silverlight - 在图像 wp7 上实现缩放

Question

我正在尝试使用像其他应用程序功能（即地图）一样的点击或捏合在我的 wp7 应用程序中启用图像的缩放功能。我看到的与此相关的大多数帖子都已经过时了，我想知道是否有更新的方法来实现这一目标？

Answer 1

不知道是否有更好的东西，但这是我正在做的事情：

<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;
    }

如果您想快速双击或重置大小，您还可以跟踪原始比例。

Answer 2

您需要使用比例变换。如果您有兴趣，我可以稍后再写一篇博文。对于捏缩放拖动轻弹等，您需要使用工具包中的手势服务

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;
    }