Re: FW: [LIBART] ARGB <-> RGBA ?

[James Turner <james turner crocodile-clips com>]

> Hi!
>
> I would like to draw direct to the screen (or direct to a buffer
> that is later bitblited to the screen) using libart.  Normally
> graphiccards support ARGB 32-bit format, but libart can only (?) 
> generate RBGA.  How hard whould it be adjust/extend libart so that
> it generated ARGB instead?
I've been working on the Mac port of the new SVG rendering code in 
Mozilla (which uses libart as the backend).  Macs only support ARGB (in 
fact a pad-byte + RGB), so I've had to support this. Also, the design of 
the Mozilla X (well GDK) drawing layer is such that a 'native' rendering 
mode would give large performance improvements, and permit better 
integration with other objects rendered by Mozilla. (ability to use 
XGetImage and XPutImage, as I understand it, thougt I'm not an X coder)

Thus, I have been hacking up libArt :-)

I have added a 'pixel format' parameter to art_render_new(), and added 
new compositor functions to handle the basic formats I need (RGB, ARGB, 
and 555 RGB). The changes work, but need some polish. Thus far I have 
been able to ignore the 'clear' and 'solid' render callbacks, because 
the SVG code only seems to use the compositor ones.

The pixel format changes only affect the output system; i.e the internal 
buffers are always 24-bit RGB. Also all the changes are localised in 
art_render.c (and the header). One caveat is that the surface 
transformation code (which is a seperate interface) has not been changed.

My worry here is that while my approach clearly works, it's not quite in 
keeping with the libArt design philosophy, so I don't know if it an 
'acceptable' solution.

If people wish to see my updated versions, please get in touch,.
James Turner