Chromium Code Reviews Chromium Code Reviews
Issue 2359843003:
Turning on clip anti-aliasing by default in Chrome. (Closed)
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| (Empty) | |
| 1 <!DOCTYPE html> | |
| 2 | |
| 3 <script src="../../resources/testharness.js"></script> | |
| 4 <script src="../../resources/testharnessreport.js"></script> | |
| 5 <canvas id="myCanvas" width="240" height="240" style="border:1px solid #d3d3d3;" ></canvas> | |
| 6 | |
| 7 <script> | |
| 8 | |
| 9 test(function() { | |
| 10 var c = document.getElementById("myCanvas"); | |
| 11 var ctx = c.getContext("2d"); | |
| 12 | |
| 13 ctx.beginPath(); | |
| 14 ctx.moveTo(120, 20); | |
| 15 ctx.lineTo(220, 120); | |
| 16 ctx.lineTo(120, 220); | |
| 17 ctx.lineTo(20, 120); | |
| 18 ctx.lineTo(120, 20); | |
| 19 ctx.closePath(); | |
| 20 ctx.clip(); | |
| 21 | |
| 22 ctx.lineWidth = 1; | |
| 23 ctx.strokeStyle="#FF0000"; | |
| 24 ctx.stroke(); | |
| 25 | |
| 26 // Verifies that a stroke inside a clip of the same path displays correctly. | |
| 27 // Some sides of the shape may be clipped-out if stroking is anti-aliased | |
| 28 // but not clipping, or if clipping it is not properly aligned. | |
| 29 // We check pixels located on the vertices and in the middle of each edge. | |
| 30 var pixels = [ [120, 20], [170, 70], [220, 120], [170, 170], | |
| 31 [120, 220], [70, 170], [20, 120], [70, 70] ]; | |
| 32 | |
| 33 // There can be false alarms if we look at the exact points (specially the | |
| 34 // vertices) as the anti-aliasing algorithm may find it enough to draw some | |
| 35 // surrounding points. Therefore, we look at a 3x3 rectangle surrounding | |
| 36 // each point. | |
| 37 for(i = 0; i < 8; i++) { | |
| 38 var pixelDrawn = false; | |
| 39 for(j = -1; j <=1; j++) { | |
| 40 for(k = -1; k <=1; k++) { | |
| 41 var colorData = ctx.getImageData(pixels[i][0] + j, pixels[i][1] + k, 1, 1).data; | |
| 42 if(colorData[0] == 255 && colorData[3] > 0) { | |
| 43 pixelDrawn = true; | |
| 44 } | |
| 45 } | |
| 46 } | |
| 47 | |
| 48 assert_equals(pixelDrawn, true); | |
| 49 } | |
| 50 | |
| 51 }, 'canvas-2d-clip-anti-aliasing should not return any error'); | |
|
Justin Novosad
2016/09/22 19:56:48
This string needs to be more descriptive. What is
zakerinasab
2016/09/22 20:09:24
Done.
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| 52 | |
| 53 </script> | |
| 54 | |
| 55 | |
| 56 | |
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