[pygtk] gtk.DrawingArea

[Steve McClure]

On Fri, 2006-02-10 at 10:44 +0100, Luigi Paioro wrote:
> Thank you John.
> 
> I solved looking in the FAQ! It was only that I have to use
> 
> self.area.set_events(gtk.gdk.POINTER_MOTION_MASK)
> 
> instead of
> 
> self.area.set_events(gtk.gdk.POINTER_MOTION_MASK |
>                       gtk.gdk.POINTER_MOTION_HINT_MASK )
> 
> Thanks a lot.
> 
> Now I have another question that I can't solve.
> 
> While I can draw a line on a gtk.gdk.Drawable object, it looks that I 
> cannot delete it. For example I can draw a line using:
> 
> area = gtk.DrawingArea()
> area.window.draw_line(gc, x1, y1, x2, y2)
> 
> but I cannot delete such line... a line isn't identified by an object or 
> an ID and it doesn't exist a proper method to delete it!
> 
> Is there a trick to solve this trouble?

The DrawingArea is just a pixmap, it doesn't have any children like the
Canvas.  To erase the line you have to draw it again with a different gc
that uses the background color as its foreground.  Of course this leads
to other problems if the line is on top of anything else you've drawn,
etc.

> 
> Thanks again.
> 
> Luigi
> 
> 
> John Pye wrote:
> > Hi,
> > 
> > I don't know if this is the solution but it sounds similar to a problem
> > that I had. I had a gtk.Image inside a viewport inside a scrolling
> > window. In order to capture the 'motion-notify-event' on my gtk.Image, I
> > needed to add an EventBox on the image, and capture the events to that.
> > I used Glade to do that, and it worked fine. Have you tried an EventBox yet?
> > 
> > There was something in the PyGTK FAQ about this.
> > 
> > Cheers
> > JP
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