On Wed, Mar 7, 2012 at 2:10 PM, Chris Bagwell <ch...@cnpbagwell.com> wrote: > On Wed, Mar 7, 2012 at 2:18 PM, Nikolai Kondrashov <spbn...@gmail.com> wrote: >> Hi everyone, >> >> Today I've started implementing a driver for Waltop Sirius Battery Free >> tablet. As it turns out, it reports pen tilting, which is a rare thing for >> non-Wacom tablets! >> >> Could someone please explain what ABS_TILT_X and ABS_TILT_Y event values are >> supposed to mean? What are the units and ranges? >> >> Also, what the X applications are expecting as tilting valuator values? >> >> My expectation was that the values match the HID usage tables spec >> description of "X Tilt" and "Y Tilt" usages (see 16.3.2 Tilt Orientation). >> I.e. positive/negative fractions of the X/Y arcs, which probably cover 90 >> degrees both ways, since nobody is looking at the resolution. Interestingly >> enough, the spec says positive inclination is bottom right corner, but the >> tablet assumes top right. >> >> However, after reading xf86-input-wacom sources I got somewhat confused. >> >> Could someone clarify this? >> > > I do not have a tablet with tilt, nor experience on how userland uses > it. And probably I should have read that HID section before replying > but... > > I do see all Wacom tablets with Tilt support report tilt X/Y declaring > a value between 0 and 127. I also see these tablets advertised on web > with Tilt Range of +/- 60 degrees. So I'm going to take a wild guess > since 60 + 60 ~= 127 the units are degrees. > > Hopefully, those missing degree's aren't hard coded in apps such as gimp! > > Chris > Our kernel driver reports values from [0, 127] with 0 corresponding to top/left and 127 to bottom/right. The midpoint is assumed to be vertical, with one unit of change corresponding roughly to one degree of change. The Xorg driver centers the data from the kernel about zero (resulting in a range [-64, 63]) and reports them for applications in the 4th (X tilt) and 5th (Y tilt) valuators.
Jason --- Day xee-nee-svsh duu-'ushtlh-ts'it; nuu-wee-ya' duu-xan' 'vm-nvshtlh-ts'it. Huu-chan xuu naa~-gha. ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Linuxwacom-devel mailing list Linuxwacom-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxwacom-devel
