[cairo] CAIRO_FORMAT_A8 / stride

[Owen Taylor]

On Sun, 2006-07-02 at 14:48 -0700, Keith Packard wrote:
> On Sun, 2006-07-02 at 13:26 -0400, Owen Taylor wrote:
> 
> > I don't quite understand what your problem is ... as far as I know,
> > Cairo will work fine with non-word-aligned rowstrides, though it
> > may be less efficient.
> 
> no, pixman only handles 32-bit aligned strides for all rendering.
> 
> Fixing that would be hard in general as the pixman code often accesses
> pixel data 32 bits at a time, and many processors don't like unaligned
> data accesses.

I can't imagine it's anything but trivial to make it work for A8, at
least slowly, ... after all, there's a pixel-at-a-time path in the code,
so you could always fall back to that, though I don't think there is
actually anything in the non-mmx code paths at least, that *should* 
require 32-bit rowstrides for A8 images.

						Owen


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