Aha! I did not know that I could configure the GC to draw using various functions of the source and dest pixels values. Thanks ! Stewart > -----Original Message----- > From: Paul Davis [mailto:paul@xxxxxxxxxxxxxxxxxxxxx] > Sent: Tuesday, November 27, 2007 11:13 PM > To: stewart.weiss@xxxxxxx > Cc: richard boaz; gtk-list@xxxxxxxxx > Subject: RE: GDK_POINTER_MOTION_HINT_MASK has no effect > > > On Tue, 2007-11-27 at 22:17 -0500, Stewart Weiss wrote: > > Richard: > > > > Thanks for this suggestion. Last night after sending the message, I > > did, in fact, resort to > > doing pretty much what you suggested below, by getting the mouse-down, > > then tracking it > > with button-motion-notify, and then getting the mouse-up event. But I > > am not using a temporary > > pixmap, and I have to erase each previously drawn line. > > > > What I want to achieve is a typical Line Tool, like the one in Windows > > Paint, one that will > > continuously redraw the line as I drag the mouse. In order to solve > > this, in my motion-notify-event > > handler I erase the previous line by drawing it on the window (not the > > pixmap) using the background > > color of my pixmap, then draw a new one in the window (not in the > > pixmap). When I get the mouse up event, > > I draw the last line into the pixmap and render it to the screen. But > > I still have some problems. > > When I erase the previous line, I also erase pixels that might have > > been drawn as part of something > > else in the window, so my solution is that when I get the button-up > > event I invalidate the entire > > window to redraw it. But until I release the mouse button, the erase > > pixels remain erased. I was thinking > > of invalidating the rectangle containing the line each time to se if > > that would work, but I have not tried it > > yet (busy day). But any other ideas would be appreciated. > > google for "draw xor gtk" and read on ... > > _______________________________________________ gtk-list mailing list gtk-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gtk-list
