Android实现光点模糊渐变的自旋转圆环特效

/**
 * Created by jiangzn on 17/2/3.
 */
public class RoundLightBarView extends ImageView {
  private int mTotalWidth, mTotalHeight;
  private int mCenterX, mCenterY;
  //底色画笔
  private Paint mCirclePaint;
  //进度条画笔
  private Paint mProgressPaint;
  //圆点画笔
  private Paint mbitmapPaint;
  private Matrix mMatrix; // 矩阵,用于对图片进行一些操作
  private float[] pos;   // 当前点的实际位置
  private float[] tan;   // 当前点的tangent值,用于计算图片所需旋转的角度
 
 
  private int mCircleR;
 
 
  private Context mContext;
  //距离外围的边距
  private float interval ;
 
  private int startAngle = 1;
 
  //球
  private Bitmap mLititleBitmap; // 圆点图片
 
  public RoundLightBarView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
 
  }
 
  public RoundLightBarView(Context context, AttributeSet attrs) {
    super(context, attrs);
    mContext = context;
    interval = DensityUtils.px2dip(mContext, 50);
    //初始化画笔
    initPaint();
    //初始化bitmap
    initBitmap();
  }
 
  private void initBitmap() {
    mMatrix=new Matrix();
    pos = new float[2];
    tan = new float[2];
    mLititleBitmap= ((BitmapDrawable) getResources()
        .getDrawable(R.mipmap.white_round))
        .getBitmap();
  }
 
  private void initPaint() {
    //画黑底的深色圆画笔
    mCirclePaint = new Paint();
    //抗锯齿
    mCirclePaint.setAntiAlias(true);
    // 防抖动
    mCirclePaint.setDither(true);
    // 开启图像过滤，对位图进行滤波处理。
    mCirclePaint.setFilterBitmap(true);
    mCirclePaint.setColor(Color.BLACK);
    //空心圆
    mCirclePaint.setStyle(Paint.Style.STROKE);
    //圆半径
    mCircleR = DensityUtils.px2dip(mContext, 20);
    mCirclePaint.setStrokeWidth(mCircleR);
 
    //画彩色圆弧的画笔
    mProgressPaint = new Paint();
    //抗锯齿
    mProgressPaint.setAntiAlias(true);
    // 防抖动
    mProgressPaint.setDither(true);
    // 开启图像过滤，对位图进行滤波处理。
    mProgressPaint.setFilterBitmap(true);
    mProgressPaint.setColor(Color.BLUE);
    //空心圆
    mProgressPaint.setStyle(Paint.Style.STROKE);
    //设置笔刷样式为原型
    mProgressPaint.setStrokeCap(Paint.Cap.ROUND);
    //设置圆弧粗
    mProgressPaint.setStrokeWidth(mCircleR);
    //将绘制的内容显示在第一次绘制内容之上
    mProgressPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));
 
 
    //圆点画笔
    mbitmapPaint = new Paint();
    mbitmapPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP));
    mbitmapPaint.setStyle(Paint.Style.FILL);
    mbitmapPaint.setAntiAlias(true);
 
  }
 
  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    //canvas去锯齿
    canvas.setDrawFilter(
        new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG));
    //画底色圆
    canvas.drawCircle(mCenterX, mCenterY, mCenterX - mCircleR - interval, mCirclePaint);
    //画进度条
    int colorSweep[] = {Color.TRANSPARENT, Color.parseColor("#3bbaea"),Color.parseColor("#7ac9d3"),Color.parseColor("#7cc9d0")};
 
    //设置渐变色
    sweepGradient = new SweepGradient(mCenterX, mCenterY, colorSweep, null);
    //按照圆心旋转
    Matrix matrix = new Matrix();
    matrix.setRotate(startAngle, mCenterX, mCenterY);
    sweepGradient.setLocalMatrix(matrix);
 
    mProgressPaint.setShader(sweepGradient);
 
    canvas.drawArc(
        new RectF(0 + mCircleR + interval, 0 + mCircleR + interval,
            mTotalWidth - mCircleR - interval, mTotalHeight - mCircleR - interval),
        2 + startAngle, 350, false, mProgressPaint);
 
    startAngle++;
    if (startAngle == 360) {
      startAngle = 1;
    }
 
    //绘制白色小星星
    Path orbit = new Path();
    //通过Path类画一个90度（180―270）的内切圆弧路径
    orbit.addArc(
        new RectF(0 + mCircleR + interval, 0 + mCircleR + interval,
            mTotalWidth - mCircleR - interval, mTotalHeight - mCircleR - interval)
        , 2 + startAngle, 350);
    // 创建 PathMeasure
    PathMeasure measure = new PathMeasure(orbit, false);
    measure.getPosTan(measure.getLength() * 1, pos, tan);
    mMatrix.reset();
    mMatrix.postScale(2,2);
    mMatrix.postTranslate(pos[0] - mLititleBitmap.getWidth() , pos[1] - mLititleBitmap.getHeight() );  // 将图片绘制中心调整到与当前点重合
    canvas.drawBitmap(mLititleBitmap, mMatrix, mbitmapPaint);//绘制球
    mbitmapPaint.setColor(Color.WHITE);
    //绘制实心小圆圈
    canvas.drawCircle(pos[0], pos[1], 5, mbitmapPaint);
 
    //启动绘制
    postInvalidateDelayed(10);
  }
 
  SweepGradient sweepGradient;
 
  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    mTotalWidth = w;
    mTotalHeight = h;
    mCenterX = mTotalWidth / 2;
    mCenterY = mTotalHeight / 2;
 
 
  }
 
}

 // 创建 PathMeasure
    PathMeasure measure = new PathMeasure(orbit, false);
    measure.getPosTan(measure.getLength() * 1, pos, tan);
    mMatrix.reset();
    mMatrix.postScale(2,2);
    mMatrix.postTranslate(pos[0] - mLititleBitmap.getWidth() , pos[1] - mLititleBitmap.getHeight() );  // 将图片绘制中心调整到与当前点重合
    canvas.drawBitmap(mLititleBitmap, mMatrix, mbitmapPaint);//绘制球
    mbitmapPaint.setColor(Color.WHITE);
    //绘制实心小圆圈
    canvas.drawCircle(pos[0], pos[1], 5, mbitmapPaint);