BottomSectorMenuView.Converter(mFab)
        .setToggleDuration(500, 800)
        .setAnchorRotationAngle(135f)
        .addMenuItem(R.drawable.icon_camera, "拍照") { Toast.makeText(this@MainActivity, "拍照", Toast.LENGTH_SHORT).show() }
        .addMenuItem(R.drawable.icon_photo, "圖片") { Toast.makeText(this@MainActivity, "圖片", Toast.LENGTH_SHORT).show() }
        .addMenuItem(R.drawable.icon_text, "文字") { Toast.makeText(this@MainActivity, "文字", Toast.LENGTH_SHORT).show() }
        .addMenuItem(R.drawable.icon_video, "視頻") { Toast.makeText(this@MainActivity, "視頻", Toast.LENGTH_SHORT).show() }
        .addMenuItem(R.drawable.icon_camera_shooting, "攝像") { Toast.makeText(this@MainActivity, "攝像", Toast.LENGTH_SHORT).show() }
        .apply()

/**
 * Email: frankchoochina@gmail.com
 * Created by FrankChoo on 2017/10/9.
 * Description: 底部扇形菜單, 通過Adapter添加Item
 *       1. 調用openMenu打開菜單
 *       2. 調用closeMenu關閉菜單
 */
public class SectorMenuView extends FrameLayout {
  // 每個ItemView之間的角度差
  private double mAngle;
  // 圓心坐標
  private Point mCenterPoint;
  // ItemView到圓心的半徑
  private float mMaxItemRadius;
  private float mCurItemRadius;
  // 背景圓的半徑
  private float mMaxBkgRadius;
  private float mCurBkgRadius;
  private Paint mPaint;

  private SectorMenuAdapter mAdapter;
  private OnMenuOpenedListener mMenuOpenedListener;
  private OnMenuClosedListener mMenuClosedListener;

  public SectorMenuView(Context context) {
    this(context, null);
  }

  public SectorMenuView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

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

  private void init() {
    // 初始化畫筆
    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    mPaint.setDither(true);
    mPaint.setStyle(Paint.Style.FILL);
    mPaint.setColor(Color.WHITE);
    // 設置背景圓繪制的半徑
    int displayWidth = getResources().getDisplayMetrics().widthPixels;
    mMaxBkgRadius = (int) Math.sqrt(Math.pow(displayWidth/2, 2.0) + Math.pow(displayWidth/2, 2.0));
    // 開啟ViewGroup的繪制
    setWillNotDraw(false);
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    // 這里直接將寬高寫死, 不支持Margin
    int width = getResources().getDisplayMetrics().widthPixels;
    int height = (int) Math.sqrt(Math.pow(width / 2, 2.0) + Math.pow(width / 2, 2.0));
    setMeasuredDimension(width, height);
    // 計算半徑
    int realWidth = width - getPaddingRight() - getPaddingLeft();
    int realHeight = height - getPaddingTop() - getPaddingBottom();
    mMaxItemRadius = realWidth / 2;
    // 計算圓心
    int centerX = getPaddingLeft() + realWidth / 2;
    int centerY = getPaddingTop() + realHeight;
    mCenterPoint = new Point(centerX, centerY);
  }

  @Override
  protected void onLayout(boolean changed, int l, int t, int r, int b) {
    super.onLayout(changed, l, t, r, b);
    for (int i = 0; i < getChildCount(); i++) {
      View child = getChildAt(i);
      double curAngle = Math.PI - mAngle * (i + 1);
      int childCenterX = (int) (mCenterPoint.x + mCurItemRadius * Math.cos(curAngle));
      int childCenterY = (int) (mCenterPoint.y - mCurItemRadius * Math.sin(curAngle));
      child.layout(
          childCenterX - child.getMeasuredWidth() / 2,
          childCenterY - child.getMeasuredHeight() / 2,
          childCenterX + child.getMeasuredWidth() / 2,
          childCenterY + child.getMeasuredHeight() / 2
      );
      // 這里動態的去設置子View的透明度
      child.setAlpha(mCurItemRadius / mMaxItemRadius);
    }
  }

  @Override
  protected void onDraw(Canvas canvas) {
    canvas.drawCircle(mCenterPoint.x, mCenterPoint.y, mCurBkgRadius, mPaint);
    super.onDraw(canvas);
  }

  public void setAdapter(SectorMenuAdapter adapter) {
    mAdapter = adapter;
    for (int i = 0; i < mAdapter.getCount(); i++) {
      View child = mAdapter.getView(i, null, this);
      addView(child);
    }
    mAngle = Math.PI / (mAdapter.getCount() + 1);
  }

  public void setBackgroudColor(@ColorInt int color) {
    mPaint.setColor(color);
  }

  public void setBackgroundResource(@ColorRes int colorResId) {
    mPaint.setColor(ContextCompat.getColor(getContext(), colorResId));
  }

  /**
   * 打開菜單
   */
  public void openMenu() {
    if (mMaxItemRadius == 0) {
      mMaxItemRadius = getResources().getDisplayMetrics().widthPixels / 2
          - getPaddingRight() - getPaddingLeft();
    }
    // 背景動畫
    ValueAnimator bkgAnim = ValueAnimator.ofFloat(0f, mMaxBkgRadius).setDuration(300);
    bkgAnim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        mCurBkgRadius = (float) animation.getAnimatedValue();
        invalidate();
      }
    });
    // item的位置動畫
    ValueAnimator itemTranslationAnim = ValueAnimator.ofFloat(0f, mMaxItemRadius).setDuration(300);
    itemTranslationAnim.setInterpolator(new OvershootInterpolator(2f));
    itemTranslationAnim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        mCurItemRadius = (float) animation.getAnimatedValue();
        requestLayout();
      }
    });
    // 動畫集合
    final AnimatorSet set = new AnimatorSet();
    set.playSequentially(bkgAnim, itemTranslationAnim);
    set.addListener(new AnimatorListenerAdapter() {
      @Override
      public void onAnimationStart(Animator animation) {
        setAlpha(1f);
        setVisibility(View.VISIBLE);
      }
      @Override
      public void onAnimationEnd(Animator animation) {
        if (mMenuOpenedListener != null) {
          mMenuOpenedListener.opened();
        }
      }
    });
    set.start();
  }

  /**
   * 關閉菜單
   */
  public void closeMenu() {
    // Item動畫
    ValueAnimator itemViewAnim = ValueAnimator.ofFloat(mMaxItemRadius, 0f).setDuration(300);
    itemViewAnim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        mCurItemRadius = (float) animation.getAnimatedValue();
        requestLayout();
      }
    });
    itemViewAnim.setInterpolator(new AnticipateInterpolator(2f));

    // 背景動畫
    ValueAnimator backgroundAnim = ValueAnimator.ofFloat(mMaxBkgRadius, 0f).setDuration(300);
    backgroundAnim.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator animation) {
        mCurBkgRadius = (float) animation.getAnimatedValue();
        invalidate();
      }
    });
    // 這里設置了該View整體透明度的變化, 防止消失的背景不在錨點處, 顯示效果突兀
    ObjectAnimator alphaAnim = ObjectAnimator.ofFloat(this, "alpha", 1f, 0f).setDuration(250);

    // 動畫集合
    AnimatorSet animatorSet = new AnimatorSet();
    animatorSet.play(itemViewAnim).before(backgroundAnim);
    animatorSet.play(backgroundAnim).with(alphaAnim);
    animatorSet.addListener(new AnimatorListenerAdapter() {
      @Override
      public void onAnimationEnd(Animator animation) {
        if (mMenuClosedListener != null) {
          mMenuClosedListener.closed();
        }
        setVisibility(View.INVISIBLE);
      }
    });
    animatorSet.start();
  }

  public void setOnMenuOpenedListener(OnMenuOpenedListener listener) {
    mMenuOpenedListener = listener;
  }

  public void setOnMenuClosedListener(OnMenuClosedListener listener) {
    mMenuClosedListener = listener;
  }


  /**
   * 供外界調用的Adapter
   */
  public abstract static class SectorMenuAdapter extends BaseAdapter {

    @Override
    public long getItemId(int position) {
      return 0;
    }

    @Override
    public Object getItem(int position) {
      return null;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
      return createView(position, parent);
    }

    protected abstract View createView(int position, ViewGroup parent);

    @Override
    public abstract int getCount();
  }

  public interface OnMenuOpenedListener {
    void opened();
  }

  public interface OnMenuClosedListener {
    void closed();
  }
}