不塌​​陷工具栏时RecyclerView适合屏幕

问题描述

我使用的 Android的设计库制作一个应用程序，有一个工具栏和TabLayout。
其实2选项卡是present，都与2 RecyclerView，滚动时自动折叠工具栏。

I've made an app using Android Design Library, with a Toolbar and TabLayout.
Actually 2 tabs are present, both with 2 RecyclerView, that automatically collapse the Toolbar when scrolled.

我的问题是：我可以禁用工具栏崩溃时RecyclerView有几个项目，完全（在TAB 2等）适应屏幕

My question is: can I disable Toolbar collapsing when RecyclerView has few items and completely fits the screen (like in TAB 2)?

我已经看到了很多像 CheeseSquare 的例子，由谷歌员工做那里的问题还是present：即使RecyclerView刚刚1项，在工具栏一直躲在滚动

I've seen a lot of examples like CheeseSquare, made by a Google employee where the issue is still present: even if the RecyclerView has just 1 item, the toolbar keeps hiding on scroll.

我想我可以找出是否RecyclerView的第一个项目是在屏幕上可见，如果是禁用的工具栏崩溃。前者很容易实现，那么后者？

I think I can just find out if the first item of the RecyclerView is visible on screen and if yes disable toolbar collapsing. The former is easy to implement, what about the latter?

这是我的布局：

<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/coordinator_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

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

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

        <android.support.design.widget.TabLayout
            android:id="@+id/tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@color/glucosio_pink"
            app:tabSelectedTextColor="@android:color/white"
            app:tabIndicatorColor="@color/glucosio_accent"
            app:tabTextColor="#80ffffff"/>
        </android.support.design.widget.AppBarLayout>

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

    <android.support.design.widget.FloatingActionButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/main_fab"
        android:layout_margin="16dp"
        android:onClick="onFabClicked"
        app:backgroundTint="@color/glucosio_accent"
        android:src="@drawable/ic_add_black_24dp"
        android:layout_gravity="bottom|right"
        />
    </android.support.design.widget.CoordinatorLayout>

中国

推荐答案

您可以检查 RecyclerView 的最后一个项目是可见的。如果它不然后关闭滚动编程方式使用此方法：

You can check if the last item in RecyclerView is visible. If it's not then turn off scrolling programmatically using this method:

            //turn off scrolling
            AppBarLayout.LayoutParams toolbarLayoutParams = (AppBarLayout.LayoutParams) mToolbar.getLayoutParams();
            toolbarLayoutParams.setScrollFlags(0);
            mToolbar.setLayoutParams(toolbarLayoutParams);

            CoordinatorLayout.LayoutParams appBarLayoutParams = (CoordinatorLayout.LayoutParams) appBarLayout.getLayoutParams();
            appBarLayoutParams.setBehavior(null);
            appBarLayout.setLayoutParams(appBarLayoutParams);

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