#!/bin/bash
#
# im_histogram [option] 'math_expression' 'basename'
#
# Plot a graph the mathematical expression (gnuplot format), generating a two
# graphs of the expression, one as a small GIF thumbnail and a larger JPG
# image.
#
# Options:
#     -l         include a line from 0,0 to 1,1
#     -d data    read and mark control points from file.
#     -t title   A title string to use on the main JPEG plot image
#
# For example
#    im_histogram -t "Tint Vector Function" \
#               '1-(4.0*((x-0.5)*(x-0.5)))' tint_plot
#
# See Also
#    im_graph    draw a histogram of the given IM options on a gradient
#    im_profile  draw a horizontal profile of a gradient image
#
####
#
# WARNING: Input arguments are NOT tested for correctness.
# This script represents a security risk if used ONLINE.
# I accept no responsiblity for misuse. Use at own risk.
#
# Anthony Thyssen,  October 2004
#
PROGNAME=`type $0 | awk '{print $3}'`  # search for executable on path
PROGDIR=`dirname $PROGNAME`            # extract directory of program
PROGNAME=`basename $PROGNAME`          # base name of program
Usage() {                              # output the script comments as docs
  echo >&2 "$PROGNAME:" "$@"
  sed >&2 -n '/^###/q; /^#/!q; s/^#//; s/^ //; 3s/^/Usage: /; 2,$ p' \
          "$PROGDIR/$PROGNAME"
  exit 10;
} 

while [  $# -gt 0 ]; do
  case "$1" in
  --help|--doc*)  Usage ;;   # Documentation
  -l) line=true ;;
  -d) shift; data=$1 ;;
  -t) shift; title=$1 ;;
  --) shift; break ;;    # end of user options
  -*) Usage "Unknown option \"$1\"" ;;
  *)  break ;;           # end of user options
  esac
  shift   # next option
done

[ $# -eq 0 ] && Usage "Missing function to plot"
[ $# -eq 1 ] && Usage "Missing output filename"
[ $# -gt 2 ] && Usage "Too many arguments"

func=$1; shift;
name=$1; shift;

# ---------------------------------------------

# Main plot image (JPG)
( echo 'set terminal png'
  echo 'set key left'
  echo 'set xtics .5'
  echo 'set ytics .5'
  echo 'set mxtics .25'
  echo 'set mytics .25'
  [ "$title" ] && echo "set title \"$title\""
  if [ "$line" ]; then
    if [ "$data" ]; then
      echo "plot [0:1][0:1] '$data', $func, x"
    else
      echo "plot [0:1][0:1] $func, x"
    fi
  elif [ "$data" ]; then
    echo "plot [0:1][0:1] '$data', $func"
  else
    echo "plot [0:1][0:1] $func"
  fi
) | gnuplot | magick - $name.jpg
chmod 644 $name.jpg

# ------

# Icon plot image (GIF)
( echo 'set terminal png'
  echo 'unset key'
  echo 'set xtics .5'
  echo 'set ytics .5'
  echo "set size .3,.3"
  if [ "$line" ]; then
    if [ "$data" ]; then
      echo "plot [0:1][0:1] '$data', $func, x"
    else
      echo "plot [0:1][0:1] $func, x"
    fi
  elif [ "$data" ]; then
    echo "plot [0:1][0:1] '$data', $func"
  else
    echo "plot [0:1][0:1] $func"
  fi
) | gnuplot | \
  magick - -trim +repage -bordercolor white -border 5 \
          -resize '150x100!'  -colors 256  $name.gif