Trustin's single/dual monitor setup script for laptops with nVidia GPU

reconfigure-display.sh

#!/bin/bash
if [[ $# -gt 0 ]]; then
  CLONE=1
else
  CLONE=0
fi

function get_max_resolution() {
  xrandr | grep -A100 "^$1 " | grep -P '^\s+[0-9]+x[0-9]+\s+[0-9\.]+\s*\*?\+.*$' | head -1 | awk '{ print $1; }'
}

function get_resolution() {
  local RES=$(xrandr | grep -A100 "^$1 " | grep -P '^\s+[0-9]+x[0-9]+\s+[0-9\.]+\s*\*?\+.*$' | head -1 | awk '{ print $1; }')
  local REFRESH_RATE=$(xrandr | grep -A100 "^$1 " | grep -P '^\s+'"$RES"'\s+[0-9\.]+\s*\*?\+.*$' | head -1 | awk '{ print $2; }' | sed 's#\..*##g')

  # Avoid using the mode with low refresh rate.
  if [[ "$REFRESH_RATE" =~ (^[0-9]+$) ]] && [[ "$REFRESH_RATE" -lt 50 ]]; then
    case "$RES" in
    3840x2160)
      echo -n '1920x1080'
      ;;
    *)
      echo -n "$RES"
      ;;
    esac
    return
  fi

  echo -n "$RES"
}

function get_width() {
  echo "$1" | cut -dx -f1
}

function get_height() {
  echo "$1" | cut -dx -f2
}

# MBP's default output is DP-2.
#PRI_PORT=LVDS1
PRI_PORT=DP-2
PRI_RES=$(get_resolution $PRI_PORT)
PRI_WIDTH=$(get_width $PRI_RES)
PRI_HEIGHT=$(get_height $PRI_RES)

echo "Primary: $PRI_PORT $PRI_RES"

SEC_PORT=$(nvidia-settings -q dpys |
           grep -P '\s*\[[0-9]+\] [^ ]+ \([^\)]+\) \(connected' |
           awk '{ print $3; }' | sed 's/[()]//g' | grep -vF "$PRI_PORT" | head -1)

if [[ -z "$SEC_PORT" ]]; then
  # No external display
  nvidia-settings -a CurrentMetaMode="
    $PRI_PORT: nvidia-auto-select +0+0 {ViewPortIn=$PRI_RES}" | grep -vP '^$'
else
  # Has external display
  SEC_MAX_RES=$(get_max_resolution $SEC_PORT)
  SEC_RES=$(get_resolution $SEC_PORT)
  echo "Secondary: $SEC_PORT $SEC_RES out of $SEC_MAX_RES"

  MAX_SEC_WIDTH=$(get_width $SEC_MAX_RES)
  MAX_SEC_HEIGHT=$(get_height $SEC_MAX_RES)

  if [[ $MAX_SEC_WIDTH -le 1900 ]] || [[ $MAX_SEC_HEIGHT -le 1200 ]]; then
    # Low-DPI display - very likely to unsupport scaling from high-DPI.
    SEC_IS_PRI=1
  else
    SEC_IS_PRI=0
  fi

  SEC_WIDTH=$(get_width $SEC_RES)
  SEC_HEIGHT=$(get_height $SEC_RES)

  OLD_PRI_WIDTH=$PRI_WIDTH
  OLD_PRI_HEIGHT=$PRI_HEIGHT
  OLD_PRI_RES=$PRI_RES

  if [[ $SEC_IS_PRI -eq 0 ]]; then
    if [[ $((PRI_WIDTH * SEC_HEIGHT)) -gt $((SEC_WIDTH * PRI_HEIGHT)) ]]; then
      PRI_WIDTH=$((PRI_HEIGHT * SEC_WIDTH / SEC_HEIGHT))
    else
      PRI_HEIGHT=$((PRI_WIDTH * SEC_HEIGHT / SEC_WIDTH))
    fi

    PRI_RES=${PRI_WIDTH}x${PRI_HEIGHT}
    PRI_OUT_RES=$PRI_RES

    OFFSET_X=$(((OLD_PRI_WIDTH - PRI_WIDTH) / 2))
    OFFSET_Y=$(((OLD_PRI_HEIGHT - PRI_HEIGHT) / 2))
    if [[ $OFFSET_X -ge 0 ]]; then
      OFFSET_X="+$OFFSET_X"
    fi
    if [[ $OFFSET_Y -ge 0 ]]; then
      OFFSET_Y="+$OFFSET_Y"
    fi

    OFFSETS=$OFFSET_X$OFFSET_Y
  else
    if [[ $((PRI_HEIGHT * SEC_WIDTH)) -gt $((SEC_HEIGHT * PRI_WIDTH)) ]]; then
      PRI_OUT_WIDTH=$PRI_WIDTH
      PRI_OUT_HEIGHT=$((PRI_WIDTH * SEC_HEIGHT / SEC_WIDTH))
    else
      PRI_OUT_WIDTH=$((PRI_HEIGHT * SEC_WIDTH / SEC_HEIGHT))
      PRI_OUT_HEIGHT=$PRI_HEIGHT
    fi

    PRI_WIDTH=$SEC_WIDTH
    PRI_HEIGHT=$SEC_HEIGHT
    PRI_RES=${PRI_WIDTH}x${PRI_HEIGHT}
    PRI_OUT_RES=${PRI_OUT_WIDTH}x${PRI_OUT_HEIGHT}

    OFFSET_X=$(((OLD_PRI_WIDTH - PRI_OUT_WIDTH) / 2))
    OFFSET_Y=$(((OLD_PRI_HEIGHT - PRI_OUT_HEIGHT) / 2))
    if [[ $OFFSET_X -ge 0 ]]; then
      OFFSET_X="+$OFFSET_X"
    fi
    if [[ $OFFSET_Y -ge 0 ]]; then
      OFFSET_Y="+$OFFSET_Y"
    fi
    OFFSETS=$OFFSET_X$OFFSET_Y
  fi

  echo "Primary: $PRI_PORT $PRI_RES scaled to $PRI_OUT_RES$OFFSETS"

  if [[ $CLONE -ne 0 ]]; then
    nvidia-settings -a CurrentMetaMode="
      $SEC_PORT: $SEC_RES +0+0 {ViewPortIn=$PRI_RES, ViewPortOut=$SEC_RES},
      $PRI_PORT: nvidia-auto-select +0+0 {ViewPortIn=$PRI_RES, ViewPortOut=$PRI_OUT_RES$OFFSETS}" | grep -vP '^$'
  else
    nvidia-settings -a CurrentMetaMode="
      $SEC_PORT: $SEC_RES +0+0 {ViewPortIn=$PRI_RES, ViewPortOut=$SEC_RES}" | grep -vP '^$'
  fi
fi

nvidia-settings -q CurrentMetaMode

if [[ "$EUID" -eq `id -u trustin` ]]; then
  # Restart Openbox just in case it does not detect the resolution changes properly.
  openbox --restart >/dev/null 2>&1 &
fi
exit 0