Map touch screens to displays

settouchscreens.sh

#!/bin/bash

#--------------------------------------------------
# Set touchscreen to monitor mapping

declare -A mapping
mapping["ELAN9008:00 04F3:4063"]="eDP-1"
mapping["ELAN9009:00 04F3:4068"]="DP-1"


#--------------------------------------------------
# Generic

fix_width() {
    local input="$1"
    local width="$2"

    input=$(echo "$input" | sed 's/\.0*$//' | sed 's/\(\.[0-9]*[1-9]\)0*$/\1/')

    if [ ${#input} -gt $width ]; then
        input="${input:0:$width}"
    else
        while ((${#input} < $width)); do
            input="$input "
        done
    fi

    echo "$input"
}


#--------------------------------------------------
# Show pointer devices

# Connected pointing devices
echo "--- Pointer devices ---"
xinput list | grep "slave  pointer"
echo


#--------------------------------------------------
# Get monitor information

# Get monitor information
monitor_info=$(xrandr --query | grep ' connected')

# Extract monitor names, resolutions, and positions
declare -A monitors

longest_name=0
while IFS= read -r line; do
    name=$(echo $line | awk '{print $1}')
    resolution=$(echo $line | grep -oP '[0-9]+x[0-9]+\+[0-9]+\+[0-9]+')
    width=$(echo $resolution | cut -d'x' -f1)
    height=$(echo $resolution | cut -d'x' -f2 | cut -d'+' -f1)
    x_pos=$(echo $resolution | cut -d'+' -f2)
    y_pos=$(echo $resolution | cut -d'+' -f3)

    if [ ${#name} -gt $longest_name ]; then
        longest_name=${#name}
    fi

    monitors[$name]="$width $height $x_pos $y_pos"
done <<< "$monitor_info"

# Example output of monitor information
echo "--- Monitor information ---"
for name in "${!monitors[@]}"; do
    echo "Monitor: $(fix_width "$name" $longest_name) -- ${monitors[$name]}"
done
echo


#--------------------------------------------------
# Calculate total screen dimensions

min_x=0
min_y=0
max_x=0
max_y=0

for info in "${monitors[@]}"; do
    width=$(echo $info | cut -d' ' -f1)
    height=$(echo $info | cut -d' ' -f2)
    x_pos=$(echo $info | cut -d' ' -f3)
    y_pos=$(echo $info | cut -d' ' -f4)

    # Calculate extents for x
    if [ $x_pos -lt $min_x ]; then
        min_x=$x_pos
    fi
    right_edge=$((x_pos + width))
    if [ $right_edge -gt $max_x ]; then
        max_x=$right_edge
    fi

    # Calculate extents for y
    if [ $y_pos -lt $min_y ]; then
        min_y=$y_pos
    fi
    bottom_edge=$((y_pos + height))
    if [ $bottom_edge -gt $max_y ]; then
        max_y=$bottom_edge
    fi
done

# Calculate total width and height considering negative offsets
total_width=$((max_x - min_x))
total_height=$((max_y - min_y))

# Total dimensions
echo "Total Width : $total_width"
echo "Total Height: $total_height"


#--------------------------------------------------
# Map touchscreen to monitor

map_touchscreen_to_monitor() {

    touchscreen_name=$1
    monitor_name=$2

    if [ -z "${monitors[$monitor_name]}" ]; then
        echo "Monitor $monitor_name not found."
        exit 1
    fi

    # Get monitor's width, height, x_pos, and y_pos
    width=$(echo ${monitors[$monitor_name]} | cut -d' ' -f1)
    height=$(echo ${monitors[$monitor_name]} | cut -d' ' -f2)
    x_pos=$(echo ${monitors[$monitor_name]} | cut -d' ' -f3)
    y_pos=$(echo ${monitors[$monitor_name]} | cut -d' ' -f4)

    # Adjust x_pos and y_pos to be relative to the overall screen space
    adjusted_x_pos=$((x_pos - min_x))
    adjusted_y_pos=$((y_pos - min_y))

    # Calculate the transformation matrix
    x_scale=$(bc -l <<< "$width / $total_width")
    y_scale=$(bc -l <<< "$height / $total_height")
    x_trans=$(bc -l <<< "$adjusted_x_pos / $total_width")
    y_trans=$(bc -l <<< "$adjusted_y_pos / $total_height")

    # sw = touch_area_width / total_width
    # sh = touch_area_height / total_height
    # xo = touch_area_x_offset / total_width
    # yo = touch_area_y_offset / total_height
    #
    # The matrix is
    # [ sw 0  xo ]
    # [ 0  sh yo ]
    # [ 0  0  1  ]

    # Apply the transformation matrix using xinput
    xinput --map-to-output "$touchscreen_name" "$monitor_name"
    xinput set-prop "$touchscreen_name" "Coordinate Transformation Matrix" $x_scale 0 $x_trans 0 $y_scale $y_trans 0 0 1

    echo
    echo "Mapped $touchscreen_name to $monitor_name"
    echo "[ $(fix_width $x_scale 6) 0      $(fix_width $x_trans 6) ]"
    echo "[ 0      $(fix_width $y_scale 6) $(fix_width $y_trans 6) ]"
    echo "[ 0      0      1      ]"
    echo "X = ${x_trans:0:6} --> ${x_scale:0:6}"
    echo "Y = ${y_trans:0:6} --> ${y_scale:0:6}"
}

for touchscreen in "${!mapping[@]}"; do
    monitor=${mapping[$touchscreen]}
    map_touchscreen_to_monitor "$touchscreen" "$monitor"
done