ActionScript 3.0 Design Patterns.pdf - VideoTutorials-bg.com

Example 7-19. InvokerKeyboard.as (continued)
}
}
public function InvokerKeyboard(stageTarget:Stage)
{
this.commandList = new Array( );
this.keyList = new Array( );
stageTarget.addEventListener(KeyboardEvent.KEY_DOWN,
this.onKeyPress);
}
public function setCommand(keycode:int, c:ICommand):void
{
this.keyList.push(keycode);
this.commandList.push(c);
}
private function onKeyPress(event:KeyboardEvent)
{
for (var i:int = 0; i < keyList.length; i++)
{
if (keyList[i] === event.keyCode)
{
this.commandList[i].execute( );
break;
}
}
}
Sharing Command Objects from the Client
Now that the keyboard invoker has been implemented, we can add the following at
the end of the client code shown in Example 7-18. This creates a new
InvokerKeyboard instance, and assigns the same command objects to it that were
used for the InvokerPanel.
var kb:InvokerKeyboard = new InvokerKeyboard(this.stage);
// add commands to keyboard shortcut invoker
kb.setCommand(Keyboard.RIGHT, incCommand);
kb.setCommand(Keyboard.LEFT, decCommand);
kb.setCommand(Keyboard.NUMPAD_ADD, incCommand);
kb.setCommand(Keyboard.NUMPAD_SUBTRACT, decCommand);
The keyboard right arrow key and the plus key on the numeric keypad should perform
the increment command. Conversely, the left arrow key and negative key on
the numeric keypad should perform the decrement command.
Command sharing is a powerful feature of the command pattern and makes extending
applications much easier to manage. For example, if we decide to use a different
receiver, we just need to pass an instance of the new receiver when creating the command
object. Because the same command object is used in multiple invokers, the
Extended Example: Sharing Command Objects | 265