[cairo] IncludeInferiors, Pixmap/Window distinction

Karl Tomlinson cairo at karlt.net
Thu Jul 22 18:53:03 PDT 2010

Thanks for your comments, Bill.

Bill Spitzak writes:

> 3. If you really really think you need "scrolling", then use a
> child window with much larger area, and move it. It will be
> clipped to the parent and you will get normal (and correct!)
> expose events for the exposed area. And this correctly moves this
> bi-directional communication out of the drawing library and into
> the windowing library.
> With that, the only purpose of using a window as a source is to
> get a "screen shot".

Valid point that without graphics-exposures, the usefulness of a
window as a source is limited.

FWIW, this kind of scrolling and guffaw scrolling are not suitable
for scrolling portions of a window, but yes, there are other ways
to do scrolling.

> I think you should get an image that is the
> size of the window (ie not clipped to the screen area), and that
> "wrong" pixels should be transparent black, not unknown
> values.

Hmm. Sounds good, but also tricky with IncludeInferiors.

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