[cairo] bounded operators

Andrea Canciani ranma42 at gmail.com
Tue Nov 9 03:54:28 PST 2010

On Tue, Nov 9, 2010 at 10:53 AM, L A <l.thee.a at gmail.com> wrote:
> + cairo list  ,sorry about the repost..
> On Sat, Nov 6, 2010 at 3:11 AM, Andrea Canciani <ranma42 at gmail.com> wrote:
>> On Sat, Nov 6, 2010 at 11:03 AM, L A <l.thee.a at gmail.com> wrote:
>>> Probably a stupid question: why are CAIRO_OPERATOR_SOURCE and
>>> CAIRO_OPERATOR_CLEAR not bounded? _cairo_operator_bounded_by_source
>>> call seems to be returning false for these two.
>> They are bounded by the mask, not by the souce (see
>> _cairo_operator_bounded_by_mask).
>> You might also want a high level overview of the operators:
>> http://cairographics.org/operators/
>> Notice that throughout the whole document "bounded" means "bounded by mask" (as
>> explained in the section "The Source").
>> Andrea
> Thanks, that makes sense. Another question: if the mask is empty (ie:
> NULL), can we assume that op is source bounded?

The shape of the mask does not affect the definition of op.

If by "empty mask" you mean the one that you would get for a
paint operation (opposed to the one that would be used for
fill/stroke/mask), then...
If you paint with op==CLEAR, you will make the whole clipping region
clear (no matter what your source is).


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