[sugar] PenTablet user interface

[Patrick Dubroy]

(This was posted to olpc-devel a few weeks ago, but I just realized
that it belongs more on this list)

Hi,

 I'm working on a project to improve the PenTablet support. I have two
 main goals:

 1. Build a GTK widget that an application developer could use to get
 tablet support "for free". The widget would provide a 1-to-1 mapping
 between the physical tablet and the on-screen drawing area. For
 example, a penmanship application might have an area on-screen where a
 child could practice their writing.

 2. For the more complicated case of freehand drawing in e.g. the Paint
 activity, my goal is to define the interface through which the user
 will be able to draw on an arbitrary area of the canvas.

 Of course, this is all pending proper driver support for the
 PenTablet. For now, I am prototyping these applications by reading
 directly from /dev/input/event5.

 I know that this has been discussed previously on the mailing list,
 but to my knowledge there's been no agreement on exactly how the UI
 will work for the PenTablet. I've created a page in the wiki
 (http://wiki.laptop.org/go/PenTablet_UI) that summarizes the previous
 suggestions that I am aware of. If you have any opinions on this,
 please take a look at let me know what you think.

 My personal feeling is that the best option is this:
 - the tablet is always mapped to a rectangle in the center of the
 screen. Using the grab button and the stylus, the canvas can be moved
 around underneath the rectangle (Option 1 for Adjusting the Mapping)
 - to allow for precise drawing, the user can engage a "hover mode" by
 holding down the Alt key while dragging the stylus (Option B for
 Precise Drawing)

 I have an application which demonstrates some of these techniques,
 which I could make available to anyone who is interested. I am also
 planning on doing a small, informal user study to test some of the
 techniques.

 Pat
 --
 Patrick Dubroy
 http://dubroy.com/blog - on programming, usability, and hci