On Tue, Sep 13, 2011 at 12:36 PM, Ping Cheng <pinglinux@xxxxxxxxx> wrote: > On Tue, Sep 13, 2011 at 7:13 AM, Chris Bagwell <chris@xxxxxxxxxxxxxx> wrote: >> On Tue, Sep 13, 2011 at 3:09 AM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote: >>> Hi Jason, >>> >>>> Adds INPUT_PROP_POINTER or INPUT_PROP_DIRECT as necessary to the >>>> hardware supported by the Wacom driver. The DIRECT property is >>>> assigned to devices with an embedded screen (i.e. touchscreens >>>> and display tablets). The POINTER property is assigned to those >>>> without embedded screens. >>>> >>>> Signed-off-by: Jason Gerecke <killertofu@xxxxxxxxx> >>>> --- >>> >>> According to the discussion leading up to the properties interface >>> (https://lkml.org/lkml/2010/12/15/263), a tablet is a direct pointer >>> device, as opposed to a touchpad, which is an indirect pointer >>> device. The distinction determines the direction of two-finger scroll, >>> for instance. The question is then what behavior should be assigned to >>> a large tablet without an embedded screen. It should have POINTER set >>> for sure, but should it also have DIRECT set? > > We have discussed and debated the above before the patch was posted. > > As Ikbel pointed out, a standalone tablet can be DIRECT or INDIRECT, > depending on how it is used. So, it is more a property that is decided > by the client than by the kernel driver. I've a couple questions that would help me decide how things should be declared. Can DIRECT be translated to mean treat coordinates as absolute coordinates mapped to screen? Or is it meant to be reserved only for the more specific touchscreen-like application were the touch is laid directly on top of the object being manipulated (or picture is overlaid the touch for projector case)? If some company shipped a touchpad+projector, would that ideally declare DIRECT and not declare POINTER since user is directly touching objects and the display of a pointer would serve no purpose? What I'm getting at with the second question is if user pairs up a touch tablet/touchpad with a projector then declaring even POINTER may be just as wrong as not declaring DIRECT. I don't think we can every get custom HW applications declared correctly, so do we punish all cases and not declare anything? > >> Here are all the possible combinations based on my understanding of >> their intended usage. >> >> * Touch interface without screen should have POINTER only to >> indicate pointer needed and to treat absolute coordinates as relative >> movement. Relative movement is product's default behavior as >> documented in its own manual and what I think should be advertised by >> default. >> * Pen interface without screen should have both POINTER and DIRECT to >> indicate pointer needed and to treat absolute coordinates as absolute >> movement. > > Reporting it as DIRECT indicates it can only be used as DIRECT. We > don't want client to make that assumption. User-land clients can > distinguish a touch POINTER from a pen POINTER by the tool types. I see your logic now and patch does follow that logic. I can actually buy into that although it seems to make the need for both POINTER and DIRECT redundant. Touchscreen = DIRECT while Tablet (pen, touch, or both) = POINTER. No overlap. If we do allow DIRECT on tablets then I do see now it becomes a relaxed DIRECT since application will most likely still offer switching pens to relative mode. Chris > >> * Touch interfaces with screen should have DIRECT only to indicate no >> pointer displayed and absolute coordinates as absolute movement. >> * Pen interface with screen should have DIRECT only to indicate no >> pointer displayed and absolute coordinates as absolute movement. >> * A Pen+Touch touchscreen (only the wacom_w8001.c), should have DIRECT >> only to indicate no pointer displayed and absolute coordinates as >> absolute movement. >> >> Assuming we all agree on those combination, then in the patch the >> Graphire and Intuos tablets are missing a DIRECT, the touchscreens are >> correct, and the Bamboo's need to add DIRECT for the PEN interface >> only. > > I agree with all the other assumptions except this one. > > Ping > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
