#!/bin/bash
#
# Developed by Fred Weinhaus 12/1/2009 .......... revised 11/2/2016
#
# ------------------------------------------------------------------------------
# 
# Licensing:
# 
# Copyright © Fred Weinhaus
# 
# My scripts are available free of charge for non-commercial use, ONLY.
# 
# For use of my scripts in commercial (for-profit) environments or 
# non-free applications, please contact me (Fred Weinhaus) for 
# licensing arrangements. My email address is fmw at alink dot net.
# 
# If you: 1) redistribute, 2) incorporate any of these scripts into other 
# free applications or 3) reprogram them in another scripting language, 
# then you must contact me for permission, especially if the result might 
# be used in a commercial or for-profit environment.
# 
# My scripts are also subject, in a subordinate manner, to the ImageMagick 
# license, which can be found at: http://www.imagemagick.org/script/license.php
# 
# ------------------------------------------------------------------------------
# 
# USAGE: aspectpad [-a aspect] [-m mode] [-p pcolor] [-t toler] infile outfile
# USAGE: aspectpad [-help]
#
# OPTIONS:
#
# -a      aspect	       	aspect ratio value desired; float>=1; default=2
# -m      mode              mode for aspect; al, ap, l or p; default=al
#                           l=force landscape pad; p=force portrait pad;
#                           al=automatic pad (landscape for square images);
#                           ap=automatic pad (portrait for square images)
# -p      pcolor            pad color; any valid IM color; default=black
# -t      toler             aspect tolerance; float>=0; if absolute difference 
#                           between desired aspect and image aspect is less 
#                           than or equal to tolerance, then no padding; 
#                           default=0
#
###
#
# NAME: ASPECTPAD 
# 
# PURPOSE: To pad an image with a color to a specified aspect ratio 
# and orientation.
# 
# DESCRIPTION: ASPECTPAD pads an image with a color to a specified aspect
# ratio and orientation. The user can choose to force the pad to either 
# landscape or portrait orientation or preserve the orientation in automatic 
# mode. All padding will result in the image being centered.
# 
# OPTIONS: 
# 
# -a aspect ... ASPECT is the desired aspect ratio. Values are floats>=1. 
# The default=2
# 
# -m mode ... MODE is the padding mode. Choices are: l, p, al or ap. When 
# mode=l, the padding will force the result to be landscape at the desired 
# aspect value. When mode=p, the padding will force the result to be portrait.
# When mode=al, the padding will preserve the aspect of the original image, but 
# will pad a square image into landscape format. When mode=ap, the padding will 
# preserve the aspect of the original image, but will pad a square image into 
# portrait format. The default=al.
# 
# -p pcolor ... PCOLOR is the desired padding color. Any valid IM color 
# specification may be used. The default=black
# 
# -t toler ... TOLER is the aspect tolerance. If the absolute difference 
# between desired aspect and image aspect is less than or equal to toler, 
# then no padding will be applied. Values are floats>=0. The default=0
# 
# CAVEAT: No guarantee that this script will work on all platforms, 
# nor that trapping of inconsistent parameters is complete and 
# foolproof. Use At Your Own Risk. 
# 
######
#

# set default values
aspect="2"				# aspect>=1
mode="al"				# al, ap, l, p; a=auto
pcolor="black"			# pad color
toler=0					# toler>=0

# set directory for temporary files
dir="."    # suggestions are dir="." or dir="/tmp"

# set up functions to report Usage and Usage with Description
PROGNAME=`type $0 | awk '{print $3}'`  # search for executable on path
PROGDIR=`dirname $PROGNAME`            # extract directory of program
PROGNAME=`basename $PROGNAME`          # base name of program
usage1() 
	{
	echo >&2 ""
	echo >&2 "$PROGNAME:" "$@"
	sed >&2 -e '1,/^####/d;  /^###/g;  /^#/!q;  s/^#//;  s/^ //;  4,$p' "$PROGDIR/$PROGNAME"
	}
usage2() 
	{
	echo >&2 ""
	echo >&2 "$PROGNAME:" "$@"
	sed >&2 -e '1,/^####/d;  /^######/g;  /^#/!q;  s/^#*//;  s/^ //;  4,$p' "$PROGDIR/$PROGNAME"
	}


# function to report error messages
errMsg()
	{
	echo ""
	echo $1
	echo ""
	usage1
	exit 1
	}


# function to test for minus at start of value of second part of option 1 or 2
checkMinus()
	{
	test=`echo "$1" | grep -c '^-.*$'`   # returns 1 if match; 0 otherwise
    [ $test -eq 1 ] && errMsg "$errorMsg"
	}

# test for correct number of arguments and get values
if [ $# -eq 0 ]
	then
	# help information
   echo ""
   usage2
   exit 0
elif [ $# -gt 10 ]
	then
	errMsg "--- TOO MANY ARGUMENTS WERE PROVIDED ---"
else
	while [ $# -gt 0 ]
		do
			# get parameter values
			case "$1" in
		     -help)    # help information
					   echo ""
					   usage2
					   exit 0
					   ;;
				-m)    # get mode
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID MODE SPECIFICATION ---"
					   checkMinus "$1"
					   mode=`echo "$1" | tr '[A-Z]' '[a-z]'`
					   case "$mode" in 
					   		l) ;;
					   		p) ;;
					   		al) ;;
					   		ap) ;;
					   		*) errMsg "--- MODE=$mode IS AN INVALID VALUE ---" 
					   	esac
					   ;;
				-a)    # get aspect
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID ASPECT SPECIFICATION ---"
					   checkMinus "$1"
					   aspect=`expr "$1" : '\([.0-9]*\)'`
					   aspecttest=`echo "$aspect < 1" | bc`
					   [ $aspecttest -eq 1 ] && errMsg "--- ASPECT=$aspect MUST BE A FLOAT GREATER THAN OR EQUAL TO 1 ---"
					   ;;
				-p)    # get pcolor
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID PCOLOR SPECIFICATION ---"
					   checkMinus "$1"
					   pcolor="$1"
					   ;;
				-t)    # get toler
					   shift  # to get the next parameter
					   # test if parameter starts with minus sign 
					   errorMsg="--- INVALID TOLER SPECIFICATION ---"
					   checkMinus "$1"
					   toler=`expr "$1" : '\([.0-9]*\)'`
					   tolertest=`echo "$toler < 0" | bc`
					   [ $tolertest -eq 1 ] && errMsg "--- TOLER=$toler MUST BE A NON-NEGATIVE FLOAT ---"
					   ;;
				 -)    # STDIN and end of arguments
					   break
					   ;;
				-*)    # any other - argument
					   errMsg "--- UNKNOWN OPTION ---"
					   ;;
		     	 *)    # end of arguments
					   break
					   ;;
			esac
			shift   # next option
	done
	#
	# get infile and outfile
	infile="$1"
	outfile="$2"
fi

# test that infile provided
[ "$infile" = "" ] && errMsg "NO INPUT FILE SPECIFIED"

# test that outfile provided
[ "$outfile" = "" ] && errMsg "NO OUTPUT FILE SPECIFIED"

# setup temporary images
tmpA1="$dir/aspectpad_1_$$.mpc"
tmpA2="$dir/aspectpad_1_$$.cache"
trap "rm -f $tmpA1 $tmpA2;" 0
trap "rm -f $tmpA1 $tmpA2; exit 1" 1 2 3 15
trap "rm -f $tmpA1 $tmpA2; exit 1" ERR


# read the input image and test validity.
convert -quiet "$infile" +repage "$tmpA1" ||
	errMsg "--- FILE $infile DOES NOT EXIST OR IS NOT AN ORDINARY FILE, NOT READABLE OR HAS ZERO SIZE  ---"

# get size and aspect ratio of input
ww=`convert $tmpA1 -ping -format "%w" info:`
hh=`convert $tmpA1 -ping -format "%h" info:`
wratio=`convert xc: -format "%[fx:$ww/$hh]" info:`
hratio=`convert xc: -format "%[fx:$hh/$ww]" info:`
#echo "ww=$ww; hh=$hh wratio=$wratio; hratio=$hratio"

# test if aspect >= ratio
wtest=`convert xc: -format "%[fx:$aspect>=$wratio?1:0]" info:`
htest=`convert xc: -format "%[fx:$aspect>=$hratio?1:0]" info:`
#echo "wtest=$wtest; htest=$htest"

# test if within toler of desired aspect
tratio=`convert xc: -format "%[fx:$wratio>=1?$wratio:$hratio]" info:`
ttest=`convert xc: -format "%[fx:abs($tratio-$aspect)<=$toler?1:0]" info:`
#echo "tratio=$tratio; ttest=$ttest"

# copy input to output if image aspect is within toler
if [ $ttest -eq 1 ]; then
	convert $tmpA1 "$outfile"
	exit
fi

# force landscape mode
if [ "$mode" = "l" -a $wtest -eq 1 ]; then
	ww=`convert xc: -format "%[fx:$hh*$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
elif [ "$mode" = "l" -a $wtest -eq 0 ]; then
	hh=`convert xc: -format "%[fx:$hh*$wratio/$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
fi

# force portrait mode
if [ "$mode" = "p" -a $htest -eq 1 ]; then
	hh=`convert xc: -format "%[fx:$ww*$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
elif [ "$mode" = "p" -a $htest -eq 0 ]; then
	ww=`convert xc: -format "%[fx:$ww*$hratio/$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
fi


# auto square image
if [ "$mode" = "al" -a $ww -eq $hh ]; then
	ww=`convert xc: -format "%[fx:$hh*$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
elif [ "$mode" = "ap" -a $ww -eq $hh ]; then
	hh=`convert xc: -format "%[fx:$ww*$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
fi


# auto landscape image 
if [ $ww -gt $hh -a $wtest -eq 1 ]; then
	ww=`convert xc: -format "%[fx:$hh*$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
elif [ $ww -gt $hh -a $wtest -eq 0 ]; then
	hh=`convert xc: -format "%[fx:$hh*$wratio/$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
fi


# auto portrait image
if [ $hh -gt $ww -a $htest -eq 1 ]; then
	hh=`convert xc: -format "%[fx:$ww*$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
elif [ $hh -gt $ww -a $htest -eq 0 ]; then
	ww=`convert xc: -format "%[fx:$ww*$hratio/$aspect]" info:`
	convert $tmpA1 -gravity center -background "$pcolor" -extent ${ww}x${hh} "$outfile"
	exit
fi