Bug 96698 - Lots of repaints in the top left tile on this site
Summary: Lots of repaints in the top left tile on this site
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Simon Fraser (smfr)
URL: http://www.telegraaf.nl/
Depends on:
Reported: 2012-09-13 14:53 PDT by Simon Fraser (smfr)
Modified: 2019-07-15 01:27 PDT (History)
3 users (show)

See Also:

Patch (2.17 KB, patch)
2012-09-13 16:39 PDT, Simon Fraser (smfr)
andersca: review+
Details | Formatted Diff | Diff

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Description Simon Fraser (smfr) 2012-09-13 14:53:59 PDT
Note how, when you load http://www.telegraaf.nl/, the top left tile is continually repainting. If you scroll down you'll see a ticker on the right; deleting this ticker stops the repaints.

But why is the top left tile repainting?

TileCache::setNeedsDisplayInRect() calls:
  getTileIndexRangeForRect(intersection(enclosingIntRect(scaledRect), m_tileCoverageRect), topLeft, bottomRight);

but in some cases intersection(enclosingIntRect(scaledRect), m_tileCoverageRect) returns an empty rect. However, getTileIndexRangeForRect happily returns tile 0,0 in that case, so we dirty the top left tile anyway.
Comment 1 Simon Fraser (smfr) 2012-09-13 14:55:58 PDT
Oh, I think the repaint will fall outside of the tile rect so this is probably a no-op. However, with repaint counters on, we dirty the repaint counter in the tile. So some cleanup would be good.
Comment 2 Simon Fraser (smfr) 2012-09-13 16:39:16 PDT
Created attachment 163999 [details]
Comment 3 Simon Fraser (smfr) 2012-09-13 17:02:41 PDT