android - ViewPager's height in Coordinator layout is more than available

Question

I have a CoordinatorLayout with a Toolbar and a TabLayout inside the AppBarLayout. Additionally, I have a ViewPager inside the CoordinatorLayout but outside the ViewPager.

The problem is that the ViewPager's height is bigger than what is actually available, resulting in some views from my Fragment being cut.

<?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:background="@color/lightGray"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/app_bar_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar2"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:popupTheme="@style/AppTheme.PopupOverlay"
            app:layout_scrollFlags="scroll|enterAlways"/>

        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:scrollbars="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fillViewport="false"/>

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

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

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

And this what I mean when I say that the ViewPager has the wrong height.

Answer 1

Based on Yevhenii's answer above, I think I managed to solve this in an even simpler way:

class KeepWithinParentBoundsScrollingBehavior : AppBarLayout.ScrollingViewBehavior {

    constructor() : super()

    constructor(context: Context, attrs: AttributeSet) : super(context, attrs)


    override fun onDependentViewChanged(parent: CoordinatorLayout, child: View, dependency: View): Boolean {
        if (dependency !is AppBarLayout) {
            return super.onDependentViewChanged(parent, child, dependency)
        }

        val layoutParams = child.layoutParams as CoordinatorLayout.LayoutParams
        layoutParams.height = parent.height - dependency.bottom
        child.layoutParams = layoutParams
        return super.onDependentViewChanged(parent, child, dependency)
    }
}

Then set app:layout_behavior="your.package.KeepWithinParentBoundsScrollingBehavior" on your ViewPager or whatever view you have below the AppBar.

Take note that this is not a generic solution for all CoordinatorLayouts, but it seems to work when you have a view below an app bar that you don't want to let extend beyond the bottom of the parent CoordinatorLayout.

UPDATE: You should also set app:layout_anchor="@id/app_bar" on your ViewPager for the situation when the keyboard disappears. If you don't the ViewPager layout will not be refreshed when the keyboard disappears and the ViewPager will appear cut off.