| <!DOCTYPE html> |
| <title>Test using a placeholder canvas as an image source.</title> |
| <script src="../../resources/testharness.js"></script> |
| <script src="../../resources/testharnessreport.js"></script> |
| |
| <script> |
| var t = async_test("Test that using a placeholder canvas as a source image accesses the image that was committed to the associated OffscreenCanvas."); |
| var canvas = document.createElement('canvas'); |
| canvas.width = 100; |
| canvas.height = 100; |
| var offscreen = canvas.transferControlToOffscreen(); |
| |
| var ctx = offscreen.getContext('2d'); |
| ctx.fillStyle = '#0f0'; |
| ctx.fillRect(0, 0, 100, 100); |
| ctx.commit(); |
| verifyImage(canvas, [0, 0, 0, 0], "Verify that OffscreenCanvas.commit() does not propagate the image synchronously to the placeholder canvas."); |
| |
| setTimeout(function() { |
| // setTimeout is a synchronization barrier that guarantees |
| // that the offscreen commit has been processed by the event loop, |
| // as long as the timeout event is queued after the call to commit(). |
| var green = [0, 255, 0, 255]; |
| verifyImage(canvas, green, "verify that drawImage works with placeholder canvas as a source."); |
| var testImage = new Image(); |
| testImage.src = canvas.toDataURL(); |
| testImage.onload = function() { |
| verifyImage(canvas, green, "verify that toDataURL works on placeholder canvas."); |
| canvas.toBlob(blob => { |
| createImageBitmap(blob).then(image => { |
| verifyImage(image, green, "verify that toBlob works on placeholder canvas."); |
| t.done(); |
| }) |
| }); |
| } |
| }, 0); |
| |
| function verifyImage(image, expectedColor, description) { |
| var testCanvas = document.createElement('canvas'); |
| var testCtx = testCanvas.getContext('2d'); |
| testCtx.drawImage(image, 0, 0); |
| |
| t.step(function() { |
| var pixel = testCtx.getImageData(50, 50, 1, 1).data; |
| assert_array_equals(pixel, expectedColor, description); |
| }); |
| } |
| </script> |