Android自定义View画圆功能

<?xml version="1.0" encoding="utf-8"?> 
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:id="@+id/activity_main" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 android:paddingbottom="@dimen/activity_vertical_margin" 
 android:paddingleft="@dimen/activity_horizontal_margin" 
 android:paddingright="@dimen/activity_horizontal_margin" 
 android:paddingtop="@dimen/activity_vertical_margin" 
 tools:context="com.bwie.test.xuejian1508a20170928.mainactivity"> 
 
 <com.bwie.test.xuejian1508a20170928.viview 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
  /> 
</relativelayout>

public class viview extends view{ 
 paint paint; 
 context context; 
 //构造方法 
 public viview(context context) { 
 super(context); 
 } 
 
 public viview(context context, attributeset attrs) { 
 super(context, attrs); 
 } 
 
 public viview(context context, attributeset attrs, int defstyleattr) { 
 super(context, attrs, defstyleattr); 
 } 
 
 public viview(context context, attributeset attrs, int defstyleattr, int defstyleres) { 
 super(context, attrs, defstyleattr, defstyleres); 
 this.context=context; 
 } 
 
 @override 
 protected void onmeasure(int widthmeasurespec, int heightmeasurespec) { 
 super.onmeasure(widthmeasurespec, heightmeasurespec); 
 } 
 
 @override 
 protected void onlayout(boolean changed, int left, int top, int right, int bottom) { 
 super.onlayout(changed, left, top, right, bottom); 
 
 } 
 
 /*绘图*/ 
 @override 
 protected void ondraw(canvas canvas) { 
 super.ondraw(canvas); 
 //得到屏幕宽高 
 int width = getwidth(); 
 int radius = width - 450/2; 
 int height = getheight(); 
// 创建画笔 
 paint paint1 = new paint(); 
 paint paint2 = new paint(); 
 paint paint3= new paint(); 
// 消除锯齿 
 paint1.setantialias(true); 
 paint2.setantialias(true); 
 paint3.setantialias(true); 
 //画笔颜色 
 paint1.setcolor(color.red); 
 paint2.setcolor(color.white); 
 paint3.setcolor(color.blue); 
// 画圆。确定位置 
// canvas.drawrect(100,100,width/2,height/2,paint1); 
// canvas.drawcircle(100,100,100,paint1); 
// canvas.drawcircle(250,250,200,paint2); 
// canvas.drawcircle(500,500,300,paint3); 
 //设置圆环形状和大小 
 rectf oval = new rectf(width-radius,width-radius,width+radius,width+radius); 
 paint1.setstrokewidth(450); 
 canvas.drawarc(oval,-90,90,false,paint1); 
 
 canvas.drawcircle(width/2,height/2,450,paint1); 
 canvas.drawcircle(width/2,height/2,300,paint2); 
 canvas.drawcircle(width/2,height/2,200,paint3); 
 } 
 
 @override 
 public boolean ontouchevent(motionevent event) { 
 return super.ontouchevent(event); 
 } 
}