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最新推荐文章于 2025-04-02 10:49:25 发布

原创最新推荐文章于 2025-04-02 10:49:25 发布 · 395 阅读

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本文介绍了一种通过抽象基类实现不同版本绘图功能的方法。具体展示了如何利用多态特性来实现不同版本的绘图功能，包括绘制直线和圆形，并通过具体的例子说明了这种设计模式的应用。

#include <iostream>
using namespace std;
class DP1
{
public:
static void draw_a_line (double x1, double y1, double x2, double y2)
{
    cout << "DP1 draw_a_line" << x1 << y1 << x2 << y2 <<endl;
}
static void draw_a_circle (double x, double y, double r)
{
    cout << "DP1 draw_a_circle" << x << y << r << endl;
}
};
class DP2 {
public:
static void drawline (double x1, double x2, double y1, double y2)
{
    cout << "DP2 drawLine" << x1 << y1 << x2 << y2 << endl;
}
static void drawcircle (double x, double y, double r)
{
    cout << "DP2 drawCircle" << x << y << r << endl;
}
};
class Drawing {
public:
virtual void drawLine (double x1, double y1, double x2, double y2)=0;
virtual void drawCircle(double x, double y, double radious) = 0;
};
class V1Drawing : public Drawing
{
public:
void drawLine (double x1, double y1, double x2, double y2);
void drawCircle(double x, double y, double r);
};
void V1Drawing::drawLine (double x1, double y1, double x2, double y2)
{
DP1::draw_a_line(x1,y1,x2,y2);
}
void V1Drawing::drawCircle (double x, double y, double r)
{
DP1::draw_a_circle (x,y,r);
}
class V2Drawing : public Drawing
{
public:
void drawLine (double x1, double y1, double x2, double y2);
void drawCircle(double x, double y, double r);
};
void V2Drawing::drawLine (double x1, double y1, double x2, double y2)
{
DP2::drawline(x1,x2,y1,y2);
}
void V2Drawing::drawCircle (double x, double y, double r)
{
DP2::drawcircle(x, y, r);
}
class Shape {
public:
Shape(Drawing *dp);
virtual void draw()=0;
void drawLine(double x1, double y1, double x2, double y2);
void drawCircle(double x, double y, double r);
private:
Drawing *_dp;
};
Shape::Shape (Drawing *dp) {
_dp= dp;
}
void Shape::drawLine(double x1, double y1,
       double x2, double y2)
{
_dp->drawLine(x1,y1,x2,y2);
}
void Shape::drawCircle(double x, double y, double r)
{
_dp->drawCircle(x, y, r);
}
class Rectangle:public Shape
{
private:
double _x1, _y1, _x2, _y2;
Drawing *dp;
public:
void draw();
Rectangle(Drawing *dp, double x1, double y1, double x2, double y2);

};
Rectangle::Rectangle (Drawing *dp, double x1, double y1, double x2, double y2) :Shape( dp) {
_x1= x1; _x2= x2;
_y1= y1; _y2= y2;
}
void Rectangle::draw () {
drawLine(_x1,_y1,_x2,_y1);
drawLine(_x2,_y1,_x2,_y2);
drawLine(_x2,_y2,_x1,_y2);
drawLine(_x1,_y2,_x1,_y1);
}
class Circle:public Shape
{
private:
double _x, _y, _r;
Drawing *dp;
public:
void draw();
Circle (Drawing *dp, double x, double y, double r);
};
Circle::Circle (Drawing *dp, double x, double y, double r) : Shape(dp)
{
_x= x;
_y= y;
_r= r;
}
void Circle::draw () {
drawCircle( _x, _y, _r);
}

int main() {
Shape *s1;
Shape *s2;
Drawing *dp1, *dp2;
dp1= new V1Drawing;
s1=new Rectangle(dp1,1,1,2,2);
dp2= new V2Drawing;
s2= new Circle(dp2,2,2,4);
s1->draw();
s2->draw();
delete s1; delete s2;
delete dp1; delete dp2;
return 0;
}
// NOTE: Memory management not tested.
// Includes not shown.

// We have been given the implementations for
// DP1 and DP2