Apple .icns conversion helper

icns.sh

#!/usr/bin/env bash

# helper function for constructing escape sequences
# this does NOT include the CSI character by default.
# for that, see the [`csi`] function below this.
function esc() {
	local -r escape="\x1b"
	local -a args=()
	local delim=";" prefix="" suffix="" code=""

	# parse the arguments:
	# - allow overrides for prefix, delim, and suffix.
	#   - e.g. `--prefix="["`, `-d,` or `--delim=,`, `--suffix=m]`
	# - !!! equals sign is optional, e.g. `--prefix [`
	# - short options are allowed, e.g. `-p[`, `-d,`, `-s]`
	# - all remaining arguments are treated as codes.
	# - respect the `--` argument terminator to indicate the end of options.
	# - respect the order of all positional arguments.
	while [[ $# -gt 0 ]]; do
		local arg="$1"
		# end of options, break the loop
		[[ "$arg" == "--" ]] && break;
		# handle options
		case "$arg" in
			# handle short opts, and long options with equals sign
			(--prefix=*|-p*) prefix="${arg#*=}" ;;
			(--prefix|-p) shift; prefix="$1"; shift ;;
			(--delim=*|-d*) delim="${arg#*=}" ;;
			(--delim|-d) shift; delim="$1"; shift ;;
			(--suffix=*|-s*) suffix="${arg#*=}" ;;
			(--suffix|-s) shift; suffix="$1"; shift ;;
			(--) shift; continue;;  # end of options
			(--*|-*) echo "Unknown option: $arg" >&2; return 1 ;;
			(*) {
				# if the argument is not an option, treat it as a code
				[[ "$arg" =~ ^[0-9]+$ ]] && code+="${arg}" || {
					# if the argument is not a number, treat it as a string
					# and escape it to remove non-pri ntable characters
					if [[ -n "$code" ]]; then
						code+="$delim"
					fi
				}
				code+="$(printf '%s' "$arg" | sed 's/[^[:print:]]//g')"
				continue
			} ;;
			(*) args+=("$arg")
				;;
		esac
		shift
	done
}

function main () {
	# show the usage page if no args are given, or if passed any derivation of "-h" "--help" "-?" etc
	if [ $# -eq 0 ] || [[ "$1" =~ ^[-]{0,2}(h(elp)?|[?])$ ]]; then
		local bold undl ital dark reset
		bold=$(printf '\033[1m')
		dark=$(printf '\033[2m')
		ital=$(printf '\033[3m')
		undl=$(printf '\033[4m')
		reset=$(printf '\033[0m')

cat<<EOL

${bold}icns.sh${reset}${dark} - automated macOS .icns conversion helper${reset}

${bold}${undl}USAGE${reset}

    ./icns.sh <${bold}${undl}${ital}source.png${reset}> <${bold}${undl}${ital}destination.icns${reset}>

${bold}${undl}SUMMARY${reset}

    Resizes ${bold}${undl}${ital}source.png${reset} to the required sizes, formatted into one file,
    output to ${bold}${undl}${ital}destination.icns${reset} in Apple .icns, in these resolutions:

    16x16       32x32       128x128       256x256       512x512
    16x16${dark}@2x${reset}    32x32${dark}@2x${reset}    128x128${dark}@2x${reset}    256x256${dark}@2x${reset}    512x512${dark}@2x${reset}


${bold}${undl}RECOMMENDATIONS${reset}

    o Use a ${bold}${undl}${ital}source.png${reset} >= 1024x1024 resolution.
    o Use absolute paths for ${bold}${undl}${ital}source.png${reset} and ${bold}${undl}${ital}destination.icns${reset}
      ${dark}(reduces the chance of a file mishap during conversion)${reset}


${bold}${undl}LICENSE${reset}: MIT © ${ital}Nicholas Berlette${reset} <${dark}${ital}${undl}https://github.com/nberlette${reset}>

EOL
		# non-zero exit code if no arguments are provided
		[ $# = 0 ] && return 1 || return 0;

	else
		# main program
		local input output iconset
		input=${1:-"./AppIcon.png"}
		output=${2:-"./icon.icns"}
		iconset="$(dirname "$output")/$(basename "$output" | cut -d. -f1).iconset"
		# outputpng="$(dirname "$output")/icon.png"
		mkdir -p "$iconset" >&/dev/null

		local xy
		for xy in 16 32 128 256 512; do
				sips -z $xy $xy  "$input" --out "${iconset}/icon_${xy}x${xy}.png" > /dev/null
				sips -z $((xy * 2)) $((xy * 2)) "$input" --out "${iconset}/icon_${xy}x${xy}@2x.png" > /dev/null
		done
		iconutil -c icns "$iconset" && rm -rf "$iconset"
	fi
}

{ main "$@" && unset -f main; } || exit $?;

USAGE

    ./icns.sh <source.png> <destination.icns>

SUMMARY

    Resizes source.png to the required sizes, formatted into one file,
    output to destination.icns in Apple .icns, in these resolutions:

    16x16       32x32       128x128       256x256       512x512
    16x16@2x    32x32@2x    128x128@2x    256x256@2x    512x512@2x

RECOMMENDATIONS

    o Use a source.png >= 1024x1024 resolution.
    o Use absolute paths for source.png and destination.icns