[PATCH 1/2] composite: Don't backfill non-bg-None windows

[Keith Packard]

On Thu, 06 May 2010 10:30:25 -0400, Adam Jackson <ajax at nwnk.net> wrote:

> Oh, gross.  If I'm reading this right, miPaintWindow clips by children
> (not IncludeInferiors, and called after map and validate), which means
> if you map an entire subtree at once, the bg=None regions poke through.
> Is that accurate?

Yes. bg=None means leave the contents on the screen, however deep the
window is in the tree.

> I'm not totally convinced that's required by the protocol, but I can
> imagine it being required by applications.  It's easy enough to check,
> and the tree walk will almost certainly be faster than the blit.

It's not required, but applications expect it, which is why the current
code does the expensive copy. Walking the tree and collecting the None
region would be a great option.

-- 
keith.packard at intel.com
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