#!/bin/sh

img="$1"; export img
[ ! "${img}" ] && exit
[ ! -s "${img}" ] && exit

wrk="tmp/mkgrid.$$.wrk"; export wrk

fn="$( basename "${img}" |
sed -e "
s~\.jpg$~~
s~\.gif$~~
s~\.png$~~
" )"; export fn

w=$( convert ${img} -format "%w" info: ); export w

h=$( convert ${img} -format "%h" info: ); export h

convert \
${img} \
-crop 550x1000+50+950 \
+repage \
-trim \
+repage \
-crop 550x35+0+48 \
+repage \
-trim \
+repage \
mkgrid.crop.gif
cp mkgrid.crop.gif ..
w=$( convert mkgrid.crop.gif -format "%w" info: ); export w
h=$( convert mkgrid.crop.gif -format "%h" info: ); export h

{
echo -n "convert \
mkgrid.crop.gif \
-fill black "
x="50"; export x
y="50"; export y
while [ ${x} -lt ${w} ]
do
echo -n "-draw \"line ${x},0 ${x},${h}\" "
x="$(( ${x} + 50 ))"
done

while [ ${y} -lt ${h} ]
do
echo -n "-draw \"line 0,${y} ${w},${y}\" "
y="$(( ${y} + 50 ))"
done
echo "mkgrid.jpg"
} >${wrk}
. ${wrk}

cp mkgrid.jpg ..