मैं डब्ल्यूपीएफ में डीपीआई कैसे प्राप्त कर सकता हूं?

Question

मैं WPF में डीपीआई कैसे प्राप्त कर सकता हूं?

Answer 1

http://blogs.msdn.com/jaimer/archive/2007/03/07/getting-system-dpi-in-wpf-app.aspx

PresentationSource source = PresentationSource.FromVisual(this); 

double dpiX, dpiY; 
if (source != null) { 
    dpiX = 96.0 * source.CompositionTarget.TransformToDevice.M11; 
    dpiY = 96.0 * source.CompositionTarget.TransformToDevice.M22; 
} 

Answer 2

var dpiXProperty = typeof(SystemParameters).GetProperty("DpiX", BindingFlags.NonPublic | BindingFlags.Static); 
var dpiYProperty = typeof(SystemParameters).GetProperty("Dpi", BindingFlags.NonPublic | BindingFlags.Static); 

var dpiX = (int)dpiXProperty.GetValue(null, null); 
var dpiY = (int)dpiYProperty.GetValue(null, null); 

Answer 3

काम करने के लिए मैं "असली" मॉनिटर डीपीआई निम्नलिखित है पाने के लिए मिल गया एक ही रास्ता लगता है। अन्य सभी उल्लिखित तकनीकें केवल 96 कहती हैं जो अधिकांश मॉनीटर के लिए सही नहीं है।

public class ScreenInformations 
{ 
    public static uint RawDpi { get; private set; } 

    static ScreenInformations() 
    { 
     uint dpiX; 
     uint dpiY; 
     GetDpi(DpiType.RAW, out dpiX, out dpiY); 
     RawDpi = dpiX; 
    } 

    /// <summary> 
    /// Returns the scaling of the given screen. 
    /// </summary> 
    /// <param name="dpiType">The type of dpi that should be given back..</param> 
    /// <param name="dpiX">Gives the horizontal scaling back (in dpi).</param> 
    /// <param name="dpiY">Gives the vertical scaling back (in dpi).</param> 
    private static void GetDpi(DpiType dpiType, out uint dpiX, out uint dpiY) 
    { 
     var point = new System.Drawing.Point(1, 1); 
     var hmonitor = MonitorFromPoint(point, _MONITOR_DEFAULTTONEAREST); 

     switch (GetDpiForMonitor(hmonitor, dpiType, out dpiX, out dpiY).ToInt32()) 
     { 
      case _S_OK: return; 
      case _E_INVALIDARG: 
       throw new ArgumentException("Unknown error. See https://msdn.microsoft.com/en-us/library/windows/desktop/dn280510.aspx for more information."); 
      default: 
       throw new COMException("Unknown error. See https://msdn.microsoft.com/en-us/library/windows/desktop/dn280510.aspx for more information."); 
     } 
    } 

    //https://msdn.microsoft.com/en-us/library/windows/desktop/dd145062.aspx 
    [DllImport("User32.dll")] 
    private static extern IntPtr MonitorFromPoint([In]System.Drawing.Point pt, [In]uint dwFlags); 

    //https://msdn.microsoft.com/en-us/library/windows/desktop/dn280510.aspx 
    [DllImport("Shcore.dll")] 
    private static extern IntPtr GetDpiForMonitor([In]IntPtr hmonitor, [In]DpiType dpiType, [Out]out uint dpiX, [Out]out uint dpiY); 

    const int _S_OK = 0; 
    const int _MONITOR_DEFAULTTONEAREST = 2; 
    const int _E_INVALIDARG = -2147024809; 
} 

/// <summary> 
/// Represents the different types of scaling. 
/// </summary> 
/// <seealso cref="https://msdn.microsoft.com/en-us/library/windows/desktop/dn280511.aspx"/> 
public enum DpiType 
{ 
    EFFECTIVE = 0, 
    ANGULAR = 1, 
    RAW = 2, 
} 

Answer 4

यहाँ एक विधि है कि Direct2D प्रौद्योगिकी (SP2 और उच्च और सर्वर के साथ Windows Vista पर समर्थित) पर निर्भर करता है, इसलिए यह WPF (जो इसी आधार पर आधारित है) में ठीक काम करता है। यह ID2D1Factory::GetDesktopDpi method

public static class DpiUtilities 
    { 
     private static Lazy<Tuple<float, float>> _dpi = new Lazy<Tuple<float, float>>(ReadDpi); 

     public static float DesktopDpiX 
     { 
      get 
      { 
       return _dpi.Value.Item1; 
      } 
     } 

     public static float DesktopDpiY 
     { 
      get 
      { 
       return _dpi.Value.Item2; 
      } 
     } 

     public static void Reload() 
     { 
      ID2D1Factory factory; 
      int hr = D2D1CreateFactory(D2D1_FACTORY_TYPE.D2D1_FACTORY_TYPE_SINGLE_THREADED, typeof(ID2D1Factory).GUID, IntPtr.Zero, out factory); 
      if (hr != 0) 
       Marshal.ThrowExceptionForHR(hr); 

      factory.ReloadSystemMetrics(); 
      Marshal.ReleaseComObject(factory); 
     } 

     private static Tuple<float, float> ReadDpi() 
     { 
      ID2D1Factory factory; 
      int hr = D2D1CreateFactory(D2D1_FACTORY_TYPE.D2D1_FACTORY_TYPE_SINGLE_THREADED, typeof(ID2D1Factory).GUID, IntPtr.Zero, out factory); 
      if (hr != 0) 
       Marshal.ThrowExceptionForHR(hr); 

      float x; 
      float y; 
      factory.GetDesktopDpi(out x, out y); 
      Marshal.ReleaseComObject(factory); 
      return new Tuple<float, float>(x, y); 
     } 

     [DllImport("d2d1.dll")] 
     private static extern int D2D1CreateFactory(D2D1_FACTORY_TYPE factoryType, [MarshalAs(UnmanagedType.LPStruct)] Guid riid, IntPtr pFactoryOptions, out ID2D1Factory ppIFactory); 

     private enum D2D1_FACTORY_TYPE 
     { 
      D2D1_FACTORY_TYPE_SINGLE_THREADED = 0, 
      D2D1_FACTORY_TYPE_MULTI_THREADED = 1, 
     } 

     [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)] 
     [Guid("06152247-6f50-465a-9245-118bfd3b6007")] 
     private interface ID2D1Factory 
     { 
      int ReloadSystemMetrics(); 

      [PreserveSig] 
      void GetDesktopDpi(out float dpiX, out float dpiY); 

      // the rest is not implemented as we don't need it 
     } 
    } 

Answer 5

का उपयोग करता है के साथ नेट 4.6.2 पूर्वावलोकन और उसके बाद वाले VisualTreeHelper.GetDpi(Visual visual) कॉल कर सकते हैं। यह DpiScale संरचना देता है, जो आपको डीपीआई बताता है जिस पर दिया गया Visual दिया जाएगा या प्रस्तुत किया जाएगा।