Hi Jason,
Jason Gerecke said the following on 10/09/2012 08:36 PM:
> INPUT_PROP_* aren't bit flags -- they're bit positions. That is, if
> bit number INPUT_PROP_DIRECT is set, then it's a direct input device.
> Or, put differently (and grabbing descriptions from event-codes.txt):
>
> if (flag& (1<< INPUT_PROP_POINTER)) {
> // The INPUT_PROP_POINTER property indicates that the device is not transposed
> // on the screen and thus requires use of an on-screen pointer to trace user's
> // movements. Typical pointer devices: touchpads, tablets, mice; non-pointer
> // device: touchscreen.
> }
> if (flag& (1<< INPUT_PROP_DIRECT)) {
> // The INPUT_PROP_DIRECT property indicates that device coordinates should be
> // directly mapped to screen coordinates (not taking into account trivial
> // transformations, such as scaling, flipping and rotating). Non-direct input
> // devices require non-trivial transformation, such as absolute to relative
> // transformation for touchpads. Typical direct input devices: touchscreens,
> // drawing tablets; non-direct devices: touchpads, mice.
> }
>
> Note that INPUT_PROP_DIRECT is specified to be set for both
> touchscreens (e.g. Cintiq, tablet PC) *and* for drawing tablets (e.g.
> Intuos, Bamboo). To properly ensure that you're getting a touchscreen,
> you need to make sure that its DIRECT and non-POINTER. Because of
> this, the libwacom code technically isn't correct; the only reason it
> doesn't think an Intuos is built-in is because the guidelines weren't
> clear when my kernel patches were accepted and so they don't have the
> DIRECT flag set.
>
> To be correct and use the defines instead of hex codes, it should
> probably be written more like:
>
> int hw_flags = atoi(contents);
> int direct_flag = (1<< INPUT_PROP_DIRECT);
> int pointer_flag = (1<< INPUT_PROP_POINTER);
>
> *builtin = (hw_flags& (direct_flag | pointer_flag) == direct_flag) ?
> IS_BUILTIN_TRUE : IS_BUILTIN_FALSE;
Thanks for the clarification, I'll update the patches with this fix as
well.
Cheers,
Olivier.
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