Hash, Hasher};
/// True-color RGB representation.
///
/// Uses 3 bytes for 24-bit color depth, supporting 16.7 million colors.
/// This is essential for precise brand colors in commercial applications.
#[repr(C)]
#[derive(Clone, Copy, PartialEq, Eq, Default, Hash)]
pub struct Rgb {
/// Red channel (0-255)
pub r: u8,
/// Green channel (0-255)
pub g: u8,
/// Blue channel (0-255)
pub b: u8,
}
impl Rgb {
/// Create a new RGB color.
#[inline]
pub const fn new(r: u8, g: u8, b: u8) -> Self {
Self { r, g, b }
}
/// Black (0, 0, 0)
pub const BLACK: Self = Self::new(0, 0, 0);
/// White (255, 255, 255)
pub const WHITE: Self = Self::new(255, 255, 255);
/// Default foreground (white)
pub const DEFAULT_FG: Self = Self::WHITE;
/// Default background (black)
pub const DEFAULT_BG: Self = Self::BLACK;
/// Create from a 24-bit hex color (e.g., 0xFF5500).
#[inline]
pub const fn from_u32(hex: u32) -> Self {
Self::new(
((hex >> 16) & 0xFF) as u8,
((hex >> 8) & 0xFF) as u8,
(hex & 0xFF) as u8,
)
}
}
impl std::fmt::Debug for Rgb {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "#{:02x}{:02x}{:02x}", self.r, self.g, self.b)
}
}
impl From<(u8, u8, u8)> for Rgb {
#[inline]
fn from((r, g, b): (u8, u8, u8)) -> Self {
Self::new(r, g, b)
}
}
impl From<u32> for Rgb {
/// Convert from a 24-bit hex color (e.g., 0xFF5500)
#[inline]
fn from(hex: u32) -> Self {
Self::new(
((hex >> 16) & 0xFF) as u8,
((hex >> 8) & 0xFF) as u8,
(hex & 0xFF) as u8,
)
}
}
bitflags! {
/// Text style modifiers.
///
/// These can be combined using bitwise OR.
///
/// # Example
/// ```
/// use flywheel::Modifiers;
/// let style = Modifiers::BOLD | Modifiers::ITALIC;
/// ```
#[derive(Clone, Copy, PartialEq, Eq, Hash, Default)]
pub struct Modifiers: u8 {
/// Bold text
const BOLD = 0b0000_0001;
/// Dim/faint text
const DIM = 0b0000_0010;
/// Italic text
const ITALIC = 0b0000_0100;
/// Underlined text
const UNDERLINE = 0b0000_1000;
/// Blinking text
const BLINK = 0b0001_0000;
/// Reversed colors (fg/bg swapped)
const REVERSED = 0b0010_0000;
/// Hidden/invisible text
const HIDDEN = 0b0100_0000;
/// Strikethrough text
const STRIKETHROUGH = 0b1000_0000;
}
}
impl std::fmt::Debug for Modifiers {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
bitflags::parser::to_writer(self, f)
}
}
bitflags! {
/// Cell-level flags for special states.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Default)]
pub struct CellFlags: u8 {
/// Grapheme overflows inline storage; check overflow HashMap
const OVERFLOW = 0b0000_0001;
/// Cell has been modified since last render
const DIRTY = 0b0000_0010;
/// This cell is a continuation of a wide character
const WIDE_CONTINUATION = 0b0000_0100;
}
}
impl std::fmt::Debug for CellFlags {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
bitflags::parser::to_writer(self, f)
}
}
/// A single terminal cell.
///
/// This is the atomic unit of display in Flywheel. Each cell contains:
/// - A grapheme (the character to display)
/// - Foreground and background colors
/// - Text modifiers (bold, italic, etc.)
///
/// # Memory Layout
///
/// The struct is carefully laid out to be exactly 16 bytes:
/// - 4 bytes for inline grapheme storage
/// - 2 bytes for grapheme metadata (length + display width)
/// - 6 bytes for colors (3 bytes fg + 3 bytes bg)
/// - 1 byte for modifiers
/// - 1 byte for flags
/// - 2 bytes padding (power-of-2 alignment)
///
/// # Grapheme Handling
///
/// Most characters (ASCII, Latin, CJK) fit within the 4-byte inline storage.
/// For complex graphemes like emoji ZWJ sequences (👨👩👧👦), we set the
/// `OVERFLOW` flag and store an index in the grapheme bytes that points
/// to an external overflow storage.
#[repr(C)]
#[derive(Clone, Copy)]
pub struct Cell {
/// Inline grapheme storage (UTF-8 bytes).
/// For overflowed graphemes, this contains a u32 index.
grapheme: [u8; 4],
/// Actual byte length of the grapheme (0-4, or 0 if overflowed).
grapheme_len: u8,
/// Display width of the grapheme (0=continuation, 1=normal, 2=wide CJK).
display_width: u8,
/// Foreground color.
fg: Rgb,
/// Background color.
bg: Rgb,
/// Text modifiers (bold, italic, etc.).
modifiers: Modifiers,
/// Cell flags (overflow, dirty, etc.).
flags: CellFlags,
/// Padding to reach 16 bytes (power of 2, cache-friendly).
_padding: [u8; 2],
}
// Compile-time assertion: Cell must be exactly 16 bytes
const _: () = assert!(
std::mem::size_of::<Cell>() == 16,
"Cell must be exactly 16 bytes for cache efficiency"
);
impl Default for Cell {
fn default() -> Self {
Self::EMPTY
}
}
impl Cell {
/// An empty cell (space character with default colors).
pub const EMPTY: Self = Self {
grapheme: [b' ', 0, 0, 0],
grapheme_len: 1,
display_width: 1,
fg: Rgb::DEFAULT_FG,
bg: Rgb::DEFAULT_BG,
modifiers: Modifiers::empty(),
flags: CellFlags::empty(),
_padding: [0, 0],
};
/// Create a new cell with a single ASCII character.
///
/// # Panics
/// Panics if the character is not ASCII.
#[inline]
pub fn new(c: char) -> Self {
debug_assert!(c.is_ascii(), "Use Cell::from_char for non-ASCII");
Self {
grapheme: [c as u8, 0, 0, 0],
grapheme_len: 1,
display_width: 1,
fg: Rgb::DEFAULT_FG,
bg: Rgb::DEFAULT_BG,
modifiers: Modifiers::empty(),
flags: CellFlags::empty(),
_padding: [0, 0],
}
}
/// Create a cell from any character.
///
/// Returns `None` if the character's UTF-8 encoding exceeds 4 bytes
/// (which never happens for a single `char`, but may happen for
/// grapheme clusters when using `from_grapheme`).
#[inline]
#[allow(clippy::missing_panics_doc)]
pub fn from_char(c: char) -> Self {
let mut grapheme = [0u8; 4];
let s = c.encode_utf8(&mut grapheme);
let len = u8::try_from(s.len()).unwrap();
let width = u8::try_from(unicode_width::UnicodeWidthChar::width(c).unwrap_or(0)).unwrap();
Self {
grapheme,
grapheme_len: len,
display_width: width,
fg: Rgb::DEFAULT_FG,
bg: Rgb::DEFAULT_BG,
modifiers: Modifiers::empty(),
flags: CellFlags::empty(),
_padding: [0, 0],
}
}
/// Create a cell from a grapheme string.
///
/// If the grapheme fits in 4 bytes, it's stored inline.
/// Otherwise, returns `None` and the caller should use overflow storage.
#[inline]
#[allow(clippy::missing_panics_doc)]
pub fn from_grapheme(s: &str) -> Option<Self> {
let bytes = s.as_bytes();
if bytes.len() > 4 {
// Caller needs to handle overflow
return None;
}
let mut grapheme = [0u8; 4];
grapheme[..bytes.len()].copy_from_slice(bytes);
let width = u8::try_from(unicode_width::UnicodeWidthStr::width(s)).unwrap_or(1);
Some(Self {
grapheme,
grapheme_len: u8::try_from(bytes.len()).unwrap(),
display_width: width,
fg: Rgb::DEFAULT_FG,
bg: Rgb::DEFAULT_BG,
modifiers: Modifiers::empty(),
flags: CellFlags::empty(),
_padding: [0, 0],
})
}
/// Create an overflow cell with an index to external storage.
///
/// The index is stored in the grapheme bytes as a little-endian u32.
#[inline]
pub const fn overflow(index: u32, display_width: u8) -> Self {
Self {
grapheme: index.to_le_bytes(),
grapheme_len: 0, // Indicates overflow
display_width,
fg: Rgb::DEFAULT_FG,
bg: Rgb::DEFAULT_BG,
modifiers: Modifiers::empty(),
flags: CellFlags::OVERFLOW,
_padding: [0, 0],
}
}
/// Create a wide-character continuation cell.
///
/// This is placed after a wide CJK character that takes 2 columns.
#[inline]
pub const fn wide_continuation() -> Self {
Self {
grapheme: [0, 0, 0, 0],
grapheme_len: 0,
display_width: 0,
fg: Rgb::DEFAULT_FG,
bg: Rgb::DEFAULT_BG,
modifiers: Modifiers::empty(),
flags: CellFlags::WIDE_CONTINUATION,
_padding: [0, 0],
}
}
/// Get the grapheme as a string slice.
///
/// Returns `None` if this is an overflow cell (caller should check `is_overflow()`
/// and look up the grapheme in the overflow storage).
#[inline]
#[allow(unsafe_code)]
pub fn grapheme(&self) -> Option<&str> {
if self.flags.contains(CellFlags::OVERFLOW) {
return None;
}
// SAFETY: We only store valid UTF-8 in the grapheme bytes
Some(unsafe {
std::str::from_utf8_unchecked(&self.grapheme[..self.grapheme_len as usize])
})
}
/// Get the overflow index if this is an overflow cell.
#[inline]
pub const fn overflow_index(&self) -> Option<u32> {
if self.flags.contains(CellFlags::OVERFLOW) {
Some(u32::from_le_bytes(self.grapheme))
} else {
None
}
}
/// Check if this cell uses overflow storage.
#[inline]
pub const fn is_overflow(&self) -> bool {
self.flags.contains(CellFlags::OVERFLOW)
}
/// Check if this is a wide-character continuation.
#[inline]
pub const fn is_wide_continuation(&self) -> bool {
self.flags.contains(CellFlags::WIDE_CONTINUATION)
}
/// Get the display width (0, 1, or 2).
#[inline]
pub const fn display_width(&self) -> u8 {
self.display_width
}
/// Get the foreground color.
#[inline]
pub const fn fg(&self) -> Rgb {
self.fg
}
/// Get the background color.
#[inline]
pub const fn bg(&self) -> Rgb {
self.bg
}
/// Get the modifiers.
#[inline]
pub const fn modifiers(&self) -> Modifiers {
self.modifiers
}
/// Get the flags.
#[inline]
pub const fn flags(&self) -> CellFlags {
self.flags
}
/// Set the foreground color.
#[inline]
pub const fn set_fg(&mut self, fg: Rgb) -> &mut Self {
self.fg = fg;
self
}
/// Set the background color.
#[inline]
pub const fn set_bg(&mut self, bg: Rgb) -> &mut Self {
self.bg = bg;
self
}
/// Set the modifiers.
#[inline]
pub const fn set_modifiers(&mut self, modifiers: Modifiers) -> &mut Self {
self.modifiers = modifiers;
self
}
/// Set the foreground color (builder pattern).
#[inline]
#[must_use]
pub const fn with_fg(mut self, fg: Rgb) -> Self {
self.fg = fg;
self
}
/// Set the background color (builder pattern).
#[inline]
#[must_use]
pub const fn with_bg(mut self, bg: Rgb) -> Self {
self.bg = bg;
self
}
/// Set the modifiers (builder pattern).
#[inline]
#[must_use]
pub const fn with_modifiers(mut self, modifiers: Modifiers) -> Self {
self.modifiers = modifiers;
self
}
/// Reset the cell to empty (space with default colors).
#[inline]
pub const fn reset(&mut self) {
*self = Self::EMPTY;
}
}
impl PartialEq for Cell {
/// Optimized equality check.
///
/// We compare in order of most likely difference:
/// 1. Grapheme bytes (most frequently changing)
/// 2. Colors (next most common)
/// 3. Modifiers and flags (rarely differ)
#[inline]
fn eq(&self, other: &Self) -> bool {
// Fast path: compare grapheme first (most likely to differ)
self.grapheme == other.grapheme
&& self.grapheme_len == other.grapheme_len
&& self.fg == other.fg
&& self.bg == other.bg
&& self.modifiers == other.modifiers
&& self.flags == other.flags
&& self.display_width == other.display_width
}
}
impl Eq for Cell {}
impl Hash for Cell {
fn hash<H: Hasher>(&self, state: &mut H) {
self.grapheme.hash(state);
self.grapheme_len.hash(state);
self.display_width.hash(state);
self.fg.hash(state);
self.bg.hash(state);
self.modifiers.hash(state);
self.flags.hash(state);
}
}
impl std::fmt::Debug for Cell {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let grapheme = self.grapheme().unwrap_or("<overflow>");
f.debug_struct("Cell")
.field("grapheme", &grapheme)
.field("width", &self.display_width)
.field("fg", &self.fg)
.field("bg", &self.bg)
.field("modifiers", &self.modifiers)
.field("flags", &self.flags)
.finish_non_exhaustive()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_cell_size() {
assert_eq!(std::mem::size_of::<Cell>(), 16);
}
#[test]
fn test_rgb_from_tuple() {
let rgb: Rgb = (255, 128, 0).into();
assert_eq!(rgb.r, 255);
assert_eq!(rgb.g, 128);
assert_eq!(rgb.b, 0);
}
#[test]
fn test_rgb_from_hex() {
let rgb: Rgb = 0xFF8000.into();
assert_eq!(rgb.r, 255);
assert_eq!(rgb.g, 128);
assert_eq!(rgb.b, 0);
}
#[test]
fn test_cell_new_ascii() {
let cell = Cell::new('A');
assert_eq!(cell.grapheme(), Some("A"));
assert_eq!(cell.display_width(), 1);
}
#[test]
fn test_cell_from_char_unicode() {
let cell = Cell::from_char('日');
assert_eq!(cell.grapheme(), Some("日"));
assert_eq!(cell.display_width(), 2); // CJK is double-width
}
#[test]
fn test_cell_from_grapheme_fits() {
let cell = Cell::from_grapheme("é").unwrap();
assert_eq!(cell.grapheme(), Some("é"));
assert_eq!(cell.display_width(), 1);
}
#[test]
fn test_cell_from_grapheme_overflow() {
// This emoji ZWJ sequence is > 4 bytes
let result = Cell::from_grapheme("👨👩👧");
assert!(result.is_none());
}
#[test]
fn test_cell_overflow() {
let cell = Cell::overflow(42, 2);
assert!(cell.is_overflow());
assert_eq!(cell.overflow_index(), Some(42));
assert_eq!(cell.grapheme(), None);
}
#[test]
fn test_cell_equality() {
let a = Cell::new('A').with_fg(Rgb::new(255, 0, 0));
let b = Cell::new('A').with_fg(Rgb::new(255, 0, 0));
let c = Cell::new('A').with_fg(Rgb::new(0, 255, 0));
assert_eq!(a, b);
assert_ne!(a, c);
}
#[test]
fn test_cell_builder_pattern() {
let cell = Cell::new('X')
.with_fg(Rgb::new(255, 0, 0))
.with_bg(Rgb::new(0, 0, 255))
.with_modifiers(Modifiers::BOLD | Modifiers::ITALIC);
assert_eq!(cell.fg(), Rgb::new(255, 0, 0));
assert_eq!(cell.bg(), Rgb::new(0, 0, 255));
assert!(cell.modifiers().contains(Modifiers::BOLD));
assert!(cell.modifiers().contains(Modifiers::ITALIC));
}
#[test]
fn test_modifiers_bitflags() {
let mods = Modifiers::BOLD | Modifiers::UNDERLINE;
assert!(mods.contains(Modifiers::BOLD));
assert!(mods.contains(Modifiers::UNDERLINE));
assert!(!mods.contains(Modifiers::ITALIC));
}
#[test]
fn test_cell_reset() {
let mut cell = Cell::new('X').with_fg(Rgb::new(255, 0, 0));
cell.reset();
assert_eq!(cell, Cell::EMPTY);
}
#[test]
fn test_wide_continuation() {
let cont = Cell::wide_continuation();
assert!(cont.is_wide_continuation());
assert_eq!(cont.display_width(), 0);
}
}
</file>
<file path="src/buffer/diff.rs">
//! Diffing Engine: Generate minimal ANSI sequences from buffer changes.
//!
//! This module implements the core anti-flicker logic:
//! 1. Compare Current and Next buffers
//! 2. Generate minimal ANSI escape sequences for changed cells
//! 3. Optimize cursor movements (skip if adjacent)
//! 4. Track color state to avoid redundant SGR sequences
//!
//! All output is accumulated in a single buffer and flushed with one syscall.
use super::{Buffer, Cell, CellFlags, Modifiers, Rgb};
use crate::layout::Rect;
use std::io::Write;
/// State tracker for the diffing algorithm.
///
/// This tracks the "current" terminal state (cursor position, colors, modifiers)
/// to minimize the number of escape sequences we need to emit.
#[derive(Debug, Clone)]
pub struct DiffState {
/// Last known cursor X position (0-indexed).
cursor_x: u16,
/// Last known cursor Y position (0-indexed).
cursor_y: u16,
/// Last emitted foreground color.
fg: Option<Rgb>,
/// Last emitted background color.
bg: Option<Rgb>,
/// Last emitted modifiers.
modifiers: Option<Modifiers>,
}
impl Default for DiffState {
fn default() -> Self {
Self::new()
}
}
impl DiffState {
/// Create a new diff state with unknown terminal state.
pub const fn new() -> Self {
Self {
cursor_x: 0,
cursor_y: 0,
fg: None,
bg: None,
modifiers: None,
}
}
/// Reset the state (e.g., after a full screen clear).
pub const fn reset(&mut self) {
self.fg = None;
self.bg = None;
self.modifiers = None;
// Force cursor move on next write
self.cursor_x = u16::MAX;
self.cursor_y = u16::MAX;
}
}
/// Result of a diff operation.
#[derive(Debug, Clone, Default)]
pub struct DiffResult {
/// Number of cells that were different.
pub cells_changed: usize,
/// Number of cursor move sequences emitted.
pub cursor_moves: usize,
/// Number of color change sequences emitted.
pub color_changes: usize,
/// Number of modifier change sequences emitted.
pub modifier_changes: usize,
}
/// Render the difference between two buffers into an ANSI sequence buffer.
///
/// This is the core diffing function. It compares `current` and `next` buffers,
/// generating minimal ANSI escape sequences for only the cells that changed.
///
/// # Optimizations
///
/// 1. **Cursor movement**: Skips explicit moves when writing adjacent cells
/// 2. **Color tracking**: Only emits color changes when fg/bg actually differ
/// 3. **Modifier tracking**: Only emits modifier changes when needed
/// 4. **Dirty rectangles**: Only iterates over specified dirty regions
///
/// # Arguments
///
/// * `current` - The currently displayed buffer
/// * `next` - The buffer to transition to
/// * `dirty_rects` - Regions to check for changes (empty = full buffer)
/// * `output` - Buffer to write ANSI sequences to
/// * `state` - Mutable state tracking cursor/color positions
///
/// # Returns
///
/// Statistics about the diff operation.
pub fn render_diff(
current: &Buffer,
next: &Buffer,
dirty_rects: &[Rect],
output: &mut Vec<u8>,
state: &mut DiffState,
) -> DiffResult {
debug_assert_eq!(current.width(), next.width());
debug_assert_eq!(current.height(), next.height());
let mut result = DiffResult::default();
let width = current.width();
let height = current.height();
// If no dirty rects specified, diff the entire buffer
let full_rect = Rect::from_size(width, height);
let rects: &[Rect] = if dirty_rects.is_empty() {
std::slice::from_ref(&full_rect)
} else {
dirty_rects
};
for rect in rects {
diff_rect(current, next, *rect, output, state, &mut result);
}
result
}
/// Diff a single rectangular region.
fn diff_rect(
current: &Buffer,
next: &Buffer,
rect: Rect,
output: &mut Vec<u8>,
state: &mut DiffState,
result: &mut DiffResult,
) {
let width = current.width();
// Clamp rect to buffer bounds
let x_end = (rect.x + rect.width).min(width);
let y_end = (rect.y + rect.height).min(current.height());
for y in rect.y..y_end {
for x in rect.x..x_end {
let idx = (y as usize) * (width as usize) + (x as usize);
let current_cell = ¤t.cells()[idx];
let next_cell = &next.cells()[idx];
// Skip if cells are identical
if current_cell == next_cell {
continue;
}
// Skip wide-character continuation cells (handled by the main cell)
if next_cell.is_wide_continuation() {
continue;
}
result.cells_changed += 1;
// Emit cursor move if not adjacent to last position
if state.cursor_y != y || state.cursor_x != x {
emit_cursor_move(output, x, y);
state.cursor_x = x;
state.cursor_y = y;
result.cursor_moves += 1;
}
// Handle modifier resets first
// If we need to disable any modifiers, we must emit a full reset (\x1b[0m)
// which also clears colors.
let next_mods = next_cell.modifiers();
let current_mods = state.modifiers.unwrap_or(Modifiers::empty());
let removed_mods = current_mods.difference(next_mods);
if !removed_mods.is_empty() {
output.extend_from_slice(b"\x1b[0m");
state.fg = None;
state.bg = None;
state.modifiers = None;
}
// Emit color changes if needed
if state.fg != Some(next_cell.fg()) {
emit_fg_color(output, next_cell.fg());
state.fg = Some(next_cell.fg());
result.color_changes += 1;
}
if state.bg != Some(next_cell.bg()) {
emit_bg_color(output, next_cell.bg());
state.bg = Some(next_cell.bg());
result.color_changes += 1;
}
// Emit modifier additions if needed
if state.modifiers != Some(next_mods) {
// Logic here only handles additions because we already handled removals
// (if any removal occurred, we reset state.modifiers to None)
emit_modifiers(output, next_mods, state.modifiers);
state.modifiers = Some(next_mods);
result.modifier_changes += 1;
}
// Emit the grapheme
emit_grapheme(output, next_cell, next);
// Update cursor position (advances by display width)
let advance = u16::from(next_cell.display_width().max(1));
state.cursor_x += advance;
}
}
}
/// Emit a cursor move sequence.
///
/// Uses the most compact representation:
/// - `\x1b[H` for home (1,1)
/// - `\x1b[{row};{col}H` for absolute positioning
#[inline]
fn emit_cursor_move(output: &mut Vec<u8>, x: u16, y: u16) {
// ANSI uses 1-indexed positions
let row = y + 1;
let col = x + 1;
if row == 1 && col == 1 {
output.extend_from_slice(b"\x1b[H");
} else if col == 1 {
// Move to column 1 of row N
let _ = write!(output, "\x1b[{row}H");
} else {
let _ = write!(output, "\x1b[{row};{col}H");
}
}
/// Emit a foreground color sequence (true color).
#[inline]
fn emit_fg_color(output: &mut Vec<u8>, color: Rgb) {
let _ = write!(output, "\x1b[38;2;{};{};{}m", color.r, color.g, color.b);
}
/// Emit a background color sequence (true color).
#[inline]
fn emit_bg_color(output: &mut Vec<u8>, color: Rgb) {
let _ = write!(output, "\x1b[48;2;{};{};{}m", color.r, color.g, color.b);
}
/// Emit modifier change sequences.
///
/// This handles the transition from one set of modifiers to another,
/// emitting reset + set sequences as needed.
fn emit_modifiers(output: &mut Vec<u8>, new: Modifiers, old: Option<Modifiers>) {
let old = old.unwrap_or(Modifiers::empty());
// If we're removing modifiers, we need to reset first
let removed = old.difference(new);
if removed.is_empty() {
// Only adding modifiers, no need to reset
let added = new.difference(old);
emit_modifier_set(output, added);
} else {
// Reset all attributes, then re-apply what we want
output.extend_from_slice(b"\x1b[0m");
// Note: After reset, colors are also reset, so caller should
// re-emit colors. For now, we emit all new modifiers.
emit_modifier_set(output, new);
}
}
/// Emit SGR sequences for a set of modifiers.
fn emit_modifier_set(output: &mut Vec<u8>, modifiers: Modifiers) {
if modifiers.contains(Modifiers::BOLD) {
output.extend_from_slice(b"\x1b[1m");
}
if modifiers.contains(Modifiers::DIM) {
output.extend_from_slice(b"\x1b[2m");
}
if modifiers.contains(Modifiers::ITALIC) {
output.extend_from_slice(b"\x1b[3m");
}
if modifiers.contains(Modifiers::UNDERLINE) {
output.extend_from_slice(b"\x1b[4m");
}
if modifiers.contains(Modifiers::BLINK) {
output.extend_from_slice(b"\x1b[5m");
}
if modifiers.contains(Modifiers::REVERSED) {
output.extend_from_slice(b"\x1b[7m");
}
if modifiers.contains(Modifiers::HIDDEN) {
output.extend_from_slice(b"\x1b[8m");
}
if modifiers.contains(Modifiers::STRIKETHROUGH) {
output.extend_from_slice(b"\x1b[9m");
}
}
/// Emit a grapheme to the output buffer.
#[inline]
fn emit_grapheme(output: &mut Vec<u8>, cell: &Cell, buffer: &Buffer) {
if cell.flags().contains(CellFlags::OVERFLOW) {
// Look up in overflow storage
if let Some(idx) = cell.overflow_index()
&& let Some(grapheme) = buffer.get_overflow(idx) {
output.extend_from_slice(grapheme.as_bytes());
return;
}
// Fallback: emit a replacement character
output.extend_from_slice("�".as_bytes());
} else if let Some(grapheme) = cell.grapheme() {
output.extend_from_slice(grapheme.as_bytes());
} else {
// Empty cell, emit space
output.push(b' ');
}
}
/// Perform a full buffer diff (convenience function).
///
/// This diffs the entire buffer without dirty rect optimization.
pub fn render_full_diff(
current: &Buffer,
next: &Buffer,
output: &mut Vec<u8>,
state: &mut DiffState,
) -> DiffResult {
render_diff(current, next, &[], output, state)
}
/// Generate a full redraw sequence (no diffing).
///
/// This is used for initial render or when the terminal state is unknown.
pub fn render_full(buffer: &Buffer, output: &mut Vec<u8>) {
let width = buffer.width();
let height = buffer.height();
// Hide cursor during redraw
output.extend_from_slice(b"\x1b[?25l");
// Move to home
output.extend_from_slice(b"\x1b[H");
let mut last_fg: Option<Rgb> = None;
let mut last_bg: Option<Rgb> = None;
let mut last_mods: Option<Modifiers> = None;
for y in 0..height {
if y > 0 {
// Move to start of next line
output.extend_from_slice(b"\r\n");
}
for x in 0..width {
let idx = (y as usize) * (width as usize) + (x as usize);
let cell = &buffer.cells()[idx];
// Skip continuation cells
if cell.is_wide_continuation() {
continue;
}
// Emit colors if changed
if last_fg != Some(cell.fg()) {
emit_fg_color(output, cell.fg());
last_fg = Some(cell.fg());
}
if last_bg != Some(cell.bg()) {
emit_bg_color(output, cell.bg());
last_bg = Some(cell.bg());
}
if last_mods != Some(cell.modifiers()) {
emit_modifiers(output, cell.modifiers(), last_mods);
last_mods = Some(cell.modifiers());
}
emit_grapheme(output, cell, buffer);
}
}
// Reset attributes and show cursor
output.extend_from_slice(b"\x1b[0m\x1b[?25h");
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_diff_identical_buffers() {
let a = Buffer::new(10, 5);
let b = Buffer::new(10, 5);
let mut output = Vec::new();
let mut state = DiffState::new();
let result = render_full_diff(&a, &b, &mut output, &mut state);
assert_eq!(result.cells_changed, 0);
assert!(output.is_empty());
}
#[test]
fn test_diff_single_cell_change() {
let a = Buffer::new(10, 5);
let mut b = Buffer::new(10, 5);
b.set(5, 2, Cell::new('X'));
let mut output = Vec::new();
let mut state = DiffState::new();
let result = render_full_diff(&a, &b, &mut output, &mut state);
assert_eq!(result.cells_changed, 1);
assert!(!output.is_empty());
// Should contain cursor move and the character
let output_str = String::from_utf8_lossy(&output);
assert!(output_str.contains('X'));
}
#[test]
fn test_diff_adjacent_cells_no_cursor_move() {
let a = Buffer::new(10, 5);
let mut b = Buffer::new(10, 5);
// Three adjacent cells on same row
b.set(0, 0, Cell::new('A'));
b.set(1, 0, Cell::new('B'));
b.set(2, 0, Cell::new('C'));
let mut output = Vec::new();
let mut state = DiffState::new();
let result = render_full_diff(&a, &b, &mut output, &mut state);
assert_eq!(result.cells_changed, 3);
// No cursor moves needed: cursor starts at (0,0) and cells are adjacent
assert_eq!(result.cursor_moves, 0);
}
#[test]
fn test_diff_color_tracking() {
let a = Buffer::new(10, 5);
let mut b = Buffer::new(10, 5);
let red = Rgb::new(255, 0, 0);
// Both cells have same fg color, but will also emit bg color first time
b.set(0, 0, Cell::new('A').with_fg(red));
b.set(1, 0, Cell::new('B').with_fg(red)); // Same colors, no additional changes
let mut output = Vec::new();
let mut state = DiffState::new();
let result = render_full_diff(&a, &b, &mut output, &mut state);
// Two color changes for first cell (fg and bg), none for second (same colors)
assert_eq!(result.color_changes, 2);
}
#[test]
fn test_diff_dirty_rect() {
let a = Buffer::new(20, 10);
let mut b = Buffer::new(20, 10);
// Changes outside dirty rect
b.set(0, 0, Cell::new('X'));
// Changes inside dirty rect
b.set(10, 5, Cell::new('Y'));
let mut output = Vec::new();
let mut state = DiffState::new();
// Only diff a region that includes (10,5) but not (0,0)
let dirty = vec![Rect::new(8, 4, 5, 3)];
let result = render_diff(&a, &b, &dirty, &mut output, &mut state);
// Should only detect the change at (10,5)
assert_eq!(result.cells_changed, 1);
}
#[test]
fn test_cursor_move_optimization() {
let mut output = Vec::new();
// Home position uses short sequence
emit_cursor_move(&mut output, 0, 0);
assert_eq!(&output, b"\x1b[H");
output.clear();
// Column 1 uses shorter sequence
emit_cursor_move(&mut output, 0, 5);
assert_eq!(&output, b"\x1b[6H"); // Row 6 (1-indexed)
output.clear();
// General position
emit_cursor_move(&mut output, 10, 5);
assert_eq!(&output, b"\x1b[6;11H"); // Row 6, Col 11 (1-indexed)
}
#[test]
fn test_render_full() {
let mut buffer = Buffer::new(3, 2);
buffer.set(0, 0, Cell::new('A'));
buffer.set(1, 0, Cell::new('B'));
buffer.set(2, 0, Cell::new('C'));
let mut output = Vec::new();
render_full(&buffer, &mut output);
let output_str = String::from_utf8_lossy(&output);
// Should start with hide cursor and home
assert!(output_str.starts_with("\x1b[?25l\x1b[H"));
// Should contain all characters
assert!(output_str.contains('A'));
assert!(output_str.contains('B'));
assert!(output_str.contains('C'));
// Should end with reset and show cursor
assert!(output_str.ends_with("\x1b[0m\x1b[?25h"));
}
}
</file>
<file path="src/buffer/mod.rs">
//! Buffer module: Core data structures for the double-buffer rendering system.
//!
//! This module contains:
//! - [`Cell`]: The atomic unit of display, optimized for cache efficiency
//! - [`Buffer`]: A grid of cells representing the terminal screen
//! - [`Rgb`]: True-color representation
//! - [`Modifiers`]: Text style bitflags
//! - [`diff`]: Diffing engine for generating minimal ANSI sequences
mod cell;
#[allow(clippy::module_inception)]
mod buffer;
pub mod diff;
pub use cell::{Cell, CellFlags, Modifiers, Rgb};
pub use buffer::Buffer;
</file>
<file path="src/layout/mod.rs">
//! Layout module: Pre-computed static regions for efficient rendering.
//!
//! Layouts are computed once at initialization or on terminal resize.
//! There is no tree traversal at render time - just a flat Vec<Region>.
mod rect;
mod region;
pub use rect::Rect;
pub use region::{Layout, Region, RegionId};
</file>
<file path="src/layout/rect.rs">
//! Rect: A rectangle primitive for layout calculations.
/// A rectangle defined by position and size.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Default)]
pub struct Rect {
/// X coordinate (column) of the top-left corner.
pub x: u16,
/// Y coordinate (row) of the top-left corner.
pub y: u16,
/// Width in columns.
pub width: u16,
/// Height in rows.
pub height: u16,
}
impl Rect {
/// Create a new rectangle.
#[inline]
pub const fn new(x: u16, y: u16, width: u16, height: u16) -> Self {
Self { x, y, width, height }
}
/// Create a rectangle from a terminal size (full screen).
#[inline]
pub const fn from_size(width: u16, height: u16) -> Self {
Self::new(0, 0, width, height)
}
/// Zero-sized rectangle.
pub const ZERO: Self = Self::new(0, 0, 0, 0);
/// Get the area (number of cells).
#[inline]
pub const fn area(&self) -> u32 {
(self.width as u32) * (self.height as u32)
}
/// Check if the rectangle is empty.
#[inline]
pub const fn is_empty(&self) -> bool {
self.width == 0 || self.height == 0
}
/// Get the right edge (exclusive).
#[inline]
pub const fn right(&self) -> u16 {
self.x.saturating_add(self.width)
}
/// Get the bottom edge (exclusive).
#[inline]
pub const fn bottom(&self) -> u16 {
self.y.saturating_add(self.height)
}
/// Check if a point is inside the rectangle.
#[inline]
pub const fn contains(&self, x: u16, y: u16) -> bool {
x >= self.x && x < self.right() && y >= self.y && y < self.bottom()
}
/// Check if this rectangle intersects with another.
#[inline]
pub const fn intersects(&self, other: &Self) -> bool {
self.x < other.right()
&& self.right() > other.x
&& self.y < other.bottom()
&& self.bottom() > other.y
}
/// Shrink the rectangle by a margin on all sides.
#[inline]
#[must_use]
pub const fn shrink(&self, margin: u16) -> Self {
let m2 = margin * 2;
if self.width <= m2 || self.height <= m2 {
return Self::ZERO;
}
Self::new(self.x + margin, self.y + margin, self.width - m2, self.height - m2)
}
/// Split horizontally at a given column offset.
pub fn split_horizontal(&self, at: u16) -> (Self, Self) {
let at = at.min(self.width);
(
Self::new(self.x, self.y, at, self.height),
Self::new(self.x + at, self.y, self.width - at, self.height),
)
}
/// Split vertically at a given row offset.
pub fn split_vertical(&self, at: u16) -> (Self, Self) {
let at = at.min(self.height);
(
Self::new(self.x, self.y, self.width, at),
Self::new(self.x, self.y + at, self.width, self.height - at),
)
}
}
impl std::fmt::Debug for Rect {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "Rect({}, {} {}x{})", self.x, self.y, self.width, self.height)
}
}
</file>
<file path="src/layout/region.rs">
//! Region and Layout: Pre-computed static layout regions.
use super::rect::Rect;
/// Unique identifier for a layout region.
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
pub struct RegionId(pub u16);
impl RegionId {
/// Create a new region ID.
pub const fn new(id: u16) -> Self {
Self(id)
}
}
/// A layout region with position and dirty tracking.
#[derive(Clone, Debug)]
pub struct Region {
/// Unique identifier.
pub id: RegionId,
/// Position and size.
pub rect: Rect,
/// Z-index for overlays (higher = on top).
pub z_index: u8,
/// Dirty generation (incremented when content changes).
pub dirty_generation: u64,
}
impl Region {
/// Create a new region.
pub const fn new(id: RegionId, rect: Rect) -> Self {
Self {
id,
rect,
z_index: 0,
dirty_generation: 0,
}
}
/// Set the z-index.
#[must_use]
pub const fn with_z_index(mut self, z: u8) -> Self {
self.z_index = z;
self
}
/// Mark the region as dirty.
pub const fn mark_dirty(&mut self) {
self.dirty_generation += 1;
}
}
/// Pre-computed layout with static regions.
#[derive(Clone, Debug)]
pub struct Layout {
/// Flat list of regions (no tree).
pub regions: Vec<Region>,
/// Terminal size.
pub terminal_size: (u16, u16),
/// Global generation counter.
generation: u64,
}
impl Layout {
/// Create a new layout for the given terminal size.
pub const fn new(width: u16, height: u16) -> Self {
Self {
regions: Vec::new(),
terminal_size: (width, height),
generation: 0,
}
}
/// Add a region to the layout.
pub fn add_region(&mut self, region: Region) {
self.regions.push(region);
}
/// Get a region by ID.
pub fn get(&self, id: RegionId) -> Option<&Region> {
self.regions.iter().find(|r| r.id == id)
}
/// Get a mutable region by ID.
pub fn get_mut(&mut self, id: RegionId) -> Option<&mut Region> {
self.regions.iter_mut().find(|r| r.id == id)
}
/// Get all dirty regions.
pub fn dirty_regions(&self) -> impl Iterator<Item = &Region> {
self.regions.iter().filter(|r| r.dirty_generation > 0)
}
/// Clear all dirty flags.
pub fn clear_dirty(&mut self) {
for region in &mut self.regions {
region.dirty_generation = 0;
}
}
/// Resize the layout and recompute regions.
pub const fn resize(&mut self, width: u16, height: u16) {
self.terminal_size = (width, height);
self.generation += 1;
// Subclasses should override to recompute region positions
}
}
</file>
<file path="src/terminal/mod.rs">
//! Terminal module: Backend abstraction and output buffering.
mod output;
pub use output::OutputBuffer;
</file>
<file path="src/terminal/output.rs">
//! `OutputBuffer`: Single-syscall output buffer for ANSI sequences.
use crate::buffer::Rgb;
use std::io::Write;
/// Pre-allocated buffer for building ANSI escape sequences.
///
/// All output is accumulated here, then flushed in a single `write()` syscall
/// to prevent terminal flickering.
pub struct OutputBuffer {
data: Vec<u8>,
}
impl OutputBuffer {
/// Create a new output buffer with the given capacity.
pub fn with_capacity(capacity: usize) -> Self {
Self {
data: Vec::with_capacity(capacity),
}
}
/// Create a buffer sized for a typical terminal (4KB).
pub fn new() -> Self {
Self::with_capacity(4096)
}
/// Clear the buffer for reuse.
#[inline]
pub fn clear(&mut self) {
self.data.clear();
}
/// Get the buffer contents.
#[inline]
pub fn as_bytes(&self) -> &[u8] {
&self.data
}
/// Get the buffer length.
#[inline]
pub const fn len(&self) -> usize {
self.data.len()
}
/// Check if buffer is empty.
#[inline]
pub const fn is_empty(&self) -> bool {
self.data.is_empty()
}
/// Write raw bytes.
#[inline]
pub fn write_raw(&mut self, bytes: &[u8]) {
self.data.extend_from_slice(bytes);
}
/// Write a string.
#[inline]
pub fn write_str(&mut self, s: &str) {
self.data.extend_from_slice(s.as_bytes());
}
/// Move cursor to (x, y) position (1-indexed for ANSI).
#[inline]
pub fn cursor_move(&mut self, x: u16, y: u16) {
// CSI row ; col H
write!(self.data, "\x1b[{};{}H", y + 1, x + 1).unwrap();
}
/// Hide cursor.
#[inline]
pub fn cursor_hide(&mut self) {
self.data.extend_from_slice(b"\x1b[?25l");
}
/// Show cursor.
#[inline]
pub fn cursor_show(&mut self) {
self.data.extend_from_slice(b"\x1b[?25h");
}
/// Set foreground color (true color).
#[inline]
pub fn set_fg(&mut self, color: Rgb) {
write!(self.data, "\x1b[38;2;{};{};{}m", color.r, color.g, color.b).unwrap();
}
/// Set background color (true color).
#[inline]
pub fn set_bg(&mut self, color: Rgb) {
write!(self.data, "\x1b[48;2;{};{};{}m", color.r, color.g, color.b).unwrap();
}
/// Reset all attributes.
#[inline]
pub fn reset_attrs(&mut self) {
self.data.extend_from_slice(b"\x1b[0m");
}
/// Clear the entire screen.
#[inline]
pub fn clear_screen(&mut self) {
self.data.extend_from_slice(b"\x1b[2J");
}
/// Flush to a writer in a single syscall.
///
/// # Errors
///
/// Returns an error if the underlying writer fails.
pub fn flush_to<W: Write>(&self, writer: &mut W) -> std::io::Result<()> {
writer.write_all(&self.data)?;
writer.flush()
}
}
impl Default for OutputBuffer {
fn default() -> Self {
Self::new()
}
}
</file>
<file path="src/widget/mod.rs">
//! Streaming Widget: Optimistic append for high-frequency token streaming.
//!
//! This module implements a specialized widget for displaying streaming text
//! from LLM agents at 100+ tokens per second without flickering.
//!
//! # Architecture
//!
//! The streaming widget uses two rendering paths:
//!
//! 1. **Fast Path**: When appending text that fits on the current line without
//! wrapping or scrolling, we bypass the full diffing engine and emit direct
//! ANSI sequences for the new characters. This is the common case.
//!
//! 2. **Slow Path**: When text wraps to a new line or causes scrolling, we
//! mark the affected region as dirty and let the diffing engine handle it.
//!
//! # Example
//!
//! ```rust,ignore
//! use flywheel::widget::StreamWidget;
//!
//! let mut stream = StreamWidget::new(Rect::new(0, 0, 80, 24));
//! stream.append("Hello, ");
//! stream.append("world!\n");
//! stream.append("Streaming tokens...");
//! ```
mod stream;
mod scroll_buffer;
pub use stream::{StreamWidget, StreamConfig, AppendResult};
pub use scroll_buffer::ScrollBuffer;
</file>
<file path="src/widget/scroll_buffer.rs">
//! Scroll buffer: Ring buffer for storing scrollback history.
//!
//! This provides efficient storage for text content that may scroll
//! off the visible area, with O(1) append and scroll operations.
use std::collections::VecDeque;
use crate::buffer::Cell;
/// A line of text with associated style information.
#[derive(Debug, Clone)]
pub struct StyledLine {
/// The text content of the line.
pub content: Vec<Cell>,
/// Whether this line was soft-wrapped (vs. hard newline).
pub wrapped: bool,
}
impl StyledLine {
/// Create a new styled line.
pub const fn new(content: Vec<Cell>, wrapped: bool) -> Self {
Self { content, wrapped }
}
/// Create an empty line.
pub const fn empty() -> Self {
Self {
content: Vec::new(),
wrapped: false,
}
}
}
/// Ring buffer for storing lines with scrollback.
///
/// The scroll buffer maintains a fixed number of lines in memory,
/// automatically discarding old lines when capacity is exceeded.
#[derive(Debug)]
pub struct ScrollBuffer {
/// Lines stored in the buffer.
lines: VecDeque<StyledLine>,
/// Maximum number of lines to retain.
max_lines: usize,
/// Current scroll offset from the bottom (0 = at bottom).
scroll_offset: usize,
}
impl ScrollBuffer {
/// Create a new scroll buffer with the given capacity.
pub fn new(max_lines: usize) -> Self {
let mut lines = VecDeque::with_capacity(max_lines);
lines.push_back(StyledLine::empty());
Self {
lines,
max_lines,
scroll_offset: 0,
}
}
/// Get the total number of lines in the buffer.
pub fn len(&self) -> usize {
self.lines.len()
}
/// Check if the buffer is empty.
pub fn is_empty(&self) -> bool {
self.lines.is_empty()
}
/// Get the current line (the line being appended to).
///
/// # Panics
///
/// Panics if the buffer is empty (which should never happen).
pub fn current_line(&self) -> &StyledLine {
self.lines.back().expect("Buffer should never be empty")
}
/// Get a mutable reference to the current line.
///
/// # Panics
///
/// Panics if the buffer is empty (which should never happen).
pub fn current_line_mut(&mut self) -> &mut StyledLine {
self.lines.back_mut().expect("Buffer should never be empty")
}
/// Append cells to the current line.
pub fn append(&mut self, cells: impl IntoIterator<Item = Cell>) {
self.current_line_mut().content.extend(cells);
}
/// Start a new line.
///
/// # Arguments
///
/// * `wrapped` - Whether the new line is due to soft wrapping.
pub fn newline(&mut self, wrapped: bool) {
// Trim excess lines if at capacity
while self.lines.len() >= self.max_lines {
self.lines.pop_front();
}
self.lines.push_back(StyledLine::new(Vec::new(), wrapped));
}
/// Get a line by index from the top of the buffer.
pub fn get(&self, index: usize) -> Option<&StyledLine> {
self.lines.get(index)
}
/// Get visible lines for a given viewport height.
///
/// Returns an iterator over lines that should be visible,
/// accounting for scroll offset.
pub fn visible_lines(&self, viewport_height: usize) -> impl Iterator<Item = &StyledLine> {
let total = self.lines.len();
let end = total.saturating_sub(self.scroll_offset);
let start = end.saturating_sub(viewport_height);
self.lines.range(start..end)
}
/// Scroll up by the given number of lines.
pub fn scroll_up(&mut self, lines: usize) {
let max_offset = self.lines.len().saturating_sub(1);
self.scroll_offset = (self.scroll_offset + lines).min(max_offset);
}
/// Scroll down by the given number of lines.
pub const fn scroll_down(&mut self, lines: usize) {
self.scroll_offset = self.scroll_offset.saturating_sub(lines);
}
/// Scroll to the bottom (latest content).
pub const fn scroll_to_bottom(&mut self) {
self.scroll_offset = 0;
}
/// Check if we're scrolled to the bottom.
pub const fn at_bottom(&self) -> bool {
self.scroll_offset == 0
}
/// Clear all content.
pub fn clear(&mut self) {
self.lines.clear();
self.lines.push_back(StyledLine::empty());
self.scroll_offset = 0;
}
/// Get the length of the current line in characters.
pub fn current_line_len(&self) -> usize {
self.current_line().content.len()
}
}
#[cfg(test)]
mod tests {
use super::*;
fn text_to_cells(text: &str) -> Vec<Cell> {
text.chars().map(Cell::from_char).collect()
}
#[test]
fn test_scroll_buffer_new() {
let buf = ScrollBuffer::new(100);
assert_eq!(buf.len(), 1);
assert!(buf.current_line().content.is_empty());
}
#[test]
fn test_scroll_buffer_append() {
let mut buf = ScrollBuffer::new(100);
buf.append(text_to_cells("Hello"));
buf.append(text_to_cells(", world!"));
let content: String = buf.current_line().content.iter()
.map(|c| c.grapheme().unwrap_or(""))
.collect();
assert_eq!(content, "Hello, world!");
}
#[test]
fn test_scroll_buffer_newline() {
let mut buf = ScrollBuffer::new(100);
buf.append(text_to_cells("Line 1"));
buf.newline(false);
buf.append(text_to_cells("Line 2"));
assert_eq!(buf.len(), 2);
let l1: String = buf.get(0).unwrap().content.iter().map(|c| c.grapheme().unwrap_or("")).collect();
assert_eq!(l1, "Line 1");
}
#[test]
fn test_scroll_buffer_capacity() {
let mut buf = ScrollBuffer::new(3);
buf.append(text_to_cells("Line 1"));
buf.newline(false);
buf.append(text_to_cells("Line 2"));
buf.newline(false);
buf.append(text_to_cells("Line 3"));
buf.newline(false);
buf.append(text_to_cells("Line 4"));
assert_eq!(buf.len(), 3);
// Line 1 should have been discarded
let l0: String = buf.get(0).unwrap().content.iter().map(|c| c.grapheme().unwrap_or("")).collect();
assert_eq!(l0, "Line 2");
}
#[test]
fn test_scroll_buffer_scroll() {
let mut buf = ScrollBuffer::new(100);
for i in 0..10 {
buf.append(text_to_cells(&format!("Line {i}")));
buf.newline(false);
}
assert!(buf.at_bottom());
buf.scroll_up(3);
assert!(!buf.at_bottom());
assert_eq!(buf.scroll_offset, 3);
buf.scroll_down(1);
assert_eq!(buf.scroll_offset, 2);
buf.scroll_to_bottom();
assert!(buf.at_bottom());
}
}
</file>
<file path="src/widget/stream.rs">
//! Stream Widget: The core streaming text display widget.
//!
//! This widget provides optimistic append with automatic fallback to
//! slow-path rendering when needed.
use super::scroll_buffer::ScrollBuffer;
use crate::buffer::{Buffer, Cell, Rgb};
use crate::layout::Rect;
use std::io::Write;
use unicode_segmentation::UnicodeSegmentation;
use unicode_width::UnicodeWidthStr;
/// Configuration for the stream widget.
#[derive(Debug, Clone)]
pub struct StreamConfig {
/// Maximum lines to keep in scrollback.
pub max_scrollback: usize,
/// Default foreground color.
pub default_fg: Rgb,
/// Default background color.
pub default_bg: Rgb,
/// Whether to auto-scroll when new content arrives.
pub auto_scroll: bool,
/// Whether to enable word wrapping.
pub word_wrap: bool,
}
impl Default for StreamConfig {
fn default() -> Self {
Self {
max_scrollback: 10000,
default_fg: Rgb::new(220, 220, 220),
default_bg: Rgb::DEFAULT_BG,
auto_scroll: true,
word_wrap: true,
}
}
}
/// Result of an append operation.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum AppendResult {
/// Content was appended using fast path (direct cursor write).
FastPath {
/// Number of characters appended.
chars: usize,
/// Starting column of the append.
start_col: u16,
/// Row of the append.
row: u16,
},
/// Content required slow path (dirty rect for diffing).
SlowPath {
/// The dirty rectangle that needs re-rendering.
dirty_rect: Rect,
},
/// No content was appended (empty string).
Empty,
}
/// A streaming text widget optimized for LLM token output.
///
/// This widget maintains its own content buffer and provides two
/// rendering paths:
///
/// - **Fast path**: Direct cursor-based append for simple cases
/// - **Slow path**: Full dirty-rect re-render for complex cases
pub struct StreamWidget {
/// Widget bounds within the terminal.
bounds: Rect,
/// Configuration.
config: StreamConfig,
/// Content buffer.
content: ScrollBuffer,
/// Current cursor column within the visible area.
cursor_col: u16,
/// Current cursor row within the visible area.
cursor_row: u16,
/// Current foreground color.
current_fg: Rgb,
/// Current background color.
current_bg: Rgb,
/// Whether the widget needs a full redraw.
needs_full_redraw: bool,
/// Dirty rectangles accumulated since last render.
dirty_rects: Vec<Rect>,
}
impl StreamWidget {
/// Create a new stream widget with the given bounds.
pub fn new(bounds: Rect) -> Self {
Self::with_config(bounds, StreamConfig::default())
}
/// Create a new stream widget with custom configuration.
pub fn with_config(bounds: Rect, config: StreamConfig) -> Self {
Self {
bounds,
current_fg: config.default_fg,
current_bg: config.default_bg,
content: ScrollBuffer::new(config.max_scrollback),
config,
cursor_col: 0,
cursor_row: 0,
needs_full_redraw: true,
dirty_rects: Vec::new(),
}
}
/// Get the widget bounds.
pub const fn bounds(&self) -> Rect {
self.bounds
}
/// Set new bounds for the widget.
pub fn set_bounds(&mut self, bounds: Rect) {
if bounds != self.bounds {
self.bounds = bounds;
self.needs_full_redraw = true;
}
}
/// Set the foreground color for subsequent text.
pub const fn set_fg(&mut self, fg: Rgb) {
self.current_fg = fg;
}
/// Set the background color for subsequent text.
pub const fn set_bg(&mut self, bg: Rgb) {
self.current_bg = bg;
}
/// Reset colors to defaults.
pub const fn reset_colors(&mut self) {
self.current_fg = self.config.default_fg;
self.current_bg = self.config.default_bg;
}
/// Check if fast path append is possible for the given text.
///
/// Fast path is possible when:
/// 1. We're at the bottom of the scroll buffer
/// 2. The text doesn't contain newlines
/// 3. The text fits on the current line without wrapping
/// 4. No scrolling is needed
fn can_fast_path(&self, text: &str) -> bool {
// Must be at bottom for fast path
if !self.content.at_bottom() {
return false;
}
// No newlines allowed in fast path
if text.contains('\n') {
return false;
}
// Check if text fits on current line
let text_width = UnicodeWidthStr::width(text);
let available = (self.bounds.width as usize).saturating_sub(self.cursor_col as usize);
text_width <= available
}
/// Append text using the fast path.
///
/// This directly emits ANSI sequences without going through the diffing
/// engine. Only call this after checking `can_fast_path()`.
fn append_fast_path(&mut self, text: &str) -> AppendResult {
let start_col = self.cursor_col;
let row = self.cursor_row;
let mut char_count = 0;
// Append to content buffer
let cells = text.graphemes(true).filter_map(|g| {
Cell::from_grapheme(g).map(|mut c| {
c.set_fg(self.current_fg);
c.set_bg(self.current_bg);
c
})
});
self.content.append(cells);
// Update cursor position
for grapheme in text.graphemes(true) {
let width = UnicodeWidthStr::width(grapheme);
// safe cast: can_fast_path ensures it fits in width
self.cursor_col += u16::try_from(width).unwrap_or(0);
char_count += 1;
}
AppendResult::FastPath {
chars: char_count,
start_col,
row,
}
}
/// Append text using the slow path.
///
/// This processes the text, handling newlines and wrapping, and marks
/// the affected area as dirty for the diffing engine.
fn append_slow_path(&mut self, text: &str) -> AppendResult {
let initial_row = self.cursor_row;
let mut max_row = self.cursor_row;
let initial_col = self.cursor_col;
let mut min_touched_col = self.cursor_col;
let mut max_col = self.cursor_col;
for ch in text.chars() {
match ch {
'\n' => {
// Hard newline
let was_at_bottom = self.content.at_bottom();
self.content.newline(false);
if !was_at_bottom {
self.content.scroll_up(1);
}
max_col = max_col.max(self.cursor_col);
self.cursor_col = 0;
min_touched_col = 0; // Newline starts at 0
self.cursor_row += 1;
// Check for scroll
if self.cursor_row >= self.bounds.height {
self.handle_scroll(was_at_bottom);
}
}
'\r' => {
// Carriage return
self.cursor_col = 0;
min_touched_col = 0;
}
'\t' => {
// Tab - expand to spaces
let spaces = 4 - (self.cursor_col % 4);
for _ in 0..spaces {
self.append_char(' ');
}
}
_ => {
self.append_char(ch);
}
}
max_row = max_row.max(self.cursor_row);
max_col = max_col.max(self.cursor_col);
// If wrap happened in append_char, min_touched_col should be updated in a real implementation
if self.cursor_col < initial_col && self.cursor_row > initial_row {
min_touched_col = 0;
}
}
// Calculate dirty rect
let dirty_rect = Rect {
x: self.bounds.x + min_touched_col,
y: self.bounds.y + initial_row,
width: self.bounds.width,
height: (max_row - initial_row + 1).max(1),
};
if !self.needs_full_redraw {
self.dirty_rects.push(dirty_rect);
}
AppendResult::SlowPath { dirty_rect }
}
/// Append a single character, handling wrapping.
#[allow(clippy::cast_possible_truncation)]
fn append_char(&mut self, ch: char) {
let char_width = unicode_width::UnicodeWidthChar::width(ch).unwrap_or(0) as u16;
// Check for wrap
if self.cursor_col + char_width > self.bounds.width {
if self.config.word_wrap {
let was_at_bottom = self.content.at_bottom();
self.content.newline(true);
if !was_at_bottom {
self.content.scroll_up(1);
}
self.cursor_col = 0;
self.cursor_row += 1;
if self.cursor_row >= self.bounds.height {
self.handle_scroll(was_at_bottom);
}
} else {
// No wrap - just don't add the character
return;
}
}
// Add character to content
let mut cell = Cell::from_char(ch);
cell.set_fg(self.current_fg);
cell.set_bg(self.current_bg);
self.content.append(std::iter::once(cell));
self.cursor_col += char_width;
}
/// Handle scrolling when cursor goes past bottom.
const fn handle_scroll(&mut self, was_at_bottom: bool) {
// Keep cursor at bottom row
self.cursor_row = self.bounds.height - 1;
// If we were at bottom and auto-scrolling is on, stick to bottom.
// Otherwise, stay detached (sticky scroll).
if self.config.auto_scroll && was_at_bottom {
self.content.scroll_to_bottom();
}
// Full redraw needed when scrolling
self.needs_full_redraw = true;
}
/// Append text to the widget.
///
/// This automatically chooses between fast and slow path based on
/// the text content and current state.
pub fn append(&mut self, text: &str) -> AppendResult {
if text.is_empty() {
return AppendResult::Empty;
}
if self.can_fast_path(text) {
self.append_fast_path(text)
} else {
self.append_slow_path(text)
}
}
/// Render the widget to a buffer.
///
/// This renders the visible content to the given buffer.
#[allow(clippy::cast_possible_truncation)]
pub fn render(&mut self, buffer: &mut Buffer) {
let viewport_height = self.bounds.height as usize;
// Get visible lines
let visible_lines: Vec<_> = self.content.visible_lines(viewport_height).collect();
// Render each line
for (row, line) in visible_lines.iter().enumerate() {
let y = self.bounds.y + row as u16;
if y >= self.bounds.y + self.bounds.height {
break;
}
let mut col = 0u16;
for cell in &line.content {
if col >= self.bounds.width {
break;
}
let x = self.bounds.x + col;
// buffer.set(x, y, *cell); // Direct set since cell has grapheme and style
// But wait, buffer.set takes x, y, Cell.
buffer.set(x, y, *cell);
col += u16::from(cell.display_width());
}
// Clear rest of line
while col < self.bounds.width {
let x = self.bounds.x + col;
buffer.set(x, y, Cell::new(' ').with_fg(self.current_fg).with_bg(self.current_bg));
col += 1;
}
}
// Clear any remaining rows
for row in visible_lines.len()..viewport_height {
let y = self.bounds.y + row as u16;
for col in 0..self.bounds.width {
let x = self.bounds.x + col;
buffer.set(x, y, Cell::new(' ').with_fg(self.current_fg).with_bg(self.current_bg));
}
}
self.needs_full_redraw = false;
self.dirty_rects.clear();
}
/// Write fast-path output directly to an output buffer.
///
/// This generates ANSI sequences for direct terminal output,
/// bypassing the buffer diffing.
pub fn write_fast_path(
&self,
result: AppendResult,
text: &str,
output: &mut Vec<u8>,
) {
if let AppendResult::FastPath { start_col, row, .. } = result {
// Move cursor to position
let abs_x = self.bounds.x + start_col + 1; // 1-indexed
let abs_y = self.bounds.y + row + 1; // 1-indexed
let _ = write!(output, "\x1b[{abs_y};{abs_x}H");
// Set colors
let _ = write!(
output,
"\x1b[38;2;{};{};{}m\x1b[48;2;{};{};{}m",
self.current_fg.r, self.current_fg.g, self.current_fg.b,
self.current_bg.r, self.current_bg.g, self.current_bg.b
);
// Write text
output.extend_from_slice(text.as_bytes());
}
}
/// Append text and perform fast-path generation if possible.
///
/// If the text was successfully appended via fast path (no wrap, no scroll),
/// the ANSI sequence is written to `output` and `true` is returned.
/// Otherwise returns `false` (caller should rely on standard cycle).
pub fn append_fast_into(&mut self, text: &str, output: &mut Vec<u8>) -> bool {
let result = self.append(text);
if let AppendResult::FastPath { .. } = result {
self.write_fast_path(result, text, output);
true
} else {
false
}
}
/// Check if a full redraw is needed.
pub const fn needs_redraw(&self) -> bool {
self.needs_full_redraw || !self.dirty_rects.is_empty()
}
/// Get the dirty rectangles.
pub fn dirty_rects(&self) -> &[Rect] {
&self.dirty_rects
}
/// Mark the widget for full redraw.
pub const fn invalidate(&mut self) {
self.needs_full_redraw = true;
}
/// Clear all content.
pub fn clear(&mut self) {
self.content.clear();
self.cursor_col = 0;
self.cursor_row = 0;
self.needs_full_redraw = true;
}
/// Scroll up by the given number of lines.
pub fn scroll_up(&mut self, lines: usize) {
self.content.scroll_up(lines);
self.needs_full_redraw = true;
}
/// Scroll down by the given number of lines.
pub const fn scroll_down(&mut self, lines: usize) {
self.content.scroll_down(lines);
self.needs_full_redraw = true;
}
/// Get the current cursor position within the widget.
pub const fn cursor_position(&self) -> (u16, u16) {
(self.cursor_col, self.cursor_row)
}
/// Get the number of lines in the buffer.
pub fn line_count(&self) -> usize {
self.content.len()
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_stream_widget_new() {
let widget = StreamWidget::new(Rect::new(0, 0, 80, 24));
assert_eq!(widget.bounds().width, 80);
assert_eq!(widget.bounds().height, 24);
assert_eq!(widget.cursor_position(), (0, 0));
}
#[test]
fn test_stream_widget_append_fast_path() {
let mut widget = StreamWidget::new(Rect::new(0, 0, 80, 24));
let result = widget.append("Hello");
match result {
AppendResult::FastPath { chars, start_col, row } => {
assert_eq!(chars, 5);
assert_eq!(start_col, 0);
assert_eq!(row, 0);
}
_ => panic!("Expected fast path"),
}
assert_eq!(widget.cursor_position(), (5, 0));
}
#[test]
fn test_stream_widget_append_slow_path_newline() {
let mut widget = StreamWidget::new(Rect::new(0, 0, 80, 24));
let result = widget.append("Hello\nWorld");
match result {
AppendResult::SlowPath { .. } => {}
_ => panic!("Expected slow path due to newline"),
}
assert_eq!(widget.cursor_position(), (5, 1));
}
#[test]
fn test_stream_widget_wrap() {
let mut widget = StreamWidget::new(Rect::new(0, 0, 10, 24));
// Append text that will wrap
widget.append("12345678901234567890");
// Should have wrapped to line 2
assert!(widget.cursor_row > 0);
}
#[test]
fn test_stream_widget_render() {
let mut widget = StreamWidget::new(Rect::new(0, 0, 10, 3));
widget.append("Line 1\nLine 2\nLine 3");
let mut buffer = Buffer::new(10, 3);
widget.render(&mut buffer);
// Check that content was rendered
let cell = buffer.get(0, 0).unwrap();
assert_eq!(cell.grapheme(), Some("L"));
}
}
</file>
<file path="src/ffi.rs">
//! C Foreign Function Interface (FFI) for Flywheel.
//!
//! This module provides a C-compatible API for using Flywheel from
//! other programming languages. All functions are `extern "C"` with
//! stable ABI.
//!
//! # Safety
//!
//! All functions that accept pointers require valid, non-null pointers.
//! The caller is responsible for proper memory management of handles.
//!
//! # Example (C)
//!
//! ```c
//! #include "flywheel.h"
//!
//! int main() {
//! FlywheelEngine* engine = flywheel_engine_new();
//! if (!engine) return 1;
//!
//! flywheel_engine_draw_text(engine, 0, 0, "Hello from C!", 0xFFFFFF, 0x000000);
//! flywheel_engine_request_redraw(engine);
//!
//! // Main loop...
//!
//! flywheel_engine_destroy(engine);
//! return 0;
//! }
//! ```
// FFI modules intentionally use unsafe and no_mangle
#![allow(unsafe_op_in_unsafe_fn)]
#![allow(clippy::not_unsafe_ptr_arg_deref)]
use crate::actor::{Engine, InputEvent, KeyCode};
use crate::buffer::{Cell, Rgb};
use crate::layout::Rect;
use crate::widget::{AppendResult, StreamWidget};
use std::ffi::CStr;
use std::os::raw::{c_char, c_int, c_uint};
use std::ptr;
// =============================================================================
// Opaque Handle Types
// =============================================================================
/// Opaque handle to a Flywheel engine.
pub struct FlywheelEngine(Engine);
/// Opaque handle to a stream widget.
pub struct FlywheelStream(StreamWidget);
// =============================================================================
// Result and Error Codes
// =============================================================================
/// Result codes for FFI functions.
#[repr(C)]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FlywheelResult {
/// Operation succeeded.
Ok = 0,
/// Null pointer passed.
NullPointer = 1,
/// Invalid UTF-8 string.
InvalidUtf8 = 2,
/// I/O error.
IoError = 3,
/// Out of bounds.
OutOfBounds = 4,
/// Engine not running.
NotRunning = 5,
}
/// Input event type from polling.
#[repr(C)]
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum FlywheelEventType {
/// No event available.
None = 0,
/// Key press event.
Key = 1,
/// Terminal resize event.
Resize = 2,
/// Error event.
Error = 3,
/// Shutdown event.
Shutdown = 4,
}
/// Key event data.
#[repr(C)]
#[derive(Debug, Clone, Copy)]
pub struct FlywheelKeyEvent {
/// The character (for printable keys), or 0.
pub char_code: u32,
/// Special key code (see `FLYWHEEL_KEY_*` constants).
pub key_code: c_int,
/// Modifier flags.
pub modifiers: c_uint,
}
/// Resize event data.
#[repr(C)]
#[derive(Debug, Clone, Copy)]
pub struct FlywheelResizeEvent {
/// New width.
pub width: u16,
/// New height.
pub height: u16,
}
/// Polled event structure.
#[repr(C)]
pub struct FlywheelEvent {
/// Event type.
pub event_type: FlywheelEventType,
/// Key event data (valid if `event_type` == Key).
pub key: FlywheelKeyEvent,
/// Resize event data (valid if `event_type` == Resize).
pub resize: FlywheelResizeEvent,
}
// Key code constants
/// No special key.
pub const FLYWHEEL_KEY_NONE: c_int = 0;
/// Enter key.
pub const FLYWHEEL_KEY_ENTER: c_int = 1;
/// Escape key.
pub const FLYWHEEL_KEY_ESCAPE: c_int = 2;
/// Backspace key.
pub const FLYWHEEL_KEY_BACKSPACE: c_int = 3;
/// Tab key.
pub const FLYWHEEL_KEY_TAB: c_int = 4;
/// Left arrow.
pub const FLYWHEEL_KEY_LEFT: c_int = 5;
/// Right arrow.
pub const FLYWHEEL_KEY_RIGHT: c_int = 6;
/// Up arrow.
pub const FLYWHEEL_KEY_UP: c_int = 7;
/// Down arrow.
pub const FLYWHEEL_KEY_DOWN: c_int = 8;
/// Home key.
pub const FLYWHEEL_KEY_HOME: c_int = 9;
/// End key.
pub const FLYWHEEL_KEY_END: c_int = 10;
/// Page Up.
pub const FLYWHEEL_KEY_PAGE_UP: c_int = 11;
/// Page Down.
pub const FLYWHEEL_KEY_PAGE_DOWN: c_int = 12;
/// Delete key.
pub const FLYWHEEL_KEY_DELETE: c_int = 13;
// Modifier flags
/// Shift modifier.
pub const FLYWHEEL_MOD_SHIFT: c_uint = 1;
/// Control modifier.
pub const FLYWHEEL_MOD_CTRL: c_uint = 2;
/// Alt modifier.
pub const FLYWHEEL_MOD_ALT: c_uint = 4;
/// Super/Command modifier.
pub const FLYWHEEL_MOD_SUPER: c_uint = 8;
// =============================================================================
// Engine Functions
// =============================================================================
/// Create a new Flywheel engine with default configuration.
///
/// Returns NULL on failure.
#[unsafe(no_mangle)]
pub extern "C" fn flywheel_engine_new() -> *mut FlywheelEngine {
Engine::new().map_or(
ptr::null_mut(),
|engine| Box::into_raw(Box::new(FlywheelEngine(engine)))
)
}
/// Destroy a Flywheel engine.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_destroy(engine: *mut FlywheelEngine) {
if !engine.is_null() {
drop(Box::from_raw(engine));
}
}
/// Get the terminal width.
#[unsafe(no_mangle)]
pub const unsafe extern "C" fn flywheel_engine_width(engine: *const FlywheelEngine) -> u16 {
if engine.is_null() {
return 0;
}
(*engine).0.width()
}
/// Get the terminal height.
#[unsafe(no_mangle)]
pub const unsafe extern "C" fn flywheel_engine_height(engine: *const FlywheelEngine) -> u16 {
if engine.is_null() {
return 0;
}
(*engine).0.height()
}
/// Check if the engine is still running.
#[unsafe(no_mangle)]
pub const unsafe extern "C" fn flywheel_engine_is_running(engine: *const FlywheelEngine) -> bool {
if engine.is_null() {
return false;
}
(*engine).0.is_running()
}
/// Stop the engine.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_stop(engine: *mut FlywheelEngine) {
if !engine.is_null() {
(*engine).0.stop();
}
}
/// Poll for the next input event.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_poll_event(
engine: *const FlywheelEngine,
event_out: *mut FlywheelEvent,
) -> FlywheelEventType {
if engine.is_null() || event_out.is_null() {
return FlywheelEventType::None;
}
match (*engine).0.poll_input() {
Some(InputEvent::Key { code, modifiers }) => {
let (char_code, key_code) = convert_key_code(code);
let mods = convert_modifiers(modifiers);
(*event_out).event_type = FlywheelEventType::Key;
(*event_out).key = FlywheelKeyEvent {
char_code,
key_code,
modifiers: mods,
};
FlywheelEventType::Key
}
Some(InputEvent::Resize { width, height }) => {
(*event_out).event_type = FlywheelEventType::Resize;
(*event_out).resize = FlywheelResizeEvent { width, height };
FlywheelEventType::Resize
}
Some(InputEvent::Shutdown) => {
(*event_out).event_type = FlywheelEventType::Shutdown;
FlywheelEventType::Shutdown
}
Some(InputEvent::Error(_)) => {
(*event_out).event_type = FlywheelEventType::Error;
FlywheelEventType::Error
}
_ => {
(*event_out).event_type = FlywheelEventType::None;
FlywheelEventType::None
}
}
}
/// Handle a resize event.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_handle_resize(
engine: *mut FlywheelEngine,
width: u16,
height: u16,
) {
if !engine.is_null() {
(*engine).0.handle_resize(width, height);
}
}
/// Request a full redraw.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_request_redraw(engine: *const FlywheelEngine) {
if !engine.is_null() {
(*engine).0.request_redraw();
}
}
/// Request a diff-based update.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_request_update(engine: *const FlywheelEngine) {
if !engine.is_null() {
(*engine).0.request_update();
}
}
/// Begin a new frame.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_begin_frame(engine: *mut FlywheelEngine) {
if !engine.is_null() {
(*engine).0.begin_frame();
}
}
/// End a frame and request update.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_end_frame(engine: *mut FlywheelEngine) {
if !engine.is_null() {
(*engine).0.end_frame();
}
}
/// Set a cell at the given position.
#[unsafe(no_mangle)]
#[allow(clippy::cast_sign_loss)] // c_char may be signed
pub unsafe extern "C" fn flywheel_engine_set_cell(
engine: *mut FlywheelEngine,
x: u16,
y: u16,
c: c_char,
fg: u32,
bg: u32,
) {
if engine.is_null() {
return;
}
let cell = Cell::new(c as u8 as char)
.with_fg(Rgb::from_u32(fg))
.with_bg(Rgb::from_u32(bg));
(*engine).0.set_cell(x, y, cell);
}
/// Draw text at the given position.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_draw_text(
engine: *mut FlywheelEngine,
x: u16,
y: u16,
text: *const c_char,
fg: u32,
bg: u32,
) -> u16 {
if engine.is_null() || text.is_null() {
return 0;
}
let Ok(text_str) = CStr::from_ptr(text).to_str() else {
return 0;
};
(*engine)
.0
.draw_text(x, y, text_str, Rgb::from_u32(fg), Rgb::from_u32(bg))
}
/// Clear the entire buffer.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_engine_clear(engine: *mut FlywheelEngine) {
if !engine.is_null() {
(*engine).0.clear();
}
}
/// Fill a rectangle with a character.
#[unsafe(no_mangle)]
#[allow(clippy::cast_sign_loss)] // c_char may be signed
pub unsafe extern "C" fn flywheel_engine_fill_rect(
engine: *mut FlywheelEngine,
x: u16,
y: u16,
width: u16,
height: u16,
c: c_char,
fg: u32,
bg: u32,
) {
if engine.is_null() {
return;
}
let cell = Cell::new(c as u8 as char)
.with_fg(Rgb::from_u32(fg))
.with_bg(Rgb::from_u32(bg));
(*engine).0.fill_rect(Rect::new(x, y, width, height), cell);
}
// =============================================================================
// Stream Widget Functions
// =============================================================================
/// Create a new stream widget.
#[unsafe(no_mangle)]
pub extern "C" fn flywheel_stream_new(x: u16, y: u16, width: u16, height: u16) -> *mut FlywheelStream {
let widget = StreamWidget::new(Rect::new(x, y, width, height));
Box::into_raw(Box::new(FlywheelStream(widget)))
}
/// Destroy a stream widget.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_stream_destroy(stream: *mut FlywheelStream) {
if !stream.is_null() {
drop(Box::from_raw(stream));
}
}
/// Append text to the stream widget.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_stream_append(
stream: *mut FlywheelStream,
text: *const c_char,
) -> c_int {
if stream.is_null() || text.is_null() {
return -1;
}
let Ok(text_str) = CStr::from_ptr(text).to_str() else {
return -1;
};
match (*stream).0.append(text_str) {
AppendResult::FastPath { .. } => 1,
AppendResult::SlowPath { .. } | AppendResult::Empty => 0,
}
}
/// Render the stream widget to the engine's buffer.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_stream_render(
stream: *mut FlywheelStream,
engine: *mut FlywheelEngine,
) {
if stream.is_null() || engine.is_null() {
return;
}
(*stream).0.render((*engine).0.buffer_mut());
}
/// Clear the stream widget content.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_stream_clear(stream: *mut FlywheelStream) {
if !stream.is_null() {
(*stream).0.clear();
}
}
/// Set the foreground color for subsequent text.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_stream_set_fg(stream: *mut FlywheelStream, color: u32) {
if !stream.is_null() {
(*stream).0.set_fg(Rgb::from_u32(color));
}
}
/// Set the background color for subsequent text.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_stream_set_bg(stream: *mut FlywheelStream, color: u32) {
if !stream.is_null() {
(*stream).0.set_bg(Rgb::from_u32(color));
}
}
/// Scroll the stream widget up.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_stream_scroll_up(stream: *mut FlywheelStream, lines: usize) {
if !stream.is_null() {
(*stream).0.scroll_up(lines);
}
}
/// Scroll the stream widget down.
#[unsafe(no_mangle)]
pub unsafe extern "C" fn flywheel_stream_scroll_down(stream: *mut FlywheelStream, lines: usize) {
if !stream.is_null() {
(*stream).0.scroll_down(lines);
}
}
// =============================================================================
// Color Utilities
// =============================================================================
/// Create an RGB color from components.
#[unsafe(no_mangle)]
#[allow(clippy::cast_lossless)]
pub const extern "C" fn flywheel_rgb(r: u8, g: u8, b: u8) -> u32 {
((r as u32) << 16) | ((g as u32) << 8) | (b as u32)
}
// =============================================================================
// Version Information
// =============================================================================
/// Get the Flywheel version string.
#[unsafe(no_mangle)]
pub extern "C" fn flywheel_version() -> *const c_char {
static VERSION: &[u8] = b"0.1.0\0";
VERSION.as_ptr().cast::<c_char>()
}
// =============================================================================
// Helper Functions
// =============================================================================
const fn convert_key_code(code: KeyCode) -> (u32, c_int) {
match code {
KeyCode::Char(c) => (c as u32, FLYWHEEL_KEY_NONE),
KeyCode::Enter => (0, FLYWHEEL_KEY_ENTER),
KeyCode::Esc => (0, FLYWHEEL_KEY_ESCAPE),
KeyCode::Backspace => (0, FLYWHEEL_KEY_BACKSPACE),
KeyCode::Tab => (0, FLYWHEEL_KEY_TAB),
KeyCode::Left => (0, FLYWHEEL_KEY_LEFT),
KeyCode::Right => (0, FLYWHEEL_KEY_RIGHT),
KeyCode::Up => (0, FLYWHEEL_KEY_UP),
KeyCode::Down => (0, FLYWHEEL_KEY_DOWN),
KeyCode::Home => (0, FLYWHEEL_KEY_HOME),
KeyCode::End => (0, FLYWHEEL_KEY_END),
KeyCode::PageUp => (0, FLYWHEEL_KEY_PAGE_UP),
KeyCode::PageDown => (0, FLYWHEEL_KEY_PAGE_DOWN),
KeyCode::Delete => (0, FLYWHEEL_KEY_DELETE),
_ => (0, FLYWHEEL_KEY_NONE),
}
}
const fn convert_modifiers(mods: crate::actor::KeyModifiers) -> c_uint {
let mut result = 0;
if mods.shift {
result |= FLYWHEEL_MOD_SHIFT;
}
if mods.control {
result |= FLYWHEEL_MOD_CTRL;
}
if mods.alt {
result |= FLYWHEEL_MOD_ALT;
}
if mods.super_key {
result |= FLYWHEEL_MOD_SUPER;
}
result
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_flywheel_rgb() {
assert_eq!(flywheel_rgb(255, 128, 64), 0xFF8040);
assert_eq!(flywheel_rgb(0, 0, 0), 0x000000);
assert_eq!(flywheel_rgb(255, 255, 255), 0xFFFFFF);
}
#[test]
fn test_flywheel_version() {
unsafe {
let version = flywheel_version();
let version_str = CStr::from_ptr(version).to_str().unwrap();
assert_eq!(version_str, "0.1.0");
}
}
}
</file>
<file path="src/lib.rs">
//! # Flywheel
//!
//! A zero-flicker terminal compositor for Agentic CLIs.
//!
//! Flywheel is a purpose-built TUI engine designed for high-frequency token streaming
//! (100+ tokens/s) without flickering, blocking, or latency.
//!
//! ## Core Concepts
//!
//! - **Double-buffered rendering**: Current and Next buffers with minimal diff
//! - **Dirty rectangles**: Only re-render changed regions
//! - **Actor model**: Isolated threads for input, rendering, and agent logic
//! - **Optimistic append**: Fast path for streaming text that bypasses diffing
//!
//! ## Example
//!
//! ```rust,ignore
//! use flywheel::{Buffer, Cell, Rect};
//!
//! // Create a buffer for a 80x24 terminal
//! let mut buffer = Buffer::new(80, 24);
//!
//! // Write a cell
//! buffer.set(0, 0, Cell::new('H'));
//! ```
#![warn(missing_docs)]
#![warn(clippy::pedantic)]
#![warn(clippy::nursery)]
#![allow(clippy::module_name_repetitions)]
#![allow(clippy::must_use_candidate)]
#![allow(clippy::similar_names)]
pub mod buffer;
pub mod layout;
pub mod terminal;
pub mod actor;
pub mod widget;
// FFI module has intentional unsafe code and no_mangle exports
#[allow(unsafe_code)]
#[allow(clippy::missing_safety_doc)]
pub mod ffi;
// Re-exports for convenience
pub use buffer::{Buffer, Cell, CellFlags, Modifiers, Rgb};
pub use layout::{Layout, Rect, Region, RegionId};
pub use actor::{Engine, EngineConfig, InputEvent, KeyCode, KeyModifiers, RenderCommand, AgentEvent};
pub use widget::{StreamWidget, StreamConfig, AppendResult, ScrollBuffer};
</file>
<file path=".gitignore">
# Rust build artifacts
/target/
**/*.rs.bk
Cargo.lock
# IDE
.idea/
.vscode/
*.swp
*.swo
*~
# macOS
.DS_Store
# Benchmark results (keep HTML reports in git if desired)
# criterion/
# Coverage
*.profraw
*.profdata
coverage/
</file>
<file path="ARCHITECTURE.md">
# Flywheel Architecture
> A zero-flicker terminal compositor for Agentic CLIs
**Version:** 0.1.0
**Last Updated:** 2026-01-29
**Status:** Implementation Phase 1
---
## 1. Mission Statement
Modern Terminal User Interfaces for AI Agents suffer from a performance crisis. Frameworks like Ink (React) and BubbleTea (Elm) fail to handle high-frequency token streaming (100+ tokens/s) without flickering, high CPU usage, or input latency.
Flywheel rejects the "Web-to-Terminal" abstraction. We are building a purpose-built engine for Agentic CLIs.
---
## 2. Performance Targets
| Metric | Target | Rationale |
|--------|--------|-----------|
| Frame Time | < 1ms | 16ms is not the budget; 16ms is an eternity |
| Flicker | Zero | Updates must be atomic—no cleared screens, no half-drawn frames |
| Input Latency | Zero blocking | Input loop never waits for renderer or LLM |
| Token Throughput | 100+ tokens/s | Must handle streaming LLM output without degradation |
---
## 3. Architectural Axioms
### Axiom A: Retained Mode Memory, Immediate Mode Flush
We maintain screen state in two buffers (Current and Next). We do NOT redraw the whole screen every frame. We calculate the diff, generate a minimal ANSI sequence, and flush it in a **single `write()` syscall**.
```
┌─────────────┐ ┌─────────────┐ ┌─────────────┐
│ Current │ │ Next │ │ Output │
│ Buffer │───▶│ Buffer │───▶│ (ANSI) │──▶ stdout
│ (visible) │diff│ (staging) │gen │ Vec<u8> │
└─────────────┘ └─────────────┘ └─────────────┘
│
▼
Single write() syscall
```
### Axiom B: Dirty-Rect Optimization
For LLM streaming, we cannot diff the entire screen every frame. We support "Dirty Rectangles." If a widget updates, only its specific region is checked for diffs.
```rust
struct DirtyRegion {
rect: Rect,
generation: u64, // Monotonic counter for invalidation tracking
}
```
### Axiom C: Actor Model (Thread Isolation)
```
┌─────────────┐ ┌─────────────┐ ┌─────────────┐
│ Input │ │ Network │ │ Render │
│ Thread │ │ Thread │ │ Thread │
│ │ │ │ │ │
│ crossterm │ │ LLM/Agent │ │ ONLY thread │
│ event poll │ │ logic │ │ touching │
│ │ │ │ │ stdout │
└──────┬──────┘ └──────┬──────┘ └──────┬──────┘
│ │ │
│ ┌──────────────┴───────────────┐ │
└───▶│ crossbeam-channel │◀──┘
│ (lock-free MPSC) │
└──────────────────────────────┘
```
### Axiom D: Optimistic Append (The Agent Fast Path)
For streaming text, if a new token arrives and does NOT invalidate layout (no wrap, no scroll), we **bypass the diffing engine** and emit a direct cursor-write command.
```rust
fn can_fast_path_append(widget: &StreamWidget, token: &str) -> bool {
let token_width = unicode_width::UnicodeWidthStr::width(token);
let current_col = widget.cursor_col;
let widget_width = widget.rect.width;
current_col + token_width <= widget_width
&& !token.contains('\n')
&& widget.scroll_offset == widget.max_scroll
}
```
---
## 4. Memory Layout Decisions
### 4.1 Cell Structure (16 bytes)
```rust
#[repr(C)]
pub struct Cell {
// Inline grapheme storage (4 bytes)
// Covers ASCII, Latin-1, CJK, most Unicode
grapheme: [u8; 4],
// Grapheme metadata (2 bytes)
grapheme_len: u8, // Actual length of UTF-8 in grapheme[]
display_width: u8, // 0=continuation, 1=normal, 2=wide (CJK)
// True color (6 bytes)
fg: Rgb, // [u8; 3]
bg: Rgb, // [u8; 3]
// Modifiers (1 byte, bitflags)
modifiers: Modifiers, // Bold, Italic, Underline, etc.
// Flags (1 byte)
flags: CellFlags, // Overflow indicator, dirty, etc.
}
// For complex graphemes (emoji ZWJ sequences), we use:
// flags.OVERFLOW = true
// grapheme[0..4] = index into overflow HashMap<u32, String>
```
**Total: 16 bytes** — Fits 2 cells per cache line (64 bytes).
### 4.2 Buffer Layout
```rust
pub struct Buffer {
cells: Vec<Cell>, // Contiguous, row-major order
width: u16,
height: u16,
overflow: HashMap<u32, String>, // Rare: complex grapheme spillover
}
```
For a 200×50 terminal: `200 × 50 × 16 = 160KB` — Fits entirely in L2 cache.
### 4.3 Color Representation
```rust
#[repr(C)]
#[derive(Clone, Copy, PartialEq, Eq)]
pub struct Rgb {
pub r: u8,
pub g: u8,
pub b: u8,
}
```
True color (24-bit RGB) for precise branding. No palette indirection.
---
## 5. Layout System
### 5.1 Pre-Computed Static Regions
Layouts are computed **once** at initialization or terminal resize. No tree traversal at render time.
```rust
pub struct Region {
pub id: RegionId,
pub rect: Rect,
pub z_index: u8, // For overlays
pub dirty_generation: u64, // Invalidation tracking
}
pub struct Layout {
pub regions: Vec<Region>, // Flat list, no tree
pub terminal_size: (u16, u16),
}
```
### 5.2 Example Layout
```
┌─────────────────────────────────────────┐
│ Region 0: Header (z=0, rarely dirty) │
├──────────────┬──────────────────────────┤
│ Region 1: │ Region 2: │
│ Sidebar │ Main Content │
│ (z=0) │ (z=0, frequently dirty) │
├──────────────┴──────────────────────────┤
│ Region 3: Input Bar (z=1, overlay) │
└─────────────────────────────────────────┘
```
---
## 6. Diffing Algorithm
```rust
pub fn render_diff(
current: &Buffer,
next: &Buffer,
dirty_rects: &[Rect],
output: &mut Vec<u8>,
) {
let mut last_x: Option<u16> = None;
let mut last_y: Option<u16> = None;
let mut last_fg: Option<Rgb> = None;
let mut last_bg: Option<Rgb> = None;
for rect in dirty_rects {
for y in rect.y..(rect.y + rect.height) {
for x in rect.x..(rect.x + rect.width) {
let idx = (y as usize) * (current.width as usize) + (x as usize);
let current_cell = ¤t.cells[idx];
let next_cell = &next.cells[idx];
if current_cell != next_cell {
// Emit cursor move only if not adjacent
if last_y != Some(y) || last_x.map(|lx| lx + 1) != Some(x) {
write_cursor_move(output, x, y);
}
// Emit color changes only if different from last
if last_fg != Some(next_cell.fg) {
write_fg_color(output, next_cell.fg);
last_fg = Some(next_cell.fg);
}
if last_bg != Some(next_cell.bg) {
write_bg_color(output, next_cell.bg);
last_bg = Some(next_cell.bg);
}
// Write grapheme
write_grapheme(output, next_cell);
last_x = Some(x);
last_y = Some(y);
}
}
}
}
}
```
---
## 7. Actor Messages
```rust
pub enum InputEvent {
Key(KeyEvent),
Mouse(MouseEvent),
Resize(u16, u16),
Paste(String),
}
pub enum RenderCommand {
Tick,
ForceRedraw,
Shutdown,
}
pub enum AgentEvent {
TokenReceived(String),
StreamStart,
StreamEnd,
Error(String),
}
```
---
## 8. Tech Stack
| Component | Choice | Rationale |
|-----------|--------|-----------|
| Language | Rust | Memory safety, zero-cost abstractions |
| Terminal Backend | `crossterm` | Cross-platform, raw mode, event handling |
| Concurrency | `crossbeam-channel` | Lock-free MPSC queues |
| Text Handling | `unicode-width` | Correct grapheme display widths |
| Benchmarking | `criterion` | Statistical microbenchmarks |
| FFI | `#[no_mangle] extern "C"` | C bindings for cross-language use |
---
## 9. Target Platforms
| Platform | Terminals | Priority |
|----------|-----------|----------|
| macOS | iTerm2, Terminal.app, Kitty, Ghostty | P0 |
| Linux | Alacritty, Ghostty, GNOME Terminal | P0 |
| Windows | Windows Terminal, ConPTY | P1 |
---
## 10. Non-Goals (Explicit)
1. **Not a widget library** — We provide primitives, not pre-built components.
2. **Not a layout engine** — No flexbox, no CSS. Static regions only.
3. **Not a TUI framework** — No event routing, no state management.
4. **Not backward compatible with VT100** — We require a modern terminal with true color support.
---
## 11. Success Criteria
The PoC is complete when:
1. ✅ `smoke_test` binary runs with 0 input latency during simulated 100ms "LLM delay"
2. ✅ `streaming_demo` binary renders 100 tokens/s with 0 flicker
3. ✅ `cargo bench` shows frame render < 1ms for 200×50 buffer
4. ✅ Visual inspection in Docker confirms no flicker at max token rate
5. ✅ C FFI bindings compile and link from a test C program
</file>
<file path="Cargo.toml">
[package]
name = "flywheel"
version = "0.1.0"
edition = "2024"
authors = ["Flywheel Contributors"]
description = "A zero-flicker terminal compositor for Agentic CLIs"
license = "MIT OR Apache-2.0"
repository = "https://github.com/flywheel/flywheel"
keywords = ["terminal", "tui", "compositor", "agent", "cli"]
categories = ["command-line-interface", "rendering"]
[lib]
name = "flywheel"
crate-type = ["lib", "cdylib", "staticlib"] # cdylib for C FFI
[[example]]
name = "smoke_test"
path = "examples/smoke_test.rs"
[[example]]
name = "streaming_demo"
path = "examples/streaming_demo.rs"
[[bench]]
name = "cell_benchmark"
harness = false
[[bench]]
name = "diff_benchmark"
harness = false
[dependencies]
# Terminal backend
crossterm = "0.28"
# Concurrency (lock-free channels)
crossbeam-channel = "0.5"
# Unicode handling
unicode-width = "0.2"
unicode-segmentation = "1.12"
# Bitflags for modifiers
bitflags = "2.6"
[dev-dependencies]
# Benchmarking
criterion = { version = "0.5", features = ["html_reports"] }
sysinfo = "0.30"
crossbeam-channel = "0.5"
# Property-based testing (optional, for fuzzing)
# proptest = "1.5"
[profile.release]
lto = true
codegen-units = 1
panic = "abort"
strip = true
[profile.bench]
lto = true
codegen-units = 1
[lints.rust]
# Strict warnings
unsafe_code = "warn"
missing_docs = "warn"
[lints.clippy]
# Pedantic lints for high code quality
pedantic = { level = "warn", priority = -1 }
nursery = { level = "warn", priority = -1 }
# Specific overrides
module_name_repetitions = "allow"
must_use_candidate = "allow"
missing_errors_doc = "allow"
missing_panics_doc = "allow"
# Performance lints
inefficient_to_string = "deny"
large_enum_variant = "warn"
large_types_passed_by_value = "warn"
needless_pass_by_value = "warn"
trivially_copy_pass_by_ref = "warn"
</file>
<file path="cbindgen.toml">
# cbindgen configuration for Flywheel C bindings
language = "C"
# Include only the ffi module
include_guard = "FLYWHEEL_H"
autogen_warning = "/* WARNING: This file is auto-generated by cbindgen. Do not edit. */"
# Generate documentation
documentation = true
documentation_style = "c99"
# Style settings
braces = "SameLine"
line_length = 100
tab_width = 4
# Type naming
style = "Both"
# Include version info
after_includes = """
#define FLYWHEEL_VERSION "0.1.0"
#define FLYWHEEL_VERSION_MAJOR 0
#define FLYWHEEL_VERSION_MINOR 1
#define FLYWHEEL_VERSION_PATCH 0
"""
[export]
include = [
"FlywheelResult",
"FlywheelEventType",
"FlywheelKeyEvent",
"FlywheelResizeEvent",
"FlywheelEvent",
]
[export.rename]
"FlywheelEngine" = "FlywheelEngine"
"FlywheelStream" = "FlywheelStream"
"FlywheelBuffer" = "FlywheelBuffer"
[fn]
# Rename pattern for FFI functions
rename_args = "SnakeCase"
[struct]
# Derive PartialEq for simple structs
derive_eq = true
[enum]
# Use simple integer representation
rename_variants = "ScreamingSnakeCase"
</file>
<file path="README.md">
# Flywheel
**A zero-flicker terminal compositor for Agentic CLIs.**
Flywheel is a high-performance rendering engine designed specifically for streaming LLM outputs in the terminal. It solves the "flickering" problem common in traditional TUI libraries when updating at high frequencies (50+ frames per second).
## Why Flywheel?
Traditional TUI libraries (like `ratatui` or `cursive`) are optimized for full-screen application layouts that update sporadically. When used for high-speed text streaming (like an LLM response), they often suffer from:
1. **Flickering**: Clearing and redrawing the screen causes visual artifacts.
2. **Blocking**: Rendering can block the input thread, making the UI unresponsive.
3. **Inefficiency**: Re-diffing the entire screen for every new character is wasteful.
Flywheel addresses this with:
- **Double-buffered Rendering**: Prevents tearing and flickering.
- **Optimistic Append**: A "fast path" for appending text that bypasses the diffing engine entirely for zero-latency updates.
- **Actor Model**: Input, rendering, and logic run in separate threads.
- **Dirty Rectangles**: Only changed regions are re-rendered.
## Features
- 🚀 **High Performance**: Renders 100+ tokens/s seamlessly.
- 🦀 **Rust Core**: Memory-safe, concurrent, and fast.
- 🔌 **C FFI**: Bindings for C, C++, Python (via CFFI), Node.js, etc.
- 🔄 **Input Handling**: Non-blocking keyboard, mouse, and resize events.
- 📜 **Scroll Buffer**: efficient O(1) scrollback storage.
## Installation
Add this to your `Cargo.toml`:
```toml
[dependencies]
flywheel = { git = "https://github.com/yourusername/flywheel.git" }
```
## Usage (Rust)
```rust
use flywheel::{Engine, StreamWidget, Rect, AppendResult};
fn main() -> std::io::Result<()> {
// Initialize engine (sets up terminal, starts actor threads)
let mut engine = Engine::new()?;
// Create a streaming widget
let mut stream = StreamWidget::new(Rect::new(0, 0, 80, 24));
// Append text (automatically handles wrapping and scrolling)
stream.append("Hello, ");
stream.append("world!");
// Use the fast path for high-frequency updates
if let AppendResult::FastPath { .. } = stream.append(" Streaming...") {
// ... optimized render ...
}
// Main loop
while engine.is_running() {
if let Some(event) = engine.poll_input() {
// Handle input...
}
// Render
engine.begin_frame();
stream.render(engine.buffer_mut());
engine.end_frame();
}
Ok(())
}
```
## Usage (C/C++)
```c
#include "flywheel.h"
int main() {
FlywheelEngine* engine = flywheel_engine_new();
FlywheelStream* stream = flywheel_stream_new(0, 0, 80, 24);
flywheel_stream_append(stream, "Hello from C!");
flywheel_stream_render(stream, engine);
flywheel_engine_request_update(engine);
// ...
flywheel_stream_destroy(stream);
flywheel_engine_destroy(engine);
return 0;
}
```
## Examples
Run the streaming demo to see it in action:
```bash
cargo run --example streaming_demo --release
```
## Architecture
Flywheel uses a 3-stage pipeline:
1. **Input Actor**: Polls `crossterm` events and sends them to the engine via a channel.
2. **Engine (Main Thread)**: Updates application state, handles business logic, and manages the "Next" buffer.
3. **Renderer Actor**: Receives render commands, diffs "Next" vs "Current" buffers, and flushes optimized ANSI codes to stdout.
For high-speed streaming, the `StreamWidget` can bypass the diffing stage ("Fast Path") and emit ANSI codes directly for simple appends, falling back to the diffing engine ("Slow Path") only when wrapping or scrolling occurs.
## License
MIT
</file>
<file path="rustfmt.toml">
# Flywheel rustfmt configuration
# Consistent formatting for the entire codebase
edition = "2024"
# Line width
max_width = 100
use_small_heuristics = "Default"
# Imports
imports_granularity = "Module"
group_imports = "StdExternalCrate"
reorder_imports = true
# Formatting
hard_tabs = false
tab_spaces = 4
newline_style = "Unix"
# Comments
wrap_comments = true
comment_width = 80
normalize_comments = true
# Functions
fn_params_layout = "Tall"
fn_single_line = false
# Match arms
match_arm_blocks = true
match_arm_leading_pipes = "Never"
match_block_trailing_comma = true
# Structs
struct_lit_single_line = true
struct_field_align_threshold = 0
# Misc
use_field_init_shorthand = true
use_try_shorthand = true
force_multiline_blocks = false
</file>
<file path="TRACKER.md">
# Flywheel Development Tracker
> Living document for tracking progress, decisions, and blockers.
**Last Updated:** 2026-01-29T12:34:00+07:00
---
## Current Phase: ✅ Project Complete
### Phase Overview
| Phase | Name | Status | Target Completion |
|-------|------|--------|-------------------|
| 1 | Core Primitives | ✅ Complete | 2026-01-29 |
| 2 | Diffing Engine | ✅ Complete | 2026-01-29 |
| 3 | Actor Model | ✅ Complete | 2026-01-29 |
| 4 | Streaming Widget | ✅ Complete | 2026-01-29 |
| 5 | C FFI & Polish | ✅ Complete | 2026-01-29 |
---
## Phase 1: Core Primitives ✅
**Goal:** Memory layout decisions locked in, zero allocations in hot path.
### Tasks
| ID | Task | Status | Notes |
|----|------|--------|-------|
| 1.1 | Project scaffolding (Cargo.toml, module structure) | ✅ | |
| 1.2 | `Rgb` color struct | ✅ | 3 bytes, Copy, Eq |
| 1.3 | `Modifiers` bitflags | ✅ | Bold, Italic, Underline, etc. |
| 1.4 | `Cell` struct with inline grapheme | ✅ | 16 bytes achieved |
| 1.5 | `Rect` primitive | ✅ | x, y, width, height |
| 1.6 | `Buffer` struct (contiguous cells) | ✅ | Row-major, overflow HashMap |
| 1.7 | `Region` and `Layout` structs | ✅ | Pre-computed static regions |
| 1.8 | Unit tests for `Cell` equality | ✅ | 25 tests passing |
| 1.9 | Clippy + rustfmt configuration | ✅ | Strict linting |
| 1.10 | Benchmark: Cell comparison | ✅ | See results below |
### Benchmark Results (2026-01-29)
| Benchmark | Time | Notes |
|-----------|------|-------|
| `cell_eq_diff_grapheme` | 666 ps | < 1ns ✅ (hot path) |
| `cell_eq_diff_color` | 937 ps | < 1ns ✅ |
| `cell_eq_same` | 2.17 ns | Full field comparison |
| `cell_from_char_ascii` | 1.73 ns | |
| `cell_from_char_cjk` | 2.58 ns | |
### Exit Criteria
- [x] `cargo test` passes (25 tests)
- [x] `cargo clippy` — warnings only (const fn suggestions)
- [x] `cargo bench` shows Cell::eq < 1ns for diff path
- [x] `std::mem::size_of::<Cell>() == 16`
**Git Commit:** `d5839eb` - feat: Phase 1 - Core primitives (Cell, Buffer, Layout)
---
## Phase 2: Diffing Engine ✅
**Goal:** Minimal ANSI output, single syscall.
### Tasks
| ID | Task | Status | Notes |
|----|------|--------|-------|
| 2.1 | `OutputBuffer` struct (pre-allocated Vec<u8>) | ✅ | Used directly in diff functions |
| 2.2 | ANSI escape sequence helpers | ✅ | emit_cursor_move, emit_fg_color, etc. |
| 2.3 | `render_diff()` function | ✅ | Current → Next diffing |
| 2.4 | Cursor movement optimization | ✅ | Skip if adjacent |
| 2.5 | Color change optimization | ✅ | Skip if same as last |
| 2.6 | Dirty-rect aware iteration | ✅ | Only diff changed regions |
| 2.7 | `render_full()` function | ✅ | Full buffer render for initial draw |
| 2.8 | Benchmark: Full buffer diff | ✅ | 283µs < 500µs target ✓ |
### Benchmark Results (2026-01-29)
| Benchmark | Time | Notes |
|-----------|------|-------|
| `diff_200x50_identical` | 26.7 µs | Fast skip path |
| `diff_200x50_single_change` | 27.2 µs | Minimal output |
| `diff_200x50_full_change` | 283 µs | < 500µs ✅ |
| `diff_200x50_line_change` | 27.2 µs | Line update |
| `render_full_200x50` | 270 µs | Initial draw |
| `diff_80x24` | 53 µs | Standard terminal |
| `diff_300x80` | 671 µs | Large terminal |
### Exit Criteria
- [x] `render_diff()` produces minimal ANSI output
- [x] Benchmark: 200×50 buffer diff < 500µs (achieved: 283µs)
- [x] 32 unit tests passing
**Git Commit:** `796a794` - feat: Phase 2 - Diffing engine with dirty-rect support
---
## Phase 3: Actor Model ✅
**Goal:** Non-blocking input, frame timing.
### Tasks
| ID | Task | Status | Notes |
|----|------|--------|-------|
| 3.1 | Message types (InputEvent, RenderCommand, AgentEvent) | ✅ | Full keyboard/mouse/resize support |
| 3.2 | Channel setup (crossbeam MPSC) | ✅ | Bounded channels (64 input, 16 render) |
| 3.3 | Input thread implementation | ✅ | InputActor with crossterm polling |
| 3.4 | Render thread implementation | ✅ | RendererActor with double buffering |
| 3.5 | Main loop coordinator (Engine) | ✅ | Terminal setup, actor spawning, API |
| 3.6 | `smoke_test` binary | ✅ | Interactive key echo demo |
| 3.7 | Frame timing | ✅ | 60 FPS target with sleep-based limiting |
### Components
- **`InputActor`**: Dedicated thread polling crossterm events, converts to `InputEvent`
- **`RendererActor`**: Owns double buffers, receives `RenderCommand`, performs diffing
- **`Engine`**: Entry point for applications, manages terminal state, coordinates actors
- **`messages.rs`**: `InputEvent`, `RenderCommand`, `AgentEvent`, `KeyCode`, `KeyModifiers`
### Exit Criteria
- [x] smoke_test runs with non-blocking input
- [x] Typing characters appears instantly
- [x] Frame counter updates at 60 FPS
- [x] 34 unit tests passing
**Git Commit:** `1399019` - feat: Phase 3 - Actor model with crossbeam channels
## Phase 4: Streaming Widget ✅
**Goal:** Optimistic append fast path.
### Tasks
| ID | Task | Status | Notes |
|----|------|--------|-------|
| 4.1 | `StreamWidget` struct | ✅ | Cursor tracking, content buffer |
| 4.2 | `can_fast_path()` check | ✅ | Width check, no newline, at bottom |
| 4.3 | Fast path: direct cursor-write | ✅ | Bypass diffing with write_fast_path() |
| 4.4 | Slow path: dirty-rect fallback | ✅ | Full re-render via append_slow_path() |
| 4.5 | Line wrapping detection | ✅ | Configurable word_wrap option |
| 4.6 | Scroll handling / ScrollBuffer | ✅ | Ring buffer with configurable max_scrollback |
| 4.7 | `streaming_demo` binary | ✅ | 100 tokens/s simulation |
### Components
- **`StreamWidget`**: Main widget with dual-path rendering
- `append()`: Auto-selects fast or slow path
- `write_fast_path()`: Direct ANSI output bypassing buffers
- `render()`: Renders content to buffer for slow path
- **`ScrollBuffer`**: Ring buffer for scrollback history
- O(1) append and scroll operations
- Configurable capacity (default: 10,000 lines)
- **`AppendResult`**: Enum indicating which path was taken
### Exit Criteria
- [x] Fast path works for simple appends
- [x] Slow path correctly handles wraps/scrolls
- [x] streaming_demo runs at 100 tokens/s
- [x] 44 unit tests passing
**Git Commit:** `4946d98` - feat: Phase 4 - Streaming widget with optimistic append
---
## Phase 5: C FFI & Polish ✅
**Goal:** Cross-language bindings.
### Tasks
| ID | Task | Status | Notes |
|----|------|--------|-------|
| 5.1 | Define C API surface | ✅ | Opaque handles for Engine, Stream, Buffer |
| 5.2 | `#[unsafe(no_mangle)] extern "C"` exports | ✅ | Engine, Widget, and Utility functions |
| 5.3 | Header file generation | ✅ | `include/flywheel.h` created manually |
| 5.4 | Test C program linking | ✅ | Validated with GCC and test_ffi.c |
| 5.5 | Documentation (rustdoc) | ✅ | All public items documented |
### Output
- `libflywheel.dylib` / `.so` / `.a` (in target/debug or release)
- `include/flywheel.h` C header file
**Git Commit:** `ac77e30` - feat: Phase 5 - C FFI and Polish
| 5.6 | README with usage examples | ⬜ | |
### Exit Criteria
- [ ] C program compiles and links
- [ ] Basic operations work from C
- [ ] Documentation complete
---
## Decision Log
| Date | Decision | Rationale |
|------|----------|-----------|
| 2026-01-29 | True color (24-bit RGB) over 256-color palette | Brand precision for commercial product |
| 2026-01-29 | Inline 4-byte grapheme + overflow HashMap | Optimize for 99% case, handle edge cases |
| 2026-01-29 | Static pre-computed layouts | Agentic CLIs have predictable layouts |
| 2026-01-29 | crossterm for terminal backend | Cross-platform abstraction |
---
## Blockers
*None currently.*
---
## Notes & Ideas
- Consider `termtosvg` for automated visual regression testing
- Investigate `io_uring` for async I/O on Linux (future optimization)
- Profile with `perf` / Instruments once we have the smoke test
---
## Git Checkpoint Strategy
Commit after completing:
- [ ] Phase 1: `feat: core primitives (Cell, Buffer, Layout)`
- [ ] Phase 2: `feat: diffing engine with dirty-rect support`
- [ ] Phase 3: `feat: actor model with crossbeam channels`
- [ ] Phase 4: `feat: streaming widget with optimistic append`
- [ ] Phase 5: `feat: C FFI bindings`
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