/*File Event16.java Copyright 1997, R.G.Baldwin
This program is designed to be compiled and run under JDK 1.1

This program implements a custom scheme for moving the focus
among a set of visual components using the F12 key and the 
Shift-F12 key as an alternate to the Tab and Shift-Tab key.

The Tab and Shift-Tab key also work in the standard manner.
Tab and Shift-Tab are automatically implemented by the system, 
and skip the Label object and the Frame object when moving 
the focus.

This custom scheme based on the F12 key does not skip the 
Label object or the Frame object.

For simplicity, this program does not support response to
the keyboard while the component has the focus.  Such response
has been illustrated in earlier lessons and could be added 
with very little additional code.

A Button object, a TextField object, and a Label object are placed 
in a Frame object.

A FocusListener object is instantiated and registered to listen for
focusGained() and focusLost() events on the Frame and the
Label.  When these events occur, the listener object makes a color
change on the Frame or Label to provide a visual indication of focus
gained or lost.  

When the Label has the focus, its text is red.  Otherwise, its text 
is black.  When the Frame has the focus, its background color is blue.
Otherwise, it is white.

Note that the Button and the TextField components automatically provide 
a visual indication of focus without intervention by the programmer.

Also for simplicity, the ability to shift the focus to the Label and
the Frame using the mouse was not included in this program.  This
capability has been illustrated in an earlier lesson and could be added
with very little additional code required.

Note that the Button and the TextField automatically receive the
focus when clicked without intervention by the programmer.

A KeyListener object is instantiated and registered to listen for
keyPressed() events on the Frame, Label, Button, and TextField 
objects.  This object is used to listen for the F12 or Shift-F12
key and to implement the program-specified change in focus when
such a keypress occurs.

Finally, a WindowListener object is instantiated and registered to 
terminate the program when the user closes the Frame object.

This program retrieves and saves the component names that are 
automatically assigned to the visual components (under the assumption 
that the system will assign unique names) and uses those names to 
determine which component generated an event when such determination 
is necessary.

No attempt was made to synchronize this focus traversal method with
other capabilities to shift the focus.

These results were produced using JDK 1.1, Beta 3 running under 
Windows 95.
*/
//==========================================================================

import java.awt.*;
import java.awt.event.*;

public class Event16 {
  public static void main(String[] args){
    GUI gui = new GUI();//instantiate a Graphical User Interface object
  }//end main
}//end class Event16
//===========================================================================

//The following class is used to instantiate a graphical user interface object.
class GUI {
  String myTextFieldName; //save automatic component name here
  String myButtonName;
  String myFrameName;
  String myLabelName;
  Frame myFrame;//ref variable passed as parameter
  Label myLabel;
  TextField myTextField;
  Button myButton;
  int focusIndex;

  public GUI(){//constructor
    //Create several visual components
    myFrame = new Frame();
    myFrame.setSize(250,300);
    myFrame.setTitle("Copyright 1997, R.G.Baldwin");
    myFrameName = myFrame.getName();

    myButton = new Button("Button Object");
    myButtonName = myButton.getName();
    
    myTextField = new TextField("TextField Object");
    myTextFieldName = myTextField.getName();//save the name of the component

    myLabel = new Label("LabelObject");
    myLabelName = myLabel.getName();
    myLabel.setBackground(Color.yellow);//make it yellow so it will show up
  
    //Add the other objects to the frame using default border layout manager
    myFrame.add("North",myButton);
    myFrame.add("South",myTextField);
    myFrame.add("West",myLabel);
    
    myFrame.setVisible(true);//make the frame visible
    myTextField.requestFocus();//initialize the focus to the TextField
    focusIndex = 0;//set focusIndex to match

    //Instantiate and register a FocusListener object which will process
    // focus events on two different visual components.  In this case,
    // the listener object makes a color change on the visual component
    // to indicate focus gained or focus lost.
    myFocusListener focusHandler = new myFocusListener(this);
    myFrame.addFocusListener(focusHandler);  
    myLabel.addFocusListener(focusHandler);
    
    //Instantiate and register a KeyListener object which will process key
    // events on four different visual components.  This object causes the
    // focus to move in a program-defined manner when the user presses the
    // F12 key and to move in the reverse direction when the user presses
    // the Shift-F12 key.
    myKeyListener keyHandler = new myKeyListener(this);
    myFrame.addKeyListener(keyHandler);
    myTextField.addKeyListener(keyHandler);
    myButton.addKeyListener(keyHandler);
    myLabel.addKeyListener(keyHandler);    

    //Instantiate and register a WindowListener object which will terminate 
    // the program when the user closes the Frame object
    WProc1 winProcCmd1 = new WProc1();
    myFrame.addWindowListener(winProcCmd1);
  }//end constructor
}//end class GUI definition
//=======================================================================

//This is a low-level event listener class.
// This FocusListener class makes a color change on the component to 
// provide a visual indication of the gain or loss of focus.

class myFocusListener implements FocusListener{
  GUI thisObject;
  
  myFocusListener(GUI thisObjectIn){//constructor
    thisObject = thisObjectIn;
  }// end constructor
  
  public void focusGained(FocusEvent e){
    if( e.toString().indexOf("on " + thisObject.myFrameName) != -1 ){
      thisObject.myFrame.setBackground(Color.blue);
    }//end if
    if( e.toString().indexOf("on " + thisObject.myLabelName) != -1 ){
      thisObject.myLabel.setForeground(Color.red);
    }//end if
    thisObject.myFrame.repaint();
  }//end focusGained()

  public void focusLost(FocusEvent e){
    if( e.toString().indexOf("on " + thisObject.myFrameName) != -1 ){
      thisObject.myFrame.setBackground(Color.white);      
    }//end if       
    if( e.toString().indexOf("on " + thisObject.myLabelName) != -1 ){
      thisObject.myLabel.setForeground(Color.black);      
    }//end if       
    thisObject.myFrame.repaint();
  }//end focusLost()
}//end class myFocusListener
//=======================================================================

//This is a Low-Level event listener.
// This listener class implements a custom scheme for moving focus 
// among visual components when the user presses the F12 key or the 
// Shift-F12 key.  The F12 key moves the focus counter-clockwise on 
// the screen and includes the Label object and the Frame object in 
// the path.  Shift-F12 moves the focus in the reverse direction.

// The standard Tab and Shift-Tab keys work also but don't include 
// the Label object or the Frame object in the list of objects which 
// receive focus.

class myKeyListener extends KeyAdapter{
  GUI thisObject;
  
  myKeyListener(GUI thisObjectIn){//constructor
    thisObject = thisObjectIn;
  }//end constructor

  public void keyPressed(KeyEvent e){
    int keyCode = e.getKeyCode();
    if( (keyCode == KeyEvent.VK_F12) //if F12 and NOT Shift
          && (e.getModifiers() != InputEvent.SHIFT_MASK) ){
      //Move the focus counter-clockwise on the screen for F12 key
      if(++thisObject.focusIndex > 3) thisObject.focusIndex = 0;
      switch(thisObject.focusIndex){
        case 0: thisObject.myTextField.requestFocus(); break;
        case 1: thisObject.myLabel.requestFocus();break;
        case 2: thisObject.myButton.requestFocus();break;
        case 3: thisObject.myFrame.requestFocus();break;
      }//end switch statement
    }//end if statement

    if( (keyCode == KeyEvent.VK_F12) //if F12 AND Shift
          && (e.getModifiers() == InputEvent.SHIFT_MASK) ){
      //Move the focus clockwise on the screen for Shift-F12 key
      if(--thisObject.focusIndex < 0) thisObject.focusIndex = 3;
      switch(thisObject.focusIndex){
        case 0: thisObject.myTextField.requestFocus(); break;
        case 1: thisObject.myLabel.requestFocus();break;
        case 2: thisObject.myButton.requestFocus();break;
        case 3: thisObject.myFrame.requestFocus();break;
      }//end switch statement
    }//end if statement
  }//end keyPressed()
}//end class myKeyListener
//=======================================================================

//The following listener is used to terminate the 
// program when the user closes the Frame object.
class WProc1 extends WindowAdapter{
  public void windowClosing(WindowEvent e){
    System.exit(0);
  }//end windowClosing()
}//end class WProc1