test_bug1803209.html (1564B)
1 <!DOCTYPE HTML> 2 <html> 3 <head> 4 <script src="/tests/SimpleTest/SimpleTest.js"></script> 5 <script src="/tests/SimpleTest/EventUtils.js"></script> 6 <link rel="stylesheet" href="/tests/SimpleTest/test.css"/> 7 </head> 8 <body> 9 10 11 <style> 12 .box { 13 background: linear-gradient(90deg, rgba(256,0,0,1), rgba(256,0,0,1)); 14 background-attachment: fixed; 15 width: 25%; 16 height: 450px; 17 } 18 </style> 19 20 <div style="height: 1000vh;"></div> 21 <div class="box"></div> 22 23 24 25 <script> 26 SimpleTest.waitForExplicitFinish(); 27 28 add_task(async function() { 29 let utils = SpecialPowers.DOMWindowUtils; 30 31 let sc = document.getElementById("sc"); 32 let boundingClientRect = document.documentElement.getBoundingClientRect(); 33 34 let canvas = document.createElement("canvas"); 35 canvas.setAttribute("width", boundingClientRect.width); 36 canvas.setAttribute("height", boundingClientRect.height); 37 let ctx = canvas.getContext("2d"); 38 39 let rect = new window.DOMRect(boundingClientRect.x, boundingClientRect.y, 40 boundingClientRect.width, 41 boundingClientRect.height); 42 43 let image = await SpecialPowers.snapshotContext(window, rect, "rgb(255,255,255)"); 44 45 SpecialPowers.wrap(ctx).drawImage(image, 0, 0); 46 47 var data = ctx.getImageData(0, 0, boundingClientRect.width, boundingClientRect.height).data; 48 var foundRed = false; 49 for (var i = 0; i < data.length; i+=4) { 50 if (data[i] == 255 && data[i+1] == 0 && data[i+2] == 0 && data[i+3] == 255) { 51 foundRed = true; 52 break; 53 } 54 } 55 ok(foundRed, "found some red pixels"); 56 }); 57 </script> 58 </body> 59 </html>