| <!DOCTYPE html> |
| <title>PNG test: tRNS chunk</title> |
| <link rel="help" href="https://w3c.github.io/PNG-spec/#11tRNS"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <script src="/html/canvas/resources/canvas-tests.js"></script> |
| <body> |
| |
| <h1>tRNS chunk handling</h1> |
| <p class="desc">test ignored high bits on lower bit depth tRNS</p> |
| |
| <p class="output">Actual output:</p> |
| <canvas id="c" class="output" width="100" height="50"><p class="fallback">FAIL (fallback content)</p></canvas> |
| |
| <ul id="d"></ul> |
| <script> |
| var t = async_test("test ignored high bits on lower bit depth tRNS"); |
| const img = new Image(); |
| img.onload = () => { |
| _addTest(function(canvas, ctx) { |
| ctx.drawImage(img, 0, 0); |
| |
| var pixel = ctx.getImageData(5, 5, 1, 1, {colorSpace: "srgb"}).data; |
| |
| const pixel_expected = [255, 0, 0, 0]; |
| const epsilon = 2; |
| |
| _assertSame(pixel.length, pixel_expected.length, "pixel.length", "pixel_expected.length"); |
| // Ignore the color channel comparisons. |
| // The image itself stores 255 red, 0 green, 0 blue. |
| // But there may not be a requirement that this be preserved |
| // while decoding or through canvas processing. |
| assert_approx_equals(pixel[3], pixel_expected[3], epsilon); |
| }); |
| }; |
| img.src = "support/trns-high-bits-set.png"; |
| </script> |
