c# - 双指缩放大图像？

Question

我在 http://forums.create.msdn.com 找到了这个双指缩放示例

这是 xaml:

<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0"> 
            <StackPanel> 
                <TextBlock Text="Tap to center" Style="{StaticResource PhoneTextNormalStyle}"/> 
                <TextBlock Text="Tap and hold to reset" Style="{StaticResource PhoneTextNormalStyle}"/> 
                <TextBlock Text="Touch and move to drag" Style="{StaticResource PhoneTextNormalStyle}"/> 
                <TextBlock Text="Pinch (touch with two fingers) to scale and rotate" Style="{StaticResource PhoneTextNormalStyle}" TextWrapping="Wrap"/> 
                <TextBlock Text="Flick (drag and release the touch while still moving) will show flick data on bottom of screen." Style="{StaticResource PhoneTextNormalStyle}" TextWrapping="Wrap"/> 
            </StackPanel> 
            <TextBlock x:Name="flickData" Text="Flick:" Style="{StaticResource PhoneTextNormalStyle}" VerticalAlignment="Bottom"/> 
            <Image x:Name="image" Source="/map.jpg" RenderTransformOrigin="0.5,0.5" CacheMode="BitmapCache"> 
                <Image.RenderTransform> 
                    <CompositeTransform x:Name="transform"/> 
                </Image.RenderTransform> 
                <toolkit:GestureService.GestureListener> 
                    <toolkit:GestureListener  
                        Tap="OnTap" Hold="OnHold" 
                        DragStarted="OnDragStarted" DragDelta="OnDragDelta" DragCompleted="OnDragCompleted" 
                        Flick="OnFlick" 
                        PinchStarted="OnPinchStarted" PinchDelta="OnPinchDelta" PinchCompleted="OnPinchCompleted"/> 
                </toolkit:GestureService.GestureListener> 
            </Image> 
        </Grid> 

和cs源:

public partial class GestureSample : PhoneApplicationPage 
    { 
        double initialAngle; 
        double initialScale; 

        public GestureSample() 
        { 
            InitializeComponent(); 
        } 

        private void OnTap(object sender, GestureEventArgs e) 
        { 
            transform.TranslateX = transform.TranslateY = 0; 
        } 

        private void OnDoubleTap(object sender, GestureEventArgs e) 
        { 
            transform.ScaleX = transform.ScaleY = 1; 
        } 

        private void OnHold(object sender, GestureEventArgs e) 
        { 
            transform.TranslateX = transform.TranslateY = 0; 
            transform.ScaleX = transform.ScaleY = 1; 
            transform.Rotation = 0; 
        } 

        private void OnDragStarted(object sender, DragStartedGestureEventArgs e) 
        { 
            image.Opacity = 0.3; 
        } 

        private void OnDragDelta(object sender, DragDeltaGestureEventArgs e) 
        { 
            transform.TranslateX += e.HorizontalChange; 
            transform.TranslateY += e.VerticalChange; 
        } 

        private void OnDragCompleted(object sender, DragCompletedGestureEventArgs e) 
        { 
            image.Opacity = 1.0; 
        } 

        private void OnPinchStarted(object sender, PinchStartedGestureEventArgs e) 
        { 
            Point point0 = e.GetPosition(image, 0); 
            Point point1 = e.GetPosition(image, 1); 
            Point midpoint = new Point((point0.X + point1.X) / 2, (point0.Y + point1.Y) / 2); 
            image.RenderTransformOrigin = new Point(midpoint.X / image.ActualWidth, midpoint.Y / image.ActualHeight); 
            initialAngle = transform.Rotation; 
            initialScale = transform.ScaleX; 
            image.Opacity = 0.8; 
        } 

        private void OnPinchDelta(object sender, PinchGestureEventArgs e) 
        { 
            transform.Rotation = initialAngle + e.TotalAngleDelta; 
            transform.ScaleX = transform.ScaleY = initialScale * e.DistanceRatio; 
        } 

        private void OnPinchCompleted(object sender, PinchGestureEventArgs e) 
        { 
            image.Opacity = 1.0; 
        } 

        private void OnFlick(object sender, FlickGestureEventArgs e) 
        { 
            flickData.Text = string.Format("{0} Flick: Angle {1} Velocity {2},{3}", 
                e.Direction, Math.Round(e.Angle), e.HorizontalVelocity, e.VerticalVelocity); 
        } 
    }

它适用于小图像(小于 2000x2000 像素)。但在我的示例中，我有这张巨大的地铁 map ( http://www.vasttrafik.se/upload/Linjekartor_hogupplost/Goteborg2010/Linjen%C3%A4tskarta-101212.png 或矢量 http://www.vasttrafik.se/upload/Linjekartor_hogupplost/Goteborg2010/Linjen%C3%A4tskarta-101212.pdf )。如果用户可以缩放矢量图像就更好了，但即使导入这么大的矢量也是一个严重的性能问题。

也许我可以将图像分成几个“多尺度图像”并使用这个 http://dotnetbyexample.blogspot.com/2010/08/windows-phone-7-multi-touch-panzoom.html , 但我真的不知道如何使用他的类(class):(

有什么想法吗？你们会如何解决这个问题？

谢谢

理查德

Answer 1

您的解决方案的理想方法是使用 MultiScaleImage，它专门设计用于显示大型图像数据。但是，为了使用 MultiScaleImage，您需要以正确的格式准备图像数据。基本上，您需要对图像进行切片和重新缩放等操作，以便用户在放大和缩小图像时加载尽可能少的信息。

DeepZoom documentation描述了该过程并包含指向您用来准备图像数据的 DeepZoom Composer 工具的链接。

一旦您使 MultiScaleImage 方法发挥作用，您就可以考虑使用 Laurent 的多点触控行为(如有必要)来提供额外的用户交互。