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/*File SwingPane01 Copyright 1998, R.G.Baldwin
The purpose of this program is to illustrate the use of
the contentPane and the layeredPane.
The program places a JFrame object on the screen as the
primary GUI.
A red JTextField and a JLabel are placed on the
contentPane on the JFrame object. (The label is
actually rendered as gray in the metal L&F.)
The JTextField is placed in the Center of the JFrame using
the default border layout. The JLabel is placed in the
South position on the JFrame object.
A green JButton and a yellow JButton are placed on the
layeredPane of the JFrame object. Apparently the default
layout for the layeredPane is absolute or null. The
JButton objects are purposely placed so as to partially
overlap. Both buttons appear on top of the JTextField
object on the contentPane.
The green JButton is initially placed at layer position +1
on the layeredPane and the yellow JButton is initially
placed at layer position -29999 which is the limit in the
negative direction.
Action listeners are registered on the two buttons. When
the top button is clicked, the action is to swap the layer
positions of the two buttons causing the other one to
move to the top layer position.
Several lines of code are included to investigate the
parent child relationships of the various panes. The
output from this part of the program follows. Note that
line breaks were manually inserted here to force the
material to fit in this format.
Root pane is: class com.sun.java.swing.JRootPane
Parent of root pane is SwingPane01
[frame0,0,0,0x0,invalid,hidden,
layout=java.awt.BorderLayout,resizable,title=]
Glass pane is: class com.sun.java.swing.JPanel
Parent of glassPane is com.sun.java.swing.JRootPane
[,0,0,0x0,invalid,
layout=com.sun.java.swing.JRootPane$RootLayout]
Layered pane is: class com.sun.java.swing.JLayeredPane
Parent of layeredPane is com.sun.java.swing.JRootPane
[,0,0,0x0,invalid,
layout=com.sun.java.swing.JRootPane$RootLayout]
Content pane is: class com.sun.java.swing.JPanel
Parent of contentPane is com.sun.java.swing.JLayeredPane
[null.layeredPane,0,0,0x0,invalid]
An interpretation of the above is:
The root pane is a child of the JFrame object.
The glass page is a child of the root pane.
The layeredPane is a child of the root pane.
The contentPane is a child of the layeredPane.
The root pane is of type JRootPane.
The glassPane is of type JPanel.
The layeredPane is of type JLayeredPane.
The contentPane is of type JPanel.
The JavaSoft documentation indicates that the contentPane
is placed at layer position -30000 in the layeredPane.
The glassPane is something of a mystery at this point.
I was unable to draw upon the glassPane. An attempt to
place either a JButton object or a JToolTip object on the
glass plane was rejected by the compiler with error
messages that the JButton and the JToolTip could not be
converted to type JPopupMenu.
Tested using JDK 1.1.6 and Swing 1.0.1 under Win95.
**********************************************************/
import java.awt.*;
import java.awt.event.*;
import com.sun.java.swing.*;
class SwingPane01 extends JFrame{//subclass JFrame
JLayeredPane theLayeredPane;
JButton greenButton;
JButton yellowButton;
public static void main(String[] args){
new SwingPane01();
}//end main
//-----------------------------------------------------//
SwingPane01(){//constructor
//Get a ref to the layeredPane for later use.
theLayeredPane = this.getLayeredPane();
int frameWidth = 300;
int frameHeight = 200;
//Get and display types of different panes along with
// parent-child hierarchy.
System.out.println("Root pane is: " +
this.getRootPane().getClass());
System.out.println("Parent of root pane is " +
this.getRootPane().getParent() + "\n");
System.out.println("Glass pane is: " +
this.getGlassPane().getClass());
System.out.println("Parent of glassPane is " +
this.getGlassPane().getParent() + "\n");
System.out.println("Layered pane is: " +
this.getLayeredPane().getClass());
System.out.println("Parent of layeredPane is " +
this.getLayeredPane().getParent() + "\n");
System.out.println("Content pane is: " +
this.getContentPane().getClass());
System.out.println("Parent of contentPane is " +
this.getContentPane().getParent() + "\n");
//Put instructions in a JLabel on the contentPane.
JLabel theLabel = new JLabel(
" Click buttons to swap their layer positions.");
this.getContentPane().add(theLabel,"South");
//Put a red JTextField in the Center of the JFrame on
// the contentPane.
JTextField redTextField = new JTextField(
" redTextField on contentPane");
redTextField.setBackground(Color.red);
this.getContentPane().add(redTextField,"Center");
//Put a green JButton on the layeredPane at a layer
// position of +1.
greenButton = new JButton(
"greenButton on Layered Pane");
greenButton.setBackground(Color.green);
greenButton.setBounds(10,10,240,40);
greenButton.addActionListener(new MyActionListener());
theLayeredPane.add(greenButton,new Integer(1));
//Put a yellow JButton on the layeredPane at a layer
// position of -29999.
yellowButton = new JButton(
"yellowButton on Layered Pane");
yellowButton.setBackground(Color.yellow);
yellowButton.setBounds(40,20,240,40);
yellowButton.addActionListener(new MyActionListener());
theLayeredPane.add(yellowButton,new Integer(-29999));
//Set title, size, and visibility of JFrame object.
this.setTitle("Copyright 1998, R.G.Baldwin");
this.setSize(frameWidth,frameHeight);
this.setVisible(true);
//===================================================//
//Anonymous inner class to terminate program.
this.addWindowListener(new WindowAdapter(){
public void windowClosing(WindowEvent e){
System.exit(0);}});//end addWindowListener
}//end constructor
//=====================================================//
//Inner class for listener objects which swap the layer
// positions of the two JButton objects when the one on
// the top is clicked.
class MyActionListener implements ActionListener{
public void actionPerformed(ActionEvent e){
if(e.getActionCommand().equals(
"greenButton on Layered Pane")){
theLayeredPane.setLayer(greenButton,-29999);
theLayeredPane.setLayer(yellowButton,1);
}else{
theLayeredPane.setLayer(greenButton,1);
theLayeredPane.setLayer(yellowButton,-29999);
}//end else
}//end actionPerformed()
}//end class MyActionListener
}//end class SwingPane01
//=======================================================// |
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