<!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>