在图像wp7上实现缩放

Question

I am trying to enable zoom capabilities on an image in my wp7 app using either tap or pinch like other app features,ie,map. Most of the posts i've seen relating to this are a it old and am wondering if there is a more recent way to achieve this??

Answer 1

don't know if there is something better, but here is what I'm doing:

<Image Name="displayImage" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Source="{Binding photo_link}" RenderTransformOrigin="0.5, 0.5" CacheMode="BitmapCache">
      <Image.RenderTransform>
            <CompositeTransform x:Name="transform" />
      </Image.RenderTransform>
      <toolkit:GestureService.GestureListener>
             <toolkit:GestureListener PinchDelta="OnPinchDelta" PinchStarted="OnPinchStarted" />
      </toolkit:GestureService.GestureListener>
 </Image>



    private void OnPinchStarted(object sender, PinchStartedGestureEventArgs e)
    {
        var image = sender as System.Windows.Controls.Image;
        if (image == null) return;
        var transform = image.RenderTransform as CompositeTransform;
        if (transform == null) return;
        initialScale = transform.ScaleX;
    }

    private void OnPinchDelta(object sender, PinchGestureEventArgs e)
    {
        var image = sender as System.Windows.Controls.Image;
        if (image == null) return;
        var transform = image.RenderTransform as CompositeTransform;
        if (transform == null) return;

        transform.ScaleX = initialScale * e.DistanceRatio;
        transform.ScaleY = initialScale * e.DistanceRatio;
    }

You can also keep track of the original scale if you want to do a quick double-tap or something to reset the size.

Answer 2

You need to use scale transform.. I can do a blogpost later on if you are interested.for pinch zoom drag flick etc you need to use gesture service from toolkit

private void GestureListener_DragDelta(object sender, DragDeltaGestureEventArgs e)
    {
        scaleTrans.CenterX = (scaleTrans.CenterX - e.HorizontalChange);
        scaleTrans.CenterY = (scaleTrans.CenterY - e.VerticalChange);

        if (scaleTrans.CenterX < 0)
            scaleTrans.CenterX = 0;
        else if (scaleTrans.CenterX > (imgViewer.Height * scaleTrans.ScaleX))
            scaleTrans.CenterX = imgViewer.Height * scaleTrans.ScaleX;

        if(scaleTrans.CenterY < 0)
            scaleTrans.CenterY = 0;
        else if (scaleTrans.CenterY > (imgViewer.Height * scaleTrans.ScaleY))
            scaleTrans.CenterY = imgViewer.Height * scaleTrans.ScaleY;
    }