Pen Tablet Support

The XO-1 comes equipped with a unique dual-mode pointing device. It functions both as a conventional trackpad (the capactive-sensitive "Glide Sensor") and as a graphics tablet (the pressure-sensitive "Pen Tablet"). This page documents how the PenTablet is supported by the OLPC system software.

NOTE: As of Build 656 (2008-01-17), the system software does not contain built-in support for the PenTablet.

Sample Activities

The state of Pen Tablet support is currently in flux, but there are some sample applications created by Patrick Dubroy that will allow you play with the tablet. NB: These applications assume no tablet support in X, so they fork an external process (evtest) to read from the tablet.

• TabletAreaTest demonstrates a GTK widget that is mapped to tablet input
• tabletui explores some user interface prototypes for the unconstrained drawing case

For Activity Developers

• The OLPC Human Interface Guidelines explain how the dual-purpose touchpad/PenTablet works from a user's point of view: see here.
• If you want to map tablet input to a widget that's the same shape and aspect ratio as the physical tablet, see Pen Tablet Support/GTK Widget.
• If you want to use the tablet to draw a larger canvas, as in e.g. the Paint activity, see Pen Tablet Support/Unconstrained Drawing API

Ideas for Activities using the tablet

• a pen-based calculator like Harold and Will Thimbleby's:

Imagine writing a calculation down on paper and the paper magically working out the answers. We have built a calculator that works like this, which is ideal for pen based computers and interactive whiteboards in classrooms. It recognises your handwriting, and you write naturally, using ordinary mathematics notation you are already familiar with.

For OLPC Core Developers

User Interaction

It has not yet been decided how the user interaction with the PenTablet will work. The issues are discussed here: Pen Tablet UI.

Driver issues

In March 2007, Zephaniah E. Hull posted an informative description of the low-level driver details here.

The PenTablet driver has disabled for quite some time (as of March 2008) because:

• the PenTablet is not currently being correctly identified as having capability "input.tablet" (see http://dev.laptop.org/ticket/5268)
• apparently enabling this capability caused the problem of one button click being interpreted as two (see http://dev.laptop.org/ticket/6079)

According to Andres Salomon (here and here), the touchpad driver has been completely rewritten in the master branch, so Update.1 will contain correct drivers for the touchpad and the PenTablet.