Merge branch 'dev' into 0.0.0.3

Author: yanjinhuagood

src/WPFDevelopers.Shared/Controls/ScreenCut/ScreenCut.cs

@@ -36,16 +36,25 @@ public static class ScreenExtensions
     {
         public static void GetDpi(this Screen screen, DpiType dpiType, out uint dpiX, out uint dpiY)
         {
-            if (!OSVersionHelper.IsWindows8OrLater())
-            {
-                dpiX = 96;
-                dpiY = 96;
+            dpiX = 96;
+            dpiY = 96;
+            if (!CanUsePerMonitorDpi())
                 return;
-            }
             var pnt = new System.Drawing.Point(screen.Bounds.Left + 1, screen.Bounds.Top + 1);
             var mon = MonitorFromPoint(pnt, 2);
             GetDpiForMonitor(mon, dpiType, out dpiX, out dpiY);
         }
+
+        public static bool CanUsePerMonitorDpi()
+        {
+            IntPtr hModule = Win32.LoadLibrary("shcore.dll");
+            if (hModule == IntPtr.Zero)
+                return false;
+            IntPtr procAddr = Win32.GetProcAddress(hModule, "GetDpiForMonitor");
+            Win32.FreeLibrary(hModule);
+            return procAddr != IntPtr.Zero;
+        }
+
         [DllImport(Win32.User32)]
         private static extern IntPtr MonitorFromPoint([In] System.Drawing.Point pt, [In] uint dwFlags);
         [DllImport(Win32.Shcore)]

src/WPFDevelopers.Shared/Core/Helpers/OSVersionHelper.cs

@@ -87,12 +87,6 @@ private static int GetWindowsBuildNumber()
             return 0;
         }
 
-        public static bool IsWindows8OrLater()
-        {
-            return Environment.OSVersion.Version.Major >= 6 &&
-                   Environment.OSVersion.Version.Minor >= 3;
-        }
-
         public static bool IsWindows10OrLater()
         {
             using (RegistryKey key = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion"))

src/WPFDevelopers.Shared/Core/Helpers/Win32.cs

@@ -209,6 +209,15 @@ public struct RECT
             public int Right;
             public int Bottom;
         }
+
+        [DllImport(Kernel32)]
+        public static extern IntPtr LoadLibrary(string lpFileName);
+
+        [DllImport(Kernel32)]
+        public static extern IntPtr GetProcAddress(IntPtr hModule, string procName);
+
+        [DllImport(Kernel32)]
+        public static extern bool FreeLibrary(IntPtr hModule);
     }
 
     internal class WindowsMessageCodes