1 files changed, 50 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webcodecs/videoFrame-alpha.any.js b/testing/web-platform/tests/webcodecs/videoFrame-alpha.any.js
new file mode 100644
index 0000000000..f4c4dfa737
--- /dev/null
+++ b/testing/web-platform/tests/webcodecs/videoFrame-alpha.any.js
@@ -0,0 +1,50 @@
+// 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');