<!DOCTYPE HTML> <html> <head> <title>Test that scaled elements with scrolled contents don't repaint unnecessarily when we scroll inside them</title> <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script> <script type="text/javascript" src="/tests/SimpleTest/paint_listener.js"></script> <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/> </head> <body onload="setPrefAndStartTest()"> <div id="t" style="-moz-transform: scale(1.2, 1.2); -moz-transform-origin:top left; width:200px; height:500px; background:yellow; overflow:auto"> <div style="height:40px;">Hello</div> <div id="e" style="height:30px; background:lime">Kitty</div> <div style="height:800px; background:yellow">Kitty</div> </div> <pre id="test"> <script type="application/javascript"> SimpleTest.waitForExplicitFinish(); var t = document.getElementById("t"); var e = document.getElementById("e"); var utils = SpecialPowers.getDOMWindowUtils(window); function startTest() { // Do a couple of scrolls to ensure we've triggered activity heuristics. waitForAllPaintsFlushed(function () { t.scrollTop = 5; waitForAllPaintsFlushed(function () { t.scrollTop = 10; waitForAllPaintsFlushed(function () { // Clear paint state now and scroll again. utils.checkAndClearPaintedState(e); t.scrollTop = 15; waitForAllPaintsFlushed(function () { var painted = utils.checkAndClearPaintedState(e); is(painted, false, "Fully-visible scrolled element should not have been painted"); SimpleTest.finish(); }); }); }); }); } function setPrefAndStartTest() { SpecialPowers.pushPrefEnv( {"set": [["layers.single-tile.enabled", false]]}, // Need a timeout here to allow paint unsuppression before we start the test function() { setTimeout(startTest, 0); } ); } </script> </pre> </body> </html>