From 2c27fba92296ff54bde425fb7d3bd1baa844eb86 Mon Sep 17 00:00:00 2001
From: Yimeng Wu <me@kinnara.cn>
Date: Wed, 29 Jul 2020 00:29:58 +0800
Subject: [PATCH] OS version check without requiring app.manifest

---
 ModernWpf/Helpers/ColorsHelper.cs    |  7 +++---
 ModernWpf/Helpers/OSVersionHelper.cs | 35 ++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 4 deletions(-)
 create mode 100644 ModernWpf/Helpers/OSVersionHelper.cs

diff --git a/ModernWpf/Helpers/ColorsHelper.cs b/ModernWpf/Helpers/ColorsHelper.cs
index 4692b257..94968d58 100644
--- a/ModernWpf/Helpers/ColorsHelper.cs
+++ b/ModernWpf/Helpers/ColorsHelper.cs
@@ -1,10 +1,9 @@
-using ModernWpf.Media.ColorPalette;
-using System;
+using System;
 using System.Collections;
-using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Windows;
 using System.Windows.Media;
+using ModernWpf.Media.ColorPalette;
 using Windows.UI.ViewManagement;
 
 namespace ModernWpf
@@ -35,7 +34,7 @@ private ColorsHelper()
             }
         }
 
-        public static bool SystemColorsSupported { get; } = Environment.OSVersion.Version.Major >= 10;
+        public static bool SystemColorsSupported { get; } = OSVersionHelper.IsWindows10;
 
         public static ColorsHelper Current { get; } = new ColorsHelper();
 
diff --git a/ModernWpf/Helpers/OSVersionHelper.cs b/ModernWpf/Helpers/OSVersionHelper.cs
new file mode 100644
index 00000000..9cb6077a
--- /dev/null
+++ b/ModernWpf/Helpers/OSVersionHelper.cs
@@ -0,0 +1,35 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace ModernWpf
+{
+    internal static class OSVersionHelper
+    {
+        internal static bool IsWindowsNT { get; } = Environment.OSVersion.Platform == PlatformID.Win32NT;
+
+        internal static bool IsWindows10 { get; } = IsWindowsNT && IsWindows10Impl();
+
+        private static bool IsWindows10Impl()
+        {
+            var osv = new RTL_OSVERSIONINFOEX();
+            osv.dwOSVersionInfoSize = (uint)Marshal.SizeOf(osv);
+            int ret = RtlGetVersion(out osv);
+            return ret == 0 && osv.dwMajorVersion >= 10;
+        }
+
+        [DllImport("ntdll.dll")]
+        private static extern int RtlGetVersion(out RTL_OSVERSIONINFOEX lpVersionInformation);
+
+        [StructLayout(LayoutKind.Sequential)]
+        private struct RTL_OSVERSIONINFOEX
+        {
+            internal uint dwOSVersionInfoSize;
+            internal uint dwMajorVersion;
+            internal uint dwMinorVersion;
+            internal uint dwBuildNumber;
+            internal uint dwPlatformId;
+            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
+            internal string szCSDVersion;
+        }
+    }
+}