How can I programmatically find the scale, rotate, and translate values when using the MultiTouchBehavior in a Silverlight/WP7 app?

Okay, this may seem like a really silly question but I'm not quite used to the Silverlight realm yet. I'm working on a Silverlight / WP7 application that references the Multitouch.Behaviors.WP7 codeplex project (http://multitouch.codeplex.com/).

<Canvas x:Name="MyCanvas">
      <Image Source="Images/image.png"
           x:Name="MyImage" Width="120" 
           Canvas.Left="240" Canvas.Top="235">
            <i:Interaction.Behaviors>
                <tb:MultiTouchBehavior
        AreFingersVisible="True" 
        IsDebugModeActive="True" 
        IsMockActive="True" 
        IsRotateEnabled="True" 
        IsScaleEnabled="True" 
        IsTranslateXEnabled="True" 
        IsTranslateYEnabled="True" 
        MaximumScale="100"  
        MinimumScale="0.5"/&开发者_如何学运维gt;
       </i:Interaction.Behaviors>
  </Image>

Obviously, the user can drag the image around, rotate it, and scale it with the multitouch functionality. How can I access the values for how the image has been scaled/rotated/translated programatically?

The MultitouchBehavior uses a CompositeTransform as the RenderTransform for the object that it is associated with. So, you can use code similar to the following to access the transformed values:

var transform = this.MyImage.RenderTransform as CompositeTransform;
var currentScaleX = transform.ScaleX;
var angle = transform.Rotation;
var offsetX = transform.TranslateX;

You need to use Image.RenderTransform. See this post (particularly the GestureHelper section - http://timheuer.com/blog/archive/2010/09/16/silverlight-toolkit-for-windows-phone-7-released.aspx).

<Image x:Name="GesturedImage" Source="dividbyzero.jpg" 
       HorizontalAlignment="Center" VerticalAlignment="Center" 
       Width="450" RenderTransformOrigin="0.5,0.5">
    <Image.RenderTransform>
        <ScaleTransform x:Name="ImageScaling" ScaleX="1" ScaleY="1" />
    </Image.RenderTransform>
    <toolkit:GestureService.GestureListener>
        <toolkit:GestureListener PinchDelta="OnPinchDelta" />
  </toolkit:GestureService.GestureListener>
</Image>

And then use DistanceRatio to get the value for translation:

private void OnPinchDelta(object sender, PinchGestureEventArgs e)
{
   ImageScaling.ScaleX = e.DistanceRatio;
   ImageScaling.ScaleY = e.DistanceRatio;
}