Add shadow to image

image-shadow

#!/bin/bash
##
# Add shadow to image
# @author [email protected]
# @date 2014-11-22
##

usage() {
    app=$(basename $0)
    cat <<EOF
Usage: $app input_file {percent-opacity}x{sigma}+{bottom}+{right}-{left}-{top}

Options:
    percent-opacity     default 60
    sigma               default 3
    bottom              bottom shadow, default 3
    right               right shadow, default 3
    left                left shadow, default 0
    top                 top shadow, default 0

Example:
    # Shadow at bottom & right, same as '$app example.png 60x3+3+3'.
    $app example.png

    # Shadow at left & top.
    $app example.png 60x3+0+0-3-3
EOF

    exit $1
}

test $# -lt 1 && usage 1

in=$1

def_opacity=60
def_sigma=3
def_shadow_br=3
def_shadow_lt=0

options=$(echo $2 | awk -F 'x|+|-' '{print $1,$2,$3,$4,$5,$6}')
set -- $options

[[ -z $1 ]] && opt_opacity=$def_opacity || opt_opacity=$1
[[ -z $2 ]] && opt_sigma=$def_sigma || opt_sigma=$2
if [[ -z $1 ]] || [[ -z $2 ]]; then
    opt_shadow_b=$def_shadow_br
    opt_shadow_r=$def_shadow_br
    opt_shadow_l=0
    opt_shadow_t=0
else
    opt_shadow_b=${3:-0}
    opt_shadow_r=${4:-0}
    opt_shadow_l=${5:-0}
    opt_shadow_t=${6:-0}
fi

out=${in%.*}-shadow_+$opt_shadow_b+$opt_shadow_r-$opt_shadow_l-$opt_shadow_t.${in#*.}
echo "Created file: $out"

opt_shadow_groups=()

if [[ $opt_shadow_r != 0 ]] || [[ $opt_shadow_b != 0 ]]; then
    opt_shadow_groups+=(+${opt_shadow_r}+${opt_shadow_b})
fi

if [[ $opt_shadow_l != 0 ]] || [[ $opt_shadow_t != 0 ]]; then
    opt_shadow_groups+=(-${opt_shadow_l}-${opt_shadow_t})
fi

for (( i=0; i<${#opt_shadow_groups[@]}; i++ )); do
    convert $((( $i <= 0)) && echo "$in" || echo "$out") \
            \( +clone -background black -shadow ${opt_opacity}x${opt_sigma}${opt_shadow_groups[$i]} \) \
            -reverse -background none -layers merge +repage "$out"
done