Re: [Freeglut-developer] How does Multi-touch work?

[Sylvain <be...@be...>]

Hi Florian,

On Tue, May 08, 2012 at 03:42:34PM +0200, Florian Echtler wrote:
> Sylvain, thanks for adding documentation. Should have done that a long
> while ago.

:)

> On 05.05.2012 13:32, Sylvain wrote:
> > We need somebody to:
> > - check if multi-touch (multi contact points, not multiple devices) is
> >   supported on X11
> I do have a Wacom Bamboo Touch at home, but I haven't really tried that
> yet - I think the XI reporting might have changed somewhat for the
> latest X11 releases. I'll try to check that.

I just committed a test program that registers the multi-touch
callbacks (freeglut/progs/demos/multi-touch/).  It should display
small squares with different colors during a multi-touch.

I tried to plug both a mouse and my (single-touch) wacom pen tablet,
configuring them as 2 independent cursors.  Sadly I didn't manage to
get any multi-touch event with the demo :/
Would you mind testing it?


> > - check if non-multi callbacks are called on windows
> The first/oldest touch point also controls the mouse cursor, which
> triggers the regular callbacks as usual.

In the FreeGLUT source code for X11, it seems that the regular
callback is called for any touch:

  case XI_ButtonPress:
  case XI_ButtonRelease:
  	fgState.Modifiers = fgPlatformGetModifiers( event->mods.base );
  	INVOKE_WCB( *window, MultiButton, (
  		event->deviceid, 
  		event->event_x,
  		event->event_y,
  		(event->detail)-1, 
  		(event->evtype == XI_ButtonPress ? GLUT_DOWN : GLUT_UP)
  	));
  	INVOKE_WCB( *window, Mouse, (
  		(event->detail)-1, 
  		(event->evtype == XI_ButtonPress ? GLUT_DOWN : GLUT_UP),
  		event->event_x,
  		event->event_y
  	));
  	break;

(Same for motion events.)

So apparently the behavior is not consistent :/
How do you think the callbacks should behave?

Thanks for your input!
Sylvain