Re: GnomeCanvas on X client side: how to

["Dov Grobgeld" <dov grobgeld gmail com>]

Hello Fabio,

I would do this "manually" by storing two images. One is shown, and
that is the one that is being clicked on. The second image is a "label
Image" that maps the pixels to a 24-bit number (8 bits for each
color). For each pixel in the show image you have the corresponding
label in the label image. The labels of the label image are then used
to lookup further information that you want to store for each of your
points, e.g. whether it is selected, values, etc. You construct the
show image and the label image in parallell. The show image with the
color you want to display, and the label image with the label index.
This works fine - as long as you make sure that you don't use any
aliasing when you paint your label image.

Of course this is not what you asked for...

Regards,
Dov

On 9/28/06, Fabio Mariotti <Fabio Mariotti ir phys chem ethz ch> wrote:
> Hi All,
>
> I am a real newby on GTK. And also new to GUIs and X.
>
> Nevertheless I try to do my best..
>
> I do have an application which needs to draw about 30000
> clickable points on screen.
>
> I need stuff like:
> 'on-mouse-over' show values
> 'on-buttom-down' select/unselect/assign to
>
> I have implemented an application which works nicely with
> 2000 points using the GnomeCanvas Widget (on my old 512Mb notebook).
>
> The X server needs much more memory.
>
> I can step back to a drawable and handle events and image superposition
> in an old style.
>
> But because the GnomeCanvas is a nice usefull tool: Can I move and/or
> control hoe much work is given to the X server?
>
> Or.. can I make the GnomeCanvas a simple drawable for the X server?
> And handle the graphycal representstion on my X client? (Ordering,and
> events)
>
> cheers
> Fabio
>
>
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