/*
 FileName:    BufferedCanvas.java
 Description: A double buffered canvas plus an overlay that supports animation.
 Created by:  Dylan Hoen ( http://www.dylan.hoen.ca/ )
 Change Log:
 2010/02/23 | Dylan Hoen | Added this title block.
 */

import java.awt.*;
import java.awt.image.*;


public class BufferedCanvas extends Canvas
{
	int imageWidth = -1;
	int imageHeight = -1;

	Image offscreen = null;
	Image overlay = null;
	
	Image memoryMappedImage = null;
	MemoryImageSource memoryImageSource = null;
	
	boolean useOverlay = false;

	public BufferedCanvas()
	{
		imageWidth = getWidth();
		
		imageHeight = getHeight();
		
		offscreen = createImage( imageWidth,  imageHeight );
		overlay = createImage( imageWidth,  imageHeight );
		
		this.setBackground( Color.BLACK );
		
		if( offscreen != null )
		{
			Graphics graphics = offscreen.getGraphics();
			graphics.setColor( getBackground() );
			graphics.fillRect( 0, 0, imageWidth, imageHeight );
		}
		
		if( overlay != null )
		{
			Graphics graphics = overlay.getGraphics();
			graphics.setColor( getBackground() );
			graphics.fillRect( 0, 0, imageWidth, imageHeight );
		}

		repaint ();
	}

    public void update( Graphics graphics )
    {
		paint( graphics );
    }

	public void paint( Graphics graphics )
	{
		if( imageWidth != getWidth() || imageHeight != getHeight() )
		{
			imageWidth = getWidth();
			
			imageHeight = getHeight();
			
			Image tempImage = createImage( imageWidth,  imageHeight );
			
			Graphics tempGraphics = tempImage.getGraphics();
			
			tempGraphics.setColor( getBackground() );
			
			tempGraphics.fillRect( 0, 0, imageWidth, imageHeight );
			
			tempGraphics.drawImage( offscreen, 0, 0, this );
			
			offscreen = tempImage;
			
			
			tempImage = createImage( imageWidth,  imageHeight );
			
			tempGraphics = tempImage.getGraphics();
			
			tempGraphics.setColor( getBackground() );
			
			tempGraphics.fillRect( 0, 0, imageWidth, imageHeight );
			
			tempGraphics.drawImage( overlay, 0, 0, this );
			
			overlay = tempImage;
		}
		
		if( useOverlay )
		{
			graphics.drawImage( overlay, 0, 0, this );
		}
		else
		{
			graphics.drawImage( offscreen, 0, 0, this );
		}
	}

	public Graphics getBufferedGraphics()
	{
		Graphics result = null;
		
		if( offscreen != null )
		{
			result = offscreen.getGraphics();
		}
		
		return result;
	}
	
	public Graphics getOverlayGraphics()
	{
		useOverlay = true;
		
		Graphics result = null;
		
		if( overlay != null )
		{
			result = overlay.getGraphics();
		}
		
		return result;
	}
	
	public void disableOverlayGraphics()
	{
		useOverlay = false;
	}
	
	public void copyBufferToOverlay()
	{
		Graphics graphics = overlay.getGraphics();
		graphics.drawImage( offscreen, 0, 0, this );
	}
	
	public int[] createMemoryMappedImage()
	{
		int[] pixels = new int[ imageWidth * imageHeight ];
		
		int backgroundColor = getBackground().getRGB();
		
		for( int i = 0; i < pixels.length; i++ )
		{
			pixels[i] = backgroundColor;
		}
		
		createMemoryMappedImage( imageWidth, imageHeight, pixels );
		
		return pixels;
	}
	
	public void createMemoryMappedImage( int width, int height, int[] pixels )
	{
		memoryImageSource = new MemoryImageSource( width, height, pixels, 0, width );

		memoryImageSource.setAnimated(true);
		memoryImageSource.setFullBufferUpdates(true);

		memoryMappedImage = createImage( memoryImageSource );
	}
	
	
	public void drawMemoryMappedImageToBufer()
	{
		drawMemoryMappedImageToBufer( 0, 0 );
	}
	
	public void drawMemoryMappedImageToBufer( int xOffset, int yOffset )
	{
		if( memoryImageSource != null )
		{
			memoryImageSource.newPixels();
			
			Graphics graphics = getBufferedGraphics();
			
			if( graphics != null )
			{
				graphics.drawImage( memoryMappedImage, xOffset, yOffset, this );
			}
			else
			{
				throw( new IllegalStateException( "Bufer not yet initialised"  ) );
			}
		}
		else
		{
			throw( new IllegalStateException( "Memory Mapped Image not yet initialised"  ) );
		}
	}
	
	
	public void drawMemoryMappedImageToOverlay()
	{
		drawMemoryMappedImageToOverlay( 0, 0 );
	}
	
	public void drawMemoryMappedImageToOverlay( int xOffset, int yOffset )
	{
		if( memoryImageSource != null )
		{
			memoryImageSource.newPixels();
			
			Graphics graphics = this.getOverlayGraphics();
			
			if( graphics != null )
			{
				graphics.drawImage( memoryMappedImage, xOffset, yOffset, this );
			}
			else
			{
				throw( new IllegalStateException( "Overlay not yet initialised"  ) );
			}
		}
		else
		{
			throw( new IllegalStateException( "Memory Mapped Image not yet initialised"  ) );
		}
	}
}