import java.awt.*;

class TrackPanel extends Panel {
    // ------------------------------------------------------------------
    // The following items are used for double buffering.
    
    // The buffer in which to draw the image; used for double buffering.
    Image backBuffer;
    
    // The graphics context to use when double buffering.
    Graphics backG;
 
    private Rail[][] rails;    // The grid of rails.
   
    public void addToPanel(Rail[][] r) {
        rails = r;
        
        setLayout(new GridLayout(rails.length, rails[0].length, 0, 0));
        
        for (int row=0; row < rails.length; row++) {
            for (int col=0; col < rails[0].length; col++) {
                add("", rails[row][col]);
            }
        }
    }

    // paint
    // ------------------------------------------------------------------
    // Paint the display.
    
    public void paint(Graphics g) {
        update(g);
    }

    public Insets insets() {
        return new Insets(10,10,10,10);
    }

    // update
    // ------------------------------------------------------------------
    // Update the display; tell all my Tracks to update themselves.
    
    public void update(Graphics g) {
        
        // Get my width and height.
        int w = bounds().width;
        int h = bounds().height;
    
        // If we don't yet have an Image, create one.
        if (backBuffer == null
            || backBuffer.getWidth(null) != w
            || backBuffer.getHeight(null) != h) {
            backBuffer = createImage(w, h);
            if (backBuffer != null) {
            
                // If we have a backG, it belonged to an old Image.
                // Get rid of it.
                if (backG != null) {
                    backG.dispose();
                }
                backG = backBuffer.getGraphics();
            }
        }
        
        if (backBuffer != null) {
            
            // Fill in the Graphics context backG.
            g.setColor(Color.white);
            g.fillRect(0, 0, w, h);
            
            // Now copy the new image to g.
           // g.drawImage(backBuffer, 0, 0, null);
        }
        
    }
}