[cairo] Re: new clipping change patch
keithp at keithp.com
Wed May 25 10:56:45 PDT 2005
Sorry, I hit some key and my previous message was sent before I was
Evolution is not my favorite program today.
On Wed, 2005-05-25 at 09:49 -0400, Owen Taylor wrote:
> What the function does is gets the extents of the mask operation.
> (mask in the name is a verb, not a noun.) The mask argument isn't
> currently used, but would be needed for the useful optimization:
> - If the mask is a surface pattern, with extend=NONE and the
> operator does nothing for transparent source (OVER, say)
> then the size of the intermediate surface is bounded by the
> size of the (transformed mask)
Ok, so the function is just incomplete.
> (This optimization can be done for the source as well)
> Yes, your patch doesn't change the end result of the function, my
> comment was that with the patch we end up doing:
I think the patch just demonstrates how silly the original code was. If
you have a suggestion for what it should look like, I'd love to see it.
Otherwise, I'll attempt to figure out the intended algorithm and
> > The clip serial number is relative to a specific surface; change the
> > surface, and you need to get a number relative to the new surface. In
> > particular, the clip serial starts at 0 and until a surface is
> > associated, it will remain at 0. If a clip region is applied before the
> > surface is associated, this 0 clip serial will inadvertantly match the
> > surface clip serial if that surface has no clip.
> Could do with a comment :-).
> /* allocate a new serial to represent our current state. Each
> surface has its own set of serials */
> say. I think my suggestion above with surface_set_clip_serial() does
> come out a bit better here, since you can just reset to
> (unsigned int)-1.
See previous message as to why this isn't the best plan.
> > Given that we don't actually support changing surfaces, it might be
> > better to rework the gstate initialization code to include the surface
> > from the start...
> Maybe leave the set_target_surface() code around until we see if we
> need it for groups or not.
Oh, good point.
> > > * _cairo_xlib_surface_ensure_picture (surface, &surface->&src_picture);
> > >
> > > Maybe just split that into ensure_src_picture() and
> > > ensure_dst_picture()?
> > I suppose; this did save a function. Would you accept a pair of macros?
> > Or is that too 80s?
> I think GCC is going to do better with the pair of functions... if
> inlining makes sense, it has the power to do it.
Ok, I'll just do it right then.
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