Re: Status of Cairo backend

[Fred Kiefer]

Yen-Ju Chen wrote:
> On 7/3/07, Fred Kiefer <fredkiefer@gmx.de> wrote:

>> Sorry, no luck:
>> (==) NVIDIA(0): Disabling 32-bit ARGB GLX visuals.
>> (--) Depth 24 pixmap format is 32 bpp
>>
>> Either I didn't spend enough money or I am just not able to configure my
>> X correctly.
>> But now that I have a GeForce 6200, will spend my time on new games and
>> forget about cairo :-)
> 
>  I took a look of my system.
>  Here is the hardware:
> 
> (--) NV(0): Chipset: "GeForce FX 5200 (Mac)"
> (**) NV(0): Depth 24, (--) framebuffer bpp 32
> (==) NV(0): RGB weight 888
> (==) NV(0): Default visual is TrueColor
> 
>  Then I run the fdclock application from package (Ubuntu)
>  to test the alpha.
>  (It is the same application I send the link).
>  First, you need to start 'xcompmgr'
>  Then run 'fdclock -t' will give you a transparent background.
>  It indicates the alpha is working.
>  (I attach a screenshot. It may not be obvious.
>   Look at the window border to find the clock).
>  You can also try 'fdclock -o'. (I don't see the difference).
>  So I guess I am wrong about 32-bit.
>  You don't need 32-bit to be ARGB.
>  That's probably also why the code does not check depth,
>  but other things.
> 
>  I suggest ARGB is only because I thought
>  it may fix alpha issue for cairo backend
>  when it draws straight to the window.
>  If it is not the case, then you can forget about it. :)
>  Considering GNUstep support different backing (buffered, retained,
> non-retained),
>  it may still need to use buffer before drawing on window.

Turns out I only had to add the lines:
Section "Extensions"
    Option "Composite" "Enable"
EndSection

to my xorg.conf file. Now I get:

(==) NVIDIA(0): Enabling 32-bit ARGB GLX visuals.
(--) Depth 24 pixmap format is 32 bpp

and fdclock works as in your picture. The drawback is that KDE now draws
window shadows. I will learn to live with that.

OK, the next step is to test how the cairo backend copes with this
situation.

Cheers,
Fred