#!/bin/bash # # Developed by Fred Weinhaus 5/14/2020 .......... revised 5/14/2020 # # USAGE: midgradient [-l length] [-t thickness] [-c1 color1] [-c2 color2] # [-d direction] [-o offset] outfile # USAGE: midgradient [-help] # # OPTIONS: # # -l length length in pixels along the gradient; integer>0; # default=256 # -t thickness thickness in pixels of the gradient; integer>0; # default=50 # -c1 color1 color at start of gradient; any valid Imagemagick # color; default=red # -c2 color2 color at end of gradient; any valid Imagemagick # color; default=blue # -d direction direction angle of the gradient relative to # default direction 0 pointing up; integer choice of # 0, 90, 180 or 270; default=0 # -o offset offset point in percent along gradient of mid-color # (equal blend of color1 and color2); 0<=integer<=100; # default=50 (middle of the gradient) # ### # # NAME: MIDGRADIENT # # PURPOSE: To create a two-color gradient with adjustable mid-color location. # # DESCRIPTION: MIDGRADIENT creates a two-color gradient with adjustable # mid-color location. The gradient can vary, up/down or left/right according # to a direction or rotation angle relative to 0 upwards from color1 to color2. # # # OPTIONS: # # -l length ... LENGTH in pixels along the gradient. Values are integers>0. # The default=256. # # -t thickness ... THICKNESS in pixels of the gradient. Values are integers>0. # The default=50. # # -c1 color1 ... COLOR1 is the color at start of gradient. Any valid # Imagemagick color is allowed. The default=red. # # -c2 color2 ... COLOR2 is the color at end of gradient. Any valid # Imagemagick color is allowed. The default=blue. # # -d direction ... DIRECTION angle of the gradient relative to the default # direction of 0 pointing upward. Choices are integer of 0, 90, 180 or 270. # The default=0. # # -o offset ... OFFSET point in percent along gradient of mid-color # (equal blend of color1 and color2). Values are 0<=integers<=100. # The default=50 (middle of the gradient). # # 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 length=256 thickness=50 color1="red" color2="blue" direction=0 offset=50 # 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:" "$@" sed >&2 -n '/^###/q; /^#/!q; s/^#//; s/^ //; 4,$p' "$PROGDIR/$PROGNAME" } usage2() { echo >&2 "" echo >&2 "$PROGNAME:" "$@" sed >&2 -n '/^######/q; /^#/!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 13 ] 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 ;; -l) # get length shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID LENGTH SPECIFICATION ---" checkMinus "$1" length=`expr "$1" : '\([0-9]*\)'` [ "$length" = "" ] && errMsg "--- LENGTH=$length MUST BE An INTEGER ---" test=`echo "$length == 0" | bc` [ $test -eq 1 ] && errMsg "--- LENGTH=$length MUST BE A POSITIVE INTEGER ---" ;; -t) # get thickness shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID THICKNESS SPECIFICATION ---" checkMinus "$1" thickness=`expr "$1" : '\([0-9]*\)'` [ "$thickness" = "" ] && errMsg "--- THICKNESS=$thickness MUST BE An INTEGER ---" test=`echo "$thickness == 0" | bc` [ $test -eq 1 ] && errMsg "--- THICKNESS=$thickness MUST BE A POSITIVE INTEGER ---" ;; -c1) # get color1 shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID COLOR1 SPECIFICATION ---" checkMinus "$1" color1="$1" ;; -c2) # get color2 shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID COLOR2 SPECIFICATION ---" checkMinus "$1" color2="$1" ;; -d) # get direction shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID DIRECTION SPECIFICATION ---" checkMinus "$1" direction=`expr "$1" : '\([0-9]*\)'` case "$direction" in 0) ;; 90) ;; 180) ;; 270) ;; *) errMsg "--- DIRECTION=$direction IS AN INVALID VALUE ---" esac ;; -o) # get offset shift # to get the next parameter # test if parameter starts with minus sign errorMsg="--- INVALID OFFSET SPECIFICATION ---" checkMinus "$1" offset=`expr "$1" : '\([0-9]*\)'` [ "$offset" = "" ] && errMsg "--- OFFSET=$offset MUST BE An INTEGER ---" test1=`echo "$offset < 0" | bc` test2=`echo "$offset > 100" | bc` [ $test1 -eq 1 -o $test2 -eq 1 ] && errMsg "--- OFFSET=$offset MUST BE AN INTEGER BETWEEN 0 AND 100 ---" ;; -) # STDIN and end of arguments break ;; -*) # any other - argument errMsg "--- UNKNOWN OPTION ---" ;; *) # end of arguments break ;; esac shift # next option done # get outfile outfile=$1 fi # test that outfile provided [ "$outfile" = "" ] && errMsg "--- NO OUTPUT FILE SPECIFIED ---" color12=`convert \ \( -size 1x1 xc:white -fill "$color1" -colorize 100 \) \ \( -size 1x1 xc:white -fill "$color2" -colorize 100 \) \ -evaluate-sequence mean -format "%[pixel:u.p]" info:` len1=`convert xc: -format "%[fx:round($offset*$length/100)]" info:` len2=$((length-len1)) convert \ -size ${thickness}x${len1} gradient:"${color2}-${color12}" \ -size ${thickness}x${len2} gradient:"${color12}-${color1}" \ -append -rotate $direction \ "$outfile" exit 0