XCopyArea clip bug

Alexander Larsson alexl at redhat.com
Wed Feb 4 13:56:32 PST 2009

On Wed, 2009-02-04 at 14:46 +0100, Alexander Larsson wrote:
> On Wed, 2009-02-04 at 13:38 +0100, Alexander Larsson wrote:
> > I found what I think is a bug in XCopyArea. 
> > 
> > If you copy a pixmap to a window and some of the copied area is outside
> > the pixmap then that area in the destination window is cleared to the
> > background color (and possibly graphics exposes are sent).
> > 
> > If the GC has a clip region set so that the destination area that would
> > contain data from outside the pixmap is clipped out, then I would expect
> > it to not be cleared. 
> > 
> > However, that is not the case right now, even the clipped out area has
> > the destination cleared to the window background.
> > 
> > I'm attaching an xlib example.
> Oh, the same thing happens if the source is another window and not a
> pixmap.

I saw this reply in the archives:
But i don't see in in my inbox, dunno what happened to it.

Anyway, the screenshot in that mail is correct. (The red part is the
background set when copying from an obscured source, and its correctly
clipped so its only visible in the left half of the window. When I run
it I see red in the right half, while the green part is correctly

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