Zoom Issues with JScrollPane

Question

Hello all,
I have ran into an issue with zoom functionality on a JScrollPane.
Here is the situation (code to follow):
I have a JFrame with a JDesktopPane as the contentpane. Then I have a JScrollPane with a JPanel inside. On this JPanel are three rectangles. When they are clicked on, they will open up a JInternalFrame with their name (rect1, rect2, or rect3) as the title bar. Rect3 is positioned (2000,2000).
I have attached a mousewheel listener to the JPanel so I can zoom in and out.
I have also attached a mouse listener so I can detect the mouse clicks for the rectangles. I also do a transformation on the point so I can be use it during clicks while the panel is zoomed.
All of this works fantastic. The only issue I am having is that when the JScrollPane scroll bars change, I cannot select any of the rectangles.
I will give a step by step reproduction to be used with the code:
1.) Upon loading you will see two rectangles. Click the far right one. You'll see a window appear. Good. Move it to the far right side.
2.) Zoom in with your mouse wheel (push it towards you) until you cannot zoom anymore (May have to get focus back on the panel). You should see three rectangles. Click on the newly shown rectangle. Another window, titled rect3 should appear. Close both windows.
3.) This is where things get alittle tricky. Sometimes it works as intended, other times it doesn't. But do something to this affect: Scroll to the right so that only the third rectangle is showing. Try to click on it. If a window does not appear - that is the problem. But if a window does appear, close it out and try to click on the 3rd rect again. Most times, it will not display another window for me. I have to zoom out one step and back in. Then the window will appear.
After playing around with it for awhile, I first thought it may be a focus issue...I've put some code in the internal window listeners so the JPanel/JScrollPane can grab the focus upon window closing, but it still does not work. So, either the AffineTransform and/or point conversion could be the problem with the scroll bars? It only happens when the scroll bar has been moved. What affect would this have on the AffineTransform and/or point conversion?
Any help would be great.
Here is the code, it consists of two files:
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.BorderFactory;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
public class InternalFrameAffineTransformIssue
     public static void main ( String[] args )
          JFrame frame = new JFrame("AffineTransform Scroll Issue");
          frame.setLayout(null);
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          JDesktopPane desktop = new JDesktopPane();
          frame.setContentPane(desktop);
          MyJPanel panel = new MyJPanel(frame);
          JScrollPane myScrollPane = new JScrollPane(panel);
          panel.setScrollPane(myScrollPane);
          myScrollPane.setLocation(0, 0);
          myScrollPane.setSize(new Dimension(800, 800));
          myScrollPane.getVerticalScrollBar().setUnitIncrement(50);
          myScrollPane.getHorizontalScrollBar().setUnitIncrement(50);
          myScrollPane.setViewportBorder(BorderFactory.createLineBorder(Color.black));
          frame.getContentPane().add(myScrollPane);
          frame.setBounds(0, 100, 900, 900);
          frame.setVisible(true);
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import java.awt.geom.AffineTransform;
import java.awt.geom.NoninvertibleTransformException;
import java.awt.geom.Point2D;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.event.InternalFrameAdapter;
import javax.swing.event.InternalFrameEvent;
import javax.swing.event.InternalFrameListener;
public class MyJPanel extends JPanel implements MouseWheelListener
          double zoom = 1;
          Rectangle rect1 = new Rectangle(50, 50, 20, 20);
          Rectangle rect2 = new Rectangle(100, 50, 20, 20);
          Rectangle rect3 = new Rectangle(2000, 2000, 20, 20);
          AffineTransform zoomedAffineTransform;
          JFrame frame;
          JPanel myPanel = this;
          JScrollPane myScrollPane;
          public MyJPanel(JFrame inputFrame)
               setAutoscrolls(true);
               addMouseListener(new MouseAdapter(){
                    public void mousePressed ( MouseEvent e )
                         System.out.println("Clicked: " + e.getPoint());
                         AffineTransform affineTransform = zoomedAffineTransform;
                         Point2D transformedPoint = e.getPoint();
                         //Do the transform if it is not null
                         if(affineTransform != null)
                              try
                                   transformedPoint = affineTransform.inverseTransform(transformedPoint, null);
                              catch (NoninvertibleTransformException ex)
                                   ex.printStackTrace();
                         System.out.println("Tranformed Point: " + transformedPoint);
                         if(rect1.contains(transformedPoint))
                              System.out.println("You clicked on rect1.");
                              createInternalFrame("Rect1");
                         if(rect2.contains(transformedPoint))
                              System.out.println("You clicked on rect2.");
                              createInternalFrame("Rect2");
                         if(rect3.contains(transformedPoint))
                              System.out.println("You clicked on rect3.");
                              createInternalFrame("Rect3");
               addMouseWheelListener(this);
               frame = inputFrame;
               setPreferredSize(new Dimension(4000, 4000));
               setLocation(0, 0);
          public void paintComponent ( Graphics g )
               super.paintComponent(g);
               Graphics2D g2d = (Graphics2D) g;
               g2d.scale(zoom, zoom);
               zoomedAffineTransform = g2d.getTransform();
               g2d.draw(rect1);
               g2d.draw(rect2);
               g2d.draw(rect3);
          public void mouseWheelMoved ( MouseWheelEvent e )
               System.out.println("Mouse wheel is moving.");
               if(e.getWheelRotation() == 1)
                    zoom -= 0.05;
                    if(zoom <= 0.20)
                         zoom = 0.20;
               else if(e.getWheelRotation() == -1)
                    zoom += 0.05;
                    if(zoom >= 1)
                         zoom = 1;
               repaint();
          public void createInternalFrame ( String name )
               JInternalFrame internalFrame = new JInternalFrame(name, true, true, true, true);
               internalFrame.setBounds(10, 10, 300, 300);
               internalFrame.setVisible(true);
               internalFrame.addInternalFrameListener(new InternalFrameAdapter(){
                    public void internalFrameClosed ( InternalFrameEvent arg0 )
                         //myPanel.grabFocus();
                         myScrollPane.grabFocus();
                    public void internalFrameClosing ( InternalFrameEvent arg0 )
                         //myPanel.grabFocus();
                         myScrollPane.grabFocus();
               frame.getContentPane().add(internalFrame, 0);
          public void setScrollPane ( JScrollPane myScrollPane )
               this.myScrollPane = myScrollPane;
     }

Answer 1

What I'm noticing is your zoomedAffineTransform is changing when you click to close the internal frame. This ends up being passed down the line, thus mucking up your clicks until you do something to reset it (like zoom in and out).
Clicking on the JInternalFrame appears to add a translate to the g2d transform. This translation is what's throwing everything off. So in the paintComponent where you set the zoomedAffineTransform, you can verify if the transform has a translation before storing the reference:
         if (g2d.getTransform().getTranslateX() == 0.0) {
            zoomedAffineTransform = g2d.getTransform();
         }Edited by: jboeing on Oct 2, 2009 8:23 AM