Flickering on a 2D Sprite

[driiper]

Hello!

I'm currently working on a simple game in the 2D library in java, but i have stumbled over a flickering bug which i'm pretty annoyed over.

So i have a player class, in the constructor it loads a PNG sprite sheet.

And when the player presses one of the arrow keys, it changes the sprite after which array the player pressed:

public void changePlayerImage(int dir){ //Dir 0 = Image UP etc
		switch(dir){
			default:
				currentImage = grabSprite(3,2,28,46,pSprites);
				CURRENT_IMAGE_SHOWN = 1;
				break;
			case IMAGE_UP:
				if(CURRENT_IMAGE_SHOWN != IMAGE_UP)
					currentImage = grabSprite(3,145,28,46,pSprites);
					CURRENT_IMAGE_SHOWN = 0;
				break;
			case IMAGE_DOWN:
				if(CURRENT_IMAGE_SHOWN != IMAGE_DOWN)
					currentImage = grabSprite(3,2,28,46,pSprites);
					CURRENT_IMAGE_SHOWN = 1;
				break;
			case IMAGE_LEFT:
				if(CURRENT_IMAGE_SHOWN != IMAGE_LEFT)
					currentImage = grabSprite(3,52,28,46,pSprites);
					CURRENT_IMAGE_SHOWN = 2;
				break;
			case IMAGE_RIGHT:
				if(CURRENT_IMAGE_SHOWN != IMAGE_RIGHT)
					currentImage = grabSprite(3,100,28,46,pSprites);
					CURRENT_IMAGE_SHOWN = 3;
				break;
		}
	}

So, the problems seems to be that it having problem creating the first picture after the players presses the key, after adding some debugging prints i got these results from outputting the currentImage width and height:

Width: -1
Height: -1

Width: 28
Height: 46

Width: -1
Height: -1

Width: -1
Height: -1

Width: 28
Height: 46

This was when i spamclicked left and right arrow key.

The method for "finding the right sprite" is the following

	public Image grabSprite(int x, int y, int width, int height, Image Sprite){
		Image sprite;
		ImageFilter filt=new CropImageFilter(x,y,width,height);
		FilteredImageSource pro=new FilteredImageSource(pSprites.getSource(),filt);
		sprite=Toolkit.getDefaultToolkit().createImage(pro);
		return sprite;
	}

And yeh, ive been trying diffrent things in several hours, but nothing seem to work.
My draw method in the player class is fairly simple aswell, maybe that may be the problem:

public void draw(Graphics g){
		g.drawImage(pSprites, pPosX, pPosY, null);
		System.out.println("Width: " +currentImage.getWidth(null) + "\nHeight: "+ currentImage.getHeight(null)+ "\n");
		g.dispose();
	}

But yeh, i'm completly clueless.

[Norm]

Can you make a small program that compiles, executes and shows the problem for testing?

[driiper]

After yet few hours i still cant find the bug which causes this, so ill upload a jar file with the game here.
http://driiper.com/~per/Game-Learning3.jar

Thanks!

Driiper

[Norm]

Can you make a small program that compiles, executes and shows the problem for testing?
I'm not interested in going to a third site for the whole program.

[driiper]

Seems like a friend of mine found the problem, it was the Sprite image which wasnt DoubleBuffered, and the caused the flickering when changing. But thanks anyways!


Driiper

[Norm]

If you use Swing components they use double buffering.