Re: [gtk-list] Re: BIG plots in gnome-canvas

[Havoc Pennington <rhpennin midway uchicago edu>]

On Tue, 17 Nov 1998, Federico Mena Quintero wrote:
> 
> You may want to do some sort of recursive subdivision of the points
> using canvas groups; that way the canvas will be able to handle them
> efficiently.  Or you can create your own custom item type to handle
> zillions of points efficiently.
>

You pretty much have to create your own item type which draws multiple
points; even if the canvas was fast enough for each point to be a
GnomeCanvasItem, creating 1 million of them will take forever, probably at
least 10 seconds maybe more, then it will eat a *ton* of memory. Simply
blasting 100,000 X's onto a drawable takes around a second to begin with; 
if each X is two GnomeCanvasLines, it will be unusably slow.
 
> You may want to take a look at Guppi/Goose (http://www.gnome.org/guppi), 
> which does plots and (from the screenshots) seems to handle lots of
> data points just fine.  I am not sure if it is using the canvas these
> days, but you may want to take a look anyways.
> 

It is using the canvas, but it is also broken for the moment. Been working
on non-GUI bits while gtk-- sorts itself out. I do have a custom
CanvasItem that draws scatter plots, which compiles but has never actually
been on screen so I'm sure it's broken one way or another. But the idea is
there. See canvasscatter.h in guppi/src/libguppi/. 

We would love to have additional developers and maybe your application can
be worked in to the Guppi framework, depending on what it is. Guppi and
its libraries are pretty flexible if some sort of change would make them
useful to you.

Havoc