wpf bind属性在高dpi中调整bmp的大小

在XBAP WPF应用程序中，必须在多个用户的dpi设置下显示位图图像-而不是矢量，我想在启动时设置一个dpiFactor全局变量，该变量将以原始bitmSizeap的百分比计算：

i、 对于120 dpi，我希望图像的两个大小都是：newSize=originalSize*（100-（120-96））/100 也就是说，如果dpi为原始值的125%，则乘以75%

必须在启动时定义dpiFactor，然后在启动页面时缩小（或增大）所有测量。

---

我如何在XAML中用绑定属性表示呢

也许您可以使用如下所示的转换器：

  [ValueConversion(typeof(string), typeof(BitmapImage))]
  public class ImageConverter : IValueConverter
  {
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
      string imageSource = value as string;
      if (imageSource == null)
        return DependencyProperty.UnsetValue;

      try
      {
        BitmapImage originalImage = new BitmapImage(new Uri(imageSource));
        int originalWidth = originalImage.PixelWidth;
        int originalHeight = originalImage.PixelHeight;

        double originalDpiX = originalImage.DpiX;
        double originalDpiY = originalImage.DpiY;

        BitmapImage scaledImage = new BitmapImage();
        scaledImage.BeginInit();
        scaledImage.DecodePixelWidth = originalWidth; // Place your calculation here,
        scaledImage.DecodePixelHeight = originalHeight; // and here.
        scaledImage.UriSource = new Uri(imageSource);
        scaledImage.EndInit();
        scaledImage.Freeze();

        return scaledImage;
      }
      catch
      {
      }
      return new BitmapImage();
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
      throw new NotImplementedException();
    }
  }

<Window x:Class="Test.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:test="clr-namespace:Test">
  <Window.Resources>
    <test:ImageConverter x:Key="imageConverter" />
  </Window.Resources>
  <Image Source="{Binding SomePath, Converter={StaticResource imageConverter}}" />
</Window>

在xaml中，这将如下所示：

  [ValueConversion(typeof(string), typeof(BitmapImage))]
  public class ImageConverter : IValueConverter
  {
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
      string imageSource = value as string;
      if (imageSource == null)
        return DependencyProperty.UnsetValue;

      try
      {
        BitmapImage originalImage = new BitmapImage(new Uri(imageSource));
        int originalWidth = originalImage.PixelWidth;
        int originalHeight = originalImage.PixelHeight;

        double originalDpiX = originalImage.DpiX;
        double originalDpiY = originalImage.DpiY;

        BitmapImage scaledImage = new BitmapImage();
        scaledImage.BeginInit();
        scaledImage.DecodePixelWidth = originalWidth; // Place your calculation here,
        scaledImage.DecodePixelHeight = originalHeight; // and here.
        scaledImage.UriSource = new Uri(imageSource);
        scaledImage.EndInit();
        scaledImage.Freeze();

        return scaledImage;
      }
      catch
      {
      }
      return new BitmapImage();
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
      throw new NotImplementedException();
    }
  }

<Window x:Class="Test.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:test="clr-namespace:Test">
  <Window.Resources>
    <test:ImageConverter x:Key="imageConverter" />
  </Window.Resources>
  <Image Source="{Binding SomePath, Converter={StaticResource imageConverter}}" />
</Window>

要获得系统的dpi，我认为可以使用代码