Fix some media keys not working

Author: danielchalmers

RadialActions/Data/ActionUtil.cs

@@ -29,35 +29,141 @@ public static class ActionUtil
 
     #endregion
 
+    private const int WM_APPCOMMAND = 0x0319;
+    private const int APPCOMMAND_MEDIA_NEXTTRACK = 11;
+    private const int APPCOMMAND_MEDIA_PREVIOUSTRACK = 12;
+    private const int APPCOMMAND_MEDIA_STOP = 13;
+    private const int APPCOMMAND_MEDIA_PLAY_PAUSE = 14;
+
+    private const uint INPUT_KEYBOARD = 1;
+    private const uint KEYEVENTF_EXTENDEDKEY = 0x0001;
     private const uint KEYEVENTF_KEYUP = 0x0002;
 
     [DllImport("user32.dll", SetLastError = true)]
     private static extern void keybd_event(byte bVk, byte bScan, uint dwFlags, IntPtr dwExtraInfo);
 
+    [DllImport("user32.dll", SetLastError = true)]
+    private static extern uint SendInput(uint nInputs, INPUT[] pInputs, int cbSize);
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr GetForegroundWindow();
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);
+
+    [StructLayout(LayoutKind.Sequential)]
+    private struct INPUT
+    {
+        public uint type;
+        public InputUnion U;
+    }
+
+    [StructLayout(LayoutKind.Explicit)]
+    private struct InputUnion
+    {
+        [FieldOffset(0)]
+        public KEYBDINPUT ki;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    private struct KEYBDINPUT
+    {
+        public ushort wVk;
+        public ushort wScan;
+        public uint dwFlags;
+        public uint time;
+        public IntPtr dwExtraInfo;
+    }
+
     /// <summary>
     /// Simulates a key press and release.
     /// </summary>
     /// <param name="vk">The virtual key code to simulate.</param>
     public static void SimulateKey(byte vk)
     {
-        keybd_event(vk, 0, 0, IntPtr.Zero);
-        keybd_event(vk, 0, KEYEVENTF_KEYUP, IntPtr.Zero);
+        if (TrySendMediaAppCommand(vk))
+            return;
+
+        SendKey(vk, isKeyUp: false);
+        SendKey(vk, isKeyUp: true);
     }
 
     /// <summary>
     /// Simulates pressing a key down.
     /// </summary>
     private static void KeyDown(byte vk)
     {
-        keybd_event(vk, 0, 0, IntPtr.Zero);
+        SendKey(vk, isKeyUp: false);
     }
 
     /// <summary>
     /// Simulates releasing a key.
     /// </summary>
     private static void KeyUp(byte vk)
     {
-        keybd_event(vk, 0, KEYEVENTF_KEYUP, IntPtr.Zero);
+        SendKey(vk, isKeyUp: true);
+    }
+
+    private static void SendKey(byte vk, bool isKeyUp)
+    {
+        var flags = isKeyUp ? KEYEVENTF_KEYUP : 0u;
+        if (IsExtendedKey(vk))
+            flags |= KEYEVENTF_EXTENDEDKEY;
+
+        var input = new INPUT
+        {
+            type = INPUT_KEYBOARD,
+            U = new InputUnion
+            {
+                ki = new KEYBDINPUT
+                {
+                    wVk = vk,
+                    wScan = 0,
+                    dwFlags = flags,
+                    time = 0,
+                    dwExtraInfo = IntPtr.Zero
+                }
+            }
+        };
+
+        if (SendInput(1, new[] { input }, Marshal.SizeOf<INPUT>()) == 0)
+        {
+            keybd_event(vk, 0, flags, IntPtr.Zero);
+        }
+    }
+
+    private static bool IsExtendedKey(byte vk)
+    {
+        return vk is VK_MEDIA_PLAY_PAUSE
+            or VK_MEDIA_NEXT_TRACK
+            or VK_MEDIA_PREV_TRACK
+            or VK_MEDIA_STOP
+            or VK_VOLUME_MUTE
+            or VK_VOLUME_DOWN
+            or VK_VOLUME_UP;
+    }
+
+    private static bool TrySendMediaAppCommand(byte vk)
+    {
+        var appCommand = vk switch
+        {
+            VK_MEDIA_PLAY_PAUSE => APPCOMMAND_MEDIA_PLAY_PAUSE,
+            VK_MEDIA_NEXT_TRACK => APPCOMMAND_MEDIA_NEXTTRACK,
+            VK_MEDIA_PREV_TRACK => APPCOMMAND_MEDIA_PREVIOUSTRACK,
+            VK_MEDIA_STOP => APPCOMMAND_MEDIA_STOP,
+            _ => -1
+        };
+
+        if (appCommand < 0)
+            return false;
+
+        var hwnd = GetForegroundWindow();
+        if (hwnd == IntPtr.Zero)
+            return false;
+
+        var lParam = (IntPtr)(appCommand << 16);
+        SendMessage(hwnd, WM_APPCOMMAND, hwnd, lParam);
+        return true;
     }
 
     /// <summary>