MFC学习笔记（五）

早期的MFC应用程序框架结构由两个对象组成：应用程序类CWinApp 的派生类对象和窗口类CFrameWnd的派生类对象，后者作为一个成员对象嵌在前者之中

#include<windows.h>
//定义全局变量和函数------------------------------------------------------------------------
HINSTANCE hInst;								
HINSTANCE hInstance;
MSG msg;
char lpszClassName[]="window_class";
char*ShowText;
//声明函数原型--------------------------------------------------------------------------------------
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);//窗口函数
void OnLButtonDown(HWND hWnd, UINT message, 
				WPARAM wParam, LPARAM lParam);
void OnPaint(HWND hWnd, UINT message, 
				WPARAM wParam, LPARAM lParam);
void OnDestroy(HWND hWnd, UINT message, 
				WPARAM wParam, LPARAM lParam);
//窗体类-----------------------------------------------------------------------------------------
class CFrameWnd
{		
public:	
	HWND hWnd;
public:
	int RegisterWindow();	
	void Create(LPCTSTR lpClassName,
				LPCTSTR lpWindowName
				);	
	void ShowWindow(int nCmdShow);
	void UpdateWindow();
};
//窗体类的成员函数----------------------------------------------------------------
int CFrameWnd::RegisterWindow()
{	
	WNDCLASS wc;
	wc.style=0;
	wc.lpfnWndProc=WndProc;
	wc.cbClsExtra=0;
	wc.cbWndExtra=0;
	wc.hInstance=hInstance;
	wc.hIcon=LoadIcon(NULL,IDI_APPLICATION);
	wc.hCursor=LoadCursor(NULL,IDC_ARROW);
	wc.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);
	wc.lpszMenuName=NULL;
	wc.lpszClassName=lpszClassName;
	return RegisterClass(&wc);
}
void CFrameWnd::Create(LPCTSTR lpClassName,
					   LPCTSTR lpWindowName)
{
	RegisterWindow();
	hInst = hInstance; 
	hWnd = CreateWindow(lpszClassName,
						lpWindowName, 
						WS_OVERLAPPEDWINDOW,
						CW_USEDEFAULT, 
						0, 
						CW_USEDEFAULT, 
						0, 
						NULL, 
						NULL, 
						hInstance, 
						NULL);
}
void CFrameWnd::ShowWindow(int nCmdShow)
{
	::ShowWindow(hWnd, nCmdShow);
}
void CFrameWnd::UpdateWindow()
{
	::UpdateWindow(hWnd);
}

//应用程序类----------------------------------------------------------------------------------
class CWinApp
{	
public:
	CWinApp * m_pCurrentWinApp;
public:
	CWinApp( );
	~ CWinApp( ); 
public:
	CFrameWnd * m_pMainWnd;
public:
	virtual BOOL InitInstance (int nCmdShow);
	int Run( );
};

CWinApp::CWinApp( )
{ m_pCurrentWinApp = this;}

BOOL CWinApp::InitInstance(int nCmdShow)
{
	m_pMainWnd=new CFrameWnd;
	m_pMainWnd->Create(NULL,"封装的Windows程序");
	m_pMainWnd->ShowWindow(nCmdShow);
	m_pMainWnd->UpdateWindow();
	return TRUE;
}
int CWinApp::Run()
{
	while (GetMessage(&msg, NULL, 0, 0)) 
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return msg.wParam;
}
CWinApp::~ CWinApp( ) { delete m_pMainWnd; }

//程序员派生的窗体类-----------------------------------------------------------------------
class CMyWnd:public CFrameWnd
{
};

//程序员由CWinApp类派生的CMyApp类-----------------------------------------------
class CMyApp:public CWinApp
{
public:
	BOOL InitInstance(int nCmdShow);
};
//派生类CMyApp的成员函数---------------------------------------------------------------
CMyApp::InitInstance(int nCmdShow)
{
	CMyWnd*pMainWnd=new CMyWnd;//应用窗体的派生类定义窗体对象
	pMainWnd->Create(NULL,"应用窗体的派生类的程序");
	pMainWnd->ShowWindow(nCmdShow);
	pMainWnd->UpdateWindow();
	m_pMainWnd=pMainWnd;//把CMyWnd类的对象赋给m_pMainWnd
	return TRUE;
}

//程序员定义的CWinApp的对象MyApp--------------------------------------------------
CMyApp MyApp;

//全局函数AfxGetApp()----------------------------------------------------------------------
CWinApp*AfxGetApp()
{
	return MyApp.m_pCurrentWinApp;
}

//主函数------------------------------------------------------------------------------------------
int APIENTRY WinMain(HINSTANCE 	hInstance,
                     HINSTANCE 	hPrevInstance,
                     LPSTR     	lpCmdLine,
                     int       		nCmdShow)
{
	int ResultCode=-1;
	CWinApp*pApp;
	pApp=AfxGetApp();
	pApp->InitInstance(nCmdShow);
	return ResultCode=pApp->Run();
}
//窗口函数的实现--------------------------------------------------------------------------------------
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, 
WPARAM wParam, LPARAM lParam)
{
	switch (message) 
	{
	case WM_LBUTTONDOWN:	OnLButtonDown(hWnd, message, wParam, lParam);	
		break;
	case WM_PAINT:			OnPaint(hWnd, message,wParam, lParam);
		break;
	case WM_DESTROY:		OnDestroy(hWnd, message, wParam, lParam);
		break;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
   }
   return 0;
}
void OnLButtonDown(HWND hWnd, UINT message, 
				WPARAM wParam, LPARAM lParam)
{
	ShowText="Hello!";
	InvalidateRect(hWnd,NULL,1);
}
void OnPaint(HWND hWnd, UINT message, 
				WPARAM wParam, LPARAM lParam)
{
	PAINTSTRUCT ps;
	HDC hdc;
	hdc = BeginPaint(hWnd, &ps);
	TextOut(hdc,50,50,ShowText,6);
	EndPaint(hWnd, &ps);
}
void OnDestroy(HWND hWnd, UINT message, 
				WPARAM wParam, LPARAM lParam)
{
	PostQuitMessage(0);
}

 在应用程序主函数WinMain（）中，CWinApp派生类的对象theApp通过调用自己的各个成员函数来完成程序的初始化及消息循环等一系列工作。在CWinApp成员函数InitInstance()中形成应用程序的主窗口对象pMainWnd（类CMyWnd的对象），在完成窗口的创建与显示后，主窗口对象pMainWnd将被给CWinApp的成员m_pMainWnd。