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use crate::cell::{unicode_column_width, AttributeChange, CellAttributes};
use crate::color::ColorAttribute;
pub use crate::image::{ImageData, TextureCoordinate};
use crate::surface::{CursorShape, CursorVisibility, Position};
#[cfg(feature = "use_serde")]
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use unicode_segmentation::UnicodeSegmentation;
/// `Change` describes an update operation to be applied to a `Surface`.
/// Changes to the active attributes (color, style), moving the cursor
/// and outputting text are examples of some of the values.
#[cfg_attr(feature = "use_serde", derive(Serialize, Deserialize))]
#[derive(Debug, Clone, Eq, PartialEq)]
pub enum Change {
/// Change a single attribute
Attribute(AttributeChange),
/// Change all possible attributes to the given set of values
AllAttributes(CellAttributes),
/// Add printable text.
/// Control characters are rendered inert by transforming them
/// to space. CR and LF characters are interpreted by moving
/// the cursor position. CR moves the cursor to the start of
/// the line and LF moves the cursor down to the next line.
/// You typically want to use both together when sending in
/// a line break.
Text(String),
/// Clear the screen to the specified color.
/// Implicitly clears all attributes prior to clearing the screen.
/// Moves the cursor to the home position (top left).
ClearScreen(ColorAttribute),
/// Clear from the current cursor X position to the rightmost
/// edge of the screen. The background color is set to the
/// provided color. The cursor position remains unchanged.
ClearToEndOfLine(ColorAttribute),
/// Clear from the current cursor X position to the rightmost
/// edge of the screen on the current line. Clear all of the
/// lines below the current cursor Y position. The background
/// color is set ot the provided color. The cursor position
/// remains unchanged.
ClearToEndOfScreen(ColorAttribute),
/// Move the cursor to the specified `Position`.
CursorPosition { x: Position, y: Position },
/// Change the cursor color.
CursorColor(ColorAttribute),
/// Change the cursor shape
CursorShape(CursorShape),
/// Change the cursor visibility
CursorVisibility(CursorVisibility),
/// Place an image at the current cursor position.
/// The image defines the dimensions in cells.
/// TODO: check iterm rendering behavior when the image is larger than the width of the screen.
/// If the image is taller than the remaining space at the bottom
/// of the screen, the screen will scroll up.
/// The cursor Y position is unchanged by rendering the Image.
/// The cursor X position will be incremented by `Image::width` cells.
Image(Image),
/// Scroll the `region_size` lines starting at `first_row` upwards
/// by `scroll_count` lines. The `scroll_count` lines at the top of
/// the region are overwritten. The `scroll_count` lines at the
/// bottom of the region will become blank.
///
/// After a region is scrolled, the cursor position is undefined,
/// and the terminal's scroll region is set to the range specified.
/// To restore scrolling behaviour to the full terminal window, an
/// additional `Change::ScrollRegionUp { first_row: 0, region_size:
/// height, scroll_count: 0 }`, where `height` is the height of the
/// terminal, should be emitted.
ScrollRegionUp {
first_row: usize,
region_size: usize,
scroll_count: usize,
},
/// Scroll the `region_size` lines starting at `first_row` downwards
/// by `scroll_count` lines. The `scroll_count` lines at the bottom
/// the region are overwritten. The `scroll_count` lines at the top
/// of the region will become blank.
///
/// After a region is scrolled, the cursor position is undefined,
/// and the terminal's scroll region is set to the range specified.
/// To restore scrolling behaviour to the full terminal window, an
/// additional `Change::ScrollRegionDown { first_row: 0,
/// region_size: height, scroll_count: 0 }`, where `height` is the
/// height of the terminal, should be emitted.
ScrollRegionDown {
first_row: usize,
region_size: usize,
scroll_count: usize,
},
/// Change the title of the window in which the surface will be
/// rendered.
Title(String),
}
impl Change {
pub fn is_text(&self) -> bool {
matches!(self, Change::Text(_))
}
pub fn text(&self) -> &str {
match self {
Change::Text(text) => text,
_ => panic!("you must use Change::is_text() to guard calls to Change::text()"),
}
}
}
impl<S: Into<String>> From<S> for Change {
fn from(s: S) -> Self {
Change::Text(s.into())
}
}
impl From<AttributeChange> for Change {
fn from(c: AttributeChange) -> Self {
Change::Attribute(c)
}
}
/// Keeps track of a run of changes and allows reasoning about the cursor
/// position and the extent of the screen that the sequence will affect.
/// This is useful for example when implementing something like a LineEditor
/// where you don't want to take control over the entire surface but do want
/// to be able to emit a dynamically sized output relative to the cursor
/// position at the time that the editor is invoked.
pub struct ChangeSequence {
changes: Vec<Change>,
screen_rows: usize,
screen_cols: usize,
pub(crate) cursor_x: usize,
pub(crate) cursor_y: isize,
render_y_max: isize,
render_y_min: isize,
}
impl ChangeSequence {
pub fn new(rows: usize, cols: usize) -> Self {
Self {
changes: vec![],
screen_rows: rows,
screen_cols: cols,
cursor_x: 0,
cursor_y: 0,
render_y_max: 0,
render_y_min: 0,
}
}
pub fn consume(self) -> Vec<Change> {
self.changes
}
/// Returns the cursor position, (x, y).
pub fn current_cursor_position(&self) -> (usize, isize) {
(self.cursor_x, self.cursor_y)
}
pub fn move_to(&mut self, (cursor_x, cursor_y): (usize, isize)) {
self.add(Change::CursorPosition {
x: Position::Relative(cursor_x as isize - self.cursor_x as isize),
y: Position::Relative(cursor_y - self.cursor_y),
});
}
/// Returns the total number of rows affected
pub fn render_height(&self) -> usize {
(self.render_y_max - self.render_y_min).max(0).abs() as usize
}
fn update_render_height(&mut self) {
self.render_y_max = self.render_y_max.max(self.cursor_y);
self.render_y_min = self.render_y_min.min(self.cursor_y);
}
pub fn add_changes(&mut self, changes: Vec<Change>) {
for change in changes {
self.add(change);
}
}
pub fn add<C: Into<Change>>(&mut self, change: C) {
let change = change.into();
match &change {
Change::AllAttributes(_)
| Change::Attribute(_)
| Change::CursorColor(_)
| Change::CursorShape(_)
| Change::CursorVisibility(_)
| Change::ClearToEndOfLine(_)
| Change::Title(_)
| Change::ClearToEndOfScreen(_) => {}
Change::Text(t) => {
for g in t.as_str().graphemes(true) {
if self.cursor_x == self.screen_cols {
self.cursor_y += 1;
self.cursor_x = 0;
}
if g == "\n" {
self.cursor_y += 1;
} else if g == "\r" {
self.cursor_x = 0;
} else if g == "\r\n" {
self.cursor_y += 1;
self.cursor_x = 0;
} else {
let len = unicode_column_width(g, None);
self.cursor_x += len;
}
}
self.update_render_height();
}
Change::Image(im) => {
self.cursor_x += im.width;
self.render_y_max = self.render_y_max.max(self.cursor_y + im.height as isize);
}
Change::ClearScreen(_) => {
self.cursor_x = 0;
self.cursor_y = 0;
}
Change::CursorPosition { x, y } => {
self.cursor_x = match x {
Position::Relative(x) => {
((self.cursor_x as isize + x) % self.screen_cols as isize) as usize
}
Position::Absolute(x) => x % self.screen_cols,
Position::EndRelative(x) => (self.screen_cols - x) % self.screen_cols,
};
self.cursor_y = match y {
Position::Relative(y) => {
(self.cursor_y as isize + y) % self.screen_rows as isize
}
Position::Absolute(y) => (y % self.screen_rows) as isize,
Position::EndRelative(y) => {
((self.screen_rows - y) % self.screen_rows) as isize
}
};
self.update_render_height();
}
Change::ScrollRegionUp { .. } | Change::ScrollRegionDown { .. } => {
// The resultant cursor position is undefined by
// the renderer!
// We just pick something.
self.cursor_x = 0;
self.cursor_y = 0;
}
}
self.changes.push(change);
}
}
/// The `Image` `Change` needs to support adding an image that spans multiple
/// rows and columns, as well as model the content for just one of those cells.
/// For instance, if some of the cells inside an image are replaced by textual
/// content, and the screen is scrolled, computing the diff change stream needs
/// to be able to express that a single cell holds a slice from a larger image.
/// The `Image` struct expresses its dimensions in cells and references a region
/// in the shared source image data using texture coordinates.
/// A 4x3 cell image would set `width=3`, `height=3`, `top_left=(0,0)`, `bottom_right=(1,1)`.
/// The top left cell from that image, if it were to be included in a diff,
/// would be recorded as `width=1`, `height=1`, `top_left=(0,0)`, `bottom_right=(1/4,1/3)`.
#[cfg_attr(feature = "use_serde", derive(Serialize, Deserialize))]
#[derive(Debug, Clone, Eq, PartialEq)]
pub struct Image {
/// measured in cells
pub width: usize,
/// measure in cells
pub height: usize,
/// Texture coordinate for the top left of this image block.
/// (0,0) is the top left of the ImageData. (1, 1) is
/// the bottom right.
pub top_left: TextureCoordinate,
/// Texture coordinates for the bottom right of this image block.
pub bottom_right: TextureCoordinate,
/// the image data
pub image: Arc<ImageData>,
}