Who decides there is mouse pointer or touch screen present

driversmousetouch screen

I have installed a touch screen film which is connected via USB and it is recognized as a mouse device.

Hence, I can not swipe on a web page. It clicks and selects or clicks and drags something on the screen when I try to swipe.

There are questions and answers that didn't help my case:

On what level is touch screen support implemented in Linux?
Touchscreen is being recognized as a mouse in Arch Linux–how can I enable multi-touch with it and get it recognized as a touch screen?

My original problem description is here.

So, who is responsible for recognizing the input device as a mouse or a touch screen, OS or the app? So where should I search for the solution?

Searches and notes to myself

With the help of this forum thread (with a little bit changes), I could make ts_test work. I calibrated the touch screen, draw a circle on the screen, etc.

Now what? The web browser I am using still selects some text instead of scrolling in the page.

Someone says "The application should use the input device directly" and someone other says "Application has nothing to do with the input device directly".

Should I edit the xorg.conf to emulate scroll event just because my application (Midori, the web browser in this case) can not use "the touch screen", or an Android phone does the same thing already?

How does an application get the mouse events in the first place? By opening the device file (/dev/input/event*) by itself or somehow from Xorg server? If the application handles device file itself, how could Xorg server possibly emulate the mouse scrolling stuff?

If application is listening the Xorg server for the mouse/touch-multitouch/whatever events, than the application should be written these mouse/touch/whatever events in mind and Xorg should have an entry that we say "Hey, Xorg, the device you see in /etc/input/event0 is a touch screen. When you get physical signals from it, tell the applications about the touch events."

Best Answer

This is only a partial answer. Other folks should feel free to copy this as a basis for their answers.

Touch screens input devices can be opened as simple mice, or with full access to their touch-screeniness via /dev/input/... and evdev stuff.

You need to get your X server to use the input device as a touchscreen. The X server translates touch-screen events like dragging along the side into mouse-wheel events, for example. Apps that want full gesture (multi-touch) support would need to open the Linux input event device themselves, instead of just getting X11 pointer position / mouse button events.

Kernel drivers for your specific touchscreen should be getting loaded automatically when you plug it in, unless the generic USB mouse driver claims the device first.

Look in your kernel log (dmesg) to see log messages about it. lsusb could help find device ID stuff to search for in the kernel log.

Related Solutions

Xorg – ignore first click event when resuming from Screen Blanking

I know this a old question, but i had the same problem and finally solved it by using xssstart and modifying slock which is a screen locker. I called it clicklock

https://github.com/zpfvo/clicklock
https://github.com/unixdj/xssstart

xssstart runs a command as soon as the screensaver gets enabled and clicklock is just a black fullscreen window which closes after the first touch or key event.

So you have to run xssstart clicklock

Calibrating a touch-screen on dual monitors (one touch one not)

I have it working now. The first thing I did was to install the latest version of the display driver from the xorg repo. I'm not sure if this step was absolutely necessary since it doesn't seem to have changed the output from xrandr much, but it didn't hurt anyway:

$ sudo apt-add-repository ppa:xorg-edgers/ppa
$ sudo apt-get update
$ sudo apt-get dist-upgrade
$ aptitude search <my-graphics-card-brand>
$ sudo apt-get install <corresponding package>

Now xrandr shows DP-1 with more properties:

$ xrandr
Screen 0: minimum 320 x 200, current 2732 x 768, maximum 8192 x 8192
eDP-1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1366x768      60.00*+  40.00  
   1360x768      59.80    59.96  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   960x600       60.00  
   960x540       59.99  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   800x512       60.17  
   700x525       59.98  
   640x512       60.02  
   720x450       59.89  
   640x480       60.00    59.94  
   680x384       59.80    59.96  
   576x432       60.06  
   512x384       60.00  
   400x300       60.32    56.34  
   320x240       60.05  
VGA-1 disconnected (normal left inverted right x axis y axis)
DP-1 connected 1366x768+1366+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1360x768      59.80    59.96  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   960x600       60.00  
   960x540       59.99  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   800x512       60.17  
   700x525       59.98  
   640x512       60.02  
   720x450       59.89  
   640x480       60.00    59.94  
   680x384       59.80    59.96  
   576x432       60.06  
   512x384       60.00  
   400x300       60.32    56.34  
   320x240       60.05  
HDMI-1 disconnected (normal left inverted right x axis y axis)

And then start X and run the following command to assign eDP-1 as the touchscreen:

$ xinput --map-to-output $(xinput list --id-only "Elan Touchscreen") eDP-1

The manpage of xinput (v.1.6.2) mentions that the device name can be given as a string as well. Therefore, this would also work:

$ xinput --map-to-output "Elan Touchscreen" eDP-1