multi-touch-dev team mailing list archive

[Daniel Stone <daniel@xxxxxxxxxxxxx>]

Hi,

On Tue, Dec 07, 2010 at 10:54:37PM +0100, Denis Dzyubenko wrote:
> On 7 December 2010 22:44, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote:
> >> I guess different kernel driver for different device _will_ give you
> >
> >> different data. Hence my question was in context of recent discussion
> >> - getting events through slave devices vs. master devices - I would
> >> expect the data to be "unified" so that clients won't need to have
> >> device-specific workarounds. I wouldn't be surprised if some
> >> parameters would need to be configurable - the only example that comes
> >> to my mind right now is again width/height of the touch - right now I
> >> do not know what the value means and just assume that value 255 (the
> >> maximum for magic trackpad) means 50 pixels wide.
> >
> >
> > The min/max of the major/minor (aka width/height) is actually not that important
> > - they are all calibrated in devices coordinates, so using the same scale for
> > all of x/y/major/minor gives you the best result.
> 
> well I still do not know what _is_ the scale. Actually I am not using
> MTAbsX/Y right now - I mainly rely on the root_x/root_y properties.

Right, so that would explain why you're getting screen-scaled
co-ordinates ... if you want unscaled, look at the x and y valuators
attached to the event, rather than root_{x,y}, which is by definition in
screen co-ordinate space.

> I am writing this email from a macbook - at it feels like mac moves
> the mouse cursor for the same distance on the screen as I physically
> moved my finger on the touchpad (that is if you ignore acceleration
> and move it slow) - that results in my next question - getting a
> physical size of the device.

That's not really multitouch per se, but just a matter of providing the
right general input properties.  Looking at the bcm5974 driver, which is
used for my MacBook Air, it doesn't have any way to read the physical
dimensions.

Cheers,
Daniel

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