[cairo] Re: New API: cairo_xlib_surface_get_*

Bill Spitzak spitzak at d2.com
Thu May 4 14:07:37 PDT 2006

> On Thu, 23 Feb 2006 16:39:14 +1300, Robert O'Callahan wrote:

>> -- Added cairo_extract_clip_rectangles to obtain the current clip in
>> device coordinates. If the clip cannot be expressed as rectangles, the
>> function simply gives up ... for our purposes, a non-rectangular clip is
>> useless anyway.
>> Patches for these extensions are attached --- please evaluate.

Though I'm not sure what you are using this for, I think I did something 
like this before, but it really helped if the function took a rectangle 
as input, and does what is described above for the *intersection* of the 
clip with this rectangle. This avoids wasting time calculating parts of 
the clip path that are outside the area you intend to draw anyway.

Rather than "give up" a reasonable fallback might be to intersect the 
path with the rectangle and return the bounding box of the resulting 
shape. In fact this could be your initial implementation.

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