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Make remove_premultiplied_alpha mutate its input

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This commit is contained in:
Anthony Ramine 2018-09-08 13:11:53 +02:00
parent 1864edbb36
commit a5f9d03229
1 changed files with 15 additions and 16 deletions
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31
components/script/dom/webglrenderingcontext.rs
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@ -871,21 +871,6 @@ impl WebGLRenderingContext {
} }
} }
// Remove premultiplied alpha.
// This is only called when texImage2D is called using a canvas2d source and
// UNPACK_PREMULTIPLY_ALPHA_WEBGL is disabled. Pixels got from a canvas2D source
// are always RGBA8 with premultiplied alpha, so we don't have to worry about
// additional formats as happens in the premultiply_pixels method.
fn remove_premultiplied_alpha(&self, mut pixels: Vec<u8>) -> Vec<u8> {
for rgba in pixels.chunks_mut(4) {
let a = (rgba[3] as f32) / 255.0;
rgba[0] = (rgba[0] as f32 / a) as u8;
rgba[1] = (rgba[1] as f32 / a) as u8;
rgba[2] = (rgba[2] as f32 / a) as u8;
}
pixels
}
fn prepare_pixels(&self, fn prepare_pixels(&self,
internal_format: TexFormat, internal_format: TexFormat,
data_type: TexDataType, data_type: TexDataType,
@ -904,7 +889,7 @@ impl WebGLRenderingContext {
self.premultiply_pixels(internal_format, data_type, &mut pixels); self.premultiply_pixels(internal_format, data_type, &mut pixels);
} }
} else if source_premultiplied && !dest_premultiply { } else if source_premultiplied && !dest_premultiply {
pixels = self.remove_premultiplied_alpha(pixels); remove_premultiplied_alpha(&mut pixels);
} }
if source_from_image_or_canvas { if source_from_image_or_canvas {
@ -4194,3 +4179,17 @@ impl TextureUnit {
None None
} }
} }
// Remove premultiplied alpha.
// This is only called when texImage2D is called using a canvas2d source and
// UNPACK_PREMULTIPLY_ALPHA_WEBGL is disabled. Pixels got from a canvas2D source
// are always RGBA8 with premultiplied alpha, so we don't have to worry about
// additional formats as happens in the premultiply_pixels method.
fn remove_premultiplied_alpha(pixels: &mut [u8]) {
for rgba in pixels.chunks_mut(4) {
let a = (rgba[3] as f32) / 255.0;
rgba[0] = (rgba[0] as f32 / a) as u8;
rgba[1] = (rgba[1] as f32 / a) as u8;
rgba[2] = (rgba[2] as f32 / a) as u8;
}
}