> I'm using the overlay in Fl_Overlay_Window to draw on a > background image. At each redraw I only need to add a bit > more information and don't want to redraw the entire overlay. > So can I restrict the overlay so it doesn't clear the > previous state? Perhaps with clipping? > > The reason I want to do this is the overlay currently > flickers during the update on some computers. Would this > happen when there is no overlay hardware support?
I don't know for sure - haven't tried this recently, but... Are you sure the overlay window is what you really need. Some years ago, we had a tool that was doing some signal processing in (near) real-time on an input data stream, then rendering that data as an image in a window. We then used overlay window to draw assorted markers and symbology on top of the image. It flickered like a b******. Even trying things with double windows etc didn't help. So... We switched to using a "plain" double window and rendered the image and the overlay ouselves. Flicker gone. Update rates still acceptable. Loading nowhere near as bad as I'd feared... I guess what I'm saying is that maybe the overlay is not what you want, particularly if the underlying window is refreshed frequently. I think overlay is OK if the underlying window does not change a lot... ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** _______________________________________________ fltk mailing list [email protected] http://lists.easysw.com/mailman/listinfo/fltk
