Android 自定义View（ 雷达扫描）

/**

 *
 * 转载请标明出处：http://blog.csdn.net/u013598111/article/details/50444438

 *   @author：【JunTao_sun】
 *
 *
*/

因为 控件大小位移了10   上图GIF 的线没去加上偏移距离，所以看起来有点缺陷，不过效果还是不错的

具体实现：

public class demo extends FrameLayout {     //View的大小    private int viewSize = 600;      private Paint mPaintLine;      private Paint mPaint;      private boolean isStart = false;      private ScanThread mThread;      private int start = 0;      private Random random;    //两个随机点    private Paint mPointPaint1;    private Paint mPointPaint2;      private final int paintWidth = 3;private Paint mPaintC;private Paint mPaintCC;        public demo(Context context) {          super(context);          init();      }        public demo(Context context, AttributeSet attrs) {          super(context, attrs);          init();            }        /**     * 初始化     */    private void init() {          initPaint();          mThread = new ScanThread();          random=new Random();        setBackgroundColor(Color.TRANSPARENT);      }        private void initPaint() {          mPaintLine = new Paint();          mPaintLine.setStrokeWidth(paintWidth>>1);          mPaintLine.setAntiAlias(true);          mPaintLine.setStyle(Style.STROKE);          mPaintLine.setColor(0x880000ff);          mPaintLine.setStrokeCap(Paint.Cap.ROUND);                mPaintCC = new Paint();          mPaintCC.setStrokeWidth(paintWidth);          mPaintCC.setAntiAlias(true);          mPaintCC.setStyle(Style.STROKE);          mPaintCC.setColor(0xaa000000);          mPaintCC.setStrokeCap(Paint.Cap.ROUND);                mPaintC = new Paint();          mPaintC.setStrokeWidth(paintWidth>>1);          mPaintC.setAntiAlias(true);          mPaintC.setStyle(Style.STROKE);          mPaintC.setColor(0X87872300);          mPaintC.setStrokeCap(Paint.Cap.ROUND);                  mPaint = new Paint();          mPaint.setColor(0x9D00ff00);          mPaint.setAntiAlias(true);                          mPointPaint1 = new Paint();          mPointPaint1.setStrokeWidth(2);        mPointPaint1.setColor(0xffff0000);          mPointPaint1.setAntiAlias(true);        mPointPaint1.setAlpha(0);                mPointPaint2 = new Paint();          mPointPaint2.setStrokeWidth(2);        mPointPaint2.setColor(0xffff0000);          mPointPaint2.setAntiAlias(true);        mPointPaint2.setAlpha(0);                       flag_reset1=true;        flag_reset2=true;        isReverse1=false;            }        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+10, viewSize+10);      }        public void start() {          mThread.start();          isStart = true;      }        public void stop() {          if (isStart) {              Thread.interrupted();              isStart = false;          }      }     //初始化角度渐变  从透明-绿色    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);         canvas.save();                 int radius = viewSize >> 1;          //画内圆        canvas.drawCircle(radius+10, radius, radius >> 1, mPaintC);          //画外圆        canvas.drawCircle(radius+10, radius, radius - (paintWidth >> 1), mPaintCC);                          canvas.drawLine(0, radius, viewSize, radius, mPaintLine);          canvas.drawLine(radius, 0, radius, viewSize, mPaintLine);             mPaint.setShader(mShader);         //设置矩阵        canvas.concat(matrix);         //第一种//        canvas.drawCircle(radius, radius, radius - paintWidth, mPaint);         //第二种        canvas.drawArc(new RectF(0, 0, viewSize, viewSize), 0, 180, true, mPaint);        canvas.restore();        //画随机点        int centerx=radius;        int centery=radius;        canvas.save();        canvas.scale(0.5f+change1/360,0.5f+change1/360);        canvas.drawCircle(200, 200, 8, mPointPaint1);        canvas.restore();                     if(!isReverse1&&flag_reset1){        int a=random.nextInt(360);        int d=random.nextInt(radius);              x1=  (int) (centerx+d*(Math.cos(a*Math.PI/180)));               y1= (int) (centery+d*(Math.sin(a*Math.PI/180)));              flag_reset1=false;          }                        if(!isReverse2&&flag_reset2){        int a=random.nextInt(360);        int d=random.nextInt(radius);              x2=  (int) (centerx+d*(Math.cos(a*Math.PI/180)));               y2= (int) (centery+d*(Math.sin(a*Math.PI/180)));              flag_reset2=false;            }          canvas.drawCircle(x1, y1, 8, mPointPaint1);              canvas.drawCircle(x2, y2, 8, mPointPaint2);                                          if(isFisrt){        isFisrt=false;        start();                }                  }      private boolean isFisrt=true;   //两个随机点坐标值    private int x1,x2;    private int y1,y2;    //不断改变的值  用于透明度ֵ    private int change1;    private int change2;    //是否重置位置  即是否随机点坐标    private boolean flag_reset1=false;    private boolean flag_reset2=false;    //是否开始反方向变化   从透明度255-0    private boolean isReverse1=false;    private boolean isReverse2=false;        protected class ScanThread extends Thread {                private final String TAG = null;        int halfsize = viewSize >> 1;                              @Override          public void run() {              while (isStart) {               //change1 小于0或者=0 即 说，说明是反方向执行过程中  所以设置为0和重置标志 true            if(change1<0){            isReverse1=false;            change1=0;            flag_reset1=true;            }                        if(change2<0){            isReverse2=false;            change2=0;            flag_reset2=true;            }                        //正方向下的 增值            if(!isReverse2)change2+=2;            if(!isReverse1)change1+=4;                            //正方向              if(change1>=255){             isReverse1=true;              change1=255;             }            if(change2>=255){            isReverse2=true;            change2=255;            }                //                if(isReverse1)change1-=8;                if(isReverse2)change2-=4;                           mPointPaint1.setAlpha(change1);                mPointPaint2.setAlpha(change2);                if(start>=360) start=0;                start+=2;                            matrix.reset();                matrix.postRotate(start, halfsize, halfsize);                               postInvalidate();                  try {                      Thread.sleep(10);                  } catch (InterruptedException e) {                      e.printStackTrace();                  }              }          }      }