(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;

}

}