37 lines
1.3 KiB
HTML
37 lines
1.3 KiB
HTML
<!DOCTYPE html>
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<title>PNG test: tRNS chunk</title>
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<link rel="help" href="https://w3c.github.io/PNG-spec/#11tRNS">
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<script src="/resources/testharness.js"></script>
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<script src="/resources/testharnessreport.js"></script>
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<script src="/html/canvas/resources/canvas-tests.js"></script>
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<body>
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<h1>tRNS chunk handling</h1>
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<p class="desc">test ignored high bits on lower bit depth tRNS</p>
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<p class="output">Actual output:</p>
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<canvas id="c" class="output" width="100" height="50"><p class="fallback">FAIL (fallback content)</p></canvas>
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<ul id="d"></ul>
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<script>
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var t = async_test("test ignored high bits on lower bit depth tRNS");
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const img = new Image();
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img.onload = () => {
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_addTest(function(canvas, ctx) {
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ctx.drawImage(img, 0, 0);
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var pixel = ctx.getImageData(5, 5, 1, 1, {colorSpace: "srgb", storageFormat: "uint8"}).data;
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const pixel_expected = [255, 0, 0, 0];
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const epsilon = 2;
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_assertSame(pixel.length, pixel_expected.length, "pixel.length", "pixel_expected.length");
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// Ignore the color channel comparisons.
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// The image itself stores 255 red, 0 green, 0 blue.
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// But there may not be a requirement that this be preserved
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// while decoding or through canvas processing.
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assert_approx_equals(pixel[3], pixel_expected[3], epsilon);
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});
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};
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img.src = "support/trns-high-bits-set.png";
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</script>
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