A zbar wrapper utility to read barcodes from various sources

codeget.sh

#!/usr/bin/env bash
#
# CodeGet: A zbar wrapper utility to read barcodes from various sources
#
# Version: 1.4.8
#
# Written by Kevin MacMartin and released under the MIT license
#
# Requirements:
#   base64         | converts to and from base64 encoding
#   file           | detect information about files
#   fswebcam       | grabs images from the webcam
#   scrot          | grabs screenshots from the desktop
#   xclip          | saves decoded text to the clipboard
#   zbar (zbarimg) | decodes text from barcodes
#

# Store /dev/stdin in $stdin if any input is given
[[ $(file /dev/fd/0) =~ pipe:\[[0-9]*\]$ ]] \
    && stdin=$(base64 /dev/stdin)

# Variables
script_name="${0//*\/}"
temp_file="/tmp/${script_name}.tmp.jpeg"
zbar_args='--raw'
dependencies=('base64' 'file' 'fswebcam' 'scrot' 'xclip' 'zbarimg')

# Colours
[[ -t 1 ]] && {
    c_d=$'\e[1;30m' # GREY
    c_r=$'\e[1;31m' # RED
    c_g=$'\e[1;32m' # GREEN
    c_y=$'\e[1;33m' # YELLOW
    c_b=$'\e[1;34m' # BLUE
    c_m=$'\e[1;35m' # VIOLET
    c_t=$'\e[1;36m' # TEAL
    c_w=$'\e[1;37m' # WHITE
    c_c=$'\e[0m'    # DISABLES COLOUR
}

# Function: display help and exit with a status of $1
function help() {
    printf '\n%s\n\n' "${c_m}CodeGet$c_c: Scan visible zbar-compatible barcodes from the screen"
    printf '%s\n' "${c_b}USAGE$c_c"
    printf '  %s %s %s\n\n' "$c_y$script_name" "$c_d[${c_b}OPTION$c_d]" "$c_d[${c_r}FILE$c_d]$c_c"
    printf '%s\n' "${c_b}OPTIONS$c_c"
    printf '  %-20s  %s\n' "$c_w-c   → $c_c" 'output to the clipboard instead of stdout'
    printf '  %-20s  %s\n' "$c_w-v   → $c_c" 'include barcode metadata in the output'
    printf '  %-20s  %s\n' "$c_w-w   → $c_c" 'use the webcam as an input source'
    printf '  %-20s  %s\n\n' "$c_w-h   → $c_c" 'display this help and exit'
    printf '%s\n' "${c_b}SOURCES$c_c"
    printf '  %-18s  %s\n' "${c_m}display$c_c" "the current ${c_m}display$c_c is scanned by default"
    printf '  %-18s  %s\n' "${c_m}file$c_c" "a ${c_m}file$c_c is scanned when provided as an argument"
    printf '  %-18s  %s\n' "${c_m}stdin$c_c" "an image file sent to ${c_m}stdin$c_c is used when provided"
    printf '  %-18s  %s\n\n' "${c_m}webcam$c_c" "the webcam is scanned when the $c_w-w$c_c flag is set"
    exit "$1"
}

# Function: display $1 (and help if set by $2), then exit with an failed status
function error_exit() {
    printf '\n%s %s\n' "${c_r}ERROR:$c_c" "$1" >&2
    if [[ "$2" = 'help' ]]; then
        help 1
    else
        printf '\n'
    fi
    exit 1
}

# Test for programs required by this script before running
declare -a missing_dependencies=()
for dep in "${dependencies[@]}"; do
    type -P "$dep" >/dev/null \
        || missing_dependencies=( ${missing_dependencies[@]} "$dep" )
done
[[ -n "${missing_dependencies[*]}" ]] && {
    error_exit "${c_w}missing dependencies ($(
        for (( x=0; x < ${#missing_dependencies[@]}; x++ )); do
            printf '%s' "$c_m${missing_dependencies[$x]}$c_c"
            (( (( x + 1 )) < ${#missing_dependencies[@]} )) && printf '%s' ', '
        done
    )$c_w)$c_c"
}

# Unset variables that should be set by parsed arguments
unset clipboard input_source input_file zbar_verbose

# Read stdin into $stdin and set as the input source if it's an image
[[ -n "$stdin" && $(file - < <(base64 -d <<< "$stdin")) =~ image\ data ]] \
    && input_source=stdin

# Parse command-line arguments to set config variables to the values selected by the user
while (( "$#" )); do
    case "$1" in
        -c)
            clipboard=1
            ;;
        -w)
            input_source=webcam
            ;;
        -v)
            zbar_verbose=1
            ;;
        -h|--help)
            help 0
            ;;
        *)
            [[ -f "$1" ]] \
                || error_exit "$1 is not a file or valid argument" 'help'
            [[ -z "$input_source" ]] && {
                input_source=file
                input_file="$1"
            }
            ;;
    esac
    shift
done

# Add the quiet flag if verbose hasn't been set
(( "$zbar_verbose" )) \
    || zbar_args+=' -q'

# Set the input source to display if one hasn't already been set
[[ -z "$input_source" ]] \
    && input_source=display

# Remove the old temporary image file if one exists
[[ -f "$temp_file" ]] \
    && rm "$temp_file"

# Set the number of tries attempts to make based on input type
if [[ "$input_source" = 'webcam' ]]; then
    maxtries=8
else
    maxtries=1
fi

# Attempt to decode input source barcodes until successful or reaching $maxtries
tries=0; while [[ -z "$code_text" ]]; do
    # Exit the loop if $tries >= $maxtries, otherwise add one to $tries
    (( tries >= maxtries )) && break
    (( tries++ ))

    # Create the temporary image file using the selected input source
    case "$input_source" in
        display)
            # input_source: display
            scrot "$temp_file"
            ;;
        file)
            # input_source: file
            cp "$input_file" "$temp_file"
            ;;
        stdin)
            # input_source: stdin
            base64 -d <<< "$stdin" > "$temp_file"
            ;;
        webcam)
            # input_source: webcam
            fswebcam -q -r 1280x720 "$temp_file"
            ;;
    esac

    # Exit with an error if $temp_file doesn't exist
    [[ -f "$temp_file" ]] \
        || error_exit "Failed to save $temp_file"

    # Decode barcodes contained in the temporary image file
    code_text="$(zbarimg $zbar_args "$temp_file")"
done

# Clean up the temporary image file
[[ -f "$temp_file" ]] \
    && rm "$temp_file"

# Send the decoded text to the clipboard or stdout
[[ -n "$code_text" ]] && {
    if (( "$clipboard" )); then
        printf '%s' "$code_text" | xclip -in -selection clipboard
    else
        printf '%s\n' "$code_text"
    fi
}

# Exit successfully
exit 0