Recipe 9.20. Assigning Focus to a Text Field

Problem

You want to use ActionScript to bring focus to a text field.

Solution

Use the Stage.focus property.

Discussion

Use the Stage.focus property to programmatically assign focus to a specific text field. Every display object has a stage property that references the Stage instance. Therefore, from a class that extends a display object class (Sprite, MovieClip, etc.) the following code assigns focus to a text field called field:

stage.focus = field;

When an .swf first loads in a web browser, it does not have focus. Therefore, you must move focus to the Flash Player before you can programmatically assign focus to an element of the Flash application. The following is a working example that uses a sprite button to assign focus to a text field:

package {

  import flash.display.Sprite;
  import flash.text.TextField;
  import flash.text.TextFieldType;
  import flash.events.MouseEvent;

  public class TextExample extends Sprite {

    public function TextExample(  ) {
      var field:TextField = new TextField(  );
      field.border = true;
      field.background = true;
      field.type = TextFieldType.INPUT;
      addChild(field);
      var button:Sprite = new Sprite(  );
      button.graphics.lineStyle(  );
      button.graphics.beginFill(0xFFFFFF);
      button.graphics.drawRect(0, 0, 100, 50);
      button.graphics.endFill(  );
      button.addEventListener(MouseEvent.CLICK, onClick);
      button.y = 100;
      addChild(button);
    }
    
    private function onClick(event:MouseEvent):void {
      stage.focus = TextField(getChildAt(0));
    }
    
  }
}

To remove focus from a text field you should assign Stage.focus the null value:

stage.focus = null;