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

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--HG--
extra : rebase_source : f27fb737f8956ed117df0be3a71da847cc2048c0
This commit is contained in:
Robert O'Callahan 2012-05-10 17:24:20 +12:00
parent bbb8c90aac
commit ecec98a34e
3 changed files with 86 additions and 4 deletions
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42
layout/base/FrameLayerBuilder.cpp
View File

@ -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);

1
layout/base/tests/chrome/Makefile.in
View File

@ -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)

47
layout/base/tests/chrome/test_transformed_scrolling_repaints_2.html Normal file
View File

@ -0,0 +1,47 @@
<!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>