Sending key strokes to another application

emilio

hi i wanted to write a windows application that sends keyboard strokes to another application something like a virtual keyboard.

i researched the subject and read few articles.
i managed to find a code that partially works.

in the sample code above i'm trying to send strokes to a word file.
it workes partially in the first send and then it just stopps doing what it supposed to.

the code is:
// Get a handle to an application window.
[DllImport("USER32.DLL", CharSet = CharSet.Unicode)]
public static extern IntPtr FindWindow(string lpClassName,
string lpWindowName);
// Activate an application window.
[DllImport("USER32.DLL")]
public static extern bool SetForegroundWindow(IntPtr hWnd);
IntPtr wordHandle = FindWindow(null, "New Microsoft Word Document.doc - Microsoft Word");
// Verify that word is a running process.
if (wordHandle == IntPtr.Zero)
{
MessageBox.Show("word is not running.");
return;
}
SetForegroundWindow(wordHandle);
SendKeys.SendWait("{a}");

any help will be appreciated.

4 Replies

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Sam Hobbs16y ago
Accepted answer
Sending keys to other applications is often more difficult than most people think. One problem is that the keys must go to a specific control and that control must have focus. Another common problem is timing; sometimes it is necessary to include a delay.

It might be easier and more reliable to send the data more directly.
emilio16y ago
i added a short delay before i sent the strokes and it solved the problem.
thanks everyone for the help
Aleksandar Ilioski16y ago
You can allso try this..
[DllImport("USER32.DLL",EntryPoint = "FindWindow")]
        public static extern IntPtr NajdiProzorec(string lpClassName,
            string lpWindowName);
                [DllImport("USER32.DLL")]
        public static extern bool SetForegroundWindow(IntPtr hWnd);

        private void button1_Click(object sender, EventArgs e)
        {
                        IntPtr wH = NajdiProzorec("BaseWindow_RootWnd", "Player Window");

            if (wH== IntPtr.Zero)
            {
                MessageBox.Show("Winamp is not running.");
                System.Diagnostics.Process.Start("C:\\Program Files\\Winamp\\winamp.exe");
                return;
            }

            SetForegroundWindow(wH);

            SendKeys.SendWait("v");
            SendKeys.SendWait("nul");
            SendKeys.SendWait("{ESC}");
            SendKeys.SendWait("l");
            SendKeys.SendWait("{ESC}");
            SendKeys.SendWait("soft");
            SendKeys.SendWait("x");
        }
the winamp shoud start bilnk at the ritham..
Aleksandar Ilioski16y ago
i have read about this.. few months ago.. and find two solutions.. one is simular to the one you use.. and this is the another..
[DllImport("user32.dll", SetLastError = true)]
        static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);
        [DllImport("User32.Dll", EntryPoint = "PostMessageA")]
        static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);
        [DllImport("user32.dll")]
        static extern byte VkKeyScan(char ch);

        const uint WM_KEYDOWN = 0x100;

        private void button2_Click(object sender, EventArgs e)
        {

                Process[] procs = Process.GetProcessesByName("Notepad");
                foreach (Process proc in procs)
                {
                    // look for untitled notepad window
                    if (proc.MainWindowTitle == "Untitled - Notepad")
                    {
                        // get handle to Notepad's edit window
                        IntPtr hWnd = FindWindowEx(proc.MainWindowHandle, IntPtr.Zero, "edit", null);
                        // post "hello" to notepad
                        string s = "hello";
                        for (int i = 0; i < s.Length; i++)
                        {
                            PostMessage(hWnd, WM_KEYDOWN, VkKeyScan(s[i]), 0);
                        }
                        break;
                    }

            }
        }

both of them work fine for me.. i don't know why you saing that it is not working..