third_party/WebKit/LayoutTests/fast/scrolling/scrolling-apis-subpixel.html

   1 <!DOCTYPE html>
   2 <style>
   3 .spacer {
   4   height: 1000px;
   5   width: 1000px;
   6 }
   7 #scroller, body {
   8   height: 100px;
   9   width: 100px;
  10   overflow: scroll;
  11 }
  12
  13 </style>
  14 <body class=scroller>
  15 <div id=console></div>
  16
  17 <div id=scroller>
  18     <div class=spacer></div>
  19 </div>
  20 <div class=spacer></div>
  21 </body>
  22
  23 <script src="../../resources/js-test.js"></script>
  24 <script>
  25
  26 description("Verifies that scrolling APIs support fractional offsets.");
  27 // Note we current support fractional scrolling only for the special case of
  28 // browser zoom.  When http://crbug.com/414283 is fixed, we should test
  29 // other cases like device scale.
  30
  31 // FIXME: Make this smaller. crbug.com/414283.
  32 var floatPrecision = 0.01;
  33
  34 function testScroll(scrollOffset, expectedScrollOffset) {
  35
  36     debug('Scrolling DIV with scrollTop/scrollLeft');
  37     scroller.scrollTop = scrollOffset;
  38     shouldBeCloseTo('scroller.scrollTop', expectedScrollOffset, floatPrecision);
  39     scroller.scrollLeft = scrollOffset;
  40     shouldBeCloseTo('scroller.scrollLeft', expectedScrollOffset, floatPrecision);
  41
  42     // Note that the body element is a special case - we don't attempt to
  43     // test it here as it's semantics are in flux (http://goo.gl/BFHtMR).
  44
  45     debug('Scrolling the document with window.scroll');
  46     window.scroll(0,0);
  47     scrollOffset++;
  48     expectedScrollOffset++;
  49     window.scroll(scrollOffset, scrollOffset);
  50     shouldBeCloseTo('window.scrollY', expectedScrollOffset, floatPrecision);
  51     shouldBeCloseTo('window.scrollX', expectedScrollOffset, floatPrecision);
  52
  53     debug('Scrolling the document with window.scrollTo');
  54     window.scroll(0,0);
  55     window.scrollTo(scrollOffset, scrollOffset);
  56     shouldBeCloseTo('window.pageYOffset', expectedScrollOffset, floatPrecision);
  57     shouldBeCloseTo('window.pageXOffset', expectedScrollOffset, floatPrecision);
  58
  59     debug('Scrolling the document with window.scrollBy');
  60     window.scroll(1,1);
  61     window.scrollBy(scrollOffset - 1, scrollOffset - 1);
  62     shouldBeCloseTo('window.scrollY', expectedScrollOffset, floatPrecision);
  63     shouldBeCloseTo('window.scrollX', expectedScrollOffset, floatPrecision);
  64
  65     debug('');
  66 }
  67
  68 function testPageZoom(zoom) {
  69     debug('---- Testing page zoom = ' + zoom + ' ----');
  70     eventSender.setPageZoomFactor(zoom);
  71     testScroll(4, 4);
  72     testScroll(4.5, 4.5);
  73 }
  74
  75 debug("set PreferCompositingToLCDTextEnabled true");
  76 window.internals.settings.setPreferCompositingToLCDTextEnabled(true);
  77 testScroll(4.2, 4.2);
  78 testPageZoom(2);
  79
  80 // If there is no browser zoom, floating point scroll offsets are truncated.
  81 // If there is browser zoom, we can still get fractional scroll offsets
  82 // through JS.
  83 debug("set PreferCompositingToLCDTextEnabled false");
  84 window.internals.settings.setPreferCompositingToLCDTextEnabled(false);
  85 testScroll(4.2, 4);
  86 testPageZoom(2);
  87 </script>