Cardview ScrollX/ScrollY 在 ScrollView 中为 0

Question

我正在尝试通过垂直 LinearLayout 滚动到 CardView 的顶部，该 CardView 是 ScrollView 的子级。

这是布局：

<ScrollView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/scroll_view" android:fillViewport="true">
  <LinearLayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/background_color">
    <!-- Quality of Life -->
    <android.support.v7.widget.CardView android:id="@+id/cardViewQOL" android:layout_margin="8sp" android:layout_marginBottom="8sp" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" cardview:cardElevation="4sp"
      cardview:cardCornerRadius="5sp" cardview:contentPaddingTop="10sp" cardview:contentPaddingBottom="10sp" cardview:contentPaddingRight="10sp" cardview:contentPaddingLeft="10sp">
      <include layout="@layout/qualityoflife" android:layout_width="fill_parent" android:layout_height="fill_parent" />
    </android.support.v7.widget.CardView>
    <!-- Goals -->
    <android.support.v7.widget.CardView android:id="@+id/cardViewGoals" android:layout_margin="8sp" android:layout_marginBottom="8sp" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" cardview:cardElevation="4sp"
      cardview:cardCornerRadius="5sp" cardview:contentPaddingTop="10sp" cardview:contentPaddingBottom="10sp" cardview:contentPaddingRight="10sp" cardview:contentPaddingLeft="10sp">
      <include layout="@layout/goals" android:layout_width="fill_parent" android:layout_height="fill_parent" />
    </android.support.v7.widget.CardView>
    <!-- Daily routines -->
    <android.support.v7.widget.CardView android:id="@+id/cardViewDH" android:layout_margin="8sp" android:layout_marginBottom="8sp" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" cardview:cardElevation="4sp"
      cardview:cardCornerRadius="5sp" cardview:contentPaddingTop="10sp" cardview:contentPaddingBottom="10sp" cardview:contentPaddingRight="10sp" cardview:contentPaddingLeft="10sp">
      <include layout="@layout/dailyroutines" android:layout_width="fill_parent" android:layout_height="fill_parent" />
    </android.support.v7.widget.CardView>
    <!-- Weekly routines -->
    <android.support.v7.widget.CardView android:id="@+id/cardViewWH" android:layout_margin="8sp" android:layout_marginBottom="8sp" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" cardview:cardElevation="4sp"
      cardview:cardCornerRadius="5sp" cardview:contentPaddingTop="10sp" cardview:contentPaddingBottom="10sp" cardview:contentPaddingRight="10sp" cardview:contentPaddingLeft="10sp">
      <include layout="@layout/weeklyroutines" android:layout_width="fill_parent" android:layout_height="fill_parent" />
    </android.support.v7.widget.CardView>
    <!-- Monthly routines -->
    <android.support.v7.widget.CardView android:id="@+id/cardViewMH" android:layout_margin="8sp" android:layout_marginBottom="4sp" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center_horizontal" cardview:cardElevation="4sp"
      cardview:cardCornerRadius="5sp" cardview:contentPaddingTop="10sp" cardview:contentPaddingBottom="10sp" cardview:contentPaddingRight="10sp" cardview:contentPaddingLeft="10sp">
      <include layout="@layout/monthlyroutines" android:layout_width="fill_parent" android:layout_height="fill_parent" />
    </android.support.v7.widget.CardView>
    <android.support.v7.widget.CardView android:id="@+id/cardViewExperiences" android:layout_margin="8sp" android:layout_marginBottom="8sp" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center_horizontal"
      cardview:cardElevation="4sp" cardview:cardCornerRadius="5sp" cardview:contentPaddingTop="10sp" cardview:contentPaddingBottom="10sp" cardview:contentPaddingRight="10sp" cardview:contentPaddingLeft="10sp">
      <include layout="@layout/experiences" android:layout_width="fill_parent" android:layout_height="fill_parent" />
    </android.support.v7.widget.CardView>
    <android.support.v7.widget.CardView android:id="@+id/cardViewConfigNeeded" android:layout_margin="8sp" android:layout_marginBottom="8sp" android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_gravity="center_horizontal"
      cardview:cardElevation="4sp" cardview:cardCornerRadius="5sp" cardview:contentPaddingTop="10sp" cardview:contentPaddingBottom="10sp" cardview:contentPaddingRight="10sp" cardview:contentPaddingLeft="10sp" android:visibility="gone">
      <include layout="@layout/configneeded" android:layout_width="fill_parent" android:layout_height="wrap_content" />
    </android.support.v7.widget.CardView>
  </LinearLayout>
</ScrollView>

这是我的代码：

CardView dailyHabits = FindViewById<CardView>(Resource.Id.cardViewDH);
int y = dailyHabits.Top;
ScrollView scrollView = FindViewById<ScrollView>(Resource.Id.scroll_view);
scrollView.Post(() => scrollView.SmoothScrollTo(0, y));

结果是滚动在下一个cardview的顶部结束，这很奇怪……

我注意到 CardView.ScrollX/ScrollY 为 0。我想这是正常行为，因为 CardView 不是 ScrollView 的直接子项。这就是我使用 CardView 的顶部 x 坐标的原因。

Answer 1

如果不了解 Xamarin，但让我解释一下原生 Android 中可能的解决方案。

如果我们将您的代码按如下方式放入onCreate 方法中，我们将根本没有滚动：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    CardView dailyHabits = findViewById(R.id.cardViewDH);
    final int y = dailyHabits.getTop();
    final ScrollView scrollView = findViewById(R.id.scroll_view);
    scrollView.post(new Runnable() {
        @Override
        public void run() {
            scrollView.smoothScrollTo(0, y);
        }
    });
}

问题是我们在绘制卡片视图之前获取了它的顶部值，结果为 0。您可以在布局中添加树观察器或更新代码如下：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final ScrollView scrollView = findViewById(R.id.scroll_view);
    final CardView dailyHabits = findViewById(R.id.cardViewDH);
    dailyHabits.post(new Runnable() {   // could be scrollView
        @Override
        public void run() {
            int y = dailyHabits.getTop();
            scrollView.smoothScrollTo(0, y);
        }
    });
}

现在您应该在应用启动时获得所需的滚动到所需卡片视图的顶部。

至于你的代码，可以改成这样来达到同样的效果：

CardView dailyHabits = FindViewById<CardView>(Resource.Id.cardViewDH);
ScrollView scrollView = FindViewById<ScrollView>(Resource.Id.scroll_view);
scrollView.Post(() => scrollView.SmoothScrollTo(0, dailyHabits.Top));

Answer 2

如果你想在Linearlayout中实现滚动CardView，我建议你可以使用android.support.v7.widget.RecyclerView来实现，这里是github中的示例，你可以看看：

https://github.com/xamarin/monodroid-samples/tree/master/android5.0/RecyclerViewer