Commit ecec98a3 authored by Robert O'Callahan's avatar Robert O'Callahan
Browse files

Bug 681192. Part 10: Control rounding direction of scaledOffset to try to make... 

Bug 681192. Part 10: Control rounding direction of scaledOffset to try to make the residual be close to mActiveScrolledRootPosition. r=tnikkel

--HG--
extra : rebase_source : f27fb737f8956ed117df0be3a71da847cc2048c0
parent bbb8c90a

layout/base/FrameLayerBuilder.cpp

+38 −4
Original line number Diff line number Diff line
@@ -934,8 +934,39 @@ GetTranslationForThebesLayer(ThebesLayer* aLayer) 
  return nsIntPoint(PRInt32(transform.x0), PRInt32(transform.y0));

}



static PRBool FuzzyEqual(gfxPoint aV1, gfxPoint aV2) {

  return fabs(aV2.x - aV1.x) < 0.02 && fabs(aV2.y - aV1.y) < 0.02;

static const double SUBPIXEL_OFFSET_EPSILON = 0.02;



static PRBool

SubpixelOffsetFuzzyEqual(gfxPoint aV1, gfxPoint aV2)

{

  return fabs(aV2.x - aV1.x) < SUBPIXEL_OFFSET_EPSILON &&

         fabs(aV2.y - aV1.y) < SUBPIXEL_OFFSET_EPSILON;

}



/**

 * This normally computes NSToIntRoundUp(aValue). However, if that would

 * give a residual near 0.5 while aOldResidual is near -0.5, or

 * it would give a residual near -0.5 while aOldResidual is near 0.5, then

 * instead we return the integer in the other direction so that the residual

 * is close to aOldResidual.

 */

static PRInt32

RoundToMatchResidual(double aValue, double aOldResidual)

{

  PRInt32 v = NSToIntRoundUp(aValue);

  double residual = aValue - v;

  if (aOldResidual < 0) {

    if (residual > 0 && fabs(residual - 1.0 - aOldResidual) < SUBPIXEL_OFFSET_EPSILON) {

      // Round up instead

      return PRInt32(ceil(aValue));

    }

  } else if (aOldResidual > 0) {

    if (residual < 0 && fabs(residual + 1.0 - aOldResidual) < SUBPIXEL_OFFSET_EPSILON) {

      // Round down instead

      return PRInt32(floor(aValue));

    }

  }

  return v;

}



already_AddRefed<ThebesLayer>
@@ -999,7 +1030,10 @@ ContainerState::CreateOrRecycleThebesLayer(nsIFrame* aActiveScrolledRoot) 
  gfxPoint scaledOffset(

      NSAppUnitsToDoublePixels(offset.x, appUnitsPerDevPixel)*mParameters.mXScale,

      NSAppUnitsToDoublePixels(offset.y, appUnitsPerDevPixel)*mParameters.mYScale);

  nsIntPoint pixOffset(NSToIntRoundUp(scaledOffset.x), NSToIntRoundUp(scaledOffset.y));

  // We call RoundToMatchResidual here so that the residual after rounding

  // is close to data->mActiveScrolledRootPosition if possible.

  nsIntPoint pixOffset(RoundToMatchResidual(scaledOffset.x, data->mActiveScrolledRootPosition.x),

                       RoundToMatchResidual(scaledOffset.y, data->mActiveScrolledRootPosition.y));

  gfxMatrix matrix;

  matrix.Translate(gfxPoint(pixOffset.x, pixOffset.y));

  layer->SetTransform(gfx3DMatrix::From2D(matrix));
@@ -1012,7 +1046,7 @@ ContainerState::CreateOrRecycleThebesLayer(nsIFrame* aActiveScrolledRoot) 
  // If it has changed, then we need to invalidate the entire layer since the

  // pixels in the layer buffer have the content at a (subpixel) offset

  // from what we need.

  if (!FuzzyEqual(activeScrolledRootTopLeft, data->mActiveScrolledRootPosition)) {

  if (!SubpixelOffsetFuzzyEqual(activeScrolledRootTopLeft, data->mActiveScrolledRootPosition)) {

    data->mActiveScrolledRootPosition = activeScrolledRootTopLeft;

    nsIntRect invalidate = layer->GetValidRegion().GetBounds();

    layer->InvalidateRegion(invalidate);

layout/base/tests/chrome/Makefile.in

+1 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ _CHROME_FILES = \ 
	test_printpreview_bug482976.xul \

	     printpreview_bug482976_helper.xul \

	test_transformed_scrolling_repaints.html \

	test_transformed_scrolling_repaints_2.html \

    $(NULL)



libs:: $(_CHROME_FILES)

layout/base/tests/chrome/test_transformed_scrolling_repaints_2.html

0 → 100644
+47 −0
Original line number Diff line number Diff line 
<!DOCTYPE HTML>

<html>

<head>

  <title>Test that scaled elements with scrolled contents don't repaint unnecessarily when we scroll inside them (1.1 scale)</title>

  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>

  <script type="text/javascript" src="paint_listener.js"></script>

  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>

</head>

<!-- Need a timeout here to allow paint unsuppression before we start the test -->

<body onload="setTimeout(startTest,0)">

<div id="t" style="-moz-transform: scale(1.1, 1.1); -moz-transform-origin:top left; width:200px; height:100px; background:yellow; overflow:hidden">

  <div style="height:40px;">Hello</div>

  <div id="e" style="height:30px; background:lime">Kitty</div>

  <div style="height:300px; 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 = window.QueryInterface(Components.interfaces.nsIInterfaceRequestor).

               getInterface(Components.interfaces.nsIDOMWindowUtils);



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 = 33;

        waitForAllPaintsFlushed(function () {

          var painted = utils.checkAndClearPaintedState(e);

          is(painted, false, "Fully-visible scrolled element should not have been painted");

          SimpleTest.finish();

        });

      });

    });

  });

}

</script>

</pre>

</body>

</html>