samer@0: /*
samer@0:  *	Copyright (c) 2000, Samer Abdallah, King's College London.
samer@0:  *	All rights reserved.
samer@0:  *
samer@0:  *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
samer@0:  *	without even the implied warranty of MERCHANTABILITY or 
samer@0:  *	FITNESS FOR A PARTICULAR PURPOSE.
samer@0:  */
samer@0: 
samer@0: package samer.core.util.heavy;
samer@0: import  samer.core.*;
samer@0: import  samer.core.util.Tools;
samer@0: import  samer.core.util.MouseRetarget;
samer@0: import  samer.core.util.swing.MenuBuilder;
samer@0: import  samer.core.util.swing.DynamicPopupHandler;
samer@0: import  java.awt.*;
samer@0: import  java.awt.event.*;
samer@0: 
samer@0: /**
samer@0: 		<p>
samer@0: 		This is a Canvas which maintains a valid Graphics
samer@0: 		object. The Graphics associated with the Canvas
samer@0: 		becomes available only at a certain time (not
samer@0: 		during construction) so we have to setup the
samer@0: 		Graphics in response to some event. It seems that the 
samer@0: 		only event a component reliably gets after being
samer@0: 		realized is a size event. We use the first size
samer@0: 		event to get a Graphics and notify any derived
samer@0: 		classes through the <code>realized()</code>
samer@0: 		method which is there to be overridden.
samer@0: 	
samer@0:  */
samer@0: 
samer@0: public class VCanvas extends Canvas implements Viewer
samer@0: {
samer@0: 	public Graphics graphics=null;
samer@0: 	public int		 width, height;
samer@0: 
samer@0: 	/**	<b><code>void realized()</code></b>
samer@0: 	  *	This is called when the cached Graphics object
samer@0: 	  *	(see GCanvas) is created. The component is probably still
samer@0: 	  *	invisible at this point, but we can get off-screen
samer@0: 	  *	Images and do other useful setting up things that
samer@0: 	  *	don't seem to work in the constructor
samer@0: 	  *
samer@0: 	  */
samer@0: 	protected void realized() {}
samer@0: 	protected void sized() {}
samer@0: 
samer@0: 	public void clear() { clear(graphics); }
samer@0: 	public void clear(Graphics g) {
samer@0: 		g.setColor(getBackground());
samer@0: 		g.fillRect(0,0,width,height);
samer@0: 	}
samer@0: 
samer@0: 	private void cacheGraphics()
samer@0: 	{
samer@0: 		if (graphics!=null) graphics.dispose();
samer@0: 		graphics=Tools.initGraphics(getGraphics());
samer@0: 	}
samer@0: 	
samer@0: 	public void removeNotify()
samer@0: 	{
samer@0: 		detach();
samer@0: 		// graphics=null; // this might cause a problem! synchronization?
samer@0: 		super.removeNotify();
samer@0: 	}
samer@0: 
samer@0: 	public void addNotify()
samer@0: 	{
samer@0: 		super.addNotify();
samer@0: 		Dimension d = getSize();
samer@0: 		width=d.width; height=d.height;
samer@0: 		cacheGraphics();
samer@0: 		attach(); realized(); // ??
samer@0: 	}
samer@0: 
samer@0: 	public Dimension getMinimumSize() {
samer@0: 		return new Dimension(0,0);
samer@0: 	}
samer@0: 
samer@0: 	{	// initialisation code
samer@0: 		addMouseListener(MouseRetarget.listener);
samer@0: 		addComponentListener( new ComponentAdapter() {
samer@0: 			public void componentResized(ComponentEvent e) {
samer@0: 				Dimension d = getSize();
samer@0: 				width=d.width; height=d.height;
samer@0: 				cacheGraphics();
samer@0: 				sized();
samer@0: 			}
samer@0: 		} );
samer@0: 
samer@0: 		setBackground(Shell.getColor("background",null));
samer@0: 		setForeground(Shell.getColor("foreground",null));
samer@0: 	}
samer@0: 
samer@0: 	/* this is v cunning (actually - not really) */
samer@0: 	public Image createPixel() { return createPixel(1,1); }
samer@0: 	public Image createPixel(Color c) { return createPixel(c,1,1); }
samer@0: 	public Image createPixel(int w, int h) { return createPixel(getForeground(),w,h); }
samer@0: 	public Image createPixel(Color c, int w, int h)
samer@0: 	{
samer@0: 		Image img=createImage(w,h);
samer@0: 		Graphics g=img.getGraphics();
samer@0: 		g.setColor(c);
samer@0: 		g.fillRect(0,0,w,w);
samer@0: 		g.dispose();
samer@0: 		return img;
samer@0: 	}
samer@0: 
samer@0: 	// ....... MenuAnchor bits .......................
samer@0: 
samer@0: 	private DynamicPopupHandler thing=null;
samer@0: 	// private JPopupMenu thing=null;
samer@0: 
samer@0: 	public Component	getComponent() { return this; }
samer@0: 	public void			attach() {}
samer@0: 	public void			detach() {}
samer@0: 	public void	exposeCommands(Agent agent) {
samer@0: 		// menu=MenuBuilder.showCommands(agent,getComponent(),menu);
samer@0: 		thing=MenuBuilder.showCommands(agent,getComponent(),thing);
samer@0: 	}
samer@0: 
samer@0: 	protected void finalize() {
samer@0: 		if (graphics!=null) graphics.dispose();
samer@0: 	}
samer@0: 
samer@0: }
samer@0: 
samer@0: