[PD] wacom usb tablet as controller ?

[Hans-Christoph Steiner]

You misunderstood the kind of object I am building.  Look at J. Sarlo's
joystick object.  What I am doing is like that except with fixed outlets
for the axes rather than dynamically assigned axes.  A generic version of
that would not work very well.

As for the event interface object you specify, I personally would find it
less useful than specific (albeit very similar) objects for specific devices.  
When I choose a controller, I don't think of what kind of event interface I am
using, but rather whether I am using a mouse, a joystick, etc.

Its a matter of different approach.  Defining the interface and then
implementing it, versus building the interface to mirror the
implementation.  I prefer to design the interface first, then
implement.  

Plus since I work on Windows, MacOS X and Linux, I want my
objects to be cross-platform.  And I am not sure how compatible the three
different HID schemes are (I have only used the linux event system, and
read about the MacOS X HID stuff).

.hc


On Wed, 9 Apr 2003, Christian Klippel wrote:

> hi,
> 
> Am Mittwoch, 9. April 2003 07:18 schrieb Hans-Christoph Steiner:
> > The problem with writing a generic event interface object is that the
> > number of outlets would change for every device, so for example, if you
> > wrote your patch for a mouse with a wheel, that would give you
> > three outlets for the x, y, and wheel axes.  But then throw in a mouse
> > with no wheel, and you'll get one less outlet, and your patch is broken.
> >
> 
> huh ? sorry, but you are completely wrong with that.
> 
> exactly that is the reason the event interface exists.
> you have uniform messages for every kind of (not only) hid input device, like 
> mice, joysticks, keyboards, etc .....
> 
> and that is the reason i made "usbtablet" as object first, and no other 
> "special" objects, but the the generic event object as this is enough.
> 
> you may want to take a look at http://www.frogmouth.net/hid-doco/x401.html
> there you can see the input_event structure, and that is the only data you get 
> from the event interface. that is :
> 
> struct input_event {
>         struct timeval time;
>         unsigned short type;
>         unsigned short code;
>         unsigned int value;
> };
> 
> for mouse movement, it could be like type=EV_REL, code=REL_X, value=85 ...
> for a tablet it could be type=EV_ABS, code=ABS_Y, value=19282 ....
> or for a keybpard type=EV_KEY, code=KEY_SPACE, value=0 ....
> or for the mouse wheel type=EV_REL, code=REL_WHEEL, value=12 ....
> 
> as you can see, you have only 3 outlets, or four if you want to have the 
> timestamp as well.
> 
> it should be really easy to decode that output in a patch by route or select.
> that avoids the redundancy of having multiple binary objects for more or less 
> the same function. and, you dont need to add the input devices anywhere to 
> access them, like with xinput. its simply a device file, thats it ...
> 
> greets,
> 
> chris
> 

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