jj2000.disp
Class ImgKeyListener

java.lang.Object
  |
  +--java.awt.event.KeyAdapter
        |
        +--jj2000.disp.ImgKeyListener

All Implemented Interfaces:

java.util.EventListener, java.awt.event.KeyListener

public class ImgKeyListener

extends java.awt.event.KeyAdapter

This class implements the listener for keyboard events for the JJ2000 decoder that displays in a ImgScrollPane.

The following key sequences are defined:
- : scroll image up
- : scroll image down
- : scroll image left
- : scroll image right
- : scroll image up by a vertical block increment
- : scroll image down by a vertical block increment
- 'Q' or 'q': exit the application
- '-': zoom out by 2
- '=' or '+': zoom in by 2
- '1': display at a zoom of 1
- 'Ctrl-C': exit the application

The amount by which the arrows scroll the image is determined by the modifier keys. If the Ctrl key is held down, the block increment will be used, otherwise the unit increment will. If the Shift key is held down then the increment is multiplied by ACCEL_FACTOR. That is the Ctrl key selects between unit and block increments, while the Shift key selects between normal and accelerated mode.

Field Summary

static int	ACCEL_FACTOR The acceleration factor when the shift key is pressed: 10
(package private) Decoder	dec Decoder instance
(package private) java.awt.Frame	helpFrame Frame used to display tools
(package private) ImgScrollPane	isp The component where the image is displayed

Constructor Summary

ImgKeyListener(ImgScrollPane isp, Decoder dec)
Instantiate a new ImgKeyListener that will work on the specified ImgScrollPane.

Method Summary

private int	calcIncrement(java.awt.event.KeyEvent evt, java.awt.Adjustable adj) Returns the increment based on the modifier keys of the KeyEvent.
private static java.awt.TextArea	getHelp() Create a help TextArea concerning the tools associated with keys.
void	keyPressed(java.awt.event.KeyEvent evt) Hanldes the keyPressed events.
void	keyTyped(java.awt.event.KeyEvent evt) Handles the key typed event.

Methods inherited from class java.awt.event.KeyAdapter

keyReleased

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

helpFrame

java.awt.Frame helpFrame

Frame used to display tools

isp

ImgScrollPane isp

The component where the image is displayed

dec

Decoder dec

Decoder instance

ACCEL_FACTOR

public static final int ACCEL_FACTOR

The acceleration factor when the shift key is pressed: 10

See Also:

Constant Field Values

Constructor Detail

ImgKeyListener

public ImgKeyListener(ImgScrollPane isp,
                      Decoder dec)

Instantiate a new ImgKeyListener that will work on the specified ImgScrollPane.

Parameters:

isp - The image scroll pane on which the actions should operate.

dec - The decoder instance

Method Detail

keyPressed

public void keyPressed(java.awt.event.KeyEvent evt)

Hanldes the keyPressed events. Normal keys are not treated here because some don't have a defined keycode (as incredible as it might seem!).

Specified by:

keyPressed in interface java.awt.event.KeyListener

Overrides:

keyPressed in class java.awt.event.KeyAdapter

Parameters:

evt - The key event to process.

keyTyped

public void keyTyped(java.awt.event.KeyEvent evt)

Handles the key typed event. Normal (i.e. "text") keys are handled here.

Specified by:

keyTyped in interface java.awt.event.KeyListener

Overrides:

keyTyped in class java.awt.event.KeyAdapter

Parameters:

evt - The key event to process.

calcIncrement

private int calcIncrement(java.awt.event.KeyEvent evt,
                          java.awt.Adjustable adj)

Returns the increment based on the modifier keys of the KeyEvent. If control is down then the Adjustable block increment is used, otherwise the unit one is used. If the shift key is down the increment is multiplied by ACCEL_FACTOR.

Parameters:

evt - The KeyEvent fom where to obtain the modifiers

adj - The Adjustable from where to obtain the increments

getHelp

private static java.awt.TextArea getHelp()

Create a help TextArea concerning the tools associated with keys.

Returns:

The help TextArea