Collapsing and scrolling Views in a LinearLayout View - android-layout

Question

I'm trying to create a very specific behavior in an Android layout containing two Fragments when the soft keyboard opens, as depicted below from left to right.
Fragment A is a form which requires soft keyboard input, and Fragment B is a photographic slideshow, and just serves as visual filler.
The blue outline represents the root View. Fragment A is a fixed height, and Fragment B fills the remaining vertical space. As the keyboard opens, Fragment B collapses until its height is 0, at which point fragment A becomes scrollable.
I've tried the following:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="#+id/FragmentB"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<ScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content">
<FrameLayout
android:id="#+id/FragmentA"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</ScrollView>
</LinearLayout>
In this view Fragment B remains at the same height when the soft keyboard opens and instead Fragment A collapses.
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:id="#+id/FragmentB"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<FrameLayout
android:id="#+id/FragmentA"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
</ScrollView>
And in this view Fragment B is constantly collapsed, and a gap remains at the bottom of the view below Fragment A.
How can I achieve the layout behavior I laid out in the diagram above?
Thanks!

Answer 1

I found a solution here:
Min height fill_parent and height wrap_content in ScrollView?
My resulting code is:
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"> <!-- FillViewport ensures the scrollview doesn't wrap the content -->
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"> <!-- Layout weight 1 means the LinearLayout will at least fill the scrollview, or wrap content if too big -->
<FrameLayout
android:id="#+id/FragmentB"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />
<FrameLayout
android:id="#+id/FragmentA"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
</ScrollView>