>>>>> "Steve" == Steve Hill <[EMAIL PROTECTED]> writes:
Steve> Jim Gettys wrote:
>> > The type of information you get out a digitizer varies from
>> coarse > worse-than-pixel resolution (this type might be used in a
>> greasy-sceen > supermarket kiosk) to a current peak of about
>> 10,000 lines per inch > (for high-end graphic artist drawing
>> tablets).
>>
>> 10K LPI!!!! I don't believe they could possibly really be at that
>> resolution, though the hardware might make claims to be that
>> high...
>>
Steve> Actually, from experience with digitizing tablets for CAD
Steve> which use similar technology, the resolution is near that.
Of course accuracy isn't anywhere near that, but so long as the device
is monotonic, having the extra bits is potentially useful.
>> The second question is how large do tablets get?
>>
Steve> I used tablets that were 12"x12" and 36"x24", but I have seen
Steve> them as large as 48"x36".
I've seen them quite a lot bigger than that. I remember pictures of
tablets used for work on maps that were clearly bigger than a standard
old-time draftman's drafting table. Maybe six feet or so longest
dimension, perhaps even more.
My strong prerefence is to play it safe. Squeezing coordinates into
16 bits doesn't buy much and it's sufficiently close to the edge that
32 bits is clearly the safer answer.
Jim> I'm a bit skeptical about pen color: are there devices that can
Jim> change colors of pens dynamically? Can they change pen types
Jim> dynamically? If yes, then I suppose the data might be packed
Jim> into each event, and if no, just via an interface to determine
Jim> once...
Pen type -- definitely. Consider the Wacom tablet, popular among
graphic artists on PCs and Macs. They come with several pen types
(pen, puck, airbrush). Also, the pen has an "erasers" on the other
end, so you can flip it over to erase. That's a property seen across
the API.
I vaguely remember seeing mention of Wacom support in Linux and
possibly in X. Certainly that device would be an important test case
for any API, along with the perhaps more familiar architect-style puck
tablets. The sort of parameters that the Wacom device sends relate to
its need to emulate artist tools. Take a look at the "airbrush". I
don't have one, my Wacom is too old. But a regular "double action"
airbrush (the non-computer kind) has two control inputs apart from
position: air volume and paint volume, which are independent. And
position is in three coordinates, not just two (distance from the
paper matters a lot). If the Wacom device emulates all that, it means
that each sample would consist of five analog values (x, y, z, air,
paint).
Hm. Off the wall thought. Would it make sense for a digitizer API to
be applicable to 3d input devices as well, things like 3d pointers,
sensor gloves, stuff like that? There seems to be a lot of overlap,
but it may be too much of a distraction.
paul
paul
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