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Bug 941220 - Avoid calling GetVisualOverflowRectRelativeToSelf() multiple times to improve performance. r=roc

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This commit is contained in:
Mats Palmgren 2013-11-23 21:47:26 +00:00
parent afa0ccbf61
commit fa7dbb19d0
1 changed files with 15 additions and 15 deletions
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30
layout/generic/nsFrame.cpp
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@ -1812,32 +1812,32 @@ nsIFrame::BuildDisplayListForStackingContext(nsDisplayListBuilder* aBuilder,
aBuilder->SetContainsBlendMode(false);
if (isTransformed) {
const nsRect overflow = GetVisualOverflowRectRelativeToSelf();
if (aBuilder->IsForPainting() &&
nsDisplayTransform::ShouldPrerenderTransformedContent(aBuilder, this)) {
dirtyRect = GetVisualOverflowRectRelativeToSelf();
dirtyRect = overflow;
} else {
// Trying to back-transform arbitrary rects gives us really weird results. I believe
// this is from points that lie beyond the vanishing point. As a workaround we transform t
// he overflow rect into screen space and compare in that coordinate system.
if (overflow.IsEmpty() && !Preserves3DChildren()) {
return;
}
// Trying to back-transform arbitrary rects gives us really weird results. I believe
// this is from points that lie beyond the vanishing point. As a workaround we transform
// the overflow rect into screen space and compare in that coordinate system.
// Transform the overflow rect into screen space
nsRect overflow = GetVisualOverflowRectRelativeToSelf();
// Transform the overflow rect into screen space.
nsPoint offset = aBuilder->ToReferenceFrame(this);
overflow += offset;
overflow = nsDisplayTransform::TransformRect(overflow, this, offset);
nsRect trans = nsDisplayTransform::TransformRect(overflow + offset, this, offset);
dirtyRect += offset;
if (dirtyRect.Intersects(overflow)) {
if (dirtyRect.Intersects(trans)) {
// If they intersect, we take our whole overflow rect. We could instead take the intersection
// and then reverse transform it but I doubt this extra work is worthwhile.
dirtyRect = GetVisualOverflowRectRelativeToSelf();
dirtyRect = overflow;
} else {
if (!Preserves3DChildren()) {
return;
}
dirtyRect.SetEmpty();
}
if (!Preserves3DChildren() && !dirtyRect.Intersects(GetVisualOverflowRectRelativeToSelf())) {
return;
}
}
inTransform = true;
}