[Render] Howto avoid black rect outside of the drawable when compositing?

[Pierre-Loup Griffais]

On Tuesday 15 July 2008 15:27:08 Clemens Eisserer wrote:
> Hello,
>
> I am trying to draw a transformed image using XRender, which works
> quite fine, however the problem I experience is that pixels which are
> outside of the src-picture are rendered black:
> http://picasaweb.google.com/linuxhippy/Transformations/photo#52233687016232
>18514
>
> The XRender-protocol-spec says:
> > When fetching pixels from the source or mask pictures, Render provides
> > three options for pixel values which fall outside the drawable (this
> > includes pixels within a window geometry obscured by other windows).
> > +	Transparent.  Missing values are replaced with transparent.
>
> However I was not able to figure out howto set "it" to "transparent".
> Any hints or ideas are really appreciated.

The spec says a lot of things...
In practice your options for fetching outside a Picture are the various 
repeatTypes (pictAttribs.repeat, bit CPRepeat):

> #define RepeatNone                          0
> #define RepeatNormal                        1
> #define RepeatPad                           2
> #define RepeatReflect                       3

None of those allow you to do what you want; you'll need to use a mask with 
the same transformation as your source Picture.

- Pierre-Loup

>
> Thank you in advance, lg Clemens
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