Name: jk109818 Date: 07/30/2002


FULL PRODUCT VERSION :
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)

FULL OPERATING SYSTEM VERSION :
Windows NT Version 4.0
Build 1381: Service Pack 5

A DESCRIPTION OF THE PROBLEM :
When columnMargin is set to a value which is visually
noticeable, the column header appears to be not centered
with respect to the vertical grid lines. Data cells are
rendered with the columnMargin and also rowMargin evenly
distributed on all sides of the cell whereas column header
cells are rendered on the far left with the columnMargin on
the far right of the column. This produces a JTable which
is esthetically unappealing.


REGRESSION. Last worked in version 1.3

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1)
Compile and run the enclosed program under Java 1.4 and
notice that the column header is not centered.

2)
Then uncomment the line
//table.setTableHeader( header );
to show the effect of workaround solution #1. This will
cause the header cell to be centered with respect to the
data cells in that column.

EXPECTED VERSUS ACTUAL BEHAVIOR :
I would expect the table header cell to be centered with
respect to the data cells in the same column.

Instead the table header is on the far left with the
columnMargin on the far right of the column and not aligned
with the data cells in the same column which are centered
in the column with the columnMargin evenly distributed on
left and right of the data cell.

I would actually prefer to see the header rendered without
adjusting for the columnMargin as was done in Java 1.3 . I
believe this is more esthetically pleasing.

This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;

public class JTableHeaderTest extends JFrame
{
   //--------------------------------------------------------------------------
   public void vcInit()
   {
      //{{INIT_CONTROLS
setTitle("JTableHeaderTest");
getContentPane().setLayout(new BorderLayout(0,0));
setSize(400,300);
setVisible(false);
getContentPane().add(scrollPane);
scrollPane.getViewport().add(table);
      //}}
   }

   //--------------------------------------------------------------------------
   //{{DECLARE_CONTROLS
javax.swing.JScrollPane scrollPane = new javax.swing.JScrollPane();
javax.swing.JTable table = new javax.swing.JTable();
//}}
//{{DECLARE_MENUS
//}}

   //--------------------------------------------------------------------------
   public JTableHeaderTest()
   {
      vcInit();
      
      ((JPanel)getContentPane()).setBorder( new EmptyBorder( 20, 20, 20, 20 ) );
      
      // Setup table
      Object[] row1 = { "now" , "is" };
      Object[] row2 = { "the" , "time" };
      Object[][] data = { row1, row2 };
      String[] columnNames = { "Column A", "Column B" } ;
      DefaultTableModel model = new DefaultTableModel( data, columnNames )
         { public boolean isCellEditable( int row, int column ) { return
false ; } };
      table.setModel( model );
      table.changeSelection( 0, 0, false, false );

      // Set column margin to a value that's visually noticeable.
      table.getColumnModel().setColumnMargin( 50 );
      
      // Workaround #1:
      // Override JTableHeader.getHeaderRect to NOT include spacing -
      // similar to JTable.getCellRect(row,column,false)
      // Note: BasicTableHeaderUI does not use the "width" component.
      JTableHeader header = new JTableHeader( table.getColumnModel() )
      {
         public Rectangle getHeaderRect( int columnIndex )
         {
            Rectangle r = super.getHeaderRect( columnIndex );
            r.x += getColumnModel().getColumnMargin() / 2 ;
            r.width -= getColumnModel().getColumnMargin();
            return r ;
         }
      };
      
      // Comment the following lines to demonstrate bug.
      // Un-comment the following line to demonstrate workaround #1
      //table.setTableHeader( header );
      
      // Workaround #2:
      // Setup sub-class of BasicTableHeaderUI (not supplied) that does
      // NOT adjust column header bounds based on column margin.
      // Un-comment the following line to demonstrate workaround #2
      //table.getTableHeader().setUI( new MyBasicTableHeaderUI() );
   }
   
   //--------------------------------------------------------------------------
   public static void main( String[] args ) throws Exception
   {
      String javaVersion = System.getProperties().getProperty("java.version");
      System.out.println( "Java version: " + javaVersion );
      
      //UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
      
      JTableHeaderTest window = new JTableHeaderTest();
window.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
window.setTitle( window.getTitle() + " - java version " +
javaVersion );
      window.pack();
      window.setVisible( true );
   }
}
---------- END SOURCE ----------

CUSTOMER WORKAROUND :
Workaround #1:
Override the getHeaderRect method in JTableHeader to NOT
include spacing - similar to JTable.getCellRect
(row,column,false).

Workaround #2:
Make of sub-class of
javax.swing.plaf.basic.BasicTableHeaderUI which does not
adjust the table header cell for the columnMargin. This
will cause the table header to be rendered with the same
appearance it had under Java 1.3 .

Release Regression From : 1.3.1
The above release value was the last known release where this
bug was known to work. Since then there has been a regression.

(Review ID: 145371)
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