Render spec clarification

[Carl Worth]

On Mon, 2008-10-13 at 11:01 -0400, Adam Jackson wrote:
>     Option B: when either of the above are true, the implementation must
>     act as though mask and src are constant pixel sources for the
>     duration of the request (ie, dst is copied aside internally to a
>     scratch picture, and the scratch is used as the logical source or
>     mask and then destroyed at the end of the request)
> 
> The former is certainly way simpler, but might break some existing
> application.  Maybe?  I can't imagine anyone being crazy enough to do
> this, but then there's lots of crazy people in the world.

So Composite with op==SOURCE couldn't be used for things like scrolling?

That would make Render a very incomplete interface, wouldn't it?

And we're sure that applications don't actually do things like that
already?

(Though I do agree taht actually using overlapping regions with
something like op==OVER must certainly never occur in practice
currently---since the current behavior cannot be useful.)

-Carl

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