[cairo] potential bug in cairo relative to intel drivers

[Carl Worth]

On Thu, 2009-07-30 at 10:54 -0700, Bill Spitzak wrote:
> Hate to be a pain about this, but I want to point out that this is yet 
> ANOTHER example that this is in fact NOT what any user expects or wants. 
> They think the driver is broken, in no way do they think it is doing the 
> correct thing!

Yes, Bill. We know that this is a common cause of confusion. I probably
made a mistake in making EXTEND_NONE the default for surface-based
patterns, (compare with gradient patterns where EXTEND_PAD is the
default). If we had EXTEND_PAD as the default, then it would be that
much easier for people to understand what cairo_paint() does and they
would be forced to fix their code to do things like
cairo_rectangle()cairo_fill() even before usiong a non-identity
transformation.

> I still think Cairo could be changed to do EXTEND_REPEAT and clip with 
> an antialiased polygon and everybody would be happier.

Certainly you mean EXTEND_PAD here, not EXTEND_REPEAT, (since
EXTEND_REPEAT will give you discontinuities unless your image happens to
be periodic).

But still, adding an additional stage of compositing to all operations
would not make me happy at all, (nor anybody else who cares about
performance).

The operation that people want is available in cairo, it just takes a
little more typing, (set_extend;rectangle;fill rather than paint), but
it's the kind of thing that's easy to wrap up as a "draw_image" function
in whatever environment is calling into cairo.

-Carl

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