Monitor Clipboard Changes c++ For all applications (Windows)

Question

I am having trouble thinking of a way of creating a program that monitors anytime the clipboard is used and have it print out in a .txt file (It should be bale to monitor the clipboard for any window/application). I used the Using the Clipboard WIn32, but I am not sure how I can have this process constantly running? I am able to get the clipboard once but my program stops. Should I use a while loop? Basically, my program only runs once when I want it to keep tracking the changes. What should I do?

///

Would Clipboard Format Listener help with what I need?

///

int main()
{
    OpenClipboard(nullptr);
    HANDLE hData = GetClipboardData(CF_TEXT);
    char* pszText = static_cast<char*>(GlobalLock(hData));
    string text = pszText;
    GlobalUnlock(hData);
    CloseClipboard();

    cout << text;
    return 0;
}

Answer 1

Subscribing to the WM_CLIPBOARDUPDATE message using AddClipboardFormatListener requires a message queue and a message pump. For a console app, this can be done with a message-only window and a corresponding message loop. Below is some barebones code to implement both.

#include <windows.h>
#include <stdio.h>

LRESULT CALLBACK ClipWndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    static BOOL bListening = FALSE;
    switch(uMsg)
    {
    case WM_CREATE:
        bListening = AddClipboardFormatListener(hWnd);
        return bListening ? 0 : -1;

    case WM_DESTROY:
        if(bListening)
        {
            RemoveClipboardFormatListener(hWnd);
            bListening = FALSE;
        }
        return 0;

    case WM_CLIPBOARDUPDATE:
        printf("WM_CLIPBOARDUPDATE\n");
        return 0;
    }

    return DefWindowProc(hWnd, uMsg, wParam, lParam);
}


int main()
{
    WNDCLASSEX wndClass = { sizeof(WNDCLASSEX) };
    wndClass.lpfnWndProc = ClipWndProc;
    wndClass.lpszClassName = L"ClipWnd";
    if(!RegisterClassEx(&wndClass))
    {   printf("RegisterClassEx error 0x%08X\n", GetLastError()); return 1; }
    HWND hWnd = CreateWindowEx(0, wndClass.lpszClassName, L"", 0, 0, 0, 0, 0, HWND_MESSAGE, NULL, GetModuleHandle(NULL), NULL);
    if(!hWnd)
    {   printf("CreateWindowEx error 0x%08X\n", GetLastError()); return 2; }

    printf("Press ^C to exit\n\n");

    MSG msg;
    while(BOOL bRet = GetMessage(&msg, 0, 0, 0)) {
        if(bRet == -1)
        {   printf("GetMessage error 0x%08X\n", GetLastError()); return 3; }
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}