1.3. chromium源代码分析 - chromiumframe - 窗口类

view之window系列
在_tWinMain中有这样两条语句：

MainWindowDelegate delegate;view::Window::CreateNativeWindow(NULL, gfx::Rect(), &delegate);

从这我们开始window相关的探索，目的就是要找到WNDCLASS与创建窗口的地方。
window顾名思义就是windows上的窗口。google对windows的原始窗口做的封装。window相关的类主要有Window / WindowDelegate / WindowWin / Widget / WidgetDelegate / WidgetWin.
我的理解，window为有标题栏和边框的窗口，widget则为无标题栏的HWND。window其实是在widget上加了标题栏和边框相关的处理。google已经在window和widget中加入默认消息处理，以及默认的窗口属性。我们自己的程序当然要有自己窗口属性和窗口行为，这时就需要继承相应的delegate类。
我在学习代码的时候画了一下类图，辅助自己理解。



根据类图，从基类开始看起。

class MessageMapInterface{public:virtual BOOL ProcessWindowMessage(HWND window,UINT message,WPARAM w_param,LPARAM l_param,LRESULT& result,DWORD msg_mad_id = 0) = 0;};

只有一个函数，主要用于处理消息，在消息响应函数(WndProc)中会调用此函数进行消息处理。

接下来就是WindowImpl类，WindowImpl中最重要的就是WndProc，这个函数就是我们注册在WNDCLASS里的消息响应函数。

class WindowImpl : public MessageMapInterface{private:static LRESULT CALLBACK WndProc(HWND window, UINT message,WPARAM w_param, LPARAM l_param);};

WndProc会使用基类指针来调用基类的ProcessWindowMessage函数，消息的控制权就交给ProcessWindowMessage，多态多态行为。

再下来是widget基类，我们可以理解为是HWND的属性 行为的封装。

class Widget{public:// Delegate类在这被加入virtual WidgetDelegate* GetWidgetDelegate() = 0;virtual void SetWidgetDelegate(WidgetDelegate* delegate) = 0;// 这都是HWND的常规属性与行为virtual void GetBounds(gfx::Rect* out, bool including_frame) const = 0;virtual void SetBounds(const gfx::Rect& bounds) = 0;virtual void MoveAbove(Widget* widget) = 0;virtual void SetShape(HRGN shape) = 0;virtual void Close() = 0;virtual void CloseNow() = 0;virtual void Show() = 0;virtual void Hide() = 0;virtual void SetAlwaysOnTop(bool on_top) = 0;virtual bool IsVisible() const = 0;virtual bool IsActive() const = 0;// tooltip、主题管理、焦点管理virtual TooltipManager* GetTooltipManager() = 0;virtual bool GetAccelerator(int cmd_id, MenuAccelerator* accelerator) = 0;virtual ThemeProvider* GetThemeProvider() const = 0;virtual ThemeProvider* GetDefaultThemeProvider() const = 0;virtual FocusManager* GetFocusManager() = 0;// 更新界面函数virtual void PaintNow(const gfx::Rect& update_rect) = 0;};

widget的实现类为WidgetWin，平台相关Win，就是windows平台的widget子类。

    class WidgetWin : public gfx::WindowImpl,        public Widget,        public MessageLoopForUI::Observer,        public FocusTraversable    {    public:        VIEW_BEGIN_MSG_MAP_EX(WidgetWin)            // Range handlers must go first!            VIEW_MESSAGE_RANGE_HANDLER_EX(WM_MOUSEFIRST, WM_MOUSELAST, OnMouseRange)            VIEW_MESSAGE_RANGE_HANDLER_EX(WM_NCMOUSEMOVE, WM_NCMOUSEMOVE, OnMouseRange)            // Reflected message handler            VIEW_MESSAGE_HANDLER_EX(kReflectedMessage, OnReflectedMessage)            // CustomFrameWindow hacks            VIEW_MESSAGE_HANDLER_EX(WM_NCUAHDRAWCAPTION, OnNCUAHDrawCaption)            VIEW_MESSAGE_HANDLER_EX(WM_NCUAHDRAWFRAME, OnNCUAHDrawFrame)            // Vista and newer            VIEW_MESSAGE_HANDLER_EX(WM_DWMCOMPOSITIONCHANGED, OnDwmCompositionChanged)            // Non-atlcrack.h handlers            VIEW_MESSAGE_HANDLER_EX(WM_GETOBJECT, OnGetObject)            VIEW_MESSAGE_HANDLER_EX(WM_NCMOUSELEAVE, OnNCMouseLeave)            VIEW_MESSAGE_HANDLER_EX(WM_MOUSELEAVE, OnMouseLeave)            VIEW_MESSAGE_HANDLER_EX(WM_MOUSEWHEEL, OnMouseWheel)            // This list is in _ALPHABETICAL_ order! OR I WILL HURT YOU.            VIEW_MSG_WM_ACTIVATE(OnActivate)            VIEW_MSG_WM_ACTIVATEAPP(OnActivateApp)            VIEW_MSG_WM_APPCOMMAND(OnAppCommand)            VIEW_MSG_WM_CANCELMODE(OnCancelMode)            VIEW_MSG_WM_CAPTURECHANGED(OnCaptureChanged)            VIEW_MSG_WM_CLOSE(OnClose)            VIEW_MSG_WM_COMMAND(OnCommand)            VIEW_MSG_WM_CREATE(OnCreate)            VIEW_MSG_WM_DESTROY(OnDestroy)            VIEW_MSG_WM_SETTEXT(OnSetText)            VIEW_MSG_WM_SETTINGCHANGE(OnSettingChange)            VIEW_MSG_WM_SIZE(OnSize)            VIEW_MSG_WM_SYSCOMMAND(OnSysCommand)            VIEW_MSG_WM_THEMECHANGED(OnThemeChanged)            VIEW_MSG_WM_VSCROLL(OnVScroll)            VIEW_MSG_WM_WINDOWPOSCHANGING(OnWindowPosChanging)            VIEW_MSG_WM_WINDOWPOSCHANGED(OnWindowPosChanged)        VIEW_END_MSG_MAP()        // Overridden from Widget:        // Overridden from MessageLoop::Observer:        // Overridden from FocusTraversable:    protected:        virtual void OnActivate(UINT action, BOOL minimized, HWND window);        virtual void OnActivateApp(BOOL active, DWORD thread_id);        virtual LRESULT OnAppCommand(HWND window, short app_command, WORD device,            int keystate);        virtual void OnCancelMode();        virtual void OnCaptureChanged(HWND hwnd);        virtual void OnClose();        virtual void OnCommand(UINT notification_code, int command_id, HWND window);        virtual LRESULT OnCreate(CREATESTRUCT* create_struct);        // WARNING: If you override this be sure and invoke super, otherwise we'll        // leak a few things.        virtual void OnDestroy();        virtual LRESULT OnSetText(const wchar_t* text);        virtual void OnSettingChange(UINT flags, const wchar_t* section);        virtual void OnSize(UINT param, const gfx::Size& size);        virtual void OnSysCommand(UINT notification_code, gfx::Point click);        virtual void OnThemeChanged();        virtual void OnVScroll(int scroll_type, short position, HWND scrollbar);        virtual void OnWindowPosChanging(WINDOWPOS* window_pos);        virtual void OnWindowPosChanged(WINDOWPOS* window_pos);        // deletes this window as it is destroyed, override to provide different        // behavior.        virtual void OnFinalMessage(HWND window);    };

从继承关系widget_win不仅实现了widget，而且还加入了消息处理相关，焦点处理等的内容。
从类的接口看，确实是在处理消息了，这就是windows消息的默认处理类了。消息是怎么传送到这里的呢？
回到祖父类，ProcessWindowMessage消息处理总函数, 再看看WidgetWin中的VIEW_BEGIN_MSG_MAP_EX宏，

#define VIEW_BEGIN_MSG_MAP_EX(theClass) \public: \BOOL m_bMsgHandled; \/* "handled" management for cracked handlers */ \BOOL IsMsgHandled() const \{ \return m_bMsgHandled; \} \void SetMsgHandled(BOOL bHandled) \{ \m_bMsgHandled = bHandled; \} \BOOL ProcessWindowMessage(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, LRESULT& lResult, DWORD dwMsgMapID = 0) \{ \BOOL bOldMsgHandled = m_bMsgHandled; \BOOL bRet = _ProcessWindowMessage(hWnd, uMsg, wParam, lParam, lResult, dwMsgMapID); \m_bMsgHandled = bOldMsgHandled; \return bRet; \} \BOOL _ProcessWindowMessage(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, LRESULT& lResult, DWORD dwMsgMapID) \{ \BOOL bHandled = TRUE; \hWnd; \uMsg; \wParam; \lParam; \lResult; \bHandled; \switch(dwMsgMapID) \{ \case 0:

已经看到ProcessWindowMessage的身影了，ProcessWindowMessage是虚函数重载，WndProc实际会把消息传送到这里，ProcessWindowMessage会调用_ProcessWindowMessage接下来就是switch case处理分发了，这应该是借鉴了WTL框架，

回看1.1的win32典型程序的消息处理函数，都是switch case 来分发消息，这里只是用宏伪装，用类进行了包装而已。

window类封装了title name，最大/小化支持等等一些窗口的属性和行为，这些都是纯虚的函数，最重要的就是在main.cpp被调用的static函数。

    class Window    {    public:        virtual ~Window() {}        // Creates an instance of an object implementing this interface.        // TODO(beng): create a version of this function that takes a HWND, for        //             constrained windows.        static Window* CreateNativeWindow(HWND parent,            const gfx::Rect& bounds, WindowDelegate* window_delegate);};

    // static    Window* Window::CreateNativeWindow(HWND parent,        const gfx::Rect& bounds,        WindowDelegate* window_delegate)    {        WindowWin* window = new WindowWin(window_delegate);   // 1. new出子类        window->GetNonClientView()->SetFrameView(window->CreateFrameViewForWindow());        window->Init(parent, bounds); //2.调用WindowWin::Init        return window;    }

// 3. 之后会掉到这

    void WindowImpl::Init(HWND parent, const Rect& bounds)    {        if(window_style_ == 0)        {            window_style_ = parent ? kWindowDefaultChildStyle : kWindowDefaultStyle;        }        if(parent && !::IsWindow(parent))        {            NOTREACHED() << "invalid parent window specified.";            parent = NULL;        }        int x, y, width, height;        if(bounds.IsEmpty())        {            x = y = width = height = CW_USEDEFAULT;        }        else        {            x = bounds.x();            y = bounds.y();            width = bounds.width();            height = bounds.height();        }        hwnd_ = CreateWindowEx(window_ex_style_, GetWindowClassName().c_str(), NULL,            window_style_, x, y, width, height, parent, NULL, NULL, this);                  // 这里就是创建窗口了        DCHECK(hwnd_);    }

到此，窗口的创建，消息的分发都已经展现出来了，剩下的就是消息循环了。

WindowWin继承自widget，重载了NC消息的处理。又继承了window类，实现窗口的行为及属性。

WindowDelegate则是window的委派，实质上应该是Window子类WindowWin的委派。我们要修改窗口的属性行为以及如何构建窗口也只需要继承WindowDelegate，重载windowDelegate的行为函数即可。main.cpp中就是这么干的，MainWindowDelegate就是继承WindowDelegate。