Bottom part of NestedScrollView hidden by navigation bar [Android]

Question

I've got a problem with NestedScrollView on layout with CollapsingToolbarLayout. When I scroll text to bottom last sentences are covered by navigation bar.

layout.xml:

 <?xml version="1.0" encoding="utf-8"?>
    <android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    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="250dp"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <android.support.design.widget.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleTextAppearance="@style/ExpandedAppBar"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            app:title="Title">

            <ImageView
                android:id="@+id/toolbar_image_view"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="centerCrop"
                android:src="@drawable/visit_at_office"
                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" />

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

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

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

        <TextView
            android:id="@+id/textView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/lorem_ipsum" />
    </android.support.v4.widget.NestedScrollView>
    </android.support.design.widget.CoordinatorLayout>

Adding margin bottom to TextView fixes this bug, but I'd like to know any better solution and why is that happens. Could anyone help me, please?

Answer 1

In case anyone is still searching for a solution of this problem:

Cause of the problem is that CoordinatorLayout is not calculating correctly size of CollapsingToolbarLayout because it has Toolbar with app:layout_collapseMode="pin" setting. It thinks that CollapsingToolbarLayout will collapse to zero height so it leaves all available space to NestedScrollView, but actually what happens is that toolbar stays pinned so NestedScrollView moves down, behind NavigationBar.

Easiest way to solve this is just to add android:minHeight="?attr/actionBarSize" (or whatever toolbar height you are using) to CollapsingToolbarLayout. This way CoordinatorLayout will know properly how much space it needs to leave for NestedScrollView.