A Win32 C++ GUI Program That Cannot Be Screen Captured

A very simple Win32 C++ program that displays a window that cannot be captured (the captured part will turn black). The core is the Win32 API <span>SetWindowDisplayAffinity</span>, and the other part is just a Hello World.

Compilation method: Use MinGW-w64 (MSYS2) to compile, the command is<span>g++ -municode -mwindows -O2 protected.cpp -o protected.exe</span>

The source code for protected.cpp is as follows:

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

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam);

int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow)
{
    const wchar_t CLASS_NAME[]  = L"Sample Window Class";

    WNDCLASS wc = { };

    wc.lpfnWndProc   = WindowProc;
    wc.hInstance     = hInstance;
    wc.lpszClassName = CLASS_NAME;

    RegisterClass(&wc);

    HWND hwnd = CreateWindowEx(
        0,
        CLASS_NAME, 
        L"Sample Program",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT,
        NULL,
        NULL,
        hInstance,
        NULL
        );

    if (hwnd == NULL)
    {
        return 0;
    }

    if (!SetWindowDisplayAffinity(hwnd, WDA_MONITOR)) {
        printf("Failed to call SetWindowDisplayAffinity() with error code %ld\n", GetLastError());
    }

    ShowWindow(hwnd, nCmdShow);

    MSG msg = { };
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return 0;
}

LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;

    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            RECT rc;
            HDC hdc = BeginPaint(hwnd, &ps);
            GetClientRect(hwnd, &rc);
            rc.bottom = rc.bottom / 2;
            FillRect(hdc, &ps.rcPaint, (HBRUSH) (COLOR_WINDOW+1));
            DrawText(hdc, L"Hello, World!", -1, &rc, DT_SINGLELINE | DT_CENTER | DT_VCENTER);
            EndPaint(hwnd, &ps);
        }
        return 0;
    }

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