Get shortcut key failed with "Alt + num" in PretranslateMsg in MFC?

StackOverflow https://stackoverflow.com/questions/22926542

  •  29-06-2023
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Question

I want to preprocess the keyboard message in PretranslateMsg in MFC. So I write the following code.

 if( pMsg->message == WM_KEYUP )   
        {
            if( GetKeyState(VK_CONTROL) || GetKeyState(VK_SHIFT) || GetKeyState(VK_MENU) )
            {
                CString csKey = TranslateKeyToString( GetKeyState(VK_CONTROL) & 0x8000 ,GetKeyState(VK_SHIFT) & 0x8000, GetKeyState(VK_MENU)&0x8000, pMsg->wParam );
                DoWorkForAcceleratorKey(csKey);
                return TRUE;
            }
        }

With above code. I can successfull get shotcut in "csKey" for "Ctrl+Alt+1" and "Ctrl+1" but I can't Get "Alt+1", when I press Alt+1, the csKey is a strange single character. So what happens for the "Alt+1", And how to solve this problem? Thank you.

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Solution

You don't get a WM_KEYUP message for the 1. With the Alt key, the entered characters are used in a different way.

Instead of a WM_KEYUP, you receive the WM_SYSKEYUP. The WM_KEYUP you receive should have the nVirtKey code of VK_MENU.

This is are the messages captured by Spy++ when I press ALT+1 in Notepad.

WM_SYSKEYDOWN nVirtKey:VK_MENU cRepeat:1 ScanCode:38 fExtended:0 fAltDown:1 fRepeat:0 fUp:0
WM_SYSKEYDOWN nVirtKey:VK_MENU cRepeat:1 ScanCode:38 fExtended:0 fAltDown:1 fRepeat:1 fUp:0
WM_SYSKEYDOWN nVirtKey:'1' cRepeat:1 ScanCode:02 fExtended:0 fAltDown:1 fRepeat:0 fUp:0
WM_SYSCHAR chCharCode:'49' (49) cRepeat:1 ScanCode:02 fExtended:0 fAltDown:1 fRepeat:0 fUp:0
WM_SYSKEYUP nVirtKey:'1' cRepeat:1 ScanCode:02 fExtended:0 fAltDown:1 fRepeat:1 fUp:1
WM_KEYUP nVirtKey:VK_MENU cRepeat:1 ScanCode:38 fExtended:0 fAltDown:0 fRepeat:1 fUp:1
WM_SYSKEYDOWN nVirtKey:VK_MENU cRepeat:1 ScanCode:38 fExtended:0 fAltDown:1 fRepeat:0 fUp:0
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