1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
|
// META: global=window,dedicatedworker
function makeRGBACanvas() {
let canvas = new OffscreenCanvas(32, 32, {alpha: true});
let ctx = canvas.getContext('2d');
// Opaque red quadrant.
ctx.fillStyle = 'rgba(255, 0, 0, 255)';
ctx.fillRect(0, 0, 16, 16);
// Opaque blue quadrant.
ctx.fillStyle = 'rgba(0, 255, 0, 255)';
ctx.fillRect(16, 0, 16, 16);
// Opaque green quadrant.
ctx.fillStyle = 'rgba(0, 0, 255, 255)';
ctx.fillRect(0, 16, 16, 16);
// Remaining quadrant should be transparent black.
return canvas;
}
function getPixel(ctx, x, y) {
let data = ctx.getImageData(x, y, 1, 1).data;
return data[0] * 2 ** 24 + data[1] * 2 ** 16 + data[2] * 2 ** 8 + data[3];
}
function verifyPicture(picture) {
let canvas = new OffscreenCanvas(32, 32, {alpha: true});
let ctx = canvas.getContext('2d');
ctx.drawImage(picture, 0, 0);
assert_equals(getPixel(ctx, 8, 8), 0xFF0000FF);
assert_equals(getPixel(ctx, 24, 8), 0x00FF00FF);
assert_equals(getPixel(ctx, 8, 24), 0x0000FFFF);
assert_equals(getPixel(ctx, 24, 24), 0x00000000);
}
promise_test(async () => {
let src = makeRGBACanvas();
let frame = new VideoFrame(src, {alpha: 'keep', timestamp: 0});
verifyPicture(frame);
verifyPicture(await createImageBitmap(frame));
}, 'OffscreenCanvas source preserves alpha');
promise_test(async () => {
let src = makeRGBACanvas().transferToImageBitmap();
let frame = new VideoFrame(src, {alpha: 'keep', timestamp: 0});
verifyPicture(frame);
verifyPicture(await createImageBitmap(frame));
}, 'ImageBitmap source preserves alpha');
|
