[Sugar-devel] Wacom Bamboo with XO?

Wade Brainerd wadetb at gmail.com
Thu Dec 11 00:29:57 EST 2008

Hey Chris, thanks for the feedback!  It's great to hear from people using
Colors! on XO.

On Wed, Dec 10, 2008 at 6:58 PM, Chris Marshall
<jns-cmarshall at comcast.net>wrote:

> It is true that reducing the update rate would lower the
> pen position resolution of lines...but the Bamboo tablet
> has a linear resolution of 2400+ lines per inch which is
> about 12X the XO pixel resolution and 24X your 2X reduced
> drawing canvas.  As a result, even with skipping pen
> deltas of 24 or less the pen output events will still
> be at the finest drawing precision.  This is not even
> including the fact that the brush is more than a single
> pixel wide typically.
> If you add an entry under the first wacom Xinput entry in
> your xorg-dcon.conf file like:
>  Option "Suppress" "60"
> you'll get much better drawing response with the existing
> infrastructure.  I tried 10-72 and to keep up with faster
> sketching or larger brushes, the rate needs to be at 50 or
> greater.  After the above edit and a 3-finger-salute to
> restart the X server on the XO, Colors! basically worked
> well with the tablet.

This is good reasoning, and I wasn't aware of the Supress option - I'm
pretty new to Linux programming and X in particular.  I had been considering
implementing that kind of filter in the PyGTK mouse handler.  I've updated
the xorg-dcon.conf on dev.laptop.org to include this setting.

There is a command line configuration program (xsetwacom)
> that could be used to configure Wacom tablet settings
> without editing the xorg-dcon.conf file.  I don't know
> if a restart of X would then be required.  It might be
> possible to base a control panel interface calling the
> underlying utility per Tomeu Vizoso's previous mention
> in this thread.

Yep, 60 works well enough though that it's probably not worth a
configuration option.  I will still work on optimizing the painting
performance though.

I tried the earlier photo snap and it was awkward to toggle
> the underlying photo image.  It would be more helpful if the
> photo could be drawn over as if on tracing paper.  The toggle
> on/off would still be useful at different levels of refinement
> of the painting.

That's a good idea.  When I reimplement Photo Snap, I'll do it that way (so
you are painting over it, e.g. the white background will show the image when
it's enabled).

> There appeared to be a problem with the Zoom in and
> out function as zooming all the way out, and then back in
> results in the canvas offset by various amounts.  I was not
> able to make it shift back without restarting the Activity.

This should be documented better, or maybe have some visual feedback.  Zoom
in & out keep the mouse cursor on the same point in the canvas before and
after the zoom operation.  This is handy for quick zooms, you just point at
the area you want to detail and zoom in.  In Git I have added a 'Center
image' toolbar button though, since it can be hard to recenter. the image.
You can also always scroll the image manually by holding the Hand button and
dragging with the mouse.

> Finally, I'm not sure how to handle this but it was difficult
> to trigger the Frame exposure via the tablet since the drawing
> area seems to be exactly the entire screen.  If it were to be
> extended a bit at the top then the Frame would be easier to
> get to from the tablet only.

Maybe one of the Wacom buttons could be assigned to the Frame key event?
Can this be done in xorg-dcon.conf?

I've got an old serial Intuos that I'll try to get configured
> this weekend.  I'll let you know how it goes...  If we get
> this working, maybe Amazon could add a "People who bought this
> item [the XO], also bought this [Wacom Bamboo]"...  :-)

Great!  Thanks again for the feedback, I'll try to release a new version
before long with these suggestions.

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