5、 MFC view windows and documents

One 、 View window

        Provide a window for displaying data

1、 View window related classes

        CView And its subclasses , The parent class is CWnd class , Encapsulates various operations on the view window , And data interaction with document class

2、 Use of view window

（1） Defines its own view class （CMyView）, Derive from CView, And override the pure virtual function of the parent class member void OnDraw(CDC* pDC), Can be used for drawing

（2） The rest of the framework class and application class program code remain unchanged

（3） Handle framework WM_CREATE When the news , Definition CMyView Class object , And call Create Function to create a view window , Of the view window ID by AFX_IDW_PANE_FIRST

3、 Create project （MFCView）

（1） Create project

（2） Programming

#include <afxwin.h>
#include "resource.h"

class CMyView:public CView
{
	DECLARE_MESSAGE_MAP()
public:
	virtual void OnDraw(CDC* pDC);
	afx_msg void OnPaint();
	afx_msg void OnNew();
};
BEGIN_MESSAGE_MAP(CMyView, CView)
	//ON_WM_PAINT()
	ON_COMMAND(ID_NEW, OnNew)
END_MESSAGE_MAP()

// When the parent class processes the drawing message, it will call OnDraw, When this class is handled by drawing messages , be OnDraw Will not be called 
void CMyView::OnDraw(CDC* pDC)
{
	pDC->TextOut(100, 100, "CMyView::OnDraw");
}
void CMyView::OnPaint()
{
	PAINTSTRUCT ps = {0};
	HDC hdc = ::BeginPaint(m_hWnd, &ps);
	::TextOutA(hdc, 200, 200, "CMyView::OnPaint", strlen("CMyView::OnPaint"));
	::EndPaint(m_hWnd, &ps);
}
void CMyView::OnNew()
{
	AfxMessageBox(" The view class handles OnNew news ");
}

class CMyFrameWnd:public CFrameWnd
{
	DECLARE_MESSAGE_MAP()
public:
	afx_msg void OnPaint();
	afx_msg int OnCreate(LPCREATESTRUCT pcs);
	afx_msg void OnNew();
};
BEGIN_MESSAGE_MAP(CMyFrameWnd, CFrameWnd)
	ON_WM_CREATE()
	ON_WM_PAINT()
	ON_COMMAND(ID_NEW, OnNew)
END_MESSAGE_MAP()

int CMyFrameWnd::OnCreate(LPCREATESTRUCT pcs)
{
	CMyView* pView = new CMyView;
	pView->Create(NULL, "MFCView", WS_CHILD|WS_VISIBLE|WS_BORDER, CRect(0, 0, 200, 200), 
				this, AFX_IDW_PANE_FIRST);		//AFX_IDW_PANE_FIRST  The generated view window will be tiled in the frame window 
	m_pViewActive = pView;	// Assign the window to the active window 
	return CFrameWnd::OnCreate(pcs);
}

void CMyFrameWnd::OnPaint()
{
	PAINTSTRUCT ps = {0};
	HDC hdc = ::BeginPaint(m_hWnd, &ps);
	::TextOutA(hdc, 100, 100, " Frame window client area ", strlen(" Frame window client area "));
	::EndPaint(m_hWnd, &ps);
}
void CMyFrameWnd::OnNew()
{
	AfxMessageBox(" The framework class handles OnNew news ");
}


class CMyWinApp:public CWinApp
{
	DECLARE_MESSAGE_MAP()
public:
	virtual BOOL InitInstance();
	afx_msg void OnNew();
};
BEGIN_MESSAGE_MAP(CMyWinApp, CWinApp)
	ON_COMMAND(ID_NEW, OnNew)
END_MESSAGE_MAP()
void CMyWinApp::OnNew()
{
	AfxMessageBox(" The framework class handles OnNew news ");
}

BOOL CMyWinApp::InitInstance()
{
	CMyFrameWnd* pFrame = new CMyFrameWnd;
	pFrame->Create(NULL, "MFCView", WS_OVERLAPPEDWINDOW, CFrameWnd::rectDefault,NULL,
				(char*)IDR_MENU1);
	m_pMainWnd = pFrame;
	pFrame->ShowWindow(SW_SHOW);
	pFrame->UpdateWindow();
	return TRUE;
}

CMyWinApp theApp;

（3） Command message processing sequence

        View class -》 Framework class -》 Application class

（4） Object graph

theApp
    theApp->m_pMainWnd = pFrame
        pFrame->m_pViewActive = pView
        
    

Two 、 Document class

        Related classes CDocument, Provides classes for managing data , Encapsulates the management of data （ Data Extraction , Data conversion , Data storage, etc ）, And interact with the view class .

1、 Create project

（1） Create project （MFCDoc）

（2） Programming

#include <afxwin.h>
#include <afxext.h>
#include "resource.h"

class CMyDoc:public CDocument
{

};

class CMyView:public CView
{
	DECLARE_DYNCREATE(CMyView)
	DECLARE_MESSAGE_MAP()
public:
	virtual void OnDraw(CDC* cDC);
	afx_msg int OnCreate(LPCREATESTRUCT pcs);
};
IMPLEMENT_DYNCREATE(CMyView, CView)
BEGIN_MESSAGE_MAP(CMyView, CView)
	ON_WM_CREATE()
END_MESSAGE_MAP()

void CMyView::OnDraw(CDC* cDC)
{
	cDC->TextOut(100, 100, " View window ");
}
int CMyView::OnCreate(LPCREATESTRUCT pcs)
{
	return CView::OnCreate(pcs);
}

class CMyFrameWnd:public CFrameWnd
{
	DECLARE_MESSAGE_MAP()
	afx_msg int OnCreate(LPCREATESTRUCT pcs);
	afx_msg void OnPaint();
};
BEGIN_MESSAGE_MAP(CMyFrameWnd, CFrameWnd)
	ON_WM_CREATE()
	ON_WM_PAINT()
END_MESSAGE_MAP()
int CMyFrameWnd::OnCreate(LPCREATESTRUCT pcs)
{
	return CFrameWnd::OnCreate(pcs);
}
void CMyFrameWnd::OnPaint()
{
	PAINTSTRUCT ps = {0};
	HDC hdc = ::BeginPaint(m_hWnd, &ps);
	::TextOutA(hdc, 200, 200, "CMyFrameWnd::OnPaint", strlen("CMyFrameWnd::OnPaint"));
	::EndPaint(m_hWnd, &ps);
}

class CMyWinApp:public CWinApp
{
public:
	virtual BOOL InitInstance();
};
BOOL CMyWinApp::InitInstance()
{
	CMyFrameWnd* pFrame = new CMyFrameWnd;
	CCreateContext cct;
	CMyDoc* pDoc = new CMyDoc;
	cct.m_pNewViewClass = RUNTIME_CLASS(CMyView);
	cct.m_pCurrentDoc = pDoc;
	pFrame->LoadFrame(IDR_MENU1, WS_OVERLAPPEDWINDOW, NULL, &cct);
	m_pMainWnd = pFrame;
	pFrame->ShowWindow(SW_SHOW);
	pFrame->UpdateWindow();
	return TRUE;
}
CMyWinApp theApp;

（3） The creation process

         Use the frame class object address （pFrame） call LoadFrame function , Create a frame window

        In the processing frame window WM_CREATE When the news ,（ Parent class CFrameWnd） Dynamically create view class objects , And create a view window

        In the processing view window WM_CREATE When the news ,（ Parent class CView） See the relationship between document class and view class objects

2、 Create a process

CMyFrameWnd* pFrame = new CMyFrameWnd;
CMyDoc* pDoc = new CMyDoc;

CCreateContext cct;
cct.m_pCurrentDoc = pDoc;// Document class object address 
cct.m_pNewViewClass = RUNTIME_CLASS(CMyView);//&CMyView::classCMyView

pFrame->LoadFrame(... &cct)// Internal function this by pFrame
{
  Create(...,&cct)// Internal function this by pFrame
  {
    CreateEx(...&cct)// Internal function this by pFrame
    {
      CREATESTRUCT cs;
      ....
      cs.lpCreateParams = &cct;
      ::CreateWindowEx(...,&cct);// Create main frame window 
    }
  }
}
// Handle frame window WM_CREATE news 
CFrameWnd::OnCreate( pcs )// Internal function this by pFrame, Parameters can be obtained ::CreateWindowEx Of 12 Parameters 
{
  CCreateContext* pContext = (CCreateContext*)pcs->lpCreateParams;// obtain &cct
  OnCreateHelper(pcs, pContext)// Internal function this by pFrame,pContext===&cct
  {
    OnCreateClient(pcs, pContext)// Internal function this by pFrame,pContext===&cct
    {
      CreateView(pContext..)// Internal function this by pFrame,pContext===&cct
      {
        CWnd* pView = pContext->m_pNewViewClass->CreateObject();
                            // Dynamically create view class objects , And return the object address 
        pView->Create(..,pContext)// Internal function this by pView,pContext===&cct
        {
          CreateEx(..,pContext）// Internal function this by pView,pContext===&cct
          {
            CREATESTRUCT cs;
            ....
            cs.lpCreateParams = pContext;//pContext===&cct
            ::CreateWindowEx(...,pContext);// Create view window          
          }
        }
      }
    }
  }
}

// Handle view window WM_CREATE news 
CView::OnCreate( pcs )// Internal function this by pView, Parameters can be obtained ::CreateWindowEx Functional 12 Parameters 
{
  CCreateContext* pContext = (CCreateContext*)lpcs->lpCreateParams;// obtain &cct
  pContext->m_pCurrentDoc->AddView(pView)// Internal function this by pDoc, The parameter is the address of the view class object 
  {
    m_viewList.AddTail(pView);// The document class object uses a linked list member variable , Save the address of the view class object 
    pView->m_pDocument = this;// The view class object uses a common member variable , Save the address of the document class object 
  }
}

3、 Object relationship

（1） The document class object uses a linked list member variable , Save the address of the view class object

（2） The view class object uses a common member variable , Save the address of the document class object

        A document object can correspond to multiple view objects （ View window ）

        A view class object （ View window ） Only one document class object can be mapped

4、 View segmentation

（1） Related classes

CSplitterWnd Irregular frame window class , Subpackaged the operation of irregular frame window

（2） Use of window segmentation

rewrite CFrameWnd Class member virtual function OnCreateClient

         Call... In a virtual function CSplitterWnd::CreateStatic Create irregular frame window

        Call... In a virtual function CSplitterWnd::CreateView Create view window

（3） Programming

#include <afxwin.h>
#include <afxext.h>
#include "resource.h"

class CMyDoc:public CDocument
{

};

class CMyView:public CView
{
	DECLARE_DYNCREATE(CMyView)
	DECLARE_MESSAGE_MAP()
public:
	virtual void OnDraw(CDC* cDC);
	afx_msg int OnCreate(LPCREATESTRUCT pcs);
};
IMPLEMENT_DYNCREATE(CMyView, CView)
BEGIN_MESSAGE_MAP(CMyView, CView)
	ON_WM_CREATE()
END_MESSAGE_MAP()

void CMyView::OnDraw(CDC* cDC)
{
	cDC->TextOut(100, 100, " View window ");
}
int CMyView::OnCreate(LPCREATESTRUCT pcs)
{
	return CView::OnCreate(pcs);
}

class CMyFrameWnd:public CFrameWnd
{
	DECLARE_MESSAGE_MAP()
	afx_msg int OnCreate(LPCREATESTRUCT pcs);
	afx_msg void OnPaint();
	virtual BOOL OnCreateClient(LPCREATESTRUCT lpcs, CCreateContext* pContext);
private:
	CSplitterWnd m_split;	// Irregular frame window 
};
BEGIN_MESSAGE_MAP(CMyFrameWnd, CFrameWnd)
	ON_WM_CREATE()
	ON_WM_PAINT()
END_MESSAGE_MAP()
int CMyFrameWnd::OnCreate(LPCREATESTRUCT pcs)
{
	return CFrameWnd::OnCreate(pcs);
}
void CMyFrameWnd::OnPaint()
{
	PAINTSTRUCT ps = {0};
	HDC hdc = ::BeginPaint(m_hWnd, &ps);
	::TextOutA(hdc, 200, 200, "CMyFrameWnd::OnPaint", strlen("CMyFrameWnd::OnPaint"));
	::EndPaint(m_hWnd, &ps);
}
BOOL CMyFrameWnd::OnCreateClient(LPCREATESTRUCT lpcs, CCreateContext* pContext)
{
	// Create two view windows 	
	m_split.CreateStatic(this, 1, 2);
	m_split.CreateView(0, 0, RUNTIME_CLASS(CMyView), CSize(100, 100), pContext);
	m_split.CreateView(0, 1, pContext->m_pNewViewClass, CSize(100, 100), pContext);
	return TRUE;
}
class CMyWinApp:public CWinApp
{
public:
	virtual BOOL InitInstance();
};
BOOL CMyWinApp::InitInstance()
{
	CMyFrameWnd* pFrame = new CMyFrameWnd;
	CCreateContext cct;
	CMyDoc* pDoc = new CMyDoc;
	cct.m_pNewViewClass = RUNTIME_CLASS(CMyView);
	cct.m_pCurrentDoc = pDoc;
	pFrame->LoadFrame(IDR_MENU1, WS_OVERLAPPEDWINDOW, NULL, &cct);
	m_pMainWnd = pFrame;
	pFrame->ShowWindow(SW_SHOW);
	pFrame->UpdateWindow();
	return TRUE;
}
CMyWinApp theApp;