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feat: add PNG encoding progress bar

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surv
2026-09-15 10:42:39 +02:00
parent a7a34adff2
commit f9a51fd2d7
4 changed files with 160 additions and 66 deletions
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src/fractal/renderer.rs
+28 -20
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@@ -418,40 +418,48 @@ impl FractalRenderer {
}
/// Convert a padded BGRA/RGBA readback into tightly-packed RGBA8 and encode it
/// as PNG bytes.
pub fn encode_png(
/// as PNG bytes, reporting progress in `[0, 1]` via `on_progress` as rows are
/// streamed to the compressor (encoding is the slow, subdividable phase).
pub fn encode_png_with_progress(
padded: &[u8],
width: u32,
height: u32,
padded_bpr: u32,
swap_rb: bool,
mut on_progress: impl FnMut(f32),
) -> Vec<u8> {
let row = (width * 4) as usize;
let mut rgba = vec![0u8; row * height as usize];
for y in 0..height as usize {
let src_off = y * padded_bpr as usize;
let src = &padded[src_off..src_off + row];
let dst = &mut rgba[y * row..y * row + row];
if swap_rb {
for x in 0..width as usize {
dst[x * 4] = src[x * 4 + 2];
dst[x * 4 + 1] = src[x * 4 + 1];
dst[x * 4 + 2] = src[x * 4];
dst[x * 4 + 3] = src[x * 4 + 3];
}
} else {
dst.copy_from_slice(src);
}
}
use std::io::Write as _;
let row = (width * 4) as usize;
let mut out = Vec::new();
{
let mut encoder = png::Encoder::new(&mut out, width, height);
encoder.set_color(png::ColorType::Rgba);
encoder.set_depth(png::BitDepth::Eight);
let mut writer = encoder.write_header().expect("png header");
writer.write_image_data(&rgba).expect("png data");
let mut stream = writer.stream_writer().expect("png stream");
let mut line = vec![0u8; row];
for y in 0..height as usize {
let src_off = y * padded_bpr as usize;
let src = &padded[src_off..src_off + row];
if swap_rb {
for x in 0..width as usize {
line[x * 4] = src[x * 4 + 2];
line[x * 4 + 1] = src[x * 4 + 1];
line[x * 4 + 2] = src[x * 4];
line[x * 4 + 3] = src[x * 4 + 3];
}
stream.write_all(&line).expect("png data");
} else {
stream.write_all(src).expect("png data");
}
if y % 64 == 0 {
on_progress(y as f32 / height as f32);
}
}
stream.finish().expect("png finish");
}
on_progress(1.0);
out
}