roundbuttontest.java

这是一个java程序

/*
 * @(#)RoundButton.java	1.6 97/06/18 Jeff Dinkins
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc. All Rights Reserved.
 *
 */

import java.applet.*;
import java.lang.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;

public class RoundButtonTest extends Frame implements ActionListener
{
	RoundButton b1, b2;
    public RoundButtonTest()
	{
        setLayout(new FlowLayout());
        setFont(new Font("Helvetica", Font.PLAIN, 14));
   
        b1 = new RoundButton("Button1");
		b2 = new RoundButton("Button2");
		b1.addActionListener(this);
		b2.addActionListener(this);
		add(b1);
		add(b2);
    }

    public boolean handleEvent(Event e) {
        if (e.id == Event.WINDOW_DESTROY) {
            System.exit(0);
        }   
        return super.handleEvent(e);
    }

	public void actionPerformed(ActionEvent e)
	{
		if( e.getActionCommand() == "Button1" )
		{
			System.out.println("Button1 was pressed!");
		}
		else
		{
			System.out.println("Button2 was pressed!");
		}
	}

    public static void main(String args[]) {
        RoundButtonTest window = new RoundButtonTest();

        window.setTitle("RoundButtonTest Application");
        window.pack();
        window.show();
    }
}


/**
 * RoundButton - a class that produces a lightweight button.
 *
 * Lightweight components can have "transparent" areas, meaning that
 * you can see the background of the container behind these areas.
 *
 */
class RoundButton extends Component
{

  ActionListener actionListener;     // Post action events to listeners
  String label;                      // The Button's text
  protected boolean pressed = false; // true if the button is detented.
  
  
  /**
   * Constructs a RoundButton with no label.
   */
  public RoundButton() {
      this("");
  }

  /**
   * Constructs a RoundButton with the specified label.
   * @param label the label of the button
   */
  public RoundButton(String label) {
      this.label = label;
      enableEvents(AWTEvent.MOUSE_EVENT_MASK);
  }

  /**
   * gets the label
   * @see setLabel
   */
  public String getLabel() {
      return label;
  }
  
  /**
   * sets the label
   * @see getLabel
   */
  public void setLabel(String label) {
      this.label = label;
      invalidate();
      repaint();
  }
  
  /**
   * paints the RoundButton
   */
  public void paint(Graphics g)
  {
      int s = Math.min(getSize().width - 1, getSize().height - 1);
      
      // paint the interior of the button
      if(pressed)
	  {
		g.setColor(getBackground().darker().darker());
      }else
	  {
		g.setColor(getBackground());
      }
      g.fillArc(0, 0, s, s, 0, 360);
      
      // draw the perimeter of the button
      g.setColor(getBackground().darker().darker().darker());
      g.drawArc(0, 0, s, s, 0, 360);
      
      // draw the label centered in the button
      Font f = getFont();
      if(f != null)
	  {
		  FontMetrics fm = getFontMetrics(getFont());
		  g.setColor(getForeground());
		  g.drawString(label,
				   s/2 - fm.stringWidth(label)/2,
				   s/2 + fm.getMaxDescent());
      }
  }
  
  /**
   * The preferred size of the button. 
   */
  public Dimension getPreferredSize()
  {
      Font f = getFont();
      if(f != null)
	  {
		  FontMetrics fm = getFontMetrics(getFont());
		  int max = Math.max(fm.stringWidth(label) + 40, fm.getHeight() + 40);
		  return new Dimension(max, max);
      }else
	  {
		return new Dimension(100, 100);
      }
  }
  
  /**
   * The minimum size of the button. 
   */
  public Dimension getMinimumSize()
  {
      return new Dimension(100, 100);
  }

  /**
   * Adds the specified action listener to receive action events
   * from this button.
   * @param listener the action listener
   */
   public void addActionListener(ActionListener listener)
   {
       actionListener = AWTEventMulticaster.add(actionListener, listener);
       enableEvents(AWTEvent.MOUSE_EVENT_MASK);
   }
 
   /**
    * Removes the specified action listener so it no longer receives
    * action events from this button.
    * @param listener the action listener
    */
   public void removeActionListener(ActionListener listener)
   {
       actionListener = AWTEventMulticaster.remove(actionListener, listener);
   }

  /**
   * Determine if click was inside round button.
   */
   public boolean contains(int x, int y)
   {
       int mx = getSize().width/2;
       int my = getSize().height/2;
       return (((mx-x)*(mx-x) + (my-y)*(my-y)) <= mx*mx);
   }
   
   /**
    * Paints the button and distribute an action event to all listeners.
    */
   public void processMouseEvent(MouseEvent e)
   {
       Graphics g;
       switch(e.getID())
	   {
          case MouseEvent.MOUSE_PRESSED:
				// render myself inverted....
				pressed = true;

					// Repaint might flicker a bit. To avoid this, you can use
					// double buffering (see the Gauge example).
				repaint(); 
				break;
          case MouseEvent.MOUSE_RELEASED:
				if(actionListener != null)
				{
				   actionListener.actionPerformed( new ActionEvent(
						this, ActionEvent.ACTION_PERFORMED, label) );
				}
				// render myself normal again
				if(pressed == true)
				{
					pressed = false;

							// Repaint might flicker a bit. To avoid this, you can use
							// double buffering (see the Gauge example).
					repaint();
				}
				break;
          case MouseEvent.MOUSE_ENTERED:

			    break;
          case MouseEvent.MOUSE_EXITED:
				if(pressed == true)
				{
					// Cancel! Don't send action event.
					pressed = false;

							// Repaint might flicker a bit. To avoid this, you can use
							// double buffering (see the Gauge example).
					repaint();

					// Note: for a more complete button implementation,
					// you wouldn't want to cancel at this point, but
					// rather detect when the mouse re-entered, and
					// re-highlight the button. There are a few state
					// issues that that you need to handle, which we leave
					// this an an excercise for the reader (I always
					// wanted to say that!)
				}
				break;
       }
       super.processMouseEvent(e);
   }
   
}