Re: efficient use of canvas lines

[Jon Trowbridge <trow ximian com>]

On 16 Jul 2001 12:27:51 -0300, Ian Britten wrote:
> > Even with a regular sized window, this implies hundreds of
> > GtkCanvasItems to represent the waveform.
> I don't have any suggestions about what to do, but I wouldn't mind hearing
> what some others approaches to dealing with large amounts of data are
> (Or moving the discussion somewhere more appropriate)

In brief, the solution to this sorft of problem is to define a your own
custom canvas item for a waveform (or a GIS rendering, or whatever)

This gives you the convenience of the canvas while still allowing for
good performance: it allows you to only render the part of the image
that is on-screen, and you can use stuff like gdk_draw_lines rather than
having to create a zillion line items.

The details of how to make a new canvas item are covered pretty well in
Havoc Pennington's "Gtk+/Gnome Applications Development"
(http://developer.gnome.org/doc/GGAD).

-JT