(11)一步一步开发一个简单CAD之策略模式

要对模型的操作中,为了实现不现的命令,可以用简单工厂+策略模式,这个也是实现mvc架构的一个重要的设计模式

具体代码如下

class CContext//使用策略模式加简单工厂
{
public:
 CContext(){m_pCmd = new CComand(), m_pEx = new CExplan(),m_pMove = new CMove();};//实现即时平移
 virtual ~CContext(){ if(m_pCmd) {delete m_pCmd; } if(m_pEx){delete m_pEx;} if(m_pMove) {delete m_pMove;}};
 
 
 
 void TypeCmd(int Num);

 void OnLButtonDown(UINT nFlags,  CPosition pos){m_pCmd->OnLButtonDown(nFlags,  pos);};
    void OnMouseMove(UINT nFlags,  CPosition pos){m_pCmd->OnMouseMove(nFlags,   pos),m_pMove->OnMouseMove(nFlags, pos);};
    void OnRButtonDown(UINT nFlags,  CPosition pos){m_pCmd->OnRButtonDown(nFlags,  pos);};
    void OnLButtonUp(UINT nFlags,  CPosition pos){m_pCmd->OnLButtonUp(nFlags,   pos);};
 void OnMouseWheel(UINT nFlags, short zDelta, CPosition pos){m_pCmd->OnMouseWheel(nFlags, zDelta, pos), m_pEx->OnMouseWheel(nFlags, zDelta, pos);};
    void OnMButtonDown(UINT nFlags, CPosition pos){m_pCmd->OnMButtonDown(nFlags,  pos), m_pMove->OnMButtonDown(nFlags, pos);};
    void OnMButtonUp(UINT nFlags, CPosition pos){m_pCmd->OnMButtonUp(nFlags, pos), m_pMove->OnMButtonUp(nFlags, pos);};
private:
 CComand *m_pCmd;
 CComand *m_pEx;//实现即时中键缩放
 CComand *m_pMove;//实现即中键平移
};

void CContext::TypeCmd(int Num)
{
  if(m_pCmd)
    {
     delete m_pCmd;
     m_pCmd = NULL;
    }
    switch(Num)
    {
    case ID_DRAW_LINE :
         m_pCmd = new CCreateLine();//改变光标
        break;
    case ID_DRAW_CIRCLE :
    m_pCmd = new CCreateCircle();
    break;
 case ID_DRAW_RECT :
   m_pCmd = new CCreateRect();
   break;
 case ID_EXPLANSMALL :
   m_pCmd = new CExsmall();
         break;
 case ID_EXPLANLarge :
   m_pCmd = new CExlarge();
         break;
 case ID_TRANSLATE :
   m_pCmd = new CBaseMove();//平移命令
         break;
    case ID_PICK :
   m_pCmd = new CSelect();//检选
   break;
    case ID_UNPICK :
   m_pCmd = new CUnSelect();//去掉捡选
   break;
    case ID_DELETE :
   m_pCmd = new CDelete();//删除
   break;
    case ID_ALLDELETE :
   m_pCmd = new CAllDelete();//全删
   break;
    case ID_MIRROR :
   m_pCmd = new CMirror();
   break;
 case ID_ROTATE :
   m_pCmd = new CMirror();
   break;

    default:
        break;
    }
}