| <!doctype HTML> |
| <html> |
| <head> |
| <title>HTML5 Canvas Test: createlinearGradient() with two points same</title> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <link rel="author" title="Microsoft" href="http://www.microsoft.com" /> |
| <link rel="help" href="http://www.w3.org/TR/2dcontext/#dom-context-2d-createlineargradient" /> |
| <meta name="assert" content="If the two points in a linear gradient have identical x,y coordinates, the canvas must paint nothing." /> |
| <script type="text/javascript"> |
| async_test(function(t) { |
| window.addEventListener("load", t.step_func_done(function runTest() { |
| var canvas = document.getElementById("canvas1"); |
| var ctx = canvas.getContext("2d"); |
| var width = canvas.width; |
| var height = canvas.height; |
| |
| // Start by drawing a left to right, green-to-blue linear gradient. |
| var lingrad = ctx.createLinearGradient(0, 50, 100, 50); |
| lingrad.addColorStop(0, "rgba(0, 255, 0, 1.0)"); |
| lingrad.addColorStop(1, "rgba(0, 0, 255, 1.0)"); |
| ctx.fillStyle = lingrad; |
| ctx.fillRect(0, 0, 100, 50); |
| |
| // Get the current state of the canvas |
| var initial = ctx.getImageData(0, 0, width, height); |
| |
| // Nothing must be drawn if the two points in the linear gradient are the same. |
| lingrad = ctx.createLinearGradient(100, 100, 100, 100); |
| lingrad.addColorStop(0, "rgba(255, 0, 0, 1.0)"); |
| lingrad.addColorStop(1, "rgba(255, 0, 0, 1.0)"); |
| ctx.fillStyle = lingrad; |
| ctx.fillRect(0, 0, 300, 150); |
| |
| // Check that nothing is drawn. |
| var after = ctx.getImageData(0, 0, width, height); |
| |
| // Asserts |
| assert_equals(initial.width, after.width, "widths are equal"); |
| assert_equals(initial.height, after.height, "heights are equal"); |
| assert_array_equals(initial.data, after.data, "data are equal"); |
| |
| for (var i = 0; i < after.data.length; i += 4) { |
| var r = after.data[i]; |
| var g = after.data[i+1]; |
| var b = after.data[i+2]; |
| var a = after.data[i+3]; |
| assert_false(r == 0xFF && g == 0 && b == 0 && a == 0xFF, "no red"); |
| } |
| })); |
| }, "linear gradient from point to self draws nothing"); |
| </script> |
| </head> |
| <body> |
| <p>Description: If the two points in a linear gradient have identical x,y coordinates, the canvas must paint nothing.</p> |
| <p>Test passes if there is one left-to-right, green-to-blue linear gradient seen on the page and no red is seen on the page.</p> |
| <canvas id="canvas1" width="300" height="150">Browser does not support HTML5 Canvas.</canvas> |
| </body> |
| </html> |
