Problem Loading Image Using Spritesheet

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Good day everyone,

I am developing a game and I am using a spritesheet for my image loading, however it seems I have run into a problem somewhere while developing this.

Now I am using a canvas on a JFrame, so if that makes a difference in what I have to do let me know please.

In all of the reading that I have done I came to the conclusion that I need to use a BufferedImage, which I am.

Below is my two classes that have to do with loading images from the sprite sheet.

ImageLoader.java

Java

public class ImageLoader {

	public BufferedImage load(String path) {
		
		try {
			return ImageIO.read(getClass().getResource(path));
		} catch (IOException e) {
			e.printStackTrace();
		}
		return null;
		
	}
	
}

SpriteSheet.java

Java

public class SpriteSheet {

	private BufferedImage sheet;
	
	public SpriteSheet(BufferedImage sheet) {
		
		this.sheet = sheet;
		
	}
	
	public BufferedImage crop(int col, int row, int w, int h) {
		
		return sheet.getSubimage(col * 16, row * 16, w, h);
		
	}
	
}

In my player class I have a render method, which can be seen below.

Player.java (Render Method)

Java

public void render(Graphics g) {
		
		g.drawImage(ss.crop(0, 0, 16, 16), x, y, 16 * OperationXMain.scale, 16 * OperationXMain.scale, null);
		
	}

In my main class, I am calling player.render, and passing g (Graphics). This happens after I render a rectangle that is the full size of the JFrame and Canvas.

Before my gameloop I am calling my init method, which is creating a new instance of the ImageLoader class that I created, then I am setting a BufferedImage variable to the value of ImageLoader.load, in which I am passing the location of my image.
Please note that I have referenced a res folder to my java project, so I know that works.
To make it easier for you to understand, I have included the code for my init method.

Java

public void init() {
		
	ImageLoader imageloader = new ImageLoader();
		
	spriteSheet = imageloader.load("res/spritesheet.png");
		
	SpriteSheet ss = new SpriteSheet(spriteSheet);
		
	player = new Player(0, 0, ss);
		
}

Sorry for the long question, just wanted to make sure I clarified everything well enough so someone can help me out.

Thanks!

Posted 25-Sep-13 5:48am

Gigabyte Giant

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Fredrik Bornander · Accepted Answer · 2013-09-25T18:54:00

You don't want to use BufferedImage.getSubImage for every frame, what you want to do with your sprite sheet is to render a portion of is rather than creating a new Image object.

Something like this can help:

Java

public class SpriteSheet {

    private final BufferedImage image;

    public SpriteSheet(final String filename) throws IOException {
        image = ImageIO.read(new File(filename));
    }

    public void render(final Graphics graphics, final Rectangle source, final Rectangle destination) {

        graphics.drawImage(
                image,
                destination.x,
                destination.y,
                destination.x + destination.width,
                destination.y + destination.height,
                source.x,
                source.y,
                source.x + source.width,
                source.y + source.height,
                null);
    }
}

Java

public class Player {

    private final SpriteSheet sheet;
    private final Rectangle source = new Rectangle(0, 0, 16, 16);
    private final Rectangle destination = new Rectangle(0, 0, 16, 16);

    public Player(final SpriteSheet sheet) {
        this.sheet = sheet;
    }

    public void render(Graphics g) {
        destination.x = x;
        destination.y = y;
        destination.width = 16 * OperationXMain.scale;
        destination.height = 16 * OperationXMain.scale;

        sheet.render(graphics, source, destination);
    }
}

Hope this helps,
Fredrik