C++--在单文档的应用程序增加多个视图

在mfc的单文档的应用程序(Application)设计时，一般是一种文档(Documnet)对应一种视图(View) 。然而在有些时候我需要一种文档用多种视图来展现，具体步骤如下：
我们有两个假设

CMyWinApp是该程序的应用程序,并声明和定义在MYWINAPP.H和MYWINAPP.CPP文件中.

CNewView是从CView上继承的视图类, 并声明和定义在NEWVIEW.H and NEWVIEW.CPP文件中.

1.修改应用程序类(Application Class);
在MYWINAPP.H加入如下声明
CView* m_pOldView;
CView* m_pNewView;
CView* SwitchView( );
 m_pOldView 和m_pNewView分别指向当前的视图类(新建程序时自动创建的一个视图类)和即将创建的新的视图类,SwitchView函数用于相应用户视图切换操作，具体实现参见下面的步骤。
在MYWINAPP.CPP文件中加入
#include <AFXPRIV.H>

2.创建和修改新的视图类 (View Class)
选择菜单的“New Class”创建新的视图类，并将构造函数和析构函数的访问类型由protected改成public，这样用于动态创建视图。完成后保存文件。

3.创建和绑定新视图(View)
为了创建和绑定新视图，我们需要修改应用程序类的InitInstance函数，在ProcessShellCommand后面添加如下代码并保存：
...
CView* pActiveView = ((CFrameWnd*) m_pMainWnd)->GetActiveView();
m_pOldView = pActiveView;
m_pNewView = (CView*) new CNewView;

CDocument* pCurrentDoc = ((CFrameWnd*)m_pMainWnd)->GetActiveDocument();

// Initialize a CCreateContext to point to the active document.
// With this context, the new view is added to the document
// when the view is created in CView::OnCreate().
CCreateContext newContext;
newContext.m_pNewViewClass = NULL;
newContext.m_pNewDocTemplate = NULL;
newContext.m_pLastView = NULL;
newContext.m_pCurrentFrame = NULL;
newContext.m_pCurrentDoc = pCurrentDoc;

// The ID of the initial active view is AFX_IDW_PANE_FIRST.
// Incrementing this value by one for additional views works
// in the standard document/view case but the technique cannot
// be extended for the CSplitterWnd case.
UINT viewID = AFX_IDW_PANE_FIRST + 1;
CRect rect(0, 0, 0, 0); // Gets resized later.

// Create the new view. In this example, the view persists for
// the life of the application. The application automatically
// deletes the view when the application is closed.
m_pNewView->Create(NULL, "AnyWindowName", WS_CHILD, rect, m_pMainWnd, viewID, &newContext);

// When a document template creates a view, the WM_INITIALUPDATE
// message is sent automatically. However, this code must
// explicitly send the message, as follows.
m_pNewView->SendMessage(WM_INITIALUPDATE, 0, 0);
...

4.实现切换功能函数(Switching Function)
在MYWINAPP.CPP文件中添加如下代码，并保存。
CView* CMyWinApp::SwitchView( )
{
   CView* pActiveView =  ((CFrameWnd*) m_pMainWnd)->GetActiveView();

   CView* pNewView= NULL;
   if(pActiveView == m_pOldView)
      pNewView= m_pNewView;
   else
      pNewView= m_pOldView;

   // Exchange view window IDs so RecalcLayout() works.
   #ifndef _WIN32
   UINT temp = ::GetWindowWord(pActiveView->m_hWnd, GWW_ID);
   ::SetWindowWord(pActiveView->m_hWnd, GWW_ID, ::GetWindowWord(pNewView->m_hWnd, GWW_ID));
   ::SetWindowWord(pNewView->m_hWnd, GWW_ID, temp);
   #else
   UINT temp = ::GetWindowLong(pActiveView->m_hWnd, GWL_ID);
   ::SetWindowLong(pActiveView->m_hWnd, GWL_ID, ::GetWindowLong(pNewView->m_hWnd, GWL_ID));
   ::SetWindowLong(pNewView->m_hWnd, GWL_ID, temp);
   #endif
   pActiveView->ShowWindow(SW_HIDE);
   pNewView->ShowWindow(SW_SHOW);
   ((CFrameWnd*) m_pMainWnd)->SetActiveView(pNewView);
   ((CFrameWnd*) m_pMainWnd)->RecalcLayout();
   pNewView->Invalidate();
   return pActiveView;
}

5.调用SwitchView函数的实现
调用SwitchView函数可以通过增加菜单项来是实现。
void CMainFrame::OnForm1()
{
SwitchView();
}
URL:http://msdn2.microsoft.com/en-us/library/s199bks0(VS.80).aspx