[linux-audio-dev] FLTK/X11 question

[Steve Harris]

On Wed, Sep 25, 2002 at 05:16:23 +0200, Frank Neumann wrote:
> > I seem to remeber that on the Amiga and in GL I could issue a call to wait
> > for the next vertical blank, forcing the redraw to be in sync with the
> > video hardware. Is there an equivalent in FLTK or X?
> 
> I am not sure how exactly you are doing this, but my first guess would
> be to ask if you are rendering into an off-screen pixmap (until
> everything in there is finished) and then do one quick Blt() to bring
> this to your on-screen window. That should at least keep the flickering
> low.

No, I'm just draw()ing the bitmap to the widget, then using line draw to
draw on the pointer. I dont think FLTK supports blits or offscreen drawing
- at least I couldn't find any mention of it.
 
> I am not sure if there are still ways to wait for vertical retrace
> nowadays, but even if there are, I imagine it would not make sense,
> given the overhead/latency the X protocol will put between the beginning
> of the VBL and your attempt to draw things onto the screen "right at
> that moment".

Thats very true. Thanks. Maybe I should be using something like SDL,
rather than FLTK.

- Steve