#!/bin/bash
#-------------------------------------------

# some kind of midi arpegiator (ab)using your window manager's
# window placement as some kind of piano roll 
# by james morris - james ( at ) http://jwm-art.net

# i make no guarantees this will work on your system.

# required software
# BASH
# xwininfo

# prefered software: xterm, and a lightweight window manager

# thanks go to Pedro Lopez-Cabanillas for providing assistance
# via the Linux Audio User mailing list with the midi stuff -
# and also for the pointing out the note names chart, linked below...


#-------------------------------------------
#  <<<<< ----- user options ----- >>>>>

# ***** values are decimals, change *****
# *****  to suit your preferences.  *****

# see http://upload.wikimedia.org/wikipedia/commons/7/7a/NoteNamesFrequenciesAndMidiNumbers.svg
# for valid ranges for notelow and notehigh.

notelow=30
notehigh=80

vellow=0
velhigh=127

# pattern: 1 = play note,  0 = don't play note
pattern="11110110"

# duration of note (seconds)
notetime=0.1

# hang time (seconds) - how long the popup-xterms hang around
hangtime=0.5

# controls for popup-xterms (affects window placement)
wwidthmin=8
wwidthmax=14
wheightmin=2
wheightmax=8

#-------------------------------------------
#  <<<<< ----- system settings ----- >>>>>

# midi device
mididev="/dev/snd/midiC1D0"

#-------------------------------------------
#       <<<<< ----- code ----- >>>>>

noteoff=$1
patix=$2

if [[ -z "$noteoff" ]]
then
# << -- INITIALIZE -- >>
noteoff="_"
if [[ -z "$DISPLAY" ]]
then
echo "This script must be run from a terminal in X"
exit
fi
exec 3>$mididev
if [[ "$?" != "0" ]]
then
echo "an error occurred trying to open midi device: $midi"
echo "set mididev to the midi device you wish to use"
echo "in the system setting of this script"
exit
fi
echo -ne '\xb0' >&3
echo -ne '\x07' >&3
echo -ne '\x7f' >&3 # volume
patix=0
# << -- END INITIALIZE -- >>
fi

playnote=${pattern:$patix:1}
patix=$(( $(( $patix + 1 )) % ${#pattern} ))

# get stats of root window
xystr="Absolute upper-left"
wininfo=`xwininfo -root -stats`

tmp=`echo "${wininfo}" | egrep "Width"`
tmp2=`expr index "$tmp" ":"`
scrmaxx=$(( ${tmp:$tmp2} ))

tmp=`echo "${wininfo}" | egrep "Height"`
tmp2=`expr index "$tmp" ":"`
scrmaxy=$(( ${tmp:$tmp2} ))

wwr=$(( $wwidthmax - $wwidthmin ))
whr=$(( $wheightmax - $wheightmin ))

ndiff=$(( $notehigh - $notelow ))
vdiff=$(( $velhigh - $vellow ))

xsc=$(( $scrmaxx / $ndiff ))
ysc=$(( $scrmaxy / $vdiff ))

wininfo=`xwininfo -stats -id $WINDOWID`

tmp=`echo "${wininfo}" | egrep "${xystr} X"`
tmp2=`expr index "$tmp" ":"`
x=$(( ${tmp:$tmp2} ))

tmp=`echo "${wininfo}" | egrep "${xystr} Y"`
tmp2=`expr index "$tmp" ":"`
y=$(( ${tmp:$tmp2} ))

r=$(( $x / 10 % 256 ))
g=$(( $x / $(( $y + 1 )) % 256 ))
b=$(( $y / 10 % 256 ))
bg=$( printf "#%02x%02x%02x\n" $r $g $b )

geo=$( printf "%sx%s" \
	$(($RANDOM % $wwr + $wwidthmin)) \
	$(($RANDOM % $whr + $wheightmin)) )

note=$(( $notelow + $x / $xsc ))
vel=$(( $vellow + ($scrmaxy - $y) / $ysc ))

if (( $note < $notelow ))
then
note=$notelow
elif (( $note > $notehigh ))
then
$note=$notehigh
fi

if (( $vel < $vellow ))
then
vel=$vellow
elif (( $vel > $velhigh ))
then
vel=$velhigh
fi

if [[ "$playnote" == "1" ]]
then
noteout='\x'$( printf "%02x" $note )
velout='\x'$( printf "%02x" $vel )
echo -ne '\x90' >&3
echo -ne $noteout >&3
echo -ne $velout >&3
else
noteout="_"
bg="#ffffff"
fi

sleep $notetime

$TERM -bg "$bg" -geo "$geo" -e $0 $noteout $patix &

if [[ "$noteoff" != "_" ]]
then
echo -ne '\x80' >&3
echo -ne $noteoff >&3
echo -ne '\x00' >&3
fi

sleep $hangtime