[cairo] Mozilla on Cairo

Owen Taylor otaylor at redhat.com
Fri Apr 22 05:01:16 PDT 2005

On Fri, 2005-04-22 at 11:23 +1200, Robert O'Callahan wrote:
> I've got Cairo-based Mozilla into a barely usable state.
> http://weblogs.mozillazine.org/roc/archives/2005/04/glimpse_of_the.html
> Most of the glitches visible are probably bugs in the glue code. The
> poor performance is a bit more of a concern. We'll be looking into
> that. Also, this page doesn't really show it, but we are running into
> the problem of antialiased fills causing artifacts where two shapes
> share a non-pixel-aligned edge. I really want to add a mode to cairo_t
> that turns antialiasing off. What are the chances that that would be
> accepted?

Leaving that question aside, I really think you should be pixel
snapping coordinates before calling Cairo in what you've shown there...

(I don't really mean to just round the coordinates immediately before
calling Pango, I mean to chose coordinates that are properly pixel
aligned. E.g., if you ask Pango for the underline thickness it always
gives you an integer value when font hinting is on ... so you don't
get the smeary underline in your screenshot)

Turning off antialiasing either is going to cause a huge performance
hit (for FSAA) or going to lose antialiasing. Now, maybe you could 
only antialias some things and not others, but in general, if you
could make that determination easily, you could pixel snap edges 

Also, note that Cairo performance will be *much* better for drawing
rectangles if you pixel snap the edges, as of recently, as it can
then use rectangle drawing fast paths.


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