2020寒假学习笔记04

 1 case class Point(var x:Double,var y:Double)extends Drawable
 2 {
 3     def shift(deltaX:Double,deltaY:Double)
 4     {
 5         x+=deltaX;
 6         y+=deltaY
 7     }
 8 }
 9 trait Drawable
10 {
11     def draw(){println(this.toString)}
12 }
13 abstract class Shape(var location:Point)//location是Shape的一个可变字段
14 {
15     def moveTo(newLocation:Point)//默认实现，只是修改位置
16     {
17         location=newLocation
18     }
19     def zoom(scale:Double)
20 }
21 class Line(beginPoint:Point,var endPoint:Point)extends Shape(beginPoint)with Drawable
22 {
23     override def draw()
24     {
25         println(s"Line:(${location.x},${location.y})--(${endPoint.x},${endPoint.y})")//按规定格式重载click        
26     }
27     
28     override def moveTo(newLocation:Point)
29     {
30         endPoint.shift(newLocation.x-location.x,newLocation.y-location.y)//直线移动时，先移动另外一个端点
31         location=newLocation //移动位置
32     }
33     
34     override def zoom(scale:Double)
35     {
36         val midPoint=Point((endPoint.x+location.x)/2,(endPoint.y+location.y)/2) //求出中点，并按中点进行缩放
37         location.x=midPoint.x+scale*(location.x-midPoint.x)
38         location.y=midPoint.y+scale*(location.y-midPoint.y)
39         endPoint.x=midPoint.x+scale*(endPoint.x-midPoint.x)
40         endPoint.y=midPoint.y+scale*(endPoint.y-midPoint.y)
41     }
42 }
43 
44 class Circle(center:Point,var radius:Double)extends Shape(center)with Drawable
45 {
46     override def draw() //按规定重载click
47     {
48         println(s"Circle center:(${location.x},${location.y}),R=$radius")
49     }
50     
51     override def zoom(scale:Double)
52     {
53         radius=radius*scale //对圆的缩放只用修改半径
54     }
55 }
56 
57 object MyDraw
58 {
59     def main(args:Array[String])
60     {
61         val p=new Point(10,30)
62         p.draw
63         
64         val line1=new Line(Point(0,0),Point(20,20))
65         line1.draw
66         line1.moveTo(Point(5,5))
67         line1.draw
68         line1.zoom(2)
69         line1.draw
70         
71         val cir=new Circle(Point(10,10),5)
72         cir.draw
73         cir.moveTo(Point(30,20))
74         cir.draw
75         cir.zoom(0.5)
76         cir.draw    
77     }
78     
79 }