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Bug 802440 - Some elements are invalidated when other elements are scrolled off the screen. r=roc.

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This commit is contained in:
Jonathan Watt 2012-11-21 02:23:57 +00:00
parent 01301949a5
commit ae1c92d135
1 changed files with 49 additions and 13 deletions
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62
gfx/layers/LayerTreeInvalidation.cpp
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@ -7,6 +7,7 @@
#include "Layers.h"
#include "ImageLayers.h"
#include "gfxUtils.h"
#include "nsDataHashtable.h"
namespace mozilla {
namespace layers {
@ -203,27 +204,61 @@ struct ContainerLayerProperties : public LayerPropertiesBase
ContainerLayer* container = mLayer->AsContainerLayer();
nsIntRegion result;
uint32_t i = 0;
// A low frame rate is especially visible to users when scrolling, so we
// particularly want to avoid unnecessary invalidation at that time. For us
// here, that means avoiding unnecessary invalidation of child items when
// other children are added to or removed from our container layer, since
// that may be caused by children being scrolled in or out of view. We are
// less concerned with children changing order.
// TODO: Consider how we could avoid unnecessary invalidation when children
// change order, and whether the overhead would be worth it.
nsDataHashtable<nsPtrHashKey<Layer>, uint32_t> oldIndexMap;
oldIndexMap.Init(mChildren.Length());
for (uint32_t i = 0; i < mChildren.Length(); ++i) {
oldIndexMap.Put(mChildren[i]->mLayer, i);
}
uint32_t i = 0; // cursor into the old child list mChildren
for (Layer* child = container->GetFirstChild(); child; child = child->GetNextSibling()) {
if (i >= mChildren.Length() || child != mChildren[i]->mLayer) {
// Child change. Invalidate the full areas.
// TODO: We could be smarter here if non-overlapping children
// swap order.
AddTransformedRegion(result, child->GetVisibleRegion(), child->GetTransform());
if (i < mChildren.Length()) {
AddRegion(result, mChildren[i]->OldTransformedBounds());
bool invalidateChildsCurrentArea = false;
if (i < mChildren.Length()) {
uint32_t childsOldIndex;
if (oldIndexMap.Get(child, &childsOldIndex)) {
if (childsOldIndex >= i) {
// Invalidate the old areas of layers that used to be between the
// current |child| and the previous |child| that was also in the
// old list mChildren (if any of those children have been reordered
// rather than removed, we will invalidate their new area when we
// encounter them in the new list):
for (uint32_t j = i; j < childsOldIndex; ++j) {
AddRegion(result, mChildren[j]->OldTransformedBounds());
}
// Invalidate any regions of the child that have changed:
AddRegion(result, mChildren[childsOldIndex]->ComputeChange(aCallback));
i = childsOldIndex + 1;
} else {
// We've already seen this child in mChildren (which means it must
// have been reordered) and invalidated its old area. We need to
// invalidate its new area too:
invalidateChildsCurrentArea = true;
}
} else {
// |child| is new
invalidateChildsCurrentArea = true;
}
} else {
// |child| is new, or was reordered to a higher index
invalidateChildsCurrentArea = true;
}
if (invalidateChildsCurrentArea) {
AddTransformedRegion(result, child->GetVisibleRegion(), child->GetTransform());
if (aCallback) {
NotifySubdocumentInvalidationRecursive(child, aCallback);
} else {
ClearInvalidations(child);
}
} else {
// Same child, check for differences within the child
AddRegion(result, mChildren[i]->ComputeChange(aCallback));
}
i++;
}
// Process remaining removed children.
@ -239,6 +274,7 @@ struct ContainerLayerProperties : public LayerPropertiesBase
return TransformRegion(result, mLayer->GetTransform());
}
// The old list of children:
nsAutoTArray<nsAutoPtr<LayerPropertiesBase>,1> mChildren;
};