C# 获取当前屏幕DPI

Graphics currentGraphics = Graphics.FromHwnd(new WindowInteropHelper(mainWindow).Handle);
double dpixRatio = currentGraphics.DpiX/96;

1     var source = PresentationSource.FromVisual(this);
2     if (source?.CompositionTarget != null)
3     {
4         var dpiX = source.CompositionTarget.TransformToDevice.M11;
5         Debug.WriteLine($"CompositionTargetRatio:{dpiX}");
6     }

1         [DllImport("user32.dll")]
2         private static extern uint GetDpiForWindow([In] IntPtr hmonitor);

1     var dpiForWindow = GetDpiForWindow(new WindowInteropHelper(this).Handle);
2     var windowRatio = (double)dpiForWindow / 96.0;
3     Debug.WriteLine($"windowRatio:{dpiRatioX}");

1     var monitor = MonitorFromWindow(new WindowInteropHelper(this).Handle, MonitorDefaultTo.MONITOR_DEFAULTTONEAREST);
2     uint dpiX, dpiY;
3     GetDpiForMonitor(monitor, DpiType.Effective, out dpiX, out dpiY);
4     var dpiRatioX = (double)dpiX / 96.0;

 1         [DllImport("user32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
 2         internal static extern IntPtr MonitorFromWindow(IntPtr hwnd, MonitorDefaultTo dwFlags);
 3         [DllImport("Shcore.dll")]
 4         private static extern IntPtr GetDpiForMonitor([In] IntPtr hmonitor, [In] DpiType dpiType, [Out] out uint dpiX, [Out] out uint dpiY);
 5         internal enum MonitorDefaultTo
 6         {
 7             MONITOR_DEFAULTTONULL,
 8             MONITOR_DEFAULTTOPRIMARY,
 9             MONITOR_DEFAULTTONEAREST,
10         }
11         public enum DpiType
12         {
13             Effective = 0,
14             Angular = 1,
15             Raw = 2,
16         }