third_party/WebKit/LayoutTests/fast/repaint/position-change-keeping-geometry.html

   1 <!DOCTYPE html>
   2 <script src="resources/text-based-repaint.js"></script>
   3 <script>
   4 function changePositionKeepingGeometry(id, newPosition) {
   5   var target = document.getElementById(id);
   6   var originalTop = target.offsetTop;
   7   var originalLeft = target.offsetLeft;
   8   target.style.position = newPosition;
   9   target.style.top = originalTop + 'px';
  10   target.style.left = originalLeft + 'px';
  11 }
  12
  13 function repaintTest()
  14 {
  15   changePositionKeepingGeometry('target1', 'absolute');
  16   changePositionKeepingGeometry('target2', 'absolute');
  17   changePositionKeepingGeometry('target3', 'fixed');
  18 }
  19 onload = runRepaintTest;
  20 </script>
  21 <style>
  22 body {
  23   margin: 0;
  24 }
  25 div {
  26   width: 100px;
  27   height: 100px;
  28   top: 20px;
  29   background-color: blue;
  30 }
  31 #target0 {
  32   left: 20px;
  33   position: relative;
  34 }
  35 #target1 {
  36   left: 20px;
  37   position: relative;
  38 }
  39 #target2 {
  40   left: 220px;
  41   position: fixed;
  42   z-index: 0;
  43 }
  44 #target3 {
  45   left: 420px;
  46   position: absolute;
  47   z-index: 0;
  48 }
  49 </style>
  50 There should be no invalildations on change of position without actual change of position and size.
  51 <!-- target0 ensures we don't strip anonymous wrappers (and trigger a layout) when the other elements change position. -->
  52 <div id="target0"></div>
  53 <div id="target1"></div>
  54 <div id="target2"></div>
  55 <div id="target3"></div>