2d.composite.globalAlpha.range.html (1237B)
1 <!DOCTYPE html> 2 <!-- DO NOT EDIT! This test has been generated by /html/canvas/tools/gentest.py. --> 3 <meta charset="UTF-8"> 4 <title>OffscreenCanvas test: 2d.composite.globalAlpha.range</title> 5 <script src="/resources/testharness.js"></script> 6 <script src="/resources/testharnessreport.js"></script> 7 <script src="/html/canvas/resources/canvas-tests.js"></script> 8 9 <h1>2d.composite.globalAlpha.range</h1> 10 <p class="desc"></p> 11 12 13 <script> 14 var t = async_test(""); 15 var t_pass = t.done.bind(t); 16 var t_fail = t.step_func(function(reason) { 17 throw reason; 18 }); 19 t.step(function() { 20 21 var canvas = new OffscreenCanvas(100, 50); 22 var ctx = canvas.getContext('2d'); 23 24 ctx.globalAlpha = 0.5; 25 // This may not set it to exactly 0.5 if it is rounded/quantised, so 26 // remember for future comparisons. 27 var a = ctx.globalAlpha; 28 _assertSame(ctx.globalAlpha, a, "ctx.globalAlpha", "a"); 29 ctx.globalAlpha = 1.1; 30 _assertSame(ctx.globalAlpha, a, "ctx.globalAlpha", "a"); 31 ctx.globalAlpha = -0.1; 32 _assertSame(ctx.globalAlpha, a, "ctx.globalAlpha", "a"); 33 ctx.globalAlpha = 0; 34 _assertSame(ctx.globalAlpha, 0, "ctx.globalAlpha", "0"); 35 ctx.globalAlpha = 1; 36 _assertSame(ctx.globalAlpha, 1, "ctx.globalAlpha", "1"); 37 t.done(); 38 39 }); 40 </script>