最近写了一个winform程序,里面有个splash窗口,因为是新开了一个窗口显示的,结果导致了后续出现的login窗口虽然显示在了最前面,但是却没法获取输入焦点,我进行了大量的搜索,使用winapi进行setforeground,返回总是false,  结果通过bing在国外网站找到了一段代码,翻译了一些win32常量,发现挺好用,在.net5下能正确运行,代码如下

 

最好新开个timer,在timeer里执行一次

 

 [DllImport("User32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);
        [DllImport("User32.dll")]
        private static extern bool SetForegroundWindow(IntPtr hWnd);

        [DllImport("user32.dll")]
        private static extern bool SetWindowPos(IntPtr hWnd, int hWndlnsertAfter, int X, int Y, int cx, int cy, uint Flags);
        [DllImport("user32.dll", EntryPoint = "SystemParametersInfo")]
        public static extern int SystemParametersInfo(int uAction, int uParam, IntPtr lpvParam, int fuWinIni);
        [DllImport("User32.dll", SetLastError = true)]
        public static extern int GetForegroundWindow();
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern int GetWindowThreadProcessId(IntPtr hwnd, out int ID);
        [DllImport("User32.dll", SetLastError = true)]
        static extern void SwitchToThisWindow(IntPtr hWnd, bool fAltTab);
        [DllImport("user32.dll")]
        internal static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
        [DllImport("user32.dll")]
        private static extern int AttachThreadInput(int CurrentForegroundThread, int MakeThisThreadForegrouond, bool boolAttach);

        [DllImport("kernel32.dll", ExactSpelling = true, CharSet = CharSet.Auto)]
        public static extern int GetCurrentThreadId();
        [DllImport("user32", CharSet = CharSet.Auto)]
        static extern bool SystemParametersInfo(int uiAction, int uiParam, ref int pvParam, int fWinIni);
        [DllImport("user32", CharSet = CharSet.Auto)]
        static extern bool LockSetForegroundWindow(int a);

        [DllImport("user32", CharSet = CharSet.Auto)]
        static extern bool AllowSetForegroundWindow(int a);




        public static void ForceWindowIntoForeground(IntPtr window)
        {
            int currentThread = GetCurrentThreadId();
            int activeWindow = GetForegroundWindow();
            int activeThread = GetWindowThreadProcessId((IntPtr)activeWindow, out int activeProcess);
            int windowThread = GetWindowThreadProcessId(window, out int windowProcess);
            if (currentThread != activeThread)
                AttachThreadInput(currentThread, activeThread, true);
            if (windowThread != currentThread)
                AttachThreadInput(windowThread, currentThread, true);


            int oldTimeout = 0, newTimeout = 0;
            SystemParametersInfo(0x2000, 0, ref oldTimeout, 0);
            SystemParametersInfo(0x2000, 0, ref newTimeout, 0);
            LockSetForegroundWindow(2);
            AllowSetForegroundWindow(-1);

            SetForegroundWindow(window);
            ShowWindow(window, 9);

            SystemParametersInfo(0x2000, 0, ref oldTimeout, 0);

            if (currentThread != activeThread)
                AttachThreadInput(currentThread, activeThread, false);
            if (windowThread != currentThread)
                AttachThreadInput(windowThread, currentThread, false);
        }