| // 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'); |