如何将Win32 WndProc封装到C++类中？

6tqwzwtp 于 2023-08-03 发布在其他

关注(0)|答案(2)|浏览(173)

这可能吗例如，假设我有以下内容：

class Window {
private:
    WNDCLASSEX wc;
public:
    inline WNDCLASSEX getWindowClass() {
        return wc;
    }
    Window();
    LRESULT CALLBACK WndProc(HWND hwnd, UINT message, LPARAM lParam, WPARAM wParam);
}

void RegisterWindow(Window win) {
    WNDCLASSEX* wc = win.getWindowClass();
    RegisterClassEx(wc);

}

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现在，在某个地方会有一个部分（可能在Window类的构造函数中，在那里需要为WNDCLASSEX分配WndProc，这在Window类中有记录。唯一的问题是，因为它是类的一部分，所以会引发错误。因此，这是如何实现的？它是静态的吗？即便如此，如果类 Package 了它，它在某种程度上仍然是类的一部分。如果我在类之外创建它，那就简单地抹杀了这一点。

c

来源：https://stackoverflow.com/questions/8780700/how-to-wrap-a-win32-wndproc-into-a-c-class

2条答案

按热度按时间

yeotifhr1#

您将this指针作为GWLP_USERDATA传递给SetWindowLongPtr，这实际上允许您简单地将自由函数转发给成员函数。

赞(0）回复(0）举报 2023-08-03

t9eec4r02#

This page的微软官方文档显示了这样的类：

template <class DERIVED_TYPE> 
class BaseWindow
{
public:
    static LRESULT CALLBACK WindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
    {
        DERIVED_TYPE *pThis = NULL;

        if (uMsg == WM_NCCREATE)
        {
            CREATESTRUCT* pCreate = (CREATESTRUCT*)lParam;
            pThis = (DERIVED_TYPE*)pCreate->lpCreateParams;
            SetWindowLongPtr(hwnd, GWLP_USERDATA, (LONG_PTR)pThis);

            pThis->m_hwnd = hwnd;
        }
        else
        {
            pThis = (DERIVED_TYPE*)GetWindowLongPtr(hwnd, GWLP_USERDATA);
        }
        if (pThis)
        {
            return pThis->HandleMessage(uMsg, wParam, lParam);
        }
        else
        {
            return DefWindowProc(hwnd, uMsg, wParam, lParam);
        }
    }

    BaseWindow() : m_hwnd(NULL) { }

    BOOL Create(
        PCWSTR lpWindowName,
        DWORD dwStyle,
        DWORD dwExStyle = 0,
        int x = CW_USEDEFAULT,
        int y = CW_USEDEFAULT,
        int nWidth = CW_USEDEFAULT,
        int nHeight = CW_USEDEFAULT,
        HWND hWndParent = 0,
        HMENU hMenu = 0
        )
    {
        WNDCLASS wc = {0};

        wc.lpfnWndProc   = DERIVED_TYPE::WindowProc;
        wc.hInstance     = GetModuleHandle(NULL);
        wc.lpszClassName = ClassName();

        RegisterClass(&wc);

        m_hwnd = CreateWindowEx(
            dwExStyle, ClassName(), lpWindowName, dwStyle, x, y,
            nWidth, nHeight, hWndParent, hMenu, GetModuleHandle(NULL), this
            );

        return (m_hwnd ? TRUE : FALSE);
    }

    HWND Window() const { return m_hwnd; }

protected:

    virtual PCWSTR  ClassName() const = 0;
    virtual LRESULT HandleMessage(UINT uMsg, WPARAM wParam, LPARAM lParam) = 0;

    HWND m_hwnd;
};

class MainWindow : public BaseWindow<MainWindow>
{
public:
    PCWSTR  ClassName() const { return L"Sample Window Class"; }
    LRESULT HandleMessage(UINT uMsg, WPARAM wParam, LPARAM lParam);
};

LRESULT MainWindow::HandleMessage(UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;

    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(m_hwnd, &ps);
            FillRect(hdc, &ps.rcPaint, (HBRUSH) (COLOR_WINDOW+1));
            EndPaint(m_hwnd, &ps);
        }
        return 0;

    default:
        return DefWindowProc(m_hwnd, uMsg, wParam, lParam);
    }
    return TRUE;
}

int WINAPI wWinMain(HINSTANCE hInstance, HINSTANCE, PWSTR pCmdLine, int nCmdShow)
{
    MainWindow win;

    if (!win.Create(L"Learn to Program Windows", WS_OVERLAPPEDWINDOW))
    {
        return 0;
    }

    ShowWindow(win.Window(), nCmdShow);

    // Run the message loop.

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

    return 0;
}

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如何将Win32 WndProc封装到C++类中？

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