Name: mf23781 Date: 07/27/98


The simple test case below runs OK on JDK 1.1.5.
But on 1.1.6, the window is not updated correctly.
Parts of the window are not cleared and become
"garbage" on the screen (also occurs with 1.2beta4)

To run the test:
[1] run "java GarbageInScrollPane"
[2] click the two radio buttons alternatively until garbage
appears

Initial investigation finds that the code of the
method sun.awt.windows.WComponentPeer.handleExpose()
was changed bewteen JDKs 1.1.5 and 1.1.6 to fix the
JavaSoft bug numbered 4081126. This fix unfortunately
introduced the new bug as mentioned above. When we revert
the code back to 1.1.5 version the garbages are greatly
reduced, but not down to zero. We think there may be other
changes that we don't know about.

------ start of GarbageInScrollPane.java

//
// Testcase for showing garbage in ScrollPane.
//

import java.awt.*;

public class GarbageInScrollPane extends Frame
{
   GarbageInScrollPane( ) {
   super("Example of Garbage in ScrollPane");

   preferredSize = new Dimension(400,400);
   gridBag = new GridBagLayout();
   gbc = new GridBagConstraints();
   setLayout(gridBag);
   gbc.anchor = GridBagConstraints.NORTH;
   gbc.fill = GridBagConstraints.HORIZONTAL;
   gbc.weightx = 1.0;
   gbc.weighty = 0;
   gbc.gridwidth = GridBagConstraints.REMAINDER;
   myInsets = new Insets(10,15,5,15);
   gbc.insets = myInsets;
   Panel topPanel = new Panel();
   topPanel.setLayout(new GridLayout(2,1));
   group = new CheckboxGroup();
   topPanel.add(showA = new Checkbox("Click first to show text (numbers)",group, false));
   topPanel.add(showB = new Checkbox("Click second to show ScrollPane(letters)", group, false));
   gridBag.setConstraints(topPanel, gbc);
   add(topPanel);

   // add the following panel as a place holder
   Insets noInsets = new Insets(0,0,0,0);
   gbc.insets = noInsets;
   gbc.weightx = 1.0;
   gbc.weighty = 1.0;
   gbc.anchor = GridBagConstraints.NORTHWEST;
   gbc.fill = GridBagConstraints.BOTH;
   gbc.gridwidth = GridBagConstraints.REMAINDER;
   gbc.gridheight = GridBagConstraints.REMAINDER;
   placeHolderPanel = new Panel();

   placeHolderPanel.setLayout(gridBag);
   gridBag.setConstraints(placeHolderPanel, gbc);
   add(placeHolderPanel);
}
public boolean action(Event evt, Object arg)
{
   if (evt.target == showA)
   {
      createA();
      if (currentPanel != null)
      {
         placeHolderPanel.removeAll();
      }
      currentPanel = panelA;
   }

   else if (evt.target == showB)
   {
      createB();
      if (currentPanel != null)
      {
         placeHolderPanel.removeAll();
      }

      currentPanel = panelB;
   }

   else return false;

   // swap panels
   myInsets.bottom = 15;
   gbc.insets = myInsets;
   gbc.fill = GridBagConstraints.BOTH;
   gridBag.setConstraints(currentPanel, gbc);
   placeHolderPanel.add(currentPanel);
   pack();

   setVisible(true);
   return true;
}

public void createA()
{
   panelA = new Panel();
   panelA.setLayout(new FlowLayout(FlowLayout.CENTER, 20, 20));
   Label line0 = new Label("00000000000000000000000000000000000000");
   panelA.add(line0);

   Label line1 = new Label("11111");
   panelA.add(line1);
}

public void createB()
{
   // In our application, Panel B is a table showing the fields in a specified
   // class - so the number of rows is 0-n. Each row in the table contains
   // a Button object and 3 Label objects.
   // We do use the FlowLayout Layout Manager as shown in the example.
   panelB = new Panel();
   scrollableContainer = new ScrollPane(ScrollPane.SCROLLBARS_AS_NEEDED);
   Panel innerPanelB = new Panel();
   innerPanelB.setLayout(new FlowLayout(FlowLayout.CENTER, 20, 30));
   Label textString = new Label("aaaa");

   innerPanelB.add(textString);
   scrollableContainer.add("North", innerPanelB);
   gridBag.setConstraints(scrollableContainer, gbc);
   panelB.add(scrollableContainer);
}

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

public Dimension getPreferredSize()
{
   return preferredSize;
}

public static void main(String args[])
{
   GarbageInScrollPane mainWindow = new GarbageInScrollPane();
   mainWindow.pack();
   mainWindow.setLocation(100,100);
   mainWindow.setVisible(true);
}

// member data
private CheckboxGroup group;
private Checkbox showA;
private Checkbox showB;
private GridBagLayout gridBag;
private GridBagConstraints gbc;
private Insets myInsets;
private Panel placeHolderPanel;
private Panel currentPanel;
private Panel panelA;
private Panel panelB;
private ScrollPane scrollableContainer;
public Dimension preferredSize;
}
------ end of GarbageInScrollPane.java

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