当 RecyclerView 适合屏幕时不要折叠工具栏 [英] Don't collapse Toolbar when RecyclerView fits the screen

问题描述

我使用 Android 设计库 制作了一个应用程序，带有工具栏和 TabLayout.
实际上存在 2 个选项卡，均带有 2 个 RecyclerView，可在滚动时自动折叠工具栏.

我的问题是:当 RecyclerView 的项目很少并且完全适合屏幕(如 TAB 2)时，我可以禁用工具栏折叠吗?

我看过很多示例，例如

我想我可以确定 RecyclerView 的第一项是否在屏幕上可见，如果是，则禁用工具栏折叠.前者容易实现，后者呢?

这是我的布局:

<android.support.design.widget.AppBarLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"机器人:fitsSystemWindows =真"android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"><android.support.v7.widget.Toolbarandroid:id="@+id/工具栏"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.TabLayoutandroid: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.ViewPagerandroid:id="@+id/寻呼机"app:layout_behavior="@string/appbar_scrolling_view_behavior"android:layout_width="match_parent"android:layout_height="wrap_content"/><android.support.design.widget.FloatingActionButtonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:id="@+id/main_fab"android:layout_margin="16dp"android:onClick="onFabClicked"应用程序:backgroundTint="@color/glucosio_accent"android:src="@drawable/ic_add_black_24dp"android:layout_gravity="底部|右"/></android.support.design.widget.CoordinatorLayout>

解决方案

最终解决方案(感谢 Michał Z.)

关闭/打开工具栏滚动的方法:

public void turnOffToolbarScrolling() {工具栏 mToolbar = (工具栏) findViewById(R.id.toolbar);AppBarLayout appBarLayout = (AppBarLayout) findViewById(R.id.appbar_layout);//关闭滚动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);}public void turnOnToolbarScrolling() {工具栏 mToolbar = (工具栏) findViewById(R.id.toolbar);AppBarLayout appBarLayout = (AppBarLayout) findViewById(R.id.appbar_layout);//开启滚动AppBarLayout.LayoutParams toolbarLayoutParams = (AppBarLayout.LayoutParams) mToolbar.getLayoutParams();toolbarLayoutParams.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL | AppBarLayout.LayoutParams.SCROLL_FLAG_ENTER_ALWAYS);mToolbar.setLayoutParams(toolbarLayoutParams);CoordinatorLayout.LayoutParams appBarLayoutParams = (CoordinatorLayout.LayoutParams) appBarLayout.getLayoutParams();appBarLayoutParams.setBehavior(new AppBarLayout.Behavior());appBarLayout.setLayoutParams(appBarLayoutParams);}

找出 RecyclerView 的最后一项是否在我的 Fragment 中可见.
如果是，请禁用滚动:

public void updateToolbarBehaviour(){if (mLayoutManager.findLastCompletelyVisibleItemPosition() == items.size()-1) {((MainActivity) getActivity()).turnOffToolbarScrolling();} 别的 {((MainActivity)getActivity()).turnOnToolbarScrolling();}}

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.

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

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.

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?

This is my layout:

<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>

解决方案

Final Solution (thanks Michał Z.)

Methods to turn off/on Toolbar scrolling:

public void turnOffToolbarScrolling() {
    Toolbar mToolbar = (Toolbar) findViewById(R.id.toolbar);
    AppBarLayout appBarLayout = (AppBarLayout) findViewById(R.id.appbar_layout);

    //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);
}

public void turnOnToolbarScrolling() {
    Toolbar mToolbar = (Toolbar) findViewById(R.id.toolbar);
    AppBarLayout appBarLayout = (AppBarLayout) findViewById(R.id.appbar_layout);

    //turn on scrolling
    AppBarLayout.LayoutParams toolbarLayoutParams = (AppBarLayout.LayoutParams) mToolbar.getLayoutParams();
    toolbarLayoutParams.setScrollFlags(AppBarLayout.LayoutParams.SCROLL_FLAG_SCROLL | AppBarLayout.LayoutParams.SCROLL_FLAG_ENTER_ALWAYS);
    mToolbar.setLayoutParams(toolbarLayoutParams);

    CoordinatorLayout.LayoutParams appBarLayoutParams = (CoordinatorLayout.LayoutParams) appBarLayout.getLayoutParams();
    appBarLayoutParams.setBehavior(new AppBarLayout.Behavior());
    appBarLayout.setLayoutParams(appBarLayoutParams);
}

Find out if last item of RecyclerView is visible in my Fragment.
If yes, disable scrolling:

public void updateToolbarBehaviour(){
    if (mLayoutManager.findLastCompletelyVisibleItemPosition() == items.size()-1) {
        ((MainActivity) getActivity()).turnOffToolbarScrolling();
    } else {
        ((MainActivity)getActivity()).turnOnToolbarScrolling();
    }
}

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