Bug 191545 – [GTK][WPE] Incorrect tile coverage when resizing a layer out of the visible area

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Miguel Gomez]

I wasn't able to reproduce this on the desktop but I was able to see it when working on some low end devices.

The problem happens when resizing a layer that has a backingStore, and that layer is at that point out of the visible area. Inside TiledBackingStore, it exactly happens when the coverRect (the rect that we keep tiles for) and the visible rect don't overlap (empty intersection).
When the layer size changes, inside TiledBackingStore::createTiles, a call to resizeEdgeTiles() is required in order to resize the tiles on the edges to the new size. But as the code is now, that doesn't happen if the coverRect is empty (and in the scenario I mentioned it's emptied). As the size change is only detected inside the scope of that function and then forgotten, it's not performed when the layer comes into the visible area again, causing a glitch.

The fix would mean remembering that there was a size change so when the layer comes into the visible area again, the edge tiles are properly resized.

[Miguel Gomez]

Created attachment 354560 [details]
Patch

[WebKit Commit Bot]

Comment on attachment 354560 [details]
Patch

Clearing flags on attachment: 354560

Committed r238126: <https://trac.webkit.org/changeset/238126>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.