Hi Dwayne, On Wed, Oct 26, 2011 at 05:10:23PM -0400, Dwayne Litzenberger wrote: > I have a quick question about the /dev/input/eventX interface with > userspace. > > Let's say I have a touchscreen, and I move my finger to (200,100). > I'll see something line this (simplified): > > EV_ABS ABS_X 200 > EV_ABS ABS_Y 100 > EV_SYN > > Next, let's say I see something like this: > > EV_ABS ABS_Y 90 > EV_SYN > > What is the meaning of that, from the perspective of userspace? > I see two possibilities. Either: > > 1. It's a move to (200,90), or > 2. It's a move to (0,90) > > Which is the correct interpretation? Door #1. > Is this documented anywhere? >From Documentation/input/event-codes.txt: "The input protocol is a stateful protocol. Events are emitted only when values of event codes have changed. However, the state is maintained within the Linux input subsystem; drivers do not need to maintain the state and may attempt to emit unchanged values without harm. Userspace may obtain the current state of event code values using the EVIOCG* ioctls defined in linux/input.h." > > Apparently, the usbhid driver is generating events that imply #1, but > xserver-xorg-input-evdev interprets these according to #2. I'm trying > to figure out what needs to be patched. :) xserver-xorg-input-evdev. Thanks. -- 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
