MFC鼠标绘图

最近刚开始学习Visual c++6.0

还是菜鸟级别

单击左键，画点

按住左键拖动，画线

单击右键，清除屏幕

改变画框大小，画面重画

// MyProg2bView.cpp : implementation of the CMyProg2bViewclass
//

#include "stdafx.h"
#include "MyProg2b.h"

#include "MyProg2bDoc.h"
#include "MyProg2bView.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CMyProg2bView

IMPLEMENT_DYNCREATE(CMyProg2bView, CView)

BEGIN_MESSAGE_MAP(CMyProg2bView, CView)
 //{{AFX_MSG_MAP(CMyProg2bView)
 ON_WM_LBUTTONDOWN()
 ON_WM_RBUTTONDOWN()
 ON_WM_MOUSEMOVE()
 ON_WM_ERASEBKGND()
 //}}AFX_MSG_MAP
 // Standard printing commands
 ON_COMMAND(ID_FILE_PRINT,CView::OnFilePrint)
 ON_COMMAND(ID_FILE_PRINT_DIRECT,CView::OnFilePrint)
 ON_COMMAND(ID_FILE_PRINT_PREVIEW,CView::OnFilePrintPreview)
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CMyProg2bView construction/destruction

CMyProg2bView::CMyProg2bView()
{
 // TODO: add construction code here

 m_MousePositions.SetSize(0,100);
 m_ButtonDown.SetSize(0,100); //用来记录按钮的状态信息
   m_nPrevIndex=0;

}

CMyProg2bView::~CMyProg2bView()
{
 ClearList();
}

BOOLCMyProg2bView::PreCreateWindow(CREATESTRUCT&cs)
{
 // TODO: Modify the Window class or styles hereby modifying
 //  the CREATESTRUCT cs

 return CView::PreCreateWindow(cs);
}

/////////////////////////////////////////////////////////////////////////////
// CMyProg2bView drawing

void CMyProg2bView::OnDraw(CDC* pDC)
{
 CMyProg2bDoc* pDoc = GetDocument();
 ASSERT_VALID(pDoc);
 // TODO: add draw code for native data here

 int nPositions=m_MousePositions.GetSize();
 if(m_nPrevIndex>=nPositions)
 {
  return;
 }

 CPoint *pPoint;
 int i=0;
 pPoint =(CPoint*)m_MousePositions[m_nPrevIndex];
 pDC->MoveTo(* pPoint);
 for(i=m_nPrevIndex;i<nPositions;i++)
 {
  pPoint=(CPoint*)m_MousePositions[i];
  if(m_ButtonDown[i])
  {
   pDC->MoveTo(*pPoint);
   pDC->SetPixel(*pPoint,RGB(0,0,0));
  }
  else
  {
   pDC->LineTo(*pPoint);
  }
  
 }
m_nPrevIndex=nPositions-1;

 
}

（增加变量m_nPrevIndex来保存最新画过的鼠标位置在表中的下标，画完之后，更新该成员保存的下标值以提示最新画过的鼠标的位置）

/////////////////////////////////////////////////////////////////////////////
// CMyProg2bView printing

BOOL CMyProg2bView::OnPreparePrinting(CPrintInfo* pInfo)
{
 // default preparation
 return DoPreparePrinting(pInfo);
}

void CMyProg2bView::OnBeginPrinting(CDC* , CPrintInfo* )
{
 // TODO: add extra initialization beforeprinting
}

void CMyProg2bView::OnEndPrinting(CDC* , CPrintInfo* )
{
 // TODO: add cleanup after printing
}

/////////////////////////////////////////////////////////////////////////////
// CMyProg2bView diagnostics

#ifdef _DEBUG
void CMyProg2bView::AssertValid() const
{
 CView::AssertValid();
}

void CMyProg2bView::Dump(CDumpContext& dc)const
{
 CView::Dump(dc);
}

CMyProg2bDoc* CMyProg2bView::GetDocument() // non-debug versionis inline
{
 ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CMyProg2bDoc)));
 return (CMyProg2bDoc*)m_pDocument;
}
#endif //_DEBUG

/////////////////////////////////////////////////////////////////////////////
// CMyProg2bView message handlers

void CMyProg2bView::OnLButtonDown(UINT nFlags, CPoint point)
{
 // TODO: Add your message handler code hereand/or call default
 
 CView::OnLButtonDown(nFlags, point);

 

 AddList(TRUE,point);
 Invalidate();
}

void CMyProg2bView::OnRButtonDown(UINT nFlags, CPointpoint)
{
 // TODO: Add your message handler code hereand/or call default
 
 CView::OnRButtonDown(nFlags, point);

 
 ClearList();
 Invalidate();

}
void CMyProg2bView::ClearList()
{
 int i;
 CPoint *pPoint;
 for(i=0;i<m_MousePositions.GetSize();i++)
 {
  pPoint=(CPoint*)m_MousePositions[i];
  delete pPoint;
 }
 m_MousePositions.RemoveAll();
 m_ButtonDown.RemoveAll();
}

//每个CPoint对象都是由一个new操作符从堆中分配内存的，所以与之对应，每个CPoint对象也要由一个delete来释放。m_MousePosition中所有指针指向的对象都已释放之后，调用RemoveAll()将用到的数组置空。

void CMyProg2bView::OnMouseMove(UINT nFlags, CPoint point)
{
 // TODO: Add your message handler code hereand/or call default
 
 CView::OnMouseMove(nFlags, point);

 if(nFlags&MK_LBUTTON)
 {
   AddList(FALSE,point);
   Invalidate(FALSE);
 }

}

void CMyProg2bView::AddList(int button, CPoint point)
{
  CPoint * pnewPoint=newCPoint(point);
 m_MousePositions.Add((void *)pnewPoint);
 
  m_ButtonDown.Add(button);
}

BOOL CMyProg2bView::OnEraseBkgnd(CDC* pDC)
{
 // TODO: Add your message handler code hereand/or call default
 
 m_nPrevIndex=0;
 return CView::OnEraseBkgnd(pDC);
}

(无论何时客户区被擦除,就发送一个名为WM_REASEBKGND的消息，WM_LBUTTONDOWN和WM_MOUSEMOVE消息引起的扥更新并不擦除背景（若要跳过擦屏，调用Invalidate（）时就要以FALSE作参数）.一收到WM_REASEBKGND消息，就知道必须用保存的信息重画整个窗口)