Java class to generate ICNS from image under MacOS

IcnsGen.java

import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.nio.file.FileSystems;
import java.nio.file.Path;
import javax.imageio.ImageIO;

public class IcnsGen {

  public static void main(final String... args) throws Exception {
    if (args.length < 1) {
      System.err.println("IcnsGen <image.file>");
      System.exit(1);
    }

    final int[][] SIZES = new int[][]{
      {16, 1},
      {32, 1},
      {32, 2},
      {64, 1},
      {64, 2},
      {256, 1},
      {256, 2},
      {512, 1},
      {512, 2},
      {1024, 1},
      {1024, 2},};

    final File srcFile = new File(args[0]);
    if (!srcFile.isFile()) {
      System.err.println("Can't find image file: " + srcFile);
    }

    final BufferedImage sourceImage = ImageIO.read(srcFile);

    String rawImageName = srcFile.getName();
    if (rawImageName.contains(".")) {
      int index = rawImageName.lastIndexOf(".");
      rawImageName = rawImageName.substring(0, index);
    }

    final Path currentFolder = FileSystems.getDefault().getPath(".").toAbsolutePath();

    final File targetFolder = new File(currentFolder.toFile(), rawImageName + ".iconset");

    if (!targetFolder.isDirectory() && !targetFolder.mkdirs()) {
      throw new Error("Can't create folder: " + targetFolder);
    }

    for (final int[] arg : SIZES) {
      System.out.print(String.format("Generated icon %d.%d.....", arg[0], arg[1]));
      scaleAndSave(sourceImage, targetFolder, arg[0], arg[1]);
      System.out.println("OK");
    }

    final File targetIcnsFile = new File(currentFolder.toFile(), rawImageName + ".icns");

    final ProcessBuilder processBuilder = new ProcessBuilder("iconutil", "-c", "icns", targetFolder.getAbsolutePath(), "-o", targetIcnsFile.getAbsolutePath());
    processBuilder.inheritIO();
    processBuilder.redirectErrorStream(true);

    final int exit = processBuilder.start().waitFor();
    if (exit == 0) {
      System.out.println("Generated icns file: " + targetIcnsFile.getAbsolutePath());
    } else {
      System.err.println("Error exit status: " + exit);
    }
    System.exit(exit);
  }

  private static void scaleAndSave(final BufferedImage src, final File folder, int width, int scale) throws Exception {
    final String name;
    if (scale == 1) {
      name = String.format("icon_%dx%d.png", width, width);
    } else {
      name = String.format("icon_%dx%d@2x.png", width / 2, width / 2);
    }

    final BufferedImage target = new BufferedImage(width, width, BufferedImage.TYPE_INT_ARGB);
    final AffineTransform transform = AffineTransform.getScaleInstance((double) width / (double) src.getWidth(), (double) width / (double) src.getHeight());

    final Graphics2D gfx = target.createGraphics();
    gfx.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
    gfx.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
    gfx.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    gfx.drawImage(src, transform, null);
    gfx.dispose();

    final ByteArrayOutputStream buffer = new ByteArrayOutputStream(100000);
    if (!ImageIO.write(target, "png", buffer)) {
      throw new Error("Can't find ONG encoder");
    }

    final byte[] fileBody = buffer.toByteArray();

    try (FileOutputStream fos = new FileOutputStream(new File(folder, name), false)) {
      fos.write(fileBody);
      fos.flush();
    }

  }

}