ruler

#!/bin/bash
# Display a simple pixel ruler.
#
# usage:
#       ruler [-b <bg-colour>] [ruler-length] [major-interval] [minor-interval]
#       all units in pixels.
#
# 2017-04-21 initial release. yaswant.pradhan.
# 2018-03-07 v1.0.1. update options. yp.
# -----------------------------------------------------------------------------
# set -e
DISPLAY_OPT=
ARGS=""
while [ $# -gt 0 ]; do
  unset OPTIND
  unset OPTARG
  while getopts hvVb:c:f: opts; do
  case $opts in
      h)  echo "usage: ${0##*/} [-b <bg-colour>] [-c <colour>] [-f <font-name>] [ruler-length] [major-interval] [minor-interval]"; exit 0 ;;
      v)  DISPLAY_OPT='-rotate 90' ;;
      V)  echo "${0##*/}: Version 1.0.1"; exit 0 ;;
      b)  bcol="$OPTARG" ;;
      c)  col="$OPTARG" ;;
      f)  font="$OPTARG" ;;
  esac
  done
  shift $((OPTIND-1))
  ARGS="${ARGS} $1"
  shift
done
ARGS=($ARGS)
# -----------------------------------------------------------------------------

rulerlength="${ARGS[0]}"
majorint="${ARGS[1]}"
minorint="${ARGS[2]}"
rulername="$TMPDIR/ruler.gif"
rulerlength="${rulerlength:=520}"
majorint="${majorint:=100}"
minorint="${minorint:=5}"
bgcol="${bcol:=orange}"
col="${col:=black}"
font="${font:=fixed}"
drawstring=""


# Build the line definitions for the ruler marks
for x1 in `seq 0 $majorint $rulerlength`; do
  drawstring="$drawstring line $x1,30 $x1,60"
  for x2 in 0 $(( majorint / 2 )); do
    (( offset = $x1 + $x2 ))
    drawstring="$drawstring line $offset,40 $offset,60"
    for x3 in `seq $minorint $minorint $(( majorint / 2))`; do
      (( offset2 = $offset + $x3 ))
      drawstring="$drawstring line $offset2,50 $offset2,60"
    done
  done
done

# Add labels
labelfont="-fill $col -font $font -pointsize 18 -draw"
labelstring="text 0,20 '0' "
for x3 in $majorint; do
  offset3=$(($x3 - 12 ))
  labelstring="$labelstring text $offset3,20 '$x3' "
done
for x4 in `seq $(( majorint * 2 )) $majorint $rulerlength`; do
  offset4=$(( $x4 - 12 ))
  labelstring="$labelstring text $offset4,20 '$x4' "
done

convert -size "${rulerlength}x60" xc:$bgcol -fill $col \
        -draw "$drawstring" $labelfont "$labelstring" "$rulername"

# Display ruler; use \ / * to rotate the ruler
display $DISPLAY_OPT -title 'Pixel Ruler' $rulername

# Housekeep
rm -rf $rulername