rubberband.java

MAP GIS 一种底层的JAVA程序

import java.awt.*;
import java.awt.event.*;
abstract public class RubberBand
{
	protected Point anchorPt = new Point(0,0);
	protected Point stretchedPt = new Point (0, 0);
	protected Point lastPt = new Point (0, 0);
	protected Point endPt = new Point (0, 0);
	
	private Component component;
	private boolean firstStretch = true;
	private boolean active = false;
	
	abstract public void drawLast(Graphics g);
	abstract public void drawNext(Graphics g);
	
	public RubberBand()
	{
	}
	public RubberBand(Component c)
	{
		setComponent(c);
	}
	public void setActive(boolean b)
	{
		active = b;
	} 
	public void setComponent(Component c)
	{
		component = c;
		component.addMouseListener(new MouseAdapter()
						{
							public void mousePressed(MouseEvent event)
							{
								if( isActive() )	anchor(event.getPoint());
							}
							public void mouseClicked(MouseEvent event)
							{
								if( isActive() )	end( event.getPoint() ) ;
							}
							public void mouseReleased(MouseEvent event)
							{
								if( isActive() )	end( event.getPoint() ) ;
							}
						});
		component.addMouseMotionListener(new MouseMotionAdapter()
						{
							public void mouseDragged(MouseEvent event)
							{
								if( isActive() )	stretch( event.getPoint() ) ;
							}
						});
	}
	public boolean isActive()	{ return active; }
	public Point getAnchor()	{ return anchorPt;}
	public Point getStretched()	{ return stretchedPt;}
	public Point getLast()	  	{ return lastPt;}
	public Point getEnd()		{ return endPt;}
	
	public void anchor(Point p)
	{
		firstStretch = true;
		anchorPt.x = p.x;
		anchorPt.y = p.y;
		
		stretchedPt.x = lastPt.x = anchorPt.x;
		stretchedPt.y = lastPt.y = anchorPt.y;
	}
	public void stretch (Point p)
	{
		lastPt.x = stretchedPt.x;
		lastPt.y = stretchedPt.y;
		stretchedPt.x = p.x;
		stretchedPt.y = p.y;
		
		Graphics g = component.getGraphics();
		if (g != null )
		{
			try
			{
				g.setXORMode(component.getBackground());
				if (firstStretch)	firstStretch = false;
				else 	drawLast(g);
				drawNext(g);
			}
			finally
			{
				g.dispose();
			}
		}
	}
	public void end (Point p)
	{
		lastPt.x = endPt.x = p.x;
		lastPt.y = endPt.y = p.y;
		
		Graphics g = component.getGraphics();
		if(g != null)
		{
			try
			{
				g.setXORMode(component.getBackground());
				drawLast(g);
			}
			finally
			{
				g.dispose();
			}
		}
	}
	public Rectangle getCurrentBounds()
	{
		return new Rectangle (	stretchedPt.x < anchorPt.x ? stretchedPt.x : anchorPt.x,
					stretchedPt.y < anchorPt.y ? stretchedPt.y : anchorPt.y,
					Math.abs(stretchedPt.x - anchorPt.x),
					Math.abs(stretchedPt.y - anchorPt.y)
				     );
	}
	public Rectangle getLastBounds()
	{
		return new Rectangle ( lastPt.x < anchorPt.x ? lastPt.x : anchorPt.x,
				       lastPt.y < anchorPt.y ? lastPt.y : anchorPt.y,
				       Math.abs(lastPt.x - anchorPt.x),
				       Math.abs(lastPt.y - anchorPt.y)
				     );
	}
}