// androidx.coordinatorlayout.widget.CoordinatorLayout#onLayout
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    final int layoutDirection = ViewCompat.getLayoutDirection(this);
    final int childCount = mDependencySortedChildren.size();
    for (int i = 0; i < childCount; i++) {
        final View child = mDependencySortedChildren.get(i);
        if (child.getVisibility() == GONE) {
            continue;
        }

        final LayoutParams lp = (LayoutParams) child.getLayoutParams();
        final Behavior behavior = lp.getBehavior();

        // 這里
        if (behavior == null || !behavior.onLayoutChild(this, child, layoutDirection)) {
            onLayoutChild(child, layoutDirection);
        }
    }
}

public void onAttachedToLayoutParams(@NonNull CoordinatorLayout.LayoutParams params) {}
public void onDetachedFromLayoutParams() {}

public int getScrimColor(@NonNull CoordinatorLayout parent, @NonNull V child)
public float getScrimOpacity(@NonNull CoordinatorLayout parent, @NonNull V child)
public boolean blocksInteractionBelow(@NonNull CoordinatorLayout parent, @NonNull V child)

public boolean onMeasureChild(@NonNull CoordinatorLayout parent, @NonNull V child, int parentWidthMeasureSpec, 
                int widthUsed, int parentHeightMeasureSpec, int heightUsed)
public boolean onLayoutChild(@NonNull CoordinatorLayout parent, @NonNull V child, int layoutDirection)

public boolean layoutDependsOn(@NonNull CoordinatorLayout parent, @NonNull V child, @NonNull View dependency)
public boolean onDependentViewChanged(@NonNull CoordinatorLayout parent, @NonNull V child, @NonNull View dependency)
public void onDependentViewRemoved(@NonNull CoordinatorLayout parent, @NonNull V child, @NonNull View dependency)

public WindowInsetsCompat onApplyWindowInsets(@NonNull CoordinatorLayout coordinatorLayout,
                @NonNull V child, @NonNull WindowInsetsCompat insets)
public boolean onRequestChildRectangleOnScreen(@NonNull CoordinatorLayout coordinatorLayout,
                @NonNull V child, @NonNull Rect rectangle, boolean immediate)
public void onRestoreInstanceState(@NonNull CoordinatorLayout parent, @NonNull V child,
                @NonNull Parcelable state)
public Parcelable onSaveInstanceState(@NonNull CoordinatorLayout parent, @NonNull V child)
public boolean getInsetDodgeRect(@NonNull CoordinatorLayout parent, @NonNull V child,
                @NonNull Rect rect)

// ViewGroup
public boolean dispatchTouchEvent(MotionEvent ev) {
    if ACTION_DOWN 事件并且 FLAG_DISALLOW_INTERCEPT 允許攔截 {
        final boolean intercepted = onInterceptTouchEvent(ev) // 注意 onInterceptTouchEvent 的位置
    }
    boolean handled;
    if !intercepted {
        if child == null {
            handled = super.dispatchTouchEvent(ev)
        } else {
            handled = child.dispatchTouchEvent(ev)
        }
    }
    return handled;
}

// View
public boolean dispatchTouchEvent(MotionEvent event) {
    if mOnTouchListener.onTouch(this, event) {
        return true
    }
    if onTouchEvent(event) { // 注意 onTouchEvent 的位置
        return true
    }
    return false
}

public boolean onInterceptTouchEvent(@NonNull CoordinatorLayout parent, @NonNull V child, @NonNull MotionEvent ev)
public boolean onTouchEvent(@NonNull CoordinatorLayout parent, @NonNull V child, @NonNull MotionEvent ev)

// androidx.recyclerview.widget.RecyclerView#onTouchEvent
public boolean onTouchEvent(MotionEvent e) {
    // ...
    switch (action) {
        case MotionEvent.ACTION_MOVE: {
            // ...
            if (dispatchNestedPreScroll(
                canScrollHorizontally ? dx : 0,
                canScrollVertically ? dy : 0,
                mReusableIntPair, mScrollOffset, TYPE_TOUCH
            )) {
                // ...
            }
        }
    }
}

public static void onNestedPreScroll(ViewParent parent, View target, int dx, int dy,
        int[] consumed, int type) {
    if (parent instanceof NestedScrollingParent2) {
        ((NestedScrollingParent2) parent).onNestedPreScroll(target, dx, dy, consumed, type);
    } else if (type == ViewCompat.TYPE_TOUCH) {
        if (Build.VERSION.SDK_INT >= 21) {
            parent.onNestedPreScroll(target, dx, dy, consumed);
        } else if (parent instanceof NestedScrollingParent) {
            ((NestedScrollingParent) parent).onNestedPreScroll(target, dx, dy, consumed);
        }
    }
}

public boolean onStartNestedScroll(@NonNull CoordinatorLayout coordinatorLayout,
                @NonNull V child, @NonNull View directTargetChild, @NonNull View target,
                @ScrollAxis int axes, @NestedScrollType int type)
public void onNestedScrollAccepted(@NonNull CoordinatorLayout coordinatorLayout,
                @NonNull V child, @NonNull View directTargetChild, @NonNull View target,
                @ScrollAxis int axes, @NestedScrollType int type)
public void onStopNestedScroll(@NonNull CoordinatorLayout coordinatorLayout,
                @NonNull V child, @NonNull View target, @NestedScrollType int type)
public void onNestedScroll(@NonNull CoordinatorLayout coordinatorLayout, @NonNull V child,
                @NonNull View target, int dxConsumed, int dyConsumed, int dxUnconsumed,
                int dyUnconsumed, @NestedScrollType int type, @NonNull int[] consumed)
public void onNestedPreScroll(@NonNull CoordinatorLayout coordinatorLayout,
                @NonNull V child, @NonNull View target, int dx, int dy, @NonNull int[] consumed,
                @NestedScrollType int type)

public boolean onNestedFling(@NonNull CoordinatorLayout coordinatorLayout,
                @NonNull V child, @NonNull View target, float velocityX, float velocityY,
                boolean consumed)
public boolean onNestedPreFling(@NonNull CoordinatorLayout coordinatorLayout,
                @NonNull V child, @NonNull View target, float velocityX, float velocityY)

// CoordinatorLayout
public boolean onStartNestedScroll(View child, View target, int axes, int type) {
    boolean handled = false;
    for 遍歷子 view {
        Behavior viewBehavior = view.getLayoutParams().getBehavior()
        final boolean accepted = viewBehavior.onStartNestedScroll();
        handled |= accepted;
        // 根據(jù) accepted 給 view 的 layoutparams 置位
        view.getLayoutParams().setNestedScrollAccepted(accepted) 
    }
    return handled;
}

// CoordinatorLayout
public void onStopNestedScroll(View target, int type) {
    for 遍歷子 view {
        // 讀取 view 的 layoutparams 的標(biāo)記位
        if view.getLayoutParams().isNestedScrollAccepted(type) {
            Behavior viewBehavior = view.getLayoutParams().getBehavior()
            // 將事件交給 behavior
            viewBehavior.onStopNestedScroll(this, view, target, type)
        }
    }
}

public void onNestedPreScroll(View target, int dx, int dy, int[] consumed, int  type) {}