Apple .icns conversion helper

icns.sh

#!/usr/bin/env bash

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