Android: Programmatically detect if device has hardware touchscreen connected

Question

I need to write a script to detect if the physical touchscreen is connected to my Android device at boot time. I tried to list the content of the folder /dev/input

Answer 1

You can read /proc/bus/input/devices to get details of your existing input devices.

Depending on your hardware's name, you could do something like that and check if there is any output:

cat /proc/bus/input/devices | grep "Name=" | grep "Touch"

This is the full output of /proc/bus/input/devices:

I: Bus=0011 Vendor=0002 Product=0008 Version=2222
N: Name="AlpsPS/2 ALPS DualPoint TouchPad"
P: Phys=isa0060/serio1/input0
S: Sysfs=/class/input/input2
H: Handlers=mouse1 event2 ts1
B: EV=f
B: KEY=420 0 70000 0 0 0 0 0 0 0 0
B: REL=3
B: ABS=1000003

[...] (blank line, next device)

The B in front stands for bitmap, N, P, S, U, H are simply first letter in corresponding name value and I is for ID. In ordered fashion:

• I → @id: id of the device (struct input_id)
  • Bus → id.bustype
  • Vendor → id.vendor
  • Product → id.product
  • Version → id.version
• N → name of the device
• P → physical path to the device in the system hierarchy
• S → sysfs path
• U → unique identification code for the device (if device has it)
• H → list of input handles associated with the device
• B → bitmaps
  • PROP → device properties and quirks
  • EV → types of events supported by the device
  • KEY → keys/buttons this device has
  • MSC → miscellaneous events supported by the device
  • LED → leds present on the device
  • REL → relative address
  • ABS → absolute address

To test if the device is actually attached, you can try simulating events and see if you get any errors:

input tap [x] [y]

Android comes with an input command-line tool that can simulate miscellaneous input events.

• input → The command line tool to send events
  • tap → the action
  • [x] → X coordinate on the screen
  • [y] → Y coordinate on the screen