Add support for dark title bars on Windows 10 1809-2004

TwitchDownloaderWPF/Services/NativeFunctions.cs

@@ -8,6 +8,6 @@ namespace TwitchDownloaderWPF.Services
     public static class NativeFunctions
     {
         [DllImport("dwmapi.dll", EntryPoint = "DwmSetWindowAttribute", PreserveSig = true)]
-        public static extern int SetWindowAttribute(IntPtr handle, int attribute, ref bool attributeValue, int attributeSize);
+        public static extern int SetWindowAttribute(IntPtr handle, int attribute, [In] ref int attributeValue, int attributeSize);
     }
 }

TwitchDownloaderWPF/Services/ThemeService.cs

@@ -1,9 +1,9 @@
 using HandyControl.Data;
 using System;
 using System.IO;
-using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 using System.Windows;
+using System.Windows.Interop;
 using System.Windows.Media;
 using System.Xml.Serialization;
 using TwitchDownloaderWPF.Models;
@@ -13,7 +13,10 @@ namespace TwitchDownloaderWPF.Services
 {
     public class ThemeService
     {
-        private const int TITLEBAR_THEME_ATTRIBUTE = 20;
+        private const int WINDOWS_1809_BUILD_NUMBER = 17763;
+        private const int WINDOWS_2004_INSIDER_BUILD_NUMBER = 18985;
+        private const int USE_IMMERSIVE_DARK_MODE_ATTRIBUTE_BEFORE_2004 = 19;
+        private const int USE_IMMERSIVE_DARK_MODE_ATTRIBUTE = 20;
 
         private bool _darkAppTitleBar = false;
         private bool _darkHandyControl = false;
@@ -84,16 +87,18 @@ public void ChangeAppTheme()
         [SupportedOSPlatform("windows")]
         public void SetTitleBarTheme(WindowCollection windows)
         {
-            // If windows 10 build is before 1903, it doesn't support dark title bars
-            if (Environment.OSVersion.Version.Build < 18362)
-            {
+            if (Environment.OSVersion.Version.Major < 10 || Environment.OSVersion.Version.Build < WINDOWS_1809_BUILD_NUMBER)
                 return;
-            }
+
+            var shouldUseDarkTitleBar = Convert.ToInt32(_darkAppTitleBar);
+            var darkTitleBarAttribute = Environment.OSVersion.Version.Build < WINDOWS_2004_INSIDER_BUILD_NUMBER
+                ? USE_IMMERSIVE_DARK_MODE_ATTRIBUTE_BEFORE_2004
+                : USE_IMMERSIVE_DARK_MODE_ATTRIBUTE;
 
             foreach (Window window in windows)
             {
-                var windowHandle = new System.Windows.Interop.WindowInteropHelper(window).Handle;
-                NativeFunctions.SetWindowAttribute(windowHandle, TITLEBAR_THEME_ATTRIBUTE, ref _darkAppTitleBar, Marshal.SizeOf(_darkAppTitleBar));
+                var windowHandle = new WindowInteropHelper(window).Handle;
+                NativeFunctions.SetWindowAttribute(windowHandle, darkTitleBarAttribute, ref shouldUseDarkTitleBar, sizeof(int));
             }
 
             Window wnd = new()
@@ -104,7 +109,8 @@ public void SetTitleBarTheme(WindowCollection windows)
             };
             wnd.Show();
             wnd.Close();
-            // Dark title bar is a bit buggy, requires window resize or focus change to fully apply
+            // Dark title bar is a bit buggy, requires window redraw (focus change, resize, transparency change) to fully apply.
+            // We *could* send a repaint message to win32.dll, but this solution works and is way easier.
             // Win11 might not have this issue but Win10 does so please leave this
         }
 

TwitchDownloaderWPF/Services/WindowsThemeService.cs

@@ -17,15 +17,13 @@ public class WindowsThemeService : ManagementEventWatcher
         private const string REGISTRY_KEY_NAME = "AppsUseLightTheme";
         private const string LIGHT_THEME = "Light";
         private const string DARK_THEME = "Dark";
+        private const int WINDOWS_1809_BUILD_NUMBER = 17763;
 
         public WindowsThemeService()
         {
             // If the OS is older than Windows 10 1809 then it doesn't have the app theme registry key
-            const int WINDOWS_1809_BUILD_NUMBER = 17763;
             if (Environment.OSVersion.Version.Major < 10 || Environment.OSVersion.Version.Build < WINDOWS_1809_BUILD_NUMBER)
-            {
                 return;
-            }
 
             var currentUser = WindowsIdentity.GetCurrent().User;