package graph.editor;
import graph.*;
import java.awt.*;
import java.util.*;

/**
 * A simple graph viewer.  It displays a graph and
 * can also draw some "Painter" objects which know
 * how to draw into the window.<p>
 *
 * For now it also has a hacky key press handler which
 * invokes a test action of some sort on the graph.
 *
 * @see graph.Editor;
 * @see graph.Graph;
 * @author Michael Shilman (michaels@eecs.berkeley.edu)
 * @version $Id$
 */

public class Viewer extends Canvas {
	/**
	 * The default viewer height.
	 */
	public static int HEIGHT = 600;
	
	/**
	 * The default viewer width.
	 */
    public static int WIDTH = HEIGHT;
	
	/**
	 * The default border around the viewer's canvas.
	 */
    public static final int BORDER = 50;
    
	/**
	 * XXX A hacky action which can be used to test various
	 *     actions.
	 */
    public Action action = null;
    
	/**
	 * The graph that is displayed in the window.
	 */
    public Graph graph = null;
    
	/**
	 * A number of other painters which can paint into the
	 * window.
	 */
    public Vector painters = new Vector();
    
	/**
	 * The offscreen image for double buffering.
	 */
    Image m_offImg = null;
    

	/**
	 * Construct a new empty viewer.
	 */
    public Viewer() {
        super();
    }

	/**
	 * Construct a viewer of size <i>w x h</i>.
	 */
    public Viewer(int w, int h) {
    	WIDTH = w;
    	HEIGHT = h;
    }
    
    public void update(Graphics g) {
        paint(g);
    }
	
    public Dimension preferredSize() {
        return new Dimension(WIDTH, HEIGHT);
    }

	/**
	 * Handle key presses.  The <i>return</i> key
	 * invokes the action member variable.
	 *
	 * @see #action
	 */
	public boolean keyDown(Event evt, int key) {
		switch(key) {
			case '\n':
				if(action != null) {
					action.apply(graph);
					repaint();
					return true;
				}
				else {
					return super.keyDown(evt, key);
				}
			default:
				return super.keyDown(evt, key);
		}
	}
	
	/**
	 * XXX A hack to more easily allow subclasses of
	 * viewer to paint something extra into the window.
	 */
	protected void viewerPaint(Graphics g) {
		
	}

	/**
	 * Paint the contents of the graph and each of the
	 * Painter objects into the canvas.
	 */
    public void paint(Graphics g) {    	
        if(m_offImg == null) {
            m_offImg = createImage(WIDTH, HEIGHT);
        }

        Graphics offg = m_offImg.getGraphics();
		super.paint(offg);
		graph.paint(offg);
		viewerPaint(offg);
		for(Enumeration e = painters.elements(); e.hasMoreElements(); ) {
			Painter p = (Painter)e.nextElement();
			p.paint(offg);
		}
        g.drawImage(m_offImg, 0, 0, this);
    }
}