class Shape{

public:

virtual void Draw(const Graphics& g)=0;

virtual ~Shape() { }

};

class Point{

public:

int x;

int y;

};

class Line: public Shape{

public:

Point start;

Point end;

Line(const Point& start, const Point& end){

this->start = start;

this->end = end;

}

//实现自己的Draw，负责画自己

virtual void Draw(const Graphics& g){

g.DrawLine(Pens.Red,

start.x, start.y,end.x, end.y);

}

};

class Rect: public Shape{

public:

Point leftUp;

int width;

int height;

Rect(const Point& leftUp, int width, int height){

this->leftUp = leftUp;

this->width = width;

this->height = height;

}

//实现自己的Draw，负责画自己

virtual void Draw(const Graphics& g){

g.DrawRectangle(Pens.Red,

leftUp,width,height);

}

};

//增加

class Circle : public Shape{

public:

//实现自己的Draw，负责画自己

virtual void Draw(const Graphics& g){

g.DrawCircle(Pens.Red,

...);

}

};