canvas coordinate

["Klaus Rudolph" <lts-rudolph gmx de>]

I started with gtkmm Gnome::Canvas::Canvas.

I am confused about the six? different coordinate systems inside the canvas.

Can someone give me a simple example how I can draw a line from the top left corner of the canvas to the center of the canvas?

All items I draw seems to be relative to some magic point. I read the coordinate description but could not find a method/function to call to get the absolute canvas pixel coordinates. I think I had not understood the basic system philosophy for this canvas system.

I used to write programs with Tcl/Tk and fltk. There are all points relative to the left/top corner of a canvas.

Any hints?

Regards
 Klaus