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import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.util.HashMap;

public class AtlasMaker {
	private final static int MAX_IMAGE_SIZE = 4096 * 4;
	private final static int DEFAULT_IMAGE_COUNT = 9;
	private final static int DEFAULT_IMAGE_SIZE = 32;
	private final int imageCount;
	private final int imageSize;
	private final HashMap<String, Integer> items = new HashMap<>();
	private final Graphics2D g2d;
	private final BufferedImage image;
	private int counter = 0;
	
	public AtlasMaker() {
		this(DEFAULT_IMAGE_SIZE, DEFAULT_IMAGE_COUNT);
	}
	public AtlasMaker(int imageSize) {
		this(imageSize, DEFAULT_IMAGE_COUNT);
	}
	public AtlasMaker(int imageSize, int imageCount) {
		if (imageSize > MAX_IMAGE_SIZE) {
			throw new Error("Max image size: " + MAX_IMAGE_SIZE);
		}
		if (imageSize < 2) {
			throw new Error("Min image size: 2");
		}
		if (imageSize < 1) {
			throw new Error("Min count size: 1");
		}
		this.imageSize = imageSize;
		this.imageCount = imageCount;
		image = new BufferedImage(imageSize * imageCount, imageSize, BufferedImage.TYPE_INT_RGB);
		g2d = image.createGraphics();
	}
	
	public BufferedImage addImage(String key, Image image) {
		if (counter == imageCount) {
			throw new Error("Je zaplnený celý atlas");
		}
		BufferedImage newImage = resize(image, imageSize, imageSize);
		items.put(key, counter);
		g2d.drawImage(newImage, imageSize * counter++, 0, null);
		return newImage;
	}
	public BufferedImage getSubImage(String key) {
		return getSubImage(items.get(key));
	}
	public BufferedImage getSubImage(int key) {
		return image.getSubimage(key * imageSize, 0, imageSize, imageSize);
	}
	public void renderImage(Graphics2D g2, String key, int x, int y) {
		renderImage(g2, items.get(key), x, y, imageSize, imageSize);
	}
	public void renderImage(Graphics2D g2, String key, int x, int y, int w, int h) {
		renderImage(g2, items.get(key), x, y, w, h);
	}
	public void renderImage(Graphics2D g2, int key, int x, int y, int w, int h) {
		g2.drawImage(image, x, y, w, h, key * imageSize, 0, imageSize, imageSize, null);
	}
	
	public BufferedImage getImage() {
		return image;
	}
	private static BufferedImage resize(Image img, int newW, int newH) { 
	    Image tmp = img.getScaledInstance(newW, newH, Image.SCALE_SMOOTH);
	    BufferedImage dimg = new BufferedImage(newW, newH, BufferedImage.TYPE_INT_RGB);

	    Graphics2D g2d = dimg.createGraphics();
	    g2d.drawImage(tmp, 0, 0, null);
	    g2d.dispose();

	    return dimg;
	}  
}