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Avoid ctx.getImageData in canvas.toDataURL

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This commit is contained in:
Anthony Ramine 2018-10-08 12:19:10 +02:00
parent 77c28bdfc9
commit 551c405b0f
2 changed files with 29 additions and 22 deletions
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35
components/script/dom/canvasrenderingcontext2d.rs
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@ -575,6 +575,28 @@ impl CanvasRenderingContext2D {
fn set_origin_unclean(&self) {
self.origin_clean.set(false)
}
pub fn get_rect(&self, rect: Rect<u32>) -> Vec<u8> {
assert!(self.origin_is_clean());
// FIXME(nox): This is probably wrong when this is a context for an
// offscreen canvas.
let canvas_size = self.canvas.as_ref().map_or(Size2D::zero(), |c| c.get_size());
assert!(Rect::from_size(canvas_size).contains_rect(&rect));
let (sender, receiver) = ipc::bytes_channel().unwrap();
self.send_canvas_2d_msg(Canvas2dMsg::GetImageData(rect, canvas_size, sender));
let mut pixels = receiver.recv().unwrap().to_vec();
for chunk in pixels.chunks_mut(4) {
let b = chunk[0];
chunk[0] = UNPREMULTIPLY_TABLE[256 * (chunk[3] as usize) + chunk[2] as usize];
chunk[1] = UNPREMULTIPLY_TABLE[256 * (chunk[3] as usize) + chunk[1] as usize];
chunk[2] = UNPREMULTIPLY_TABLE[256 * (chunk[3] as usize) + b as usize];
}
pixels
}
}
pub trait LayoutCanvasRenderingContext2DHelpers {
@ -1154,18 +1176,7 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
},
};
let (sender, receiver) = ipc::bytes_channel().unwrap();
self.send_canvas_2d_msg(Canvas2dMsg::GetImageData(read_rect, canvas_size, sender));
let mut pixels = receiver.recv().unwrap().to_vec();
for chunk in pixels.chunks_mut(4) {
let b = chunk[0];
chunk[0] = UNPREMULTIPLY_TABLE[256 * (chunk[3] as usize) + chunk[2] as usize];
chunk[1] = UNPREMULTIPLY_TABLE[256 * (chunk[3] as usize) + chunk[1] as usize];
chunk[2] = UNPREMULTIPLY_TABLE[256 * (chunk[3] as usize) + b as usize];
}
ImageData::new(&self.global(), size.width, size.height, Some(pixels))
ImageData::new(&self.global(), size.width, size.height, Some(self.get_rect(read_rect)))
}
// https://html.spec.whatwg.org/multipage/#dom-context-2d-putimagedata