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// (C) 2025 - Enzo Lombardi
//! Drawing primitives - Cell and DrawBuffer types for efficient line-based rendering.
use super::palette::Attr;
/// A single character cell with attributes
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub struct Cell {
pub ch: char,
pub attr: Attr,
}
impl Cell {
pub const fn new(ch: char, attr: Attr) -> Self {
Self { ch, attr }
}
}
/// Buffer for efficient line-based drawing
pub struct DrawBuffer {
pub data: Vec<Cell>,
}
impl DrawBuffer {
/// Create a new draw buffer with the given width
pub fn new(width: usize) -> Self {
Self {
data: vec![Cell::new(' ', Attr::from_u8(0x07)); width],
}
}
/// Fill a range with a single character and attribute
pub fn move_char(&mut self, pos: usize, ch: char, attr: Attr, count: usize) {
let end = (pos + count).min(self.data.len());
for i in pos..end {
self.data[i] = Cell::new(ch, attr);
}
}
/// Write a string with the given attribute
pub fn move_str(&mut self, pos: usize, s: &str, attr: Attr) {
use unicode_width::UnicodeWidthChar;
let mut i = pos;
for ch in s.chars() {
if i >= self.data.len() {
break;
}
let w = ch.width().unwrap_or(0);
// Skip zero-width characters (combining marks, variation
// selectors like U+FE0F). They must not occupy their own
// cell — otherwise the buffer width diverges from what the
// terminal actually renders, misaligning subsequent content.
if w == 0 {
continue;
}
self.data[i] = Cell::new(ch, attr);
i += 1;
// Wide characters (emojis, CJK) occupy 2 cells — fill the
// second cell with a zero-width padding space so the cursor
// advances correctly.
if w > 1 {
for _ in 1..w {
if i >= self.data.len() {
break;
}
self.data[i] = Cell::new('\0', attr);
i += 1;
}
}
}
}
/// Copy cells from another buffer
pub fn move_buf(&mut self, pos: usize, src: &[Cell], count: usize) {
let end = (pos + count).min(self.data.len()).min(pos + src.len());
self.data[pos..end].copy_from_slice(&src[..(end - pos)]);
}
/// Put a single character at a position
pub fn put_char(&mut self, pos: usize, ch: char, attr: Attr) {
if pos < self.data.len() {
self.data[pos] = Cell::new(ch, attr);
}
}
/// Change the attribute of a cell without changing its character
/// Matches Borland: TDrawBuffer::putAttribute (help.cc:109)
pub fn put_attribute(&mut self, pos: usize, attr: Attr) {
if pos < self.data.len() {
self.data[pos].attr = attr;
}
}
/// Get the length of the buffer
pub fn len(&self) -> usize {
self.data.len()
}
/// Check if the buffer is empty
pub fn is_empty(&self) -> bool {
self.data.is_empty()
}
/// Write a string with shortcut highlighting
/// Format: "~X~" highlights X with shortcut_attr, rest uses normal_attr
/// Example: "~F~ile" displays "File" with "F" highlighted
pub fn move_str_with_shortcut(
&mut self,
mut pos: usize,
s: &str,
normal_attr: Attr,
shortcut_attr: Attr,
) -> usize {
use unicode_width::UnicodeWidthChar;
let mut chars = s.chars();
let start_pos = pos;
// Helper: write a char at `pos`, advancing by its display width
let put_wide = |data: &mut [Cell], pos: &mut usize, ch: char, attr: Attr| {
if *pos >= data.len() {
return;
}
let w = ch.width().unwrap_or(0);
if w == 0 {
return;
}
data[*pos] = Cell::new(ch, attr);
*pos += 1;
for _ in 1..w {
if *pos >= data.len() {
break;
}
data[*pos] = Cell::new('\0', attr);
*pos += 1;
}
};
// Parse string character by character, handling ~X~ shortcut highlighting
while let Some(ch) = chars.next() {
if pos >= self.data.len() {
break;
}
if ch == '~' {
// Read characters until closing ~ and render with shortcut color
while let Some(shortcut_ch) = chars.next() {
if shortcut_ch == '~' {
break; // Found closing tilde
}
put_wide(&mut self.data, &mut pos, shortcut_ch, shortcut_attr);
}
} else if ch.is_control() {
// Skip control characters (e.g. \x03 centering directive)
// These are directives, not renderable glyphs
continue;
} else {
put_wide(&mut self.data, &mut pos, ch, normal_attr);
}
}
pos - start_pos // Return number of cells written
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::core::palette::TvColor;
#[test]
fn test_draw_buffer_basic() {
let buf = DrawBuffer::new(10);
assert_eq!(buf.len(), 10);
assert!(!buf.is_empty());
}
#[test]
fn test_move_char() {
let mut buf = DrawBuffer::new(10);
let attr = Attr::new(TvColor::White, TvColor::Black);
buf.move_char(2, 'X', attr, 3);
assert_eq!(buf.data[1].ch, ' ');
assert_eq!(buf.data[2].ch, 'X');
assert_eq!(buf.data[3].ch, 'X');
assert_eq!(buf.data[4].ch, 'X');
assert_eq!(buf.data[5].ch, ' ');
}
#[test]
fn test_move_str() {
let mut buf = DrawBuffer::new(20);
let attr = Attr::new(TvColor::White, TvColor::Black);
buf.move_str(0, "Hello, World!", attr);
assert_eq!(buf.data[0].ch, 'H');
assert_eq!(buf.data[6].ch, ' ');
assert_eq!(buf.data[12].ch, '!');
}
}