Alright, let's work through this together—since you've got root access and want to use getevent/sendevent to shift touch inputs globally (even outside your app), here's a solid step-by-step plan that’ll get you there:

The key here is to intercept the original touch events, modify their Y-coordinate, and feed the adjusted events back to the system as a virtual input device. This ensures the shift works everywhere, not just in a single app.

1. Find Your Physical Touch Device #

First, you need to identify which input device corresponds to your screen. Run this command:

getevent -l

Look for the device path (like /dev/input/event2) that spits out events when you touch the screen—you’ll see lines with ABS_MT_POSITION_X/ABS_MT_POSITION_Y (multi-touch position data).

To confirm it’s the right device, check its supported events:

getevent -p /dev/input/event2

Make sure it lists ABS_MT_POSITION_Y (usually with code 0035).

2. Set Up the Virtual Input Device (uinput) #

To make the modified events system-wide, we’ll create a virtual touch device using the uinput module (most rooted Android devices have this). First, grant permissions to access it:

chmod 666 /dev/uinput

3. Write the Event Forwarding Script #

This script will:

• Create a virtual touch device the system recognizes
• Disable the original touch device to avoid duplicate inputs
• Read original touch events, adjust the Y-coordinate, and send them to the virtual device

Create a file named touch_shift.sh with this content:

#!/system/bin/sh

# --- CONFIG THESE VALUES FIRST ---
ORIGINAL_DEVICE="/dev/input/event2"  # Replace with your touch device path
VIRTUAL_DEVICE="/dev/uinput"
OFFSET=-200  # Shift up by 200 units (negative = up, positive = down)
# --- END CONFIG ---

# Step 1: Create the virtual touch device
# Enable required event types
ioctl "$VIRTUAL_DEVICE" UI_SET_EVBIT EV_SYN
ioctl "$VIRTUAL_DEVICE" UI_SET_EVBIT EV_KEY
ioctl "$VIRTUAL_DEVICE" UI_SET_EVBIT EV_ABS

# Enable touch press/release events
ioctl "$VIRTUAL_DEVICE" UI_SET_KEYBIT BTN_TOUCH

# Enable multi-touch position tracking
ioctl "$VIRTUAL_DEVICE" UI_SET_ABSBIT ABS_MT_POSITION_X
ioctl "$VIRTUAL_DEVICE" UI_SET_ABSBIT ABS_MT_POSITION_Y
ioctl "$VIRTUAL_DEVICE" UI_SET_ABSBIT ABS_MT_TRACKING_ID

# Define device metadata (adjust Y range to match your screen resolution!)
# Get your screen's Y range from `getevent -p` on the original device (e.g., min 0, max 2339)
struct_input_id="$(printf 'x00x00x00x00x00x00x00x00')"
# ABS_MT_POSITION_X range: 0 to 1080 (adjust for your screen width)
struct_absinfo_x="$(printf 'x00x00x00x00xe8x03x00x00x00x00x00x00x00x00x00x00')"
# ABS_MT_POSITION_Y range: 0 to 2339 (adjust for your screen height)
struct_absinfo_y="$(printf 'x00x00x00x00x9fx08x00x00x00x00x00x00x00x00x00x00')"

# Finalize virtual device creation
echo "GlobalTouchShifter" > "$VIRTUAL_DEVICE"
echo "1" > "$VIRTUAL_DEVICE"
echo "1" > "$VIRTUAL_DEVICE"
echo "$struct_input_id" > "$VIRTUAL_DEVICE"
echo "0x0003" > "$VIRTUAL_DEVICE"
echo "0x30" > "$VIRTUAL_DEVICE"
echo "$struct_absinfo_x" > "$VIRTUAL_DEVICE"
echo "0x0003" > "$VIRTUAL_DEVICE"
echo "0x35" > "$VIRTUAL_DEVICE"
echo "$struct_absinfo_y" > "$VIRTUAL_DEVICE"
ioctl "$VIRTUAL_DEVICE" UI_DEV_CREATE

# Step 2: Disable original touch device to prevent duplicate inputs
echo "0" > "/sys/class/input/$(basename "$ORIGINAL_DEVICE")/enable"

# Step 3: Read, modify, and forward events
getevent "$ORIGINAL_DEVICE" | while read -r line; do
    # Split event line into components: timestamp, type, code, value
    PARTS=($line)
    TYPE=${PARTS[1]}
    CODE=${PARTS[2]}
    VALUE=${PARTS[3]}

    # Adjust Y-coordinate event (ABS_MT_POSITION_Y, code 0035)
    if [ "$TYPE" = "0003" ] && [ "$CODE" = "0035" ]; then
        NEW_VALUE=$((VALUE + OFFSET))
        # Keep value within screen bounds to avoid weird behavior
        if [ "$NEW_VALUE" -lt 0 ]; then
            NEW_VALUE=0
        fi
        # Send modified event to virtual device
        sendevent "$VIRTUAL_DEVICE" "$TYPE" "$CODE" "$NEW_VALUE"
    else
        # Forward all other events as-is
        sendevent "$VIRTUAL_DEVICE" "$TYPE" "$CODE" "$VALUE"
    fi
done

# Cleanup (runs if script is stopped)
echo "1" > "/sys/class/input/$(basename "$ORIGINAL_DEVICE")/enable"
ioctl "$VIRTUAL_DEVICE" UI_DEV_DESTROY

4. Run the Script #

First, give the script execution permissions:

chmod +x touch_shift.sh

Then run it in the background so it keeps working even if you close the terminal:

nohup sh touch_shift.sh &

Important Notes #

• Screen Resolution: Update the struct_absinfo_y line to match your screen’s actual Y-axis range (get this from getevent -p on the original device). If you skip this, touch inputs might behave strangely.
• Stopping the Script: To revert back to normal touch behavior, kill the script process or run the cleanup commands manually:

  echo "1" > "/sys/class/input/event2/enable"  # Replace with your device
  ioctl /dev/uinput UI_DEV_DESTROY
  

• Permissions: Make sure you’re running all commands as root—you might need to prepend su - if your terminal isn’t already rooted.

内容的提问来源于stack exchange，提问作者Avihu Kochero