Detecting CTRL inside CEdit::OnChar and testing nChar value?

Question

I derived my own control from CEdit and it behaves as I intend:

#define IsSHIFTpressed() ( (GetKeyState(VK_SHIFT) & (1 << (sizeof(SHORT)*8-1))) != 0   )

void CEditEx::OnChar(UINT nChar, UINT nRepCnt, UINT nFlags)
{
    if (IsCTRLpressed() && nChar == 2)
    {
        // Do something
        return;
    }

    if (IsCTRLpressed() && nChar == 9)
    {
        // Do something
        return;
    }

    CEdit::OnChar(nChar, nRepCnt, nFlags);
}

However, I have two questions about how I am detecting the key press:

1. Is it possible to detect CTRL being pressed from inside OnChar without the need to use GetKeyState?
2. Are there any constants for comparing against "b" (2) and "i" (9)? I only knew I needed to use those numeric values from when I debugged into the handler.

Answer 1

As you have noted, the value of the nChar argument to OnChar for keyboard entries of Ctrl + "a letter" (independent of the case) will be the ASCII "control-key" values, 1 (for "a") thru 26 (for "z").

To answer your second point: a search through the <WinUser.h> header file shows no VK_xxx tokens for these; however, be aware that some of these control codes are used (by convention) for other actions: Ctrl+M (decimal 13) is equivalent to Return or Enter, and the header has #define VK_RETURN 0x0D; further, for one of your specific cases, Ctrl+I (9) is the ASCII TAB character, and the header, accordingly, has the #define VK_TAB 0x09 definition.

Although the Ctrl+B ASCII code (0x02) is much less used these days (STX, or "Start of Text"), that value is used by Windows for the right mouse button (#define VK_RBUTTON 0x02).

So, to answer your first point: Yes, you will need to make the GetKeyState(VK_CONTROL) check! Without that, a right-click will likely give you a false Ctrl+B and the Tab key will give a false Ctrl+I.

Furthermore, though I have no 'hard evidence' other than your own investigations, I think that a right-click while the Control key is down will generate a different value for nChar (i.e. not 2), and Ctrl+Tab will generate an nChar different from that for Tab alone.