DuiLib（一）——窗口及消息

最近看了下开源界面库duilib的代码，写几篇相关的文章。网上已经有好多相关的文章了，我这里只是记录自己的学习过程，写到哪里算哪里，权当自娱自乐。

duilib是一轻量级的direcui界面库，所谓directui是指在一真实的窗口之上画出各种控件。所以先从界面库的窗口及消息入手比较好，可以抓住树根，再顺着往上分析。

duilib将窗口封装成类CWindowWnd，创建窗口之前要先注册窗口：

bool CWindowWnd::RegisterWindowClass()
{
    WNDCLASS wc = { 0 };
    wc.style = GetClassStyle();
    wc.cbClsExtra = 0;
    wc.cbWndExtra = 0;
    wc.hIcon = NULL;
    wc.lpfnWndProc = CWindowWnd::__WndProc;//窗口过程
    wc.hInstance = CPaintManagerUI::GetInstance();
    wc.hCursor = ::LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = NULL;
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = GetWindowClassName();//窗口类名
    ATOM ret = ::RegisterClass(&wc);
    ASSERT(ret!=NULL || ::GetLastError()==ERROR_CLASS_ALREADY_EXISTS);
    return ret != NULL || ::GetLastError() == ERROR_CLASS_ALREADY_EXISTS;
}

HWND CWindowWnd::Create(HWND hwndParent, LPCTSTR pstrName, DWORD dwStyle, DWORD dwExStyle, int x, int y, int cx, int cy, HMENU hMenu)
{
    if( GetSuperClassName() != NULL && !RegisterSuperclass() ) return NULL;
    if( GetSuperClassName() == NULL && !RegisterWindowClass() ) return NULL;
    m_hWnd = ::CreateWindowEx(dwExStyle, GetWindowClassName(), pstrName, dwStyle, x, y, cx, cy, hwndParent, hMenu, CPaintManagerUI::GetInstance(), this);
    ASSERT(m_hWnd!=NULL);
    return m_hWnd;
}

窗口过程为CWindowWnd类的静态函数__WndProc

LRESULT CALLBACK CWindowWnd::__WndProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    CWindowWnd* pThis = NULL;
    if( uMsg == WM_NCCREATE ) {//before WM_CREATE
        LPCREATESTRUCT lpcs = reinterpret_cast<LPCREATESTRUCT>(lParam);
        pThis = static_cast<CWindowWnd*>(lpcs->lpCreateParams);
        pThis->m_hWnd = hWnd;
        ::SetWindowLongPtr(hWnd, GWLP_USERDATA, reinterpret_cast<LPARAM>(pThis));
    } 
    else {
        pThis = reinterpret_cast<CWindowWnd*>(::GetWindowLongPtr(hWnd, GWLP_USERDATA));
        if( uMsg == WM_NCDESTROY && pThis != NULL ) {//after WM_DESTROY
            LRESULT lRes = ::CallWindowProc(pThis->m_OldWndProc, hWnd, uMsg, wParam, lParam);
            ::SetWindowLongPtr(pThis->m_hWnd, GWLP_USERDATA, 0L);
            if( pThis->m_bSubclassed ) pThis->Unsubclass();
            pThis->m_hWnd = NULL;
            pThis->OnFinalMessage(hWnd);
            return lRes;
        }
    }
    if( pThis != NULL ) {
        //消息处理
        return pThis->HandleMessage(uMsg, wParam, lParam);
    } 
    else {
        return ::DefWindowProc(hWnd, uMsg, wParam, lParam);
    }
}

窗口函数__WndProc：

• 处理了WM_NCCREATE消息（WM_CREATE之前发送）和WM_NCDESTROY（WM_DESTROY之后发送）。前者保存了CWindowWnd对象指针，后者获取该指针，并调用虚函数OnFinalMessage，给用户一个最后清理的机会。
• 调用虚函数HandleMessage，处理其他消息。

 消息循环在哪？不在类CWindowWnd中，在CPaintManagerUI里！

void CPaintManagerUI::MessageLoop()
{
    MSG msg = { 0 };
    while( ::GetMessage(&msg, NULL, 0, 0) ) {
        if( !CPaintManagerUI::TranslateMessage(&msg) ) {
            ::TranslateMessage(&msg);
            ::DispatchMessage(&msg);
        }
    }
}

一个简单的示例：

class CFrameWindowWnd : public CWindowWnd, public INotifyUI
{
public:
    CFrameWindowWnd() { };
    LPCTSTR GetWindowClassName() const { return _T("FrameWnd"); };
    UINT GetClassStyle() const { return UI_CLASSSTYLE_FRAME | CS_DBLCLKS; };
    void OnFinalMessage(HWND /*hWnd*/) { delete this; };

    void Notify(TNotifyUI& msg)
    {
        if( msg.sType == _T("windowinit") ) {
        }
        else if( msg.sType == _T("click") ) {
        }
    }

    //消息处理：窗口函数__WndProc ---> HandleMessage
    LRESULT HandleMessage(UINT uMsg, WPARAM wParam, LPARAM lParam)
    {
        if( uMsg == WM_CREATE ) {
            m_pm.Init(m_hWnd);
            //根据XML创建控件
            CDialogBuilder builder;
            CControlUI* pRoot = builder.Create(_T("HelloWorld.xml"), (UINT)0, NULL, &m_pm);
            ASSERT(pRoot && "Failed to parse XML");
            m_pm.AttachDialog(pRoot);
            m_pm.AddNotifier(this);
            return 0;
        }
        else if( uMsg == WM_DESTROY ) {
            ::PostQuitMessage(0L);
        }
        else if( uMsg == WM_ERASEBKGND ) {
            return 1;
        }

        //消息处理：CPaintManagerUI::MessageHandler
        LRESULT lRes = 0;
        if( m_pm.MessageHandler(uMsg, wParam, lParam, lRes) ) return lRes;
        return CWindowWnd::HandleMessage(uMsg, wParam, lParam);
    }

public:
    CPaintManagerUI m_pm;
};


int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE /*hPrevInstance*/, LPSTR /*lpCmdLine*/, int nCmdShow)
{
    CPaintManagerUI::SetInstance(hInstance);
    CPaintManagerUI::SetResourcePath(CPaintManagerUI::GetInstancePath() + _T("skin\HelloWorldRes"));

    //COM
    HRESULT Hr = ::CoInitialize(NULL);
    if( FAILED(Hr) ) return 0;

    CFrameWindowWnd* pFrame = new CFrameWindowWnd();
    if( pFrame == NULL ) return 0;

    //注册窗口类、创建窗口
    pFrame->Create(NULL, _T("HelloWorld"), UI_WNDSTYLE_FRAME, WS_EX_WINDOWEDGE);
    pFrame->CenterWindow();
    pFrame->ShowWindow(true);

    //消息循环
    CPaintManagerUI::MessageLoop();

    //COM
    ::CoUninitialize();
    return 0;
}

这个例子可以看到整个程序框架，注册、创建窗口、消息循环、消息处理等。

关于窗口和消息，先写这么多。下一篇写控件创建。