Re: Double buffering flicker on window resize.

On Wed, Mar 02, 2016 at 06:41:21AM +0200, John Found wrote:
> On Tue, 1 Mar 2016 22:54:34 +0100
> Johannes Hofmann <[email protected]> wrote:
> 
> > with  buffered_drawing=2 dillo uses the Fl_Double_Window class from
> > FLTK, so the result should be similar to e.g. the test/fonts program
> > from FLTK. Do you have it available and can test how that program
> > feels when resizing on your system?
> > In my setup I only get some light flickering at the scroll bars with
> > buffered_drawing=2. Whereas I see heavy flickering with
> > buffered_drawing=0.
> > Do you see any difference between buffered_drawing=0 and
> > buffered_drawing=2?
> > 
> 
> Yes. These are different kind of flickering. On buffered_drawing=0 I see
> how Dillo redraws the page content on the window surface. No artifacts,
> only normal redraws one after another. On buffered_drawing=1 is 
> approximately the same but a little bit rarely. 
> 
> While on buffered_drawing=2, when the user resize the window, the whole window becomes 
> full of garbage - this is specific kind of garbage. It happens when you reuse some 
> memory previously used to store images with different sizes and then allocate it for 
> a new image and draw it on the screen as it is. A mess of graphical scanlines, 
> rectangles full of color, distorted images of different kind.
> 
> Unfortunately, I can't get screenshot, because it is a dynamic effect. After stopping
> resizing window, the last redraw is OK. 

As buffered_drawing=2 uses Fl_Double_Window from FLTK which in turn
tries to use the Xorg DOUBLE-BUFFER extension, you might want to try
xdpyinfo | grep DOUBLE-BUFFER
to see if this extension is enabled on your system and either
disable or enable it in your xorg.conf to see if that makes a
difference.