#!/bin/bash
#---------------------------------------------------------------------------#
# Script to switch screens using xrandr, working around a bug in the Intel  #
# driver for 945GME-type hardware which hangs the machine.                  #
#                                                                           #
# NB, only the presence of compiz is worked around here. Having other       #
# OpenGL apps running while switching screens may still lead to a crash.    #
#                                                                           #
# Usage: rnr_switch <output>[:<x-size>x<y-size>@<refresh-rate>]             #
# where <output> is the device name as reported by xrandr (e.g. LVDS1,      #
# VGA1, etc).                                                               #
#                                                                           #
# Uses zenity to report progress.                                           #
#                                                                           #
# This script is best used with a compiz keyboard shortcut to trigger it    #
# using the "Commands" plugin.  E.g., I have:                               #
#  Ctrl-Shift-F1 : rnr_switch LVDS1              (laptop panel, auto)       #
#  Ctrl-Shift-F2 : rnr_switch VGA1               (external monitor, auto)   #
#  Ctrl-Shift-F3 : rnr_switch VGA1:1280x1024@75  (external monitor, manual) #
#  Ctrl-Shift-F4 : rnr_switch VGA1:1024x768@60   (external monitor, manual) #
#                                                                           #
# To avoid problems:                                                        #
# - Always wait for the "You can now close this window" message before      #
#   attempting to run this script again.                                    #
# - Do not use this script to switch between different resolutions of the   #
#   external monitor; instead, switch to the Panel first, then back to the  #
#   external monitor. This script could be fixed to do this directly, but   #
#   one thing at a time..                                                   #
#                                                                           #
# pablomme 12.2009                                                          #
# Public Domain. No Warranty. Etc.                                          #
#---------------------------------------------------------------------------#

set +u

get_mode() {
  # Get the modeline for mode $1 x $2 @ $3
  local mode
  set -- $(cvt $1 $2 $3 | grep -vE "^#")
  shift 2
  mode=""
  while (($#>0)) ; do
    case "$1" in
    -hsync) mode="$mode -HSync" ;;
    -vsync) mode="$mode -HSync" ;;
    +hsync) mode="$mode +VSync" ;;
    +vsync) mode="$mode +VSync" ;;
    *) mode="$mode $1" ;;
    esac
    shift
  done
  echo $mode
}

check_number_N() {
  # Check whether $1 is a positive integer
  local num="$1" size i=0 c
  size=${#num} ; ((size<1)) && return 1
  while ((i<size)) ; do c=${num:$i:1} ; i=$((i+1))
    case $c in 1|2|3|4|5|6|7|8|9|0) continue ;; esac ; return 1
  done
  return 0
}

check_number_R() {
  # Check whether $1 is a real number (no Exx notation allowed)
  local num="$1" size i=0 c isfirst=1 dotfound=0 anyfigure=0
  size=${#num}
  while ((i<size)) ; do c=${num:$i:1} ; i=$((i+1))
    case $c in
    .) ((dotfound==1)) && return 1 ; dotfound=1 ;;
    1|2|3|4|5|6|7|8|9|0) anyfigure=1 ;;
    *) return 1 ;;
    esac
  done
  ((anyfigure==0)) && return 1 || return 0
}

errstop() {
  # Stop with a error posted to stdout, a zenity error dialog and (if it is
  # already open) a pre-existing zenity text-info window.
  local text="$1"
  # To stdout.
  echo "$text"
  # Convert to HTML-parseable string before passing to zenity.
  text="${text//</&lt;}"
  text="${text//>/&gt;}"
  # To zenity text-info window.
  [ -z "$COPROC_PID" ] || logzenity "$text"
  # To zenity error dialog.
  zenity --error --title="${0##*/}: Error" --text="$text"
  # Kill text-info window on exit.
  killzenity
  exit 1
}

killzenity() {
  # Kill zenity text-info window in $1 seconds (or immediately if no args).
  [ -z "$COPROC_PID" ] && return
  (($#==0)) || sleep $1
  kill $COPROC_PID
}

logzenity() {
  # Log to text-info zenity window.
  [ -z "$COPROC_PID" ] && { coproc zenity --text-info --width=500 --height=500\
     --title="${0##*/}: Changing Screens" ; sleep 1 ; }
  echo "$*" 1>&${COPROC[1]}
}

log() {
  # Log to stdout and to a text-info zenity window.
  # To stdout.
  echo "$*"
  # To zenity text-info window.
  logzenity "$*"
}

sleeplog() {
  # Sleep for $1 seconds and log it.
  log "- Waiting $1 seconds."
  sleep $1
}

# Read command-line option.
(($#==0)) && errstop\
   "Usage: ${0##*/} <device>[:<x-size>x<y-size>@<refresh-rate>] ."
mode="$1"
case "$mode" in
*:*@*)
  m=$mode
  to=${m%%:*} ; m=${m#*:}
  x=${m%%x*} ; m=${m#*x}
  y=${m%%@*} ; m=${m#*@}
  r=$m
  check_number_N $x && check_number_N $y && check_number_R $r\
     || errstop "Bad mode $mode."
  mode=${x}x${y}@$r ;;
*)
  to=$mode ; mode=auto ;;
esac

# Read current configuration to determine 'from'
from=""
{
  output=""
  while read line ; do
    set -- $line
    [ "$2" = connected ] && { output=$1 ; continue ; }
    [ -z "$output" ] && continue
    [ "$6" = \*current ] || [ "$7" = \*current ]\
       && { from=$output ; break ; }
  done
} < <(xrandr -q --current --verbose)
[ -z "$from" ] && errstop "xrandr: could not determine current output."
[ "$from" = "$to" ] && errstop "Current output same as target, '$from'."

log "Switching from '$from' to '$to' in mode '$mode'."

# Disable compiz while switching screens.
disabled_compiz=0
if (($(lspci | grep 945 | grep Intel | grep -c VGA)>0))\
   && (($(ps -u $USER -o comm | grep -cw compiz)>0)) ; then
  disabled_compiz=1
  log "- Switching from compiz to metacity."
  nohup metacity --replace >& /dev/null & disown
  sleeplog 4
fi

# Find preferred video mode.
if [ "$mode" = auto ] ; then
  log "- Autodetecting 'auto' mode."
  to_exists=0
  x=0 ; y=0 ; r=0
  output=""
  {
    while read line ; do
      set -- $line
      [ "$2" = connected ] && { output=$1 ; continue ; }
      [ "$output" = "$to" ] || continue
      to_exists=1
      [ "$6" = +preferred ] || [ "$7" = +preferred ]\
         && { x="${1%x*}" ; y="${1#*x}" ; continue ; }
      ((x>0)) || continue
      [ "$1" = v: ] || continue
      r=${11%Hz} ; break
    done
  } < <(xrandr -q --verbose)
  errmsg=""
  if ((to_exists==0)) ; then
    errmsg="Could not find output '$to'."
  elif [ "$r" = 0 ] ; then
    errmsg="Could not find preferred mode for '$to'."
  fi
  if [ ! -z "$errmsg" ] ; then
    if ((disabled_compiz==1)) ; then
      log "- Error detected, restarting compiz."
      nohup compiz --replace >& /dev/null & disown
    fi
    errstop "$errmsg"
  fi
  mode=${x}x${y}@$r
  log "- 'auto' mode resolves to '$mode'."
fi

mode=$(get_mode $x $y $r)
modename=${x}x${y}at${r}hz_$$
log "- Defining mode '$modename'."
xrandr --newmode $modename $mode
log "- Adding mode to output '$to'."
xrandr --addmode $to $modename
log "- Turning output '$from' off."
xrandr --output $from --off
log "- Turning output '$to' on."
xrandr --fb ${x}x${y} --output $to --mode $modename

# Hack: reenable compiz.
if ((disabled_compiz==1)) ; then
  sleeplog 4
  log "- Re-enabling compiz."
  nohup compiz --replace >& /dev/null & disown
  sleeplog 4
  log "- Restarting gnome-panel (in case it crashed)."
  nohup gnome-panel --replace >& /dev/null & disown
fi

log "Finished."
logzenity ""
logzenity "You can now close this window."
wait