C++ sending keys to a window

Question

I want to create a program which simulates key presses or just write a text to a specific application window. This is what I've tried but it doesn't seem to work.

void MainWindow::on_startButton_clicked()
{
    HWND windowname = FindWindow(NULL, L"<mywindowname>");
    SendMessage(windowname, WM_SETTEXT, NULL, (LPARAM)"Window");
}

Any ideas?

You'll probably want that text to be a wide string, but unless that's your own window, you're probably better off with `SetWindowText`. — chris, Nov 21 '13 at 17:45
@chris does this change the window title? because thats not what i want — Davlog, Nov 21 '13 at 17:46
@Davlog: `WM_SETTEXT` is mostly the same... if you want to simulate keypresses you have to use `SendInput` or individual `WM_KEYDOWN`/`WM_KEYUP` (but if the application bypasses the normal key messages to get input they won't work). — Matteo Italia, Nov 21 '13 at 17:55
See my answer here, which can easily be converted to c++: http://stackoverflow.com/a/41886193/1599699 — Andrew, Jan 27 '17 at 02:26

score 0 · Answer 1 · answered Nov 22 '13 at 23:14

So I found out today that SendMessage will only send a single character (at least it's the solution for my problem). So for a string I have to do the following for each character in it.

QString string = "Hello";
foreach(QChar c, string){
  SendMessage(windowname, WM_KEYDOWN, (int)c-0x20, 0);
  SendMessage(windowname, WM_CHAR, (int)c-0x20, 0);
  SendMessage(windowname, WM_KEYUP, (int)c-0x20, 0);
}

For more information about this function and deeper details on WM_KEY's etc. click here

C++ sending keys to a window

1 Answers1