package com.example.wave;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.Paint.Style;import android.graphics.Shader;import android.graphics.SweepGradient;import android.util.AttributeSet;import android.widget.FrameLayout;public class RadarView extends FrameLayout { private int viewSize = 500; private Paint mPaintLine; private Paint mPaintSector; private boolean isStart = false; private ScanThread mThread; private int start = 0; private final int paintWidth = 10; public RadarView(Context context) {  super(context);  init(); } public RadarView(Context context, AttributeSet attrs) {  super(context, attrs);  init(); } private void init() {  initPaint();  mThread = new ScanThread();  setBackgroundColor(Color.TRANSPARENT); } private void initPaint() {  mPaintLine = new Paint();  mPaintLine.setStrokeWidth(paintWidth);  mPaintLine.setAntiAlias(true);  mPaintLine.setStyle(Style.STROKE);  mPaintLine.setColor(0xffff0000);  mPaintSector = new Paint();  mPaintSector.setColor(0x9D00ff00);  mPaintSector.setAntiAlias(true); } public void setViewSize(int size) {  this.viewSize = size;  mShader = new SweepGradient(viewSize >> 1, viewSize >> 1, Color.TRANSPARENT, Color.GREEN);  setMeasuredDimension(viewSize, viewSize); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  setMeasuredDimension(viewSize, viewSize); } public void start() {  mThread.start();  isStart = true; } public void stop() {  if (isStart) {   Thread.interrupted();   isStart = false;  } } private Shader mShader = new SweepGradient(viewSize >> 1, viewSize >> 1, Color.TRANSPARENT, Color.GREEN); private Matrix matrix = new Matrix(); @Override protected void onDraw(Canvas canvas) {  super.onDraw(canvas);  int halfRadaSize = viewSize >> 1;  canvas.drawCircle(halfRadaSize, halfRadaSize, halfRadaSize >> 1, mPaintLine);  canvas.drawCircle(halfRadaSize, halfRadaSize, halfRadaSize - (paintWidth >> 1), mPaintLine);  canvas.drawLine(halfRadaSize, 0, halfRadaSize, viewSize, mPaintLine);  canvas.drawLine(0, halfRadaSize, viewSize, halfRadaSize, mPaintLine);  mPaintSector.setShader(mShader);  canvas.concat(matrix);  canvas.drawCircle(halfRadaSize, halfRadaSize, halfRadaSize - paintWidth, mPaintSector); } protected class ScanThread extends Thread {  int halfRadaSize = viewSize >> 1;  @Override  public void run() {   while (isStart) {    start = start + 2;    matrix.reset();    matrix.postRotate(start, halfRadaSize, halfRadaSize);    postInvalidate();    try {     Thread.sleep(10);    } catch (InterruptedException e) {     e.printStackTrace();    }   }  } }}