scrolldemo2.java

There a t least five Request for Enhancement s (RFE) in the JavaSoft bug database related to Mouse W

///////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2000 Davanum Srinivas ([e-mail])
// This program is free software; you can redistribute it and/or modify 
// it under the terms of the GNU General Public License as published by 
// the Free Software Foundation; either version 2 of the License, or 
// any later version. 
// 
// This program is distributed in the hope that it will be useful, but 
// WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
// details. 
//
// You should have received a copy of the GNU General Public License along with 
// this program; if not, write to the 
// Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 
///////////////////////////////////////////////////////////////////////////////

import javax.swing.*;
import javax.swing.event.MouseInputAdapter;
import java.awt.*;
import java.awt.event.*;
import java.util.*;

public class ScrollDemo2 extends JPanel 
{
    private Dimension size;		// indicates size taken up by graphics
    private Vector objects1;	// rectangular coordinates used to draw graphics
    private Vector objects2;	// rectangular coordinates used to draw graphics

    private final Color colors[] = {
        Color.red, Color.blue, Color.green, Color.orange,
        Color.cyan, Color.magenta, Color.darkGray, Color.yellow};
    private final int color_n = colors.length;

    JPanel drawingArea1;
    JPanel drawingArea2;

    public ScrollDemo2() 
	{
        setOpaque(true);
        size = new Dimension(0,0);
        objects1 = new Vector();
        objects2 = new Vector();

        //Set up the instructions.
        JLabel instructionsLeft = new JLabel(
                        "Click left mouse button to place a circle.");
        JLabel instructionsRight = new JLabel(
                        "Click right mouse button to clear drawing area.");
        JPanel instructionPanel = new JPanel(new GridLayout(0,1));
        instructionPanel.add(instructionsLeft);
        instructionPanel.add(instructionsRight);

        //Set up the drawing area.
        drawingArea1 = new JPanel() {
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);

                Rectangle rect;
                for (int i = 0; i < objects1.size(); i++) {
                    rect = (Rectangle)objects1.elementAt(i);
                    g.setColor(colors[(i % color_n)]);
                    g.fillOval(rect.x, rect.y, rect.width, rect.height);
                }
            }
        };
        drawingArea1.setBackground(Color.white);
        drawingArea1.addMouseListener(new MyMouseListener(drawingArea1,objects1));

        //Put the drawing area in a scroll pane.
        JScrollPane scroller1 = new JScrollPane(drawingArea1);
        scroller1.setPreferredSize(new Dimension(200,200));

        //Set up the drawing area.
        drawingArea2 = new JPanel() {
            protected void paintComponent(Graphics g) {
                super.paintComponent(g);

                Rectangle rect;
                for (int i = 0; i < objects2.size(); i++) {
                    rect = (Rectangle)objects2.elementAt(i);
                    g.setColor(colors[(i % color_n)]);
                    g.fillOval(rect.x, rect.y, rect.width, rect.height);
                }
            }
        };
        drawingArea2.setBackground(Color.white);
        drawingArea2.addMouseListener(new MyMouseListener(drawingArea2,objects2));

        //Put the drawing area in a scroll pane.
        JScrollPane scroller2 = new JScrollPane(drawingArea2);
        scroller2.setPreferredSize(new Dimension(200,200));

        //Layout this demo.
        setLayout(new BorderLayout());
        add(instructionPanel, BorderLayout.NORTH);
        add(scroller1, BorderLayout.EAST);
        add(scroller2, BorderLayout.WEST);
    }

    class MyMouseListener extends MouseInputAdapter 
	{
        final int W = 100;
        final int H = 100;
		JPanel drawingArea = null;
		Vector objects = null;
		public MyMouseListener(JPanel p, Vector v)
		{	
			drawingArea = p;
			objects = v;
		}

        public void mouseReleased(MouseEvent e) 
		{
            boolean changed = false;
            if (SwingUtilities.isRightMouseButton(e)) {
                // This will clear the graphic objects.
                objects.removeAllElements();
                size.width=0;
                size.height=0;
                changed = true;
            } else {
                int x = e.getX() - W/2;
                int y = e.getY() - H/2;
                if (x < 0) x = 0;
                if (y < 0) y = 0;
                Rectangle rect = new Rectangle(x, y, W, H);
                objects.addElement(rect);
                drawingArea.scrollRectToVisible(rect);

                int this_width = (x + W + 2);
                if (this_width > size.width)
                    {size.width = this_width; changed=true;}

                int this_height = (y + H + 2);
                if (this_height > size.height)
                    {size.height = this_height; changed=true;}
            }
            if (changed) {
                //Update client's preferred size because 
                //the area taken up by the graphics has
                //gotten larger or smaller (if cleared).
                drawingArea.setPreferredSize(size);

                //Let the scroll pane know to update itself
                //and its scrollbars.
                drawingArea.revalidate();
            }
            drawingArea.repaint();
        }
    }

    public static void main (String args[]) 
	{
        JFrameEx frame = new JFrameEx("ScrollDemo2");
        frame.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {System.exit(0);}
        });

        frame.setContentPane(new ScrollDemo2());
        frame.pack();
        frame.setVisible(true);
    }
}