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On Mon, Jan 02, 2012 at 03:58:27PM -0600, Favux ... wrote:
> FYI Update
> Viktoria.s has sent in the information Nick requested on the KYE
> Systems i608X. So far I don't think anyone has done that for the
> @ Peter
> On Wed, Dec 28, 2011 at 6:15 PM, Favux ... <favux.is@...> wrote:
> > On Wed, Dec 28, 2011 at 5:41 PM, Peter Hutterer
> > <peter.hutterer@...> wrote:
> >> On 29/12/11 06:03 , Favux ... wrote:
> >> 1) How do we enable pressure for "simple" tablets on the evdev driver?
> >> They have either 512 or 1024 pressure levels. The WizardPen driver
> >> supported linear pressure for them. From remarks Peter has made I
> >> gather the simple tablets are suppose to be on the evdev (2.6) driver
> >> for current releases. While the evdev manual tells us how to supply X
> >> and Y coordinates, which some of the tablets need, it is silent on the
> >> Z-axis. In other words are there Z axis coordinate options we should
> >> be using and what are they?
> > evdev doesn't really treat any axes as a special one, it just forwards them.
> > pressure is supposed to come from ABS_PRESSURE from the kernel and should
> > just be forwarded as-is. Might be worth just running evtest against it to
> > get the details. ABS_Z is for d devices that have a true z-axis.
> > there are no options specific to other axes than x and y though.
> So what then are the users to do to set Pressure Threshold? This is
> needed as I have seen values from the default of 0 ranging to 50 or
> even 100 (i.e. ~ 10% of the range) before. I don't know if this is
> due to a hardware variability or the stylus battery (fresh v.s.
> depleted). Or both?
> If I look at one of the tablets that work on evdev currently with:
> xinput list-props 'UC-LOGIC Tablet WP5540U'
> I see:
> Axis Labels (247): "Abs X" (257), "Abs Y" (258), "Abs Pressure" (259)
> But is "Abs Pressure" a property we can set, say using?
> input --set-prop "UC-LOGIC Tablet WP5540U" --type=float "Abs Pressure" 50, 1023
Abs Pressure is just a label to help clients. In XI 1.x devices can have
multiple axes but a client cannot know which one is pressure, which one is
tilt, etc. That's why GTK provides that input device dialog.
In evdev 2.2, we added axis labels. So the above property says "three axes,
first one is an absolute x axes, second one is an absolute y axis, third one
is an absolute pressure axis". it's read-only since the device won't really
change it's physical properties by changing a few bits ;)
In XI2, axis labels are built into the protocol and this property is
not necessary anymore.
As with all properties, they require driver support if they should change
anything. Right now the evdev driver has no support for a pressure threshold
feature. The above command you posted would simply create a new property
called "Abs Pressure", type float, with two values. Nothing in the driver
reads that property though, so it has little effect on the device.