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Abstract some stuff common to ctx.getImageData and ctx.putImageData

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This commit is contained in:
Anthony Ramine 2018-10-08 11:09:38 +02:00
parent e62dbabb46
commit 77c28bdfc9
4 changed files with 97 additions and 147 deletions
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199
components/script/dom/canvasrenderingcontext2d.rs
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@ -1130,13 +1130,7 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
}
// https://html.spec.whatwg.org/multipage/#dom-context-2d-getimagedata
fn GetImageData(
&self,
mut sx: i32,
mut sy: i32,
mut sw: i32,
mut sh: i32,
) -> Fallible<DomRoot<ImageData>> {
fn GetImageData(&self, sx: i32, sy: i32, sw: i32, sh: i32) -> Fallible<DomRoot<ImageData>> {
// FIXME(nox): There are many arithmetic operations here that can
// overflow or underflow, this should probably be audited.
@ -1148,57 +1142,30 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
return Err(Error::Security);
}
if sw < 0 {
sw = -sw;
sx -= sw;
}
if sh < 0 {
sh = -sh;
sy -= sh;
}
let data_width = sw;
let data_height = sh;
if sx < 0 {
sw += sx;
sx = 0;
}
if sy < 0 {
sh += sy;
sy = 0;
}
if sw <= 0 || sh <= 0 {
// All the pixels are before the start of the canvas surface.
return ImageData::new(&self.global(), data_width as u32, data_height as u32, None);
}
let (sender, receiver) = ipc::bytes_channel().unwrap();
let src_rect = Rect::new(Point2D::new(sx, sy), Size2D::new(sw, sh));
let (origin, size) = adjust_size_sign(Point2D::new(sx, sy), Size2D::new(sw, sh));
// 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())
.try_cast().unwrap();
let canvas_rect = Rect::from_size(canvas_size);
let read_rect = match src_rect.intersection(&canvas_rect) {
Some(rect) if !rect.is_empty() => rect,
_ => {
// All the pixels are past the end of the canvas surface.
return ImageData::new(&self.global(), data_width as u32, data_height as u32, None);
}
let canvas_size = self.canvas.as_ref().map_or(Size2D::zero(), |c| c.get_size());
let read_rect = match clip(origin, size, canvas_size) {
Some(rect) => rect,
None => {
// All the pixels are outside the canvas surface.
return ImageData::new(&self.global(), size.width, size.height, None);
},
};
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();
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(), sw as u32, sh as u32, Some(pixels.to_vec()))
ImageData::new(&self.global(), size.width, size.height, Some(pixels))
}
// https://html.spec.whatwg.org/multipage/#dom-context-2d-putimagedata
@ -1213,17 +1180,17 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
imagedata: &ImageData,
dx: i32,
dy: i32,
mut dirty_x: i32,
mut dirty_y: i32,
mut dirty_width: i32,
mut dirty_height: i32,
dirty_x: i32,
dirty_y: i32,
dirty_width: i32,
dirty_height: i32,
) {
// FIXME(nox): There are many arithmetic operations here that can
// overflow or underflow, this should probably be audited.
let imagedata_size = Size2D::new(imagedata.Width() as i32, imagedata.Height() as i32);
if imagedata_size.width <= 0 || imagedata_size.height <= 0 {
let imagedata_size = Size2D::new(imagedata.Width(), imagedata.Height());
if imagedata_size.area() == 0 {
return;
}
@ -1233,76 +1200,37 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
// Step 2.
// TODO: throw InvalidState if buffer is detached.
// Step 3.
if dirty_width < 0 {
dirty_x += dirty_width;
dirty_width = -dirty_width;
}
if dirty_height < 0 {
dirty_y += dirty_height;
dirty_height = -dirty_height;
}
// Ignore any pixel that would be drawn before the beginning of the
// canvas surface.
let mut dest_x = dx + dirty_x;
let mut dest_y = dy + dirty_y;
if dest_x < 0 {
dirty_x -= dest_x;
dirty_width += dest_x;
dest_x = 0;
}
if dest_y < 0 {
dirty_y -= dest_y;
dirty_height += dest_y;
dest_y = 0;
}
// Step 4.
if dirty_x < 0 {
dirty_width += dirty_x;
dirty_x = 0;
}
if dirty_y < 0 {
dirty_height += dirty_y;
dirty_y = 0;
}
// Step 5.
if dirty_x + dirty_width > imagedata_size.width {
dirty_width = imagedata_size.width - dirty_x;
}
if dirty_y + dirty_height > imagedata_size.height {
dirty_height = imagedata_size.height - dirty_y;
}
// 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()).to_i32();
let origin = Point2D::new(dest_x, dest_y);
let drawable_size = (origin - canvas_size.to_vector().to_point()).to_size().abs();
let canvas_size = self.canvas.as_ref().map_or(Size2D::zero(), |c| c.get_size());
// We take care of ignoring any pixel that would be drawn after the end
// of the canvas surface.
dirty_width = dirty_width.min(drawable_size.width);
dirty_height = dirty_height.min(drawable_size.height);
// Step 6.
if dirty_width <= 0 || dirty_height <= 0 {
return;
}
let dirty_size = Size2D::new(dirty_width, dirty_height);
let dirty_rect = Rect::new(Point2D::new(dirty_x, dirty_y), dirty_size);
// Steps 3-6.
let (src_origin, src_size) = adjust_size_sign(
Point2D::new(dirty_x, dirty_y),
Size2D::new(dirty_width, dirty_height),
);
let src_rect = match clip(src_origin, src_size, imagedata_size) {
Some(rect) => rect,
None => return,
};
let (dst_origin, _) = adjust_size_sign(
Point2D::new(dirty_x.saturating_add(dx), dirty_y.saturating_add(dy)),
Size2D::new(dirty_width, dirty_height),
);
// By clipping to the canvas surface, we avoid sending any pixel
// that would fall outside it.
let dst_rect = match clip(dst_origin, src_rect.size, canvas_size) {
Some(rect) => rect,
None => return,
};
// Step 7.
let (sender, receiver) = ipc::bytes_channel().unwrap();
self.send_canvas_2d_msg(Canvas2dMsg::PutImageData(
receiver,
origin.to_vector(),
dirty_size,
));
sender.send(unsafe { &imagedata.get_rect(dirty_rect.try_cast().unwrap()) }).unwrap();
let pixels = unsafe {
&imagedata.get_rect(Rect::new(src_rect.origin, dst_rect.size))
};
self.send_canvas_2d_msg(Canvas2dMsg::PutImageData(dst_rect, receiver));
sender.send(pixels).unwrap();
self.mark_as_dirty();
}
@ -1552,7 +1480,7 @@ fn is_rect_valid(rect: Rect<f64>) -> bool {
rect.size.width > 0.0 && rect.size.height > 0.0
}
// https://html.spec.whatwg.org/multipage/#serialisation-of-a-colour
// https://html.spec.whatwg.org/multipage/#serialisation-of-a-color
fn serialize<W>(color: &RGBA, dest: &mut W) -> fmt::Result
where
W: fmt::Write,
@ -1583,3 +1511,36 @@ where
)
}
}
fn adjust_size_sign(
mut origin: Point2D<i32>,
mut size: Size2D<i32>,
) -> (Point2D<i32>, Size2D<u32>) {
if size.width < 0 {
size.width = -size.width;
origin.x = origin.x.saturating_sub(size.width);
}
if size.height < 0 {
size.height = -size.height;
origin.y = origin.y.saturating_sub(size.height);
}
(origin, size.to_u32())
}
fn clip(
mut origin: Point2D<i32>,
mut size: Size2D<u32>,
surface: Size2D<u32>,
) -> Option<Rect<u32>> {
if origin.x < 0 {
size.width = size.width.saturating_sub(-origin.x as u32);
origin.x = 0;
}
if origin.y < 0 {
size.height = size.height.saturating_sub(-origin.y as u32);
origin.y = 0;
}
Rect::new(origin.to_u32(), size)
.intersection(&Rect::from_size(surface))
.filter(|rect| !rect.is_empty())
}