使用 C++/WinAPI/MFC 在编辑/文本框控件上捕获一个特殊的点击事件

Question

I'm coding in C++/MFC on a Windows platform (using MS VS2008.) I have this Edit control (which is basically a text box) that is set to be read-only. The control displays some basic information. I want to add an "Easter Egg" to my app, ie when a user Ctrl+Shift clicks on this edit control it must display some additional info. The question is how to trap such a click event using MFC/native WinAPIs?

Answer 1

The most straight forward way is to subclass the edit control using SetWindowLong and catch WM_LBUTTONDOWN event. You'd then want to call GetAsyncKeyState or equivalent to check whether the specific key is being pressed or not, and show the message.

Answer 2

There is no need to do subclassing. Just catch WM_PARENTNOTIFY

case WM_PARENTNOTIFY: {
    if (LOWORD(wParam) == WM_LBUTTONDOWN)
        printf("x: %i, y: %i\n", LOWORD(lParam), HIWORD(lParam));
}
break;

By default, child windows in a dialog box have the WS_EX_NOPARENTNOTIFY style and so doesn't notify the parent window. You should remove this style.

case WM_INITDIALOG: {
    HWND hChildWnd = GetDlgItem(hWnd, IDC_CHILD);
    LONG style = GetWindowLong(hChildWnd, GWL_EXSTYLE);
    style &= ~WS_EX_NOPARENTNOTIFY;
    SetWindowLong(hChildWnd, GWL_EXSTYLE, style);
    ...

PS I hope it's not too late :D