Scroll away picture and appbar title but leave tab

问题:

I use app support and CoordinatorLayout. I was able to implement CollapsingToolbarLayout with ImageView and Toolbar that hide when scrolling. I am struggled with tabs - TabLayout is not collapsed, which is good. The problem is that it does not look nice - I want it to use bottom part of the picture as background.

I moved TabLayout within CollapsingToolbarLayout and then it uses the picture as background but there are two problems - tabs are located at top of the screen and they are hidden when scrolling.

I want to achieve the effect that it will sit at bottom of picture

and it will stay at top of the screen when other parts are scrolled away

Layout:

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

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/main.collapsing"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_scrollFlags="scroll|enterAlways|snap"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPrimary"
        app:expandedTitleMarginStart="4dp"
        app:expandedTitleMarginEnd="64dp"
        >

        <ImageView
            android:id="@+id/main.backdrop"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scaleType="centerCrop"
            android:fitsSystemWindows="true"
            android:src="@drawable/digit1_hill"
            app:layout_collapseMode="parallax"
            />

        <android.support.v7.widget.Toolbar
            android:id="@+id/main.toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:layout_collapseMode="pin"
            />

        <android.support.design.widget.TabLayout
            android:id="@+id/main.tabs"
            android:layout_width="fill_parent"
            android:layout_height="?attr/actionBarSize"
            app:tabSelectedTextColor="?android:attr/textColorPrimaryInverse"
            app:tabIndicatorColor="?android:attr/textColorPrimaryInverse"
            app:tabIndicatorHeight="4dp"
            />
    </android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>

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

回答1:

You need to tell your Toolbar to app:layout_scrollFlags="scroll|enterAlways" and your CollapsingToolbarLayout to app:layout_scrollFlags="scroll|exitUntilCollapsed" while your TabLayout should have android:layout_gravity="bottom"

Try this:

<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.support.design.widget.AppBarLayout
        android:id="@+id/main.appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        android:fitsSystemWindows="true">
        <!-- Fit the system windows for your CollapsingToolbarLayout 
       also set your height to wrap_content and give image a height-->
        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/main.collapsing"
            android:fitsSystemWindows="true"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleMarginStart="4dp"
            app:expandedTitleMarginEnd="64dp">

            <ImageView
                android:id="@+id/main.backdrop"
                android:layout_width="match_parent"
                android:layout_height="244dp"
                android:scaleType="centerCrop"
                android:fitsSystemWindows="true"
                android:src="@drawable/digit1_hill"
                app:layout_collapseMode="parallax"/>
            <!-- Tell your toolbar to scroll|enterAlways -->
            <android.support.v7.widget.Toolbar
                android:id="@+id/main.toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
                app:layout_scrollFlags="scroll|enterAlways"/>
            <!-- add layout_gravity="bottom" -->
            <android.support.design.widget.TabLayout
                android:id="@+id/main.tabs"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                app:tabSelectedTextColor="?android:attr/textColorPrimaryInverse"
                app:tabIndicatorColor="?android:attr/textColorPrimaryInverse"
                app:tabIndicatorHeight="4dp"
                android:layout_gravity="bottom"/>
         </android.support.design.widget.CollapsingToolbarLayout>
     </android.support.design.widget.AppBarLayout>

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

Update Additionally, you should switch your theme or add a new theme:

<style name="NewAppTheme" parent="Theme.AppCompat.Light.NoActionBar">

   <!-- Include all items from original theming -->

</style>

and to hide the title create a style:

<style name="Invisible" parent="AppTheme"> 
    <item name="android:textColor">@android:color/transparent</item> 
</style>

and then set this as your collapsedTitleTextAppearance:

app:collapsedTitleTextAppearance="@style/Invisible"