在WP8.1中缩放图像

  <phone:PhoneApplicationPage
      x:Class="solution.FullScreenViewer"
      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
      xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
      FontFamily="{StaticResource PhoneFontFamilyNormal}"
      FontSize="{StaticResource PhoneFontSizeNormal}"
      Foreground="{StaticResource PhoneForegroundBrush}"
      SupportedOrientations="PortraitOrLandscape" Orientation="Portrait"
      mc:Ignorable="d"
      shell:SystemTray.IsVisible="True">

      <Image Name="img" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"Stretch="Uniform"/>
  </phone:PhoneApplicationPage>

  protected override void OnNavigatedTo(NavigationEventArgs e)
  {
      string context = this.NavigationContext.QueryString["context"];
      img.Source = new BitmapImage(new Uri(context, UriKind.RelativeOrAbsolute));
      base.OnNavigatedTo(e);
  }

代替你正在使用的图像，你可以使用一个网格，其中有另一个网格。在第二个网格上，使用Grid.RenderTransform通过缩放变换来调整其内容(网格内的图像)的大小。您可以使用ManipulationDelta事件来跟踪何时放大或缩小。

使用它，你可以放大图片，但这不是很好，因为你只聚焦在图像的左上角。为了避免这种情况，您可以通过在图像呈现转换标记中添加翻译转换来允许用户滚动图像。您可以在下面的代码中看到如何做到这一点:

<Grid x:Name="LayoutRoot" ManipulationDelta="LayoutRoot_ManipulationDelta">
    <Grid x:Name="ContentPanel">
        <Grid x:Name="imageGrid">
            <Grid.RenderTransform>
                <ScaleTransform x:Name="ImageTransform" />
            </Grid.RenderTransform>
            <Image x:Name="img" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" Stretch="Uniform" Source="/Resources/Logo/CTK .png"
                ManipulationDelta="img_ManipulationDelta"
                ManipulationCompleted="img_ManipulationCompleted">
                <Image.RenderTransform>
                    <TranslateTransform x:Name="PanTransform"/>
                </Image.RenderTransform>
                <Image.Resources>
                    <Storyboard x:Name="Pan">
                        <DoubleAnimation x:Name="PanAnimation"
                        Storyboard.TargetName="PanTransform"
                        Storyboard.TargetProperty="X" Duration="0:0:1">
                            <DoubleAnimation.EasingFunction>
                                <CircleEase EasingMode="EaseOut" />
                            </DoubleAnimation.EasingFunction>
                        </DoubleAnimation>
                    </Storyboard>
                </Image.Resources>
            </Image>
        </Grid>
    </Grid>
</Grid>

这是用于缩放和转换的c#代码:

    private void LayoutRoot_ManipulationDelta(object sender, System.Windows.Input.ManipulationDeltaEventArgs e)
    {
        if (e.DeltaManipulation.Scale.X > 0.0 && e.DeltaManipulation.Scale.Y > 0.0)
        {
            // Scale in the X direction
            double tmp = ImageTransform.ScaleX * ((e.DeltaManipulation.Scale.X + e.DeltaManipulation.Scale.Y) / 2);
            if (tmp < 1.0)
                tmp = 1.0;
            else if (tmp > 4.0)
                tmp = 4.0;
            ImageTransform.ScaleX = tmp;
            // Scale in the Y direction
            tmp = ImageTransform.ScaleY * ((e.DeltaManipulation.Scale.X + e.DeltaManipulation.Scale.Y) / 2);
            if (tmp < 1.0)
                tmp = 1.0;
            else if (tmp > 4.0)
                tmp = 4.0;
            ImageTransform.ScaleY = tmp;
        }
    }
    private void img_ManipulationDelta(object sender, System.Windows.Input.ManipulationDeltaEventArgs e)
    {
        // First make sure we're translating and not scaling (one finger vs. two)
        if (e.DeltaManipulation.Scale.X == 0.0 && e.DeltaManipulation.Scale.Y == 0.0)
        {
            Image photo = sender as Image;
            TranslateTransform transform = photo.RenderTransform as TranslateTransform;
            // Compute the new X component of the transform
            double x = transform.X + e.DeltaManipulation.Translation.X;
            double y = transform.Y + e.DeltaManipulation.Translation.Y;
            // Apply the computed value to the transform
            transform.X = x;
            transform.Y = y;
        }
    }
    private void img_ManipulationCompleted(object sender, System.Windows.Input.ManipulationCompletedEventArgs e)
    {
        if (e.IsInertial)
        {
            Image photo = sender as Image;
            // Compute the inertial distance to travel
            double dx = e.FinalVelocities.LinearVelocity.X / 10.0;
            double dy = e.FinalVelocities.LinearVelocity.Y / 10.0;
            TranslateTransform transform = photo.RenderTransform as TranslateTransform;
            double x = transform.X + dx;
            double y = transform.Y + dy;
            // Apply the computed value to the animation
            PanAnimation.To = x;
            // Trigger the animation
            Pan.Begin();
        }
    } 

您应该能够按照应用程序的规模缩放:

public static void ZoomToRatio(double ratio)
{
   ScaleTransform transform = new ScaleTransform()
   {
      ScaleX = ratio,
      ScaleY = ratio,
   };
   double height = 0.0;
   double width = 0.0;
   if (ratio < 1.0)
   {
      height = Application.Current.Host.Content.ActualHeight * ratio;
      width = Application.Current.Host.Content.ActualWidth * ratio;
   }
   else
   {
      height = Application.Current.Host.Content.ActualHeight / ratio;
      width = Application.Current.Host.Content.ActualWidth / ratio;          
   }
   Application.Current.RootVisual.SetValue(Canvas.HeightProperty, height);
   Application.Current.RootVisual.SetValue(Canvas.WidthProperty, width);
   Application.Current.RootVisual.RenderTransform = transform;
}