Re: Status of Cairo backend

[Yen-Ju Chen]

On 7/2/07, Fred Kiefer <fredkiefer@gmx.de> wrote:
> Fred Kiefer wrote:
> > Yen-Ju Chen wrote:
> >> Here is what I found out why cairo loses alpha processing. By
> >> default, the best depth GNUstep choose to use 24 bit (RGB), not 32
> >> bit (ARGB). (See  back/Source/x11/context.c bestContext()). So all
> >> the window are RGB (no alpha). (The buffer is 32-bit, though).
> >> Whenever cairo draw into the window straight, it loses the alpha.
> >> Therefore, it cannot render alpha correctly because the background
> >> has not alpha at all. Here is the code to find the visual for 32 bit
> >> (ARGB):
> >> 
> http://webcvs.freedesktop.org/xapps/fdclock/findargb.c?revision=1.1&view=markup
> >>
> >>
> >
> > Thank you for all these references. I tried them myself on the weekend
> > and it turns out my graphic card only supports 24 bits :-(
> > It is a wonderful GeForce4 Ti 4200 from NVidia with 128 MB and up to
> > yesterday I was quite satisfied with it, even for games (OK, old ones at
> > least). Until I buy a new one, there isn't much I can do for the
> > development of 32 bit support in GNUstep.
> >
>  OK, I bought some new hardware and am about to install it. But don't
> hold your breath it will take me a few days to get all my operating
> systems to work with the new graphics card.

 I thought X.org will emulate 32-bit if the hardware is not available.
 Maybe that is why I got empy windows.
 In that case, 32-bit cairo backend is not for everyone. (Sigh).

 Yen-Ju

> Fred