On Tue, Mar 09, 2010 at 06:38:22PM -0500, Rafi Rubin wrote: > On 03/09/2010 06:23 PM, Henrik Rydberg wrote: > >Rafi Rubin wrote: > >>>Single touch should be goverened by one of BTN_TOUCH or ABS_PRESSURE. > >>>BTN_TOOL_DOUBLETAP is a two-finger event. > >> > >>That definitely makes sense to me. I really don't know why wacom uses > >>double tap there. > >> > >>Is there any harm in letting through the BTN_0 events? Is the "rdesc" > >>mapping defined by the hardware or hid? > > > >I cannot imagine BTN_0 will do any harm. In synaptics, the BTN_X buttons are > >mapped to multibuttons without clear-cut usage. The button events that carry > >well-defined semantic meaning with regard to touch screens are BTN_TOUCH (any > >finger), BTN_TOOL_FINGER (one finger), BTN_TOOL_PEN (pen), BTN_TOOL_DOUBLETAP > >(two fingers) and BTN_TOOL_TRIPLETAP (three fingers or more). > > > >Henrik > > > > Perhaps we should have a general touch device document. > > I looked at the evdev code. And as you say for single touch > devices, BTN_TOUCH is the bit that matters. It only broken because > I pulled the TOUCH <- 0 when I removed BTN_0. > > So why does evdev associate BTN_TOOL_FINGER with touchpads > (resulting in the wrong set of assumptions and a poorly calibrated > touch screen)? I suppose that's really a discussion for another > list. > Historic reasons. When Synaptics driver was in works we needed an event that is different from BTN_TOUCH to differentiate from touchscreens. -- Dmitry -- 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
