Question

I am going to create an application in that i have to implement an Undo and Redo feature.
In the application there will be multiple objects located on stage and user can customize
the position of the objects. But when user clicks on Undo the object go back to their default
position and after clicking on redo object will move on the new position.

So my question is how can i apply these feature in my application?
Is there any library or any third party classes?

Can some one help me?

Thanks in advance.

Answer 1

 package com
 {
    import flashx.undo.IOperation;

    public class UndoOperation implements IOperation
    {

    private var _previousX:Number = 0;
    private var _previousY:Number = 0;
    private var _previousObj:Object = new Object();
    private var _currentX:Number = 0;
    private var _currentY:Number = 0;
    private var _currentObj:Object = new Object();
    private var _shape:Object = new Object();


    public function TransformOperation(currentObj:Object,previousObj:Object,previousX:Number, previousY:Number, currentX:Number, currentY:Number)
    {
        _previousX = previousX;
        _previousY = previousY;
        _previousObj = previousObj;

        _currentX = currentX;
        _currentY = currentY;
        _currentObj = currentObj;
        _shape = _currentObj;

        trace('Transform _previousX:  '+  _previousX  +' _previousY:  ' +_previousY+' _currentObj '+_currentObj+' _shape '+_shape);
        trace( 'trans _currentX    '+ _currentX +'  '+'_currentY     '+ _currentY );

    }

    public function performUndo():void
    {
        _shape = _currentObj;
        //trace('_shape.x '+_shape.x+" _shape.y "+_shape.y);
        _shape.x = _previousX;
        _shape.y = _previousY;
        //trace(_previousX +'  '+ _previousY +'  '+ _previousWidth +'  '+ _previousHeight +'  '+  _previousScaleX +'  '+  _previousScaleY +'  '+ _previousRotation);
        //trace('_shape.x '+_shape.x+" _shape.y "+_shape.y);
        //trace('_currentX    '+ _currentX +'  '+'_currentY     '+ _currentY);
    }

    public function performRedo():void
    {
        _shape.x = _currentX;
        _shape.y = _currentY;
        trace(_currentX+'  '+ _currentY);
    }
  }
}

This is my customize class afor undo and redo multiple objects on stage. There is different pattern which can be used for the undo and redo operation but for me this is the simple way for undo and redo. I have perfectly and successfully implement this in my project.

To Use this class only import the class

                 import flashx.undo.UndoManager;

and after that

            public static var _undo:UndoManager=new UndoManager();
            public static var _redo:UndoManager=new UndoManager();     
            public static var PrevX:Number=0;
            public static var PrevY:Number=0;
            var operation:TransformOperation = new TransformOperation(this,this,PrevX,PrevY,this.x,this.y);
           _undo.pushUndo(operation);

After that create click event for undo and redo:

    public static function Undo(e:MouseEvent):void
    {
        _redo.pushRedo(_undo.peekUndo());
        _undo.undo();
        if(_undo.peekUndo()==null)
        {
            PlayerPosition.getClass.getChildByName("toolbar_mc").getChildByName("undo_mc").removeEventListener(MouseEvent.CLICK,Undo);
        }
        PlayerPosition.getClass.getChildByName("toolbar_mc").getChildByName("redo_mc").addEventListener(MouseEvent.CLICK,Redo);
    }

    public static function Redo(e:MouseEvent):void
    {
        _undo.pushUndo(_redo.peekRedo());
        _redo.redo();
        if(_redo.peekRedo()==null)
        {                          PlayerPosition.getClass.getChildByName("toolbar_mc").getChildByName("redo_mc").removeEventListener(MouseEvent.CLICK,Redo);
        }
        PlayerPosition.getClass.getChildByName("toolbar_mc").getChildByName("undo_mc").addEventListener(MouseEvent.CLICK,Undo);
    }

For me this works fine… Hope this helps others too…:)