CoordinatorLayout.Behavior

Question

我在我的项目中使用具有自定义行为的CoordinatorLayout和NestedScrollView。除了一个问题，它运作良好。当我调用nestedScrollView.smoothScrollTo（0,0）时，我在MyCustomBehavior中得到了错误的Y坐标。当我用手指滚动时，我会收到正确的坐标。通过smoothScrollTo（）方法滚动时如何在行为类中获取正确的坐标？

这是我的代码：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

        <android.support.design.widget.CoordinatorLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <android.support.v7.widget.CardView
                android:layout_width="300dp"
                android:layout_height="150dp"
                android:background="#f00"
                android:layout_gravity="center_horizontal"
                app:layout_behavior="com.mysite.app.MyCustomBehavior" />

            <com.mysite.app.CustomScrollView
               android:layout_width="match_parent"
                android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"
                        android:text="Very long text here" />
            </com.mysite.app.CustomScrollView>

            <android.support.v7.widget.Toolbar
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                android:layout_marginTop="24dp"
                android:elevation="20dp" />
        </android.support.design.widget.CoordinatorLayout>
</android.support.constraint.ConstraintLayout>

CustomScrollView：

class CustomScrollView @JvmOverloads constructor(
        context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : NestedScrollView(context, attrs, defStyleAttr) {

    private val runnable = Runnable {
        if (scrollY in 1..299) {
            smoothScrollTo(0,0)
        }
    }

    override fun stopNestedScroll(type: Int) {
        super.stopNestedScroll(type)
        removeCallbacks(runnable)
        handler.postDelayed(runnable, 200)
    }
}

行为：

class CollapsingImageBehavior(private val context: Context, attrs: AttributeSet?) : CoordinatorLayout.Behavior<CardView>(context, attrs) {

    private var scroll = 0

    override fun layoutDependsOn(parent: CoordinatorLayout, child: CardView, dependency: View): Boolean {
        return dependency is NestedScrollView
    }

    override fun onStartNestedScroll(coordinatorLayout: CoordinatorLayout, child: CardView, directTargetChild: View, target: View, axes: Int, type: Int): Boolean {
        return axes == ViewCompat.SCROLL_AXIS_VERTICAL || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, axes, type)
    }

    override fun onNestedScroll(coordinatorLayout: CoordinatorLayout, child: CardView, target: View, dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, type: Int) {
        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, type)
        scroll += dyConsumed
        Log.d("tag", "onNestedScroll " + scroll)
    }

    override fun onDependentViewChanged(parent: CoordinatorLayout, child: CardView, dependency: View): Boolean {
        return true
    }
}