Appbar fitsSystemWindows - Inside a ViewPager

Question

I have an Activity that contains a ViewPager:

activity.xml:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"/>

</FrameLayout>

The fragments this pager contains – which are all generated from the same layout – have a CoordinatorLayout and CollapsingToolbarLayout to provide a collapsing image-back titlebar:

fragment.xml:

<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:id="@+id/coordinator_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

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

        <!-- Content here -->

    </android.support.v4.widget.NestedScrollView>

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="256dp"
        android:elevation="8dp"
        android:fitsSystemWindows="true">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            app:expandedTitleMarginStart="72dp"
            android:fitsSystemWindows="true">

            <ImageView
                android:id="@+id/photo"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="centerCrop"
                app:layout_collapseMode="parallax"
                android:background="@color/photo_placeholder"
                android:fitsSystemWindows="true"/>

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
                android:layout_width="match_parent"
                android:layout_height="?actionBarSize"
                app:layout_collapseMode="pin"
                android:layout_gravity="bottom">

            </android.support.v7.widget.Toolbar>

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

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

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

Without the fitsSystemWindows flags in the activity layout, the image in the fragment properly displays behind the system status bar, while the text sometimes collapses behind the status bar when scrolled up. If I add the flags in – as shown above – the text issue is resolved, but the image now cuts off at the status bar. Keeping the collapsing toolbar code in the fragment, is there a way to fit the fragment's content to the system window?

Without fitsSystemWindows in the activity (preferred behaviour):

With fitsSystemWindows in the activity:

And what is the text that sometimes collapses behind the status bar, the title of toolbar maybe? — GPack, Nov 26 '16 at 19:02
Yup. Thank you for walking me through that issue. What looks like the correct behaviour in relation to text is actually removing the padding cut behind the status bar. Looks like the correct way to solve the issue is to add a margin to the toolbar, and to not set the `fitsSystemWindows` flag on the viewpager. I need to find a reliable way to get the status bar height to set this margin, but quickly slapping a `25dp` margin on the top resolves both issues. — RedBassett, Nov 26 '16 at 19:15
Try changing the FrameLayout to a CoordinatorLayout with `fitsSystemWindows` — GPack, Nov 26 '16 at 19:22
Changing the `FrameLayout` in the activity to a `CoordinatorLayout` doesn't resolve the issue. The `fitsSystemWindow` flag still breaks the window fit in the fragment. — RedBassett, Nov 26 '16 at 19:26
Maybe it is due to the `fitsSystemWindow` in ViewPager that consumes all the insets. — GPack, Nov 26 '16 at 20:30

score 1 · Answer 1 · answered Apr 11 '17 at 07:41

You haven't declared, that you want NestedScrollView also to fitSystemWindows. So, literally, you are prohibiting WindowInsets to be passed to children off NestedScrollView, thus ViewPager is not even aware about WindowInsets.

Apply android:fitSystemWindows="true" to NestedScrollView also.

Appbar fitsSystemWindows - Inside a ViewPager

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