[Webkit-unassigned] [Bug 57269] REGRESSION (r82151): Every WKView paint now makes an extra copy of the painted bits

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=57269





--- Comment #7 from Adam Roben (:aroben) <aroben at apple.com>  2011-05-04 08:43:10 PST ---
(In reply to comment #6)
> (In reply to comment #5)
> > (From update of attachment 88643 [details] [details])
> > I don't think this patch is safe. If someone modifies the ShareableBitmap after the CGImageRef has been made but before the newMapping has been written into, the newMapping will see the modifications. This is exactly what we're trying to avoid. (And since newMapping should never be written into, we're basically never safe.)
> > 
> > This is just how copy-on-write views work in Windows. If I have two views of the same mapping, A and B, and A has FILE_MAP_WRITE and B has FILE_MAP_COPY, B will see writes to A until B is written into. From then on B will be operating on its own copy that is insulated from A.
> 
> I guess we could use A for the CGImageRef and use B for the ShareableBitmap from then on. The CGImageRef can't be written to, so that should work.

Trying this out now.

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