ZoomOut and ZoomIn Images in Windows Phone 7 using double tap

I m doi开发者_如何学JAVAng ZoomOut of an image using the following code.

private void OnDoubleTap(object sender, Microsoft.Phone.Controls.GestureEventArgs e)
{
           scale.ScaleX += <some value>
           scale.ScaleY += <some value>
}

I want to achieve the following thing. When I double tap for the first time on the image it should ZoomIn and when I double tap for the second time on the image it should come back to normal size. Any idea how to achieve it . Please let me know your suggestions.

Thanks, Mugu

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Assuming your OnDoubleTap works, and normal scale is 1.

private void OnDoubleTap(object sender, Microsoft.Phone.Controls.GestureEventArgs e)
{
 if(scale.ScaleX == 1 && scale.ScaleY == 1) //The scale is currently 1, enlarge
 {
   scale.ScaleX = 1.5;
   scale.ScaleY = 1.5;
 } else { //Its bigger, reset to 1.
   scale.ScaleX = 1;
   scale.ScaleY = 1;
 } 
}