I had this problem a while ago. While the details are a little foggy (wasn't
documenting changes as well as I should have, I've gotten better). Instead
of calling the on_expose_event, try just invalidating that area.
void myDrawingAreaClass::invalidate()
{
Glib::RefPtr<Gdk::Window> window = get_window();
if ( window )
{
Gdk::Rectangle r ( 0, 0, get_allocation().get_width(),
get_allocation().get_height() );
window->invalidate_rect ( r, false );
}
}
I think that's what worked for me.
Sorry if anyone gets this twice.
On Sun, Jun 29, 2008 at 10:00 AM, Chris Dams <[EMAIL PROTECTED]>
wrote:
> Dear all,
>
> I have a class that inherits from DrawingArea of which the visible
> contents should change a bit after a certain signal occurs. I do this
> by connecting this signal to a method that modifies the data
> representation of the drawingarea and thereafter calls
> on_expose_event(NULL) to redraw the drawing area. This on_expose_event
> is my own method that overrides the virtual function on_expose_event
> of the class DrawingArea. This seems to work just fine in principle,
> but I do notice that sometimes (not always) the redrawing causes a
> clearly visible white flash of the DrawingArea. It also happens
> sometimes that the white flash only occurs in the upper or lower part
> of the DrawingArea. A bit of experimentation with the code leads to
> the conclusion that the drawing is at first done invisibly to the user
> and that, after the drawing is finished, the visible DrawingArea is
> updated to show the new picture. My question is if there is anything I
> can do to avoid seeing the white flash, which, I think, is very ugly.
> Is this a bug in libgtk?
>
> I use gtkmm version 2.4 that came with my ubuntu installation and
> version 7.2.0 of the Xorg X-server.
>
> All the best,
> Chris
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>
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