gnome-icon-resizer.sh

#!/usr/bin/env bash

# Script to generate all the icon sizes from the 256x256@2x set

usage() {
        echo "Usage: $(basename $0) path-to-icons"
}

if ! command -v convert &> /dev/null
then
    echo "ERROR: 'convert' command not found. Install imagemagick."
    exit 1
fi

if [ -z "$1" ]; then
    echo "ERROR: path to icons not set."
    usage
    exit 1
fi

pushd $1 2>/dev/null || (echo "ERROR: Unable to access directory '$1'." && exit 1)

if [ ! -d 256x256@2x ]; then echo "no '256x256@2x' folder in $1. Create this first with the 512x512 icons."; exit 1; fi
if [ ! -d 16x16 ]; then mkdir 16x16; fi
if [ ! -d 16x16@2x ]; then mkdir 16x16@2x; fi
if [ ! -d 24x24 ]; then mkdir 24x24; fi
if [ ! -d 24x24@2x ]; then mkdir 24x24@2x; fi
if [ ! -d 32x32 ]; then mkdir 32x32; fi
if [ ! -d 32x32@2x ]; then mkdir 32x32@2x; fi
if [ ! -d 48x48 ]; then mkdir 48x48; fi
if [ ! -d 48x48@2x ]; then mkdir 48x48@2x; fi
if [ ! -d 256x256 ]; then mkdir 256x256; fi

for category in 256x256@2x/*; do
  if [ -d "${category}" ]; then
    for icon in "${category}"/*; do
      convert "${icon}" -resize 16x16 "${icon//256x256@2x/16x16/}"
      convert "${icon}" -resize 32x32 "${icon//256x256@2x/16x16@2x/}"
      convert "${icon}" -resize 32x32 "${icon//256x256@2x/32x32/}"
      convert "${icon}" -resize 24x24 "${icon//256x256@2x/24x24/}"
      convert "${icon}" -resize 48x48 "${icon//256x256@2x/24x24@2x/}"
      convert "${icon}" -resize 48x48 "${icon//256x256@2x/48x48/}"
      convert "${icon}" -resize 64x64 "${icon//256x256@2x/32x32@2x/}"
      convert "${icon}" -resize 96x96 "${icon//256x256@2x/48x48@2x/}"
      convert "${icon}" -resize 256x256 "${icon//256x256@2x/256x256/}"
    done
  fi
done