#include "math.h"  #define Pi 3.1415927    void CMfcSdiSampleView::OnDraw(CDC* pDC)  {      CMfcSdiSampleDoc* pDoc = GetDocument();      ASSERT_VALID(pDoc);      if (!pDoc)          return;        // TODO: add draw code for native data here      CRect rect;      GetClientRect(&rect);      int radius=800;      pDC->SetMapMode(MM_ISOTROPIC);      pDC->SetWindowExt(radius+100,radius+100);      pDC->SetViewportExt(rect.right/2,-rect.bottom/2);      pDC->SetViewportOrg(rect.right/2,rect.bottom/2);        //获取内容状态信息      MEMORYSTATUS mem;      ::GlobalMemoryStatus(&mem);      SIZE_T MemTotal=mem.dwTotalPhys;      SIZE_T MemAvail=mem.dwAvailPhys;      double dFree=(double)(Pi*2*MemAvail/MemTotal);      double dUsed=(double)Pi*2-dFree;      int x=-(int)(sin(dUsed)*radius);      int y= (int)(cos(dUsed)*radius);        CPen pen1,pen2,*oldpen;      CBrush brush1,brush2,*oldbrush;      //绘制已用      pen1.CreatePen(PS_SOLID,50,RGB(255,0,0));      brush1.CreateSolidBrush(RGB(255,0,0));      oldpen=pDC->SelectObject(&pen1);      oldbrush=pDC->SelectObject(&brush1);      pDC->Pie(-radius,radius,radius,-radius,0,radius,x,y);      pDC->SelectObject(oldpen);      pDC->SelectObject(oldbrush);      //绘制未用      brush2.CreateSolidBrush(RGB(0,160,255));      pen2.CreatePen(PS_SOLID,50,RGB(0,160,255));      oldpen=pDC->SelectObject(&pen2);      oldbrush=pDC->SelectObject(&brush2);      pDC->Pie(-radius,radius,radius,-radius,x,y,0,radius);      pDC->SelectObject(oldpen);      pDC->SelectObject(oldbrush);        pDC->SetBkMode(TRANSPARENT);      CString str;      str.Format(_T("Total: %dKB"),MemTotal/1024); //物理总内存      pDC->TextOut(300,300,str);      str.Format(_T("Available: %dKB"),MemAvail/1024); //剩余内存      pDC->TextOut(300,200,str);  }    void CMfcSdiSampleView::OnTimer(UINT_PTR nIDEvent)  {      // TODO: Add your message handler code here and/or call default      Invalidate();      CView::OnTimer(nIDEvent);  }    int CMfcSdiSampleView::OnCreate(LPCREATESTRUCT lpCreateStruct)  {      if (CView::OnCreate(lpCreateStruct) == -1)          return -1;        // TODO:  Add your specialized creation code here      SetTimer(1,1000,NULL);      return 0;  }