Re: What is more fast GdkDrawable or GdkPixbuf

[Carlos Eduardo Rodrigues Diogenes <cerdiogenes yahoo com br>]

Olexiy Avramchenko wrote:

> Carlos Eduardo Rodrigues Diogenes wrote:
>
> > What of these two components are fastest to copy from one to another 
> > (GdkDrawable to GdkDrawable or GkdPixbuf to GdkPixbuf)?
>
> The fastest case depends on your client's hardware (pixbufs) and X 
> server's hardware (drawables).

If they are in the same machine, there is any difference?

> GdkPixbuf is stored in client (local RAM) memory, so pixbuf -> pixbuf 
> copy is like memcpy(). You can easily measure it and result will be 
> near constant on any specific system.
>
> GdkDrawable is more tricky, it is stored in server (remote, even on 
> another box, RAM or VRAM) memory, some operations on it can be 
> performed via hardware and operations are usually asynchronous unless 
> you explicitly synchronize them.
>
> You can get sane results only for the specific client/server 
> configuration. You can not assume that these results will be true for 
> any other case.
>
> What do you want to do ? If you spend much time calculating image and 
> rarely draw on screen - use pixbufs.

I'm starting to work with gnome-mag, a magnifier service for GNOME and 
before the magnified contents (that is in a pixbuf) be showed in the 
screen it's first copied to a drawable and then copied again to the 
drawable that will show it in the user screen.

I think, I'm not sure yet, that the intermediate drawable used is like a 
cache, but if copy from GdkPixbuf to GdkPixbuf is fastest, it makes 
sense use it like a cache.

>     Olexiy
Carlos