Flash the main window taskbar icon if it is not in the foreground on …

…startup
lay295 · Nov 30, 2023 · cf35e4c · cf35e4c
1 parent c406baf
commit cf35e4c
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diff --git a/TwitchDownloaderWPF/MainWindow.xaml.cs b/TwitchDownloaderWPF/MainWindow.xaml.cs
@@ -3,8 +3,11 @@
 using System.Diagnostics;
 using System.IO;
 using System.Net;
+using System.Runtime.InteropServices;
 using System.Windows;
+using System.Windows.Interop;
 using TwitchDownloaderWPF.Properties;
+using TwitchDownloaderWPF.Services;
 using Xabe.FFmpeg;
 using Xabe.FFmpeg.Downloader;
 
@@ -98,6 +101,23 @@ private async void Window_Loaded(object sender, RoutedEventArgs e)
                 Title = oldTitle;
             }
 
+            // Flash the window taskbar icon if it is not in the foreground. This is to mitigate a problem where
+            // it will sometimes start behind other windows, usually (but not always) due to the user's actions.
+            var currentWindow = new WindowInteropHelper(this).Handle;
+            var foregroundWindow = NativeFunctions.GetForegroundWindow();
+            if (currentWindow != foregroundWindow)
+            {
+                var flashInfo = new NativeFunctions.FlashWInfo
+                {
+                    StructSize = (uint)Marshal.SizeOf<NativeFunctions.FlashWInfo>(),
+                    WindowHandle = new WindowInteropHelper(this).Handle,
+                    Flags = NativeFunctions.FlashWInfo.FLASHW_TRAY,
+                    FlashCount = uint.MaxValue,
+                    Timeout = 0
+                };
+                NativeFunctions.FlashWindowEx(flashInfo);
+            }
+
             AutoUpdater.InstalledVersion = currentVersion;
 #if !DEBUG
             if (AppContext.BaseDirectory.StartsWith(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile)))

diff --git a/TwitchDownloaderWPF/Services/NativeFunctions.cs b/TwitchDownloaderWPF/Services/NativeFunctions.cs
@@ -9,5 +9,29 @@ public static unsafe class NativeFunctions
     {
         [DllImport("dwmapi.dll", EntryPoint = "DwmSetWindowAttribute", PreserveSig = true)]
         public static extern int SetWindowAttribute(IntPtr handle, int attribute, void* attributeValue, uint attributeSize);
+
+        [DllImport("user32.dll", EntryPoint = "GetForegroundWindow", PreserveSig = true)]
+        public static extern IntPtr GetForegroundWindow();
+
+        [DllImport("user32.dll", EntryPoint = "FlashWindowEx", PreserveSig = true)]
+        public static extern bool FlashWindowEx(FlashWInfo info);
+
+        // https://learn.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-flashwinfo
+        [StructLayout(LayoutKind.Sequential)]
+        public record struct FlashWInfo
+        {
+            public uint StructSize;
+            public IntPtr WindowHandle;
+            public uint Flags;
+            public uint FlashCount;
+            public uint Timeout;
+
+            public const uint FLASHW_STOP = 0;
+            public const uint FLASHW_CAPTION = 1;
+            public const uint FLASHW_TRAY = 2;
+            public const uint FLASHW_ALL = 3;
+            public const uint FLASHW_TIMER = 4;
+            public const uint FLASHW_TIMERNOFG = 12;
+        }
     }
 }