Bash script to generate iOS and Android app icons for a Flutter project.

generate_flutter_icons.sh

#!/bin/bash

# Given a square icon image file and a path to a flutter project, 
# this will update the android and ios icon images for the project.
# Usage: generate_flutter_icons.sh -i /path/to/icon.png -p /path/to/project
# Note: -p flag can be omitted if the current working directory is 
# the target flutter project.

while getopts i:p: flag
do
    case "${flag}" in
        i) icon=${OPTARG};;
		p) project=${OPTARG};;
    esac
done

if [ -z "${icon}" ]; then
	echo "Error: Source icon image path must be set by passing the -i flag.";
	exit 1;
fi

if [ ! -f "${icon}" ]; then
    echo "Error: Source icon image file does not exist.";
	exit 1;
fi

if [ -z "${project}" ]; then
	project=$(pwd)
fi

androidpath="${project}/android/app/src/main/res"
if [ ! -d "${androidpath}" ]; then
	echo "No Android project found in the project directory, skipping."
else
	find "${androidpath}" -type f -print0 | while read -d $'\0' file; do
		mime=$(file -b --mime-type "$file");
		if [[ "$mime" == "image"* ]]; then
			width=$(identify -format "%w" "$file")> /dev/null
			height=$(identify -format "%h" "$file")> /dev/null
			convert "${icon}" -resize "$width"x"$height"\! "$file"
			echo "Updated $file."
		fi;
	done
fi

iospath="${project}/ios/Runner/Assets.xcassets/AppIcon.appiconset"
if [ ! -d "${iospath}" ]; then
	echo "No iOS project found in the project directory, skipping."
else
	find "${iospath}" -type f -print0 | while read -d $'\0' file; do
		mime=$(file -b --mime-type "$file");
		if [[ "$mime" == "image"* ]]; then
			width=$(identify -format "%w" "$file")> /dev/null
			height=$(identify -format "%h" "$file")> /dev/null
			convert "${icon}" -resize "$width"x"$height"\! "$file"
			echo "Updated $file."
		fi;
	done
fi