[SDL] Minimal example of weird pointer behaviour

Matthew Bloch mattbee-sdl at soup-kitchen.net
Tue Sep 17 03:59:01 PDT 2002


On Wednesday 11 September 2002 02:40, Matthew Bloch wrote:
> On Wednesday 11 September 2002 00:16, Sam Lantinga wrote:
> > > Can anyone with a Windows 2000 box to hand confirm the weird pointer
> > > behaviour I've seen?
> >
> > I tried your program without any problems on Windows 2000.
> > Does the problem happen with CVS SDL?
> > 	http://www.libsdl.org/cvs.php
>
> Yes.
>
> Actually the problem is most accurately demonstrated by VNC (which is how I
> normally use the PC, at least with x2vnc).  If I open an xvncviewer window
> onto the PC while watching the monitor, I can see just how small a wiggle I
> need to make on the virtual screen to make the pointer on the real screen
> zoom from one corner to another (about the middle 1/5th in both X & Y
> directions).

More on this problem:

If I hack SDL_dx5events.c and divide xrel and yrel by 16 for every input 
message in handle_mouse, the mouse movement appears to scale sensibly *but* 
suffers from a buffering problem: there appears to be a buffer of mouse 
movements an one is popped off the top every time I move the mouse.  
Unfortunately this buffer appears to be permanently a few movements behind, 
so the mouse has an irritating lag on it.  I've tried raising INPUT_QSIZE to 
512 but that doens't make any difference.

-- 
Matthew       > http://www.soup-kitchen.net/
              > ICQ 19482073





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