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Final bit of bike shedding for the draw_rect fn.

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This commit is contained in:
Mark Tomlin 2023-12-26 07:07:21 -05:00 • committed by Jeremy Soller
parent 47aad59fe4
commit 5588411644
1 changed files with 65 additions and 42 deletions
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107
src/text_box.rs
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@ -108,12 +108,18 @@ struct Offset {
y: i32,
}
//TODO: improve performance
/// This function is called Window.x * Window.y number of times
/// each time the text is scrolled or the window is resized.
/// If the window is moved, it's not called as the pixel buffer
/// is the same, it's just translated for the screen's x, y.
/// Window is the location of the pixel in the window.
/// Screen is the location of the pixel on the screen itself.
// TODO: improve performance
fn draw_rect(
buffer: &mut [u32],
canvas: Canvas,
window: Canvas,
offset: Canvas,
start: Offset,
screen: Offset,
cosmic_color: cosmic_text::Color,
) {
// Grab alpha channel and green channel
@ -124,54 +130,71 @@ fn draw_rect(
color |= (cosmic_color.0 & 0x000000FF) << 16;
let alpha = (color >> 24) & 0xFF;
if alpha == 0 {
// Do not draw if alpha is zero
} else if alpha >= 255 {
// Handle overwrite
for y in start.y..start.y + offset.h {
if y < 0 || y >= canvas.h {
// Skip if y out of bounds
continue;
}
let line_offset = y as usize * canvas.w as usize;
for x in start.x..start.x + offset.w {
if x < 0 || x >= canvas.w {
// Skip if x out of bounds
log::debug!(
"Window: {{w: {}, h: {}}}; Offset: {{w: {}, h: {}}}; Screen: {{x: {}, y: {}}}; Alpha {:#}",
window.w,
window.h,
offset.w,
offset.h,
screen.x,
screen.y,
alpha
);
match alpha {
0 => {
// Do not draw if alpha is zero.
}
255 => {
// Handle overwrite
for x in screen.x..screen.x + offset.w {
if x < 0 || x >= window.w {
// Skip if y out of bounds
continue;
}
let offset = line_offset + x as usize;
buffer[offset] = color;
for y in screen.y..screen.y + offset.h {
if y < 0 || y >= window.h {
// Skip if x out of bounds
continue;
}
let line_offset = y as usize * window.w as usize;
let offset = line_offset + x as usize;
buffer[offset] = color;
}
}
}
} else {
let n_alpha = 255 - alpha;
for y in start.y..start.y + offset.h {
if y < 0 || y >= canvas.h {
// Skip if y out of bounds
continue;
}
let line_offset = y as usize * canvas.w as usize;
for x in start.x..start.x + offset.w {
if x < 0 || x >= canvas.w {
// Skip if x out of bounds
_ => {
let n_alpha = 255 - alpha;
for y in screen.y..screen.y + offset.h {
if y < 0 || y >= window.h {
// Skip if y out of bounds
continue;
}
// Alpha blend with current value
let offset = line_offset + x as usize;
let current = buffer[offset];
if current & 0xFF000000 == 0 {
// Overwrite if buffer empty
buffer[offset] = color;
} else {
let rb =
((n_alpha * (current & 0x00FF00FF)) + (alpha * (color & 0x00FF00FF))) >> 8;
let ag = (n_alpha * ((current & 0xFF00FF00) >> 8))
+ (alpha * (0x01000000 | ((color & 0x0000FF00) >> 8)));
buffer[offset] = (rb & 0x00FF00FF) | (ag & 0xFF00FF00);
let line_offset = y as usize * window.w as usize;
for x in screen.x..screen.x + offset.w {
if x < 0 || x >= window.w {
// Skip if x out of bounds
continue;
}
// Alpha blend with current value
let offset = line_offset + x as usize;
let current = buffer[offset];
if current & 0xFF000000 == 0 {
// Overwrite if buffer empty
buffer[offset] = color;
} else {
let rb = ((n_alpha * (current & 0x00FF00FF))
+ (alpha * (color & 0x00FF00FF)))
>> 8;
let ag = (n_alpha * ((current & 0xFF00FF00) >> 8))
+ (alpha * (0x01000000 | ((color & 0x0000FF00) >> 8)));
buffer[offset] = (rb & 0x00FF00FF) | (ag & 0xFF00FF00);
}
}
}
}