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Bug 1751789 - Introduce NewLayerData helper structure. r=tnikkel

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Differential Revision: https://phabricator.services.mozilla.com/D136826
This commit is contained in:
Botond Ballo
2022-01-27 01:08:19 +00:00
parent 9125f98d11
commit 2e043e5274
1 changed files with 19 additions and 9 deletions
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28
gfx/layers/wr/WebRenderCommandBuilder.cpp
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@@ -1660,6 +1660,14 @@ void WebRenderCommandBuilder::CreateWebRenderCommands(
}
}
// A helper struct to store information needed when creating a new
// WebRenderLayerScrollData in CreateWebRenderCommandsFromDisplayList().
// This information is gathered before the recursion, and then used to
// emit the new layer after the recursion.
struct NewLayerData {
size_t mLayerCountBeforeRecursing = 0;
};
void WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(
nsDisplayList* aDisplayList, nsDisplayItem* aWrappingItem,
nsDisplayListBuilder* aDisplayListBuilder, const StackingContextHelper& aSc,
@@ -1750,13 +1758,14 @@ void WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(
}
}
bool forceNewLayerData = false;
size_t layerCountBeforeRecursing = mLayerScrollData.size();
Maybe<NewLayerData> newLayerData;
if (apzEnabled) {
// For some types of display items we want to force a new
// WebRenderLayerScrollData object, to ensure we preserve the APZ-relevant
// data that is in the display item.
forceNewLayerData = item->UpdateScrollData(nullptr, nullptr);
if (item->UpdateScrollData(nullptr, nullptr)) {
newLayerData = Some(NewLayerData());
}
// Anytime the ASR changes we also want to force a new layer data because
// the stack of scroll metadata is going to be different for this
@@ -1765,7 +1774,7 @@ void WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(
const ActiveScrolledRoot* asr = item->GetActiveScrolledRoot();
if (asr != mLastAsr) {
mLastAsr = asr;
forceNewLayerData = true;
newLayerData = Some(NewLayerData());
}
// Refer to the comment on StackingContextHelper::mDeferredTransformItem
@@ -1775,16 +1784,17 @@ void WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(
// merge the deferred transforms, but need to force a new
// WebRenderLayerScrollData item to flush the old deferred transform, so
// that we can then start deferring the new one.
if (!forceNewLayerData && item->CreatesStackingContextHelper() &&
if (!newLayerData && item->CreatesStackingContextHelper() &&
aSc.GetDeferredTransformItem() &&
aSc.GetDeferredTransformItem()->GetActiveScrolledRoot() != asr) {
forceNewLayerData = true;
newLayerData = Some(NewLayerData());
}
// If we're going to create a new layer data for this item, stash the
// ASR so that if we recurse into a sublist they will know where to stop
// walking up their ASR chain when building scroll metadata.
if (forceNewLayerData) {
if (newLayerData) {
newLayerData->mLayerCountBeforeRecursing = mLayerScrollData.size();
mAsrStack.push_back(asr);
}
}
@@ -1822,7 +1832,7 @@ void WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(
}
if (apzEnabled) {
if (forceNewLayerData) {
if (newLayerData) {
// Pop the thing we pushed before the recursion, so the topmost item on
// the stack is enclosing display item's ASR (or the stack is empty)
mAsrStack.pop_back();
@@ -1830,7 +1840,7 @@ void WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(
mAsrStack.empty() ? nullptr : mAsrStack.back();
int32_t descendants =
mLayerScrollData.size() - layerCountBeforeRecursing;
mLayerScrollData.size() - newLayerData->mLayerCountBeforeRecursing;
// See the comments on StackingContextHelper::mDeferredTransformItem
// for an overview of what deferred transforms are.