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Flex KeyboardEvent properties

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In this example working of properties charCode and keyCode of KeyboardEvent class under flash.events package is demonstrated.

Flex KeyboardEvent properties

     

In this example working of properties charCode and keyCode of KeyboardEvent class under flash.events package is demonstrated.
These properties generate numeric values whenever a key is pressed. With these values generated, the key pressed can be detected.
Before using these properties, the event listeners and event handlers for the keyboard event have to be created and applied first. Now, in the example listeners are created on the flex TextArea control, therefore whenever a key is pressed inside this control the listener of the event will be triggered.
Now, an event handler with name eventInfo  is created and inside which the statements containing properties charCode and keyCode are coded.

Property charCode generates the ASCII character set value for the value associated with the key. Here the key value is the alphabet value that the key holds.
For example : charCode of 'a' will be different to the charCode of 'A'.
 

Property keyCode generates the numeric value of the key on the keyboard. This value is unique for each key on the keyboard. 
For example : There are two keys on the keyboard to write a number three (3).  Now the charCode generated value of the keys will match but the keyCode generated value will differ because both the keys possess same values but are located at different places on the keyboard.

Key.mxml

<?xml version = '1.0' encoding = 'utf-8'?>
<mx:Application xmlns:mx = 'http://www.adobe.com/2006/mxml' 
  initialize = 'eventListener_1();'>
  <mx:Script> 
  
  import mx.controls.*;
  
  public function eventListener_1():void{
  tA.addEventListener(KeyboardEvent.KEY_UP, eventInfo);
  tA.addEventListener(KeyboardEvent.KEY_DOWN, eventInfo);
  }
  
  
  public function eventInfo(event:KeyboardEvent):void{
  var str:String = "Key code : " + event.keyCode +
 "\nChar code : " + event.charCode;
  tx.text = str;
  }  
  
  public function alert(event:Event):void{
  Alert.show("Event result\n" + tx.text);
  }  
  
  </mx:Script> 
  
  <mx:Style>
  .rachel {color : #996600}
  TextArea {font-size : 18pt}
  </mx:Style>
  
  <mx:Panel title = 'Rachel Weisz' backgroundColor = '#FFCC99
  paddingTop = '50' paddingBottom = '50' 
  paddingRight = '50' paddingLeft = '50'> 
  
  <mx:Button label = 'Click me' click = 'alert(event)
  color = '#6600CC' styleName = 'rachel'/>
  
  <mx:TextArea id = 'tA' styleName = 'rachel'/>
  <mx:Text id = 'tx' color = '#003333'/>
  
  </mx:Panel> 

</mx:Application>

 

Key.swf

 

Download the code

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Posted on: June 11, 2009

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