// (c) 1998 Ekkehard Kraemer (ekraemer@pluto.camelot.de)

import java.awt.*;

/**
 * Sorry, not documented yet.
 * <p>
 * <a href="Update.txt">Source</a>
 */
class Update extends Rectangle
{
    Update(Canvas canvas,Image backimg,int maxw,int maxh)
    {
	super(0,0,0,0);
	this.canvas=canvas;
	this.backimg=backimg;
	this.maxw=maxw;
	this.maxh=maxh;
    }

    public void add(int ax,int ay,int aw,int ah)
    {
	add(new Rectangle(ax,ay,aw,ah));	
    }

    synchronized public void add(Rectangle r)
    {
	if (r.x<0) r.x=0;
	if (r.y<0) r.y=0;
	if (width==0 && height==0)
	{
	    this.x=r.x;
	    this.y=r.y;
	    this.width=r.width;
	    this.height=r.height;
	}
	else super.add(r);
    }    


    synchronized void update()
    {
	if (width==0 && height==0) return;
	
	Graphics gr=canvas.getGraphics();
	gr.clipRect(x,y,width,height);
	gr.drawImage(backimg,0,0,null);
	gr.dispose();

	width=0;
	height=0;
    }
    
    Canvas canvas;
    Image backimg;
    int maxw,maxh;
}