a few more questions on gnome-canvas

[Dirk Luetjens <dirk luedi oche de>]

Hi,

I want to use gnome-canvas as an image-viewer within a digital image
processing program. The displayed image is overlayed with line
objects. To verify the computed line I would like to zoom the canvas
10 times or more. Unfortunatly the resulting size of the underlaying
image is way to big to handle smoothly. I thought about having some
kind of lense, where only the necessary part of the image is scaled. I 
looked through the code of gnome-canvas and gdk-imlib, and I see the
following two solutions:

1.) a seperate gnome-canvas-zoom object, which is bound to the
mouse-move event of the gnome canvas and that uses the root canvas
group and the gdk_imlib_crop_and_clone_image function to display a
larger scaled view of the area of interest.

2.) a second smaller view of the gnome-canvas and the
gnome_canvas_image_item modified to use the
gdk_imlib_crop_and_clone_image function to display only the requested
size of the image within the view area.

Any ideas?


And, why does gnome-canvas use GtkLayout as base class and not
GtkViewport/GtkScrolledWindow?

Dirk