Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: e2ffafdf3851abda0161f4adc5cfdc60fd826a28
https://github.com/WebKit/WebKit/commit/e2ffafdf3851abda0161f4adc5cfdc60fd826a28
Author: Simon Fraser <[email protected]>
Date: 2023-03-25 (Sat, 25 Mar 2023)
Changed paths:
M Source/WebKit/Shared/RemoteLayerTree/RemoteLayerBackingStore.mm
M Source/WebKit/Shared/RemoteLayerTree/RemoteLayerBackingStoreCollection.mm
Log Message:
-----------
[UI-side compositing] Unpainted regions (missing tiles) when scrolling with
the keyboard
https://bugs.webkit.org/show_bug.cgi?id=254466
rdar://107163092
Reviewed by Tim Horton.
When scrolling around a long page with Home/End keys, it's common for page
tiles to be unparented
and reparented, exercising the logic in RemoteLayerBackingStoreCollection which
maintains the
m_unparentedBackingStore set.
If a layer which does not need display (i.e. is "clean" and has not been made
volatile) is
reparented, we'd fail to fetch a new ImageBufferBackendHandle from the GPU
Process, but set the
`BackingStoreChanged` dirty bit, so the UI process would try to set layer
contents but to nil.
Fix by adding layers which are pulled out of `m_unparentedBackingStore` to the
`m_backingStoresNeedingDisplay` set, which results in them participating in
`RemoteRenderingBackend::prepareBuffersForDisplay()` which will ensure we get a
new backend handle
from the GPU process.
This is hard to test, but I added an assertion in
RemoteLayerBackingStore::encode() that we're
encoding a non-null handle which would have caught this.
* Source/WebKit/Shared/RemoteLayerTree/RemoteLayerBackingStore.mm:
(WebKit::hasValue):
(WebKit::RemoteLayerBackingStore::encode const):
* Source/WebKit/Shared/RemoteLayerTree/RemoteLayerBackingStoreCollection.mm:
(WebKit::RemoteLayerBackingStoreCollection::backingStoreWillBeDisplayed):
Canonical link: https://commits.webkit.org/262120@main
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