Bug 55836

What you want is a cairo_append_region() convenience function:

for (i in cairo_region_num_rectangles())
  cairo_rectangle(cr, cairo_region_get_rectangle(i));

No, I am looking for function like
cairo_bool_t
cairo_clip_region (cairo_t        *cr,
                   cairo_region_t *region)
as mentioned in http://www.gtkforums.com/viewtopic.php?f=3&t=54873
Thanks to Carlos for giving me the link

(In reply to comment #1)
> What you want is a cairo_append_region() convenience function:
> 
> for (i in cairo_region_num_rectangles())
>   cairo_rectangle(cr, cairo_region_get_rectangle(i));

What you are looking for and what cairo will provide are two separate things...

Separating the action of adding the path from the operation, provides much greater flexibilty. For example:
  cairo_append_region();
  cairo_clip_preserve();
  cairo_stroke();

And cairo is still free to use the knowledge that we have a region to optimise it path.

I was looking for direct function to
(1) Use cairo_region_t directly in cairo context OR
(2) Somehow, get the clipping region intersect with cairo_region_t, so
that my drawing occurs only in intersected region.

Assuming that cairoregion already exists, a workaround suggested in
the website states
(1) From Cairo Region, get ALL rectangles via cairo_region_num_rectangles
(2) For each rectangle, actually create rectangle via cairo_rectangle
(3) Use clip_path

(1) - (3) now means that the current path consists of the entire region
(4) Create a new path via cairo_line_to
(5) Clip it

I was looking for direct function which has just steps (4) and (5)
(1) Create a new path via cairo_line etc.
(2) call cairo_clip_intersect(m_cr, region)


On Wed, Oct 10, 2012 at 4:48 PM,  <bugzilla-daemon@freedesktop.org> wrote:
> Comment # 3 on bug 55836 from Chris Wilson
>
> What you are looking for and what cairo will provide are two separate
> things...
>
> Separating the action of adding the path from the operation, provides much
> greater flexibilty. For example:
>   cairo_append_region();
>   cairo_clip_preserve();
>   cairo_stroke();
>
> And cairo is still free to use the knowledge that we have a region to
> optimise
> it path.
>
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