ViewPager + CoordinatorLayout 显示

使用 ViewPager + CoordinatorLayout 滑动显示多个页面时，可能会出现 CoordinatorLayout 的 Toolbar 被状态栏覆盖的问题. StackOverflow 上有一个类似的问题 CoordinatorLayout status bar padding disappears from ViewPager 2nd page. 需要在代码中对 ViewPager 设置 windowInsetsListener.

        ViewCompat.setOnApplyWindowInsetsListener(mViewPager, new OnApplyWindowInsetsListener() {
            @Override
            public WindowInsetsCompat onApplyWindowInsets(View v, WindowInsetsCompat insets) {
                insets = ViewCompat.onApplyWindowInsets(v, insets);
                if (insets.isConsumed()) {
                    return insets;
                }

                boolean consumed = false;
                for (int i = 0, count = mViewPager.getChildCount(); i < count; ++i) {
                    ViewCompat.dispatchApplyWindowInsets(mViewPager.getChildAt(i), insets);
                    if (insets.isConsumed()) {
                        consumed = true;
                    }
                }
                return consumed ? insets.consumeSystemWindowInsets() : insets;
            }
        });

ViewPager 布局：

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.view.ViewPager
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/story_view_pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</android.support.v4.view.ViewPager>

每个 pager 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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="256dp"
        android:fitsSystemWindows="true"
        app:theme="@style/AppTheme.AppBarOverlay">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="true"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleTextAppearance="@style/AppTheme.TextAppearance.Large"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <include
                android:id="@+id/article_header_image"
                layout="@layout/fragment_article_header_item"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:fitsSystemWindows="true"
                app:layout_collapseMode="parallax"/>

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin"
                app:navigationIcon="@drawable/ic_arrow_back"
                app:popupTheme="@style/AppTheme.PopupOverlay">

                <android.support.v7.widget.ButtonBarLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent">

                    <TextView
                        android:id="@+id/toolbar_text"
                        style="@style/AppTheme.TextAppearance.Large"
                        android:layout_width="wrap_content"
                        android:layout_height="match_parent"
                        android:ellipsize="marquee"
                        android:focusable="true"
                        android:focusableInTouchMode="true"
                        android:gravity="center_vertical"
                        android:marqueeRepeatLimit="marquee_forever"
                        android:maxLines="1"
                        android:scrollHorizontally="true"
                        android:visibility="gone"/>
                </android.support.v7.widget.ButtonBarLayout>
            </android.support.v7.widget.Toolbar>
        </android.support.design.widget.CollapsingToolbarLayout>
    </android.support.design.widget.AppBarLayout>

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <WebView
            android:id="@+id/web_content"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>
    </android.support.v4.widget.NestedScrollView>

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab_share"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/default_margin"
        app:layout_anchor="@id/appbar"
        app:layout_anchorGravity="bottom|end"
        app:srcCompat="@drawable/ic_share_white_24dp"/>

    <ProgressBar
        android:id="@+id/progress_bar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:visibility="gone"/>
</android.support.design.widget.CoordinatorLayout>

styles.xml (values-v19)

    <style name="AppTheme.NoActionBar.TransparentStatus">
        <item name="android:windowTranslucentStatus">true</item>
    </style>

styles.xml (values-v21)

    <style name="AppTheme.NoActionBar.TransparentStatus">
        <item name="android:statusBarColor">@android:color/transparent</item>
    </style>