Resize to a given size maintaining proportions and automatically generate all android resource directories

rescale_for_android.sh

# Author: @vitovalov
# Description: Resize to a given size and automatically generate all android resource directories
# Usage: sh rescale_for_android.sh   <dp size (mdpi)>   <source path to original images>   <output path for results>(optional)
if [ "$#" -le 1 ]; then
    echo "\nUsage: sh rescale_for_android.sh   <dp size (mdpi)>   <source path to original images>   <output path for results>(optional)\n"
    exit 1
fi

mdpisize=$1 
hdpisize=$(echo "$mdpisize * 1.5" | bc -l)
xhdpisize="$((mdpisize * 2))"
xxhdpisize="$((mdpisize * 3))"

sourceDir=$2
if [ "$#" -eq 3 ]; then
	outDir=$3
else
	echo "Warning: output directory not specified. Source dir will be used to create drawable directories"
	outDir=$sourceDir
fi
# clean old directories
rm -rf $outDir/drawable-mdpi
rm -rf $outDir/drawable-hdpi
rm -rf $outDir/drawable-xhdpi
rm -rf $outDir/drawable-xxhdpi
# create new directories
mkdir $outDir/drawable-mdpi
mkdir $outDir/drawable-hdpi
mkdir $outDir/drawable-xhdpi
mkdir $outDir/drawable-xxhdpi

for f in $sourceDir/*.{jpg,jpeg,png};
do
	echo "resizing ${f##*/} to size $mdpisize dpi maintaining proportions"
	sips -Z $mdpisize $f --out $outDir/drawable-mdpi > /dev/null 2>&1
	echo "resizing ${f##*/} to size $hdpisize dpi maintaining proportions"
	sips -Z $hdpisize $f --out $outDir/drawable-hdpi > /dev/null 2>&1
	echo "resizing ${f##*/} to size $xhdpisize dpi maintaining proportions"
	sips -Z $xhdpisize $f --out $outDir/drawable-xhdpi > /dev/null 2>&1
	echo "resizing ${f##*/} to size $xxhdpisize dpi maintaining proportions"
	sips -Z $xxhdpisize $f --out $outDir/drawable-xxhdpi > /dev/null 2>&1

done

# "drawable-mdpi" => 1.0,
# "drawable-hdpi" => 1.5,
# "drawable-xhdpi" => 2.0,
# "drawable-xxhdpi" => 3.0,