WavingView

WavingView.java

public class WavingView extends View
    implements
    ValueAnimator.AnimatorUpdateListener,
    Animator.AnimatorListener {

  private int maxWaveRadius, minWaveRadius;
  private int centerX, centerY;
  private final long WAVE_SPREAD_DURATION = 2000;
  private final long WAVE_DELAY_DURATION = 1000;
  private final int WAVE_AMOUNT = 4;
  private boolean running;
  private ValueAnimator mAnimator;
  private Paint mPaint;
  private float totalCircle;
  private float waveDelayValue = 1f;
  private float waveDurationValue = 4f;

  private List<Wave> drawingWave;

  public WavingView(Context context) {
    super(context);
    init();
  }

  public WavingView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
  }

  public WavingView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
  }

  private void init() {
    maxWaveRadius = getResources().getDimensionPixelSize(R.dimen.wave_max_radius);
    minWaveRadius = getResources().getDimensionPixelSize(R.dimen.wave_min_radius);
    mPaint = new Paint();
    // totalCircle = (WAVE_AMOUNT-2) * waveDelayValue + waveDurationValue;
    totalCircle = waveDurationValue;
  }

  private void initAnimator() {
    mAnimator = ValueAnimator.ofFloat(0, totalCircle);
    mAnimator.setDuration((WAVE_AMOUNT - 1) * WAVE_DELAY_DURATION + WAVE_SPREAD_DURATION);
    mAnimator.setInterpolator(new LinearInterpolator());
    mAnimator.addUpdateListener(this);
    mAnimator.addListener(this);
  }

  public void startWaving() {
    if (running) {
      return;
    }
    this.running = true;

    if (drawingWave == null) {
      drawingWave = new ArrayList<>();
      for (int i = 0; i < WAVE_AMOUNT; i++) {
        drawingWave.add(new Wave(i * waveDelayValue));
      }
    }
    initAnimator();
    mAnimator.start();
  }

  public void stopWaving() {
    this.running = false;
    if (mAnimator != null) {
      mAnimator.cancel();
    }
  }

  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    drawContent(canvas);
  }

  private void drawContent(Canvas canvas) {
    if (running && drawingWave != null) {
      for (Wave wave : drawingWave) {
        mPaint.setColor(Color.argb(wave.getAlpha(), 255, 104, 55));
        canvas.drawCircle(centerX, centerY, wave.getRadius(), mPaint);
      }
    }
  }

  public void setCenterX(int centerX) {
    this.centerX = centerX;
  }

  public void setCenterY(int centerY) {
    this.centerY = centerY;
  }

  @Override
  public void onAnimationStart(Animator animation) {

  }

  @Override
  public void onAnimationEnd(Animator animation) {
    if (running) {
      initAnimator();
      mAnimator.start();
    }
  }

  @Override
  public void onAnimationCancel(Animator animation) {

  }

  @Override
  public void onAnimationRepeat(Animator animation) {

  }

  @Override
  public void onAnimationUpdate(ValueAnimator animation) {
    if (drawingWave != null) {
      for (int i = 0; i < drawingWave.size(); i++) {
        Wave wave = drawingWave.get(i);
        wave.onAnimationUpdate(i, (float) animation.getAnimatedValue());
      }
      invalidate();
    }
  }

  public class Wave {
    public float animatingValue = 0;
    private float delay;

    public Wave(float delay) {
      this.delay = delay;
      init();
    }

    private void init() {}

    public int getAlpha() {
      if (animatingValue == -1) {
        return 0;
      } else {
        return (int) ((1f - animatingValue) * 255);
      }
    }

    public int getRadius() {
      if (animatingValue == -1) {
        return 0;
      } else {
        return minWaveRadius + (int) ((maxWaveRadius - minWaveRadius) * animatingValue);
      }
    }

    private long lastUpdate = 0;

    public void onAnimationUpdate(int index, float runningValue) {
      float circleValue = ((runningValue + totalCircle - delay) % totalCircle);
      if (circleValue >= 0 && circleValue <= waveDurationValue) {
        animatingValue =
            circleValue / waveDurationValue;
      } else {
        animatingValue = -1;
      }
      if (index == 0) {
//        Log.e("SUAN", "" + (System.currentTimeMillis() - lastUpdate) + "|" + animatingValue);
      }
      lastUpdate = System.currentTimeMillis();
    }

  }

}