Android CoordinatorLayout + AppbarLayout + Viewpager总是滚动

Question

我有一个经典的布局,顶部有一个ToolBar,下面有一个TabLayout,还有一个来自TabLayout的ViewPager切换标签.当ViewPager中的内容可滚动时,工具栏应该滚动到视线之外,TabLayout应该跟随并在到达顶部时粘住.

所有这些在我当前的代码中都很好,除了ToolBar总是可滚动的,无论ViewPager的内容大小如何.请参阅下面的代码.关于如何解决这个问题的任何好主意？

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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.AppBarLayout
        android:id="@+id/app_bar_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/primary"
        android:orientation="vertical">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:theme="@style/AppTheme.ToolBar"
            app:layout_scrollFlags="scroll|enterAlways" />

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorPrimary"
            android:scrollbars="horizontal"
            app:tabIndicatorColor="@color/black_text" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/tabs_activity_view_pager"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

</android.support.design.widget.CoordinatorLayout>

编辑:

我可以看到viewPager的高度与整个根视图的高度相同.这可能是有意的,因为appbar_scrolling_view_behavior似乎确实添加了顶部和底部偏移.但它确实看起来很奇怪,因为它会导致始终滚动工具栏和tabbar.

Answer 1

我已经解决了这个问题,尝试了示例Google模板并找出答案

app:layout_behavior="@string/appbar_scrolling_view_behavior" 

必须将行添加到视图分页器属性xml中.它解决了我的问题.

Answer 2

我建议您尝试此示例。

这是与示例中的布局类似的布局。

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:layout_scrollFlags="scroll|enterAlways" />

        <android.support.design.widget.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

    </android.support.design.widget.AppBarLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end|bottom"
        android:layout_margin="@dimen/fab_margin"
        android:src="@drawable/ic_done" />

</android.support.design.widget.CoordinatorLayout>

Answer 3

基于其他示例、我自己的代码以及 appbar_scrolling_view_behavior 的（有点混乱）源代码：

        public boolean onDependentViewChanged(CoordinatorLayout parent, View child,
            View dependency) {
        final CoordinatorLayout.Behavior behavior =
                ((CoordinatorLayout.LayoutParams) dependency.getLayoutParams()).getBehavior();
        if (behavior instanceof Behavior) {
            // Offset the child so that it is below the app-bar (with any overlap)

            final int appBarOffset = ((Behavior) behavior)
                    .getTopBottomOffsetForScrollingSibling();
            final int expandedMax = dependency.getHeight() - mOverlayTop;
            final int collapsedMin = parent.getHeight() - child.getHeight();

            if (mOverlayTop != 0 && dependency instanceof AppBarLayout) {
                // If we have an overlap top, and the dependency is an AppBarLayout, we control
                // the offset ourselves based on the appbar's scroll progress. This is so that
                // the scroll happens sequentially rather than linearly
                final int scrollRange = ((AppBarLayout) dependency).getTotalScrollRange();
                setTopAndBottomOffset(AnimationUtils.lerp(expandedMax, collapsedMin,
                        Math.abs(appBarOffset) / (float) scrollRange));
            } else {
                setTopAndBottomOffset(dependency.getHeight() - mOverlayTop + appBarOffset);
            }
        }
        return false;
    }

我正在以解释问题的方式阅读本文，因为这是此代码的预期行为。

我认为我们需要编写自己的滚动行为，特别是针对 RecyclerView，