内存缓冲作图

void C***View::OnPaint() 
{
    CPaintDC dc(this); 
    RECT rect;
    GetClientRect(&rect);
    CBitmap *bitmap;
    bitmap=new CBitmap;
    bitmap->m_hObject=(HBITMAP)::LoadImage(NULL,"0.bmp",IMAGE_BITMAP,rect.right,rect.bottom,LR_LOADFROMFILE);

    CDC *mdc;
    mdc=new CDC;
    mdc->CreateCompatibleDC(&dc);
    mdc->SelectStockObject(BLACK_BRUSH);
    mdc->SelectObject(bitmap);//先加载位图
    mdc->Rectangle(0,0,300,300);    //再操作内存dc作图
    dc.BitBlt(0,0,rect.right,rect.bottom,mdc,0,0,SRCCOPY);//拷贝显示
    delete mdc;
}