wallpaper crop, resizer and watermark using ImageMagick

mkwallpaper.sh

#!/bin/bash
# wallpaper resizer and watermarker script
#=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~==~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~#
# by tassaron on march 5 2017
# updated 2017-05-04, 2018-09-21, 2021-02-01
#
#=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~==~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~#

# EDIT THESE VALUES
TMP_DIR="/tmp/mkwallpaper"
OUTPUT_DIR="${HOME}"
WATERMARK_IMG="${HOME}/Images/muffin/muffin-watermark.png"
WATERMARK_POSITION="SouthEast"
#RESOLUTION=1366x768
RESOLUTION=1920x1080
WATERMARK=0
VERBOSE=0

check_for() {
    which "$1" &> /dev/null
    if [ "$?" -ne 0 ]; then
        echo "You need to install ImageMagick for ${1} command"
        exit 1
    fi
}
check_for convert
check_for composite

# FUNCTIONS
create_resized_img() {
    # create image with correct dimensions respecting aspect ratio, then cropped to size
    if [ "$VERBOSE" = 1 ]; then echo "creating resized image for $(basename $new_img)..."; fi
    convert -gravity center -resize $RESOLUTION^ -crop $RESOLUTION+0+0 $1 $2
    if [ $? -ne 0 ]; then
        echo "Resizing ${1} failed"
        exit 2
    fi
}

create_watermark_img() {
    if ! [ -f "$WATERMARK_IMG" ]; then
        echo "Watermark image is not accessible."
        exit 3
    fi
    if [ ! -e "${TMP_DIR}/resized/${new_img}" ]; then
        create_resized_img "${new_img}" "${TMP_DIR}/resized/$(basename $new_img)"
    fi
    # add watermark to southeast corner and convert to jpg
    if [ "$VERBOSE" = 1 ]; then echo "creating watermark image for $new_img..."; fi
    composite -quality 90 -gravity $WATERMARK_POSITION "$WATERMARK_IMG" "${TMP_DIR}/resized/$(basename $new_img)" "$target"
    if [ $? -ne 0 ]; then
        echo "Compositing ${new_img} failed"
        exit 4
    fi
}

main() {
    # create watermarked resized wallpaper image
    if [ "$WATERMARK" = 1 ]; then
        target="${OUTPUT_DIR}/$(basename ${new_img})-watermark.jpg"
        if [ -f "$target" ]; then
            echo "${target} already exists. Not overwriting"
            exit 5
        fi
        if [ ! -e "$target" ]; then
            create_watermark_img
        fi
    else
        target="${TMP_DIR}/resized/$(basename ${new_img})"
        if [ ! -e "$target" ]; then
            create_resized_img "${new_img}" "$target"
        fi
        cp "$target" "${OUTPUT_DIR}/$(basename ${new_img})-resized.jpg"
        if [ $? -ne 0 ]; then
            echo "Copying ${new_img}-resized.jpg out of ${TMP_DIR} failed"
            exit 9
        fi
    fi
}

print_help () {
    echo "usage: ${0} [--help] [--verbose] [--watermark /path/img.png] [--watermark-position SouthEast]  [--res 1920x1080] input_filepath [-o output_dir]"
}

getting_res=0
getting_output=0
getting_watermark=0
getting_watermark_pos=0
pos_arg=
for argument; do
    if [ "$getting_res" = 1 ]; then RESOLUTION="$argument"; getting_res=0; continue; fi
    if [ "$getting_output" = 1 ]; then OUTPUT_DIR="$argument"; getting_output=0; continue; fi
    if [ "$getting_watermark" = 1 ]; then WATERMARK_IMG="$argument"; getting_watermark=0; continue; fi
    if [ "$getting_watermark_pos" = 1 ]; then WATERMARK_POSITION="$argument"; getting_watermark_pos=0; continue; fi
    if [ "$argument" = "-h" ] || [ "$argument" = "--help" ]; then print_help; exit 0; fi
    if [ "$argument" = "-v" ] || [ "$argument" = "--verbose" ]; then VERBOSE=1; continue; fi
    if [ "$argument" = "-w" ] || [ "$argument" = "--watermark" ]; then getting_watermark=1; WATERMARK=1; continue; fi
    if [ "$argument" = "-wpos" ] || [ "$argument" = "--watermark-position" ]; then getting_watermark_pos=1; continue; fi
    if [ "$argument" = "-r" ] || [ "$argument" = "--res" ]; then getting_res=1; continue; fi
    if [ "$argument" = "-o" ] || [ "$argument" = "--output" ]; then getting_output=1; continue; fi
    pos_arg="$argument"
done
if [ -z "$pos_arg" ]; then
    echo "Missing input filename (must be an image)"
    echo
    print_help
    exit 6
fi
if [ -d "$pos_arg" ]; then
    echo "Skipping ${pos_arg}: Is a directory"
    exit 7
fi

# create directories if they don't exist
if ! [ -d "$TMP_DIR" ]; then
    mkdir "$TMP_DIR"
    if ! [ -d "$TMP_DIR" ]; then
        echo "Failed to create $TMP_DIR"
        exit 8
    fi
fi
if [ ! -d "${TMP_DIR}/resized" ]; then
    mkdir "${TMP_DIR}/resized"
fi

new_img=$pos_arg
main