I have a ConstraintLayout with a TextView in a ScrollView at the top and three buttons in a row at the bottom. I want the text to stop at the top of the buttons, but instead, the text scrolls under the buttons as shown in the picture.

Here is my layout.xml:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    tools:context=".EventLogFragment">

    <ScrollView
        android:id="@ id/scroller"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fillViewport="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <TextView
            android:id="@ id/event_log"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/empty_log" />
    </ScrollView>

    <Button
        android:id="@ id/button_update"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/update"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@ id/button_send"
        app:layout_constraintHorizontal_chainStyle="spread"
        app:layout_constraintStart_toStartOf="parent"/>

    <Button
        android:id="@ id/button_send"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/send"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@ id/button_clear"
        app:layout_constraintStart_toEndOf="@ id/button_update"/>

    <Button
        android:id="@ id/button_clear"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/clear"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@ id/button_send"/>

</androidx.constraintlayout.widget.ConstraintLayout>

I have tried adding app:layout_constraintTop_toBottomOf="@ id/scroller" to each button, but that just pushes the buttons half-way off the screen. I tried adding android:layout_weight="1" to each button, and that did nothing.

How do I get the scrolled text to stop at the top of the buttons?

CodePudding user response：

Change the height of the ScrollView to 0dp (match_constraint) and place it into a vertical spread-inside chain with the "update" button. The other buttons can be placed into a horizontal spread chain with the "update" button. Like this:

<androidx.constraintlayout.widget.ConstraintLayout 
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ScrollView
        android:id="@ id/scroller"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:background="@android:color/holo_blue_light"
        app:layout_constraintBottom_toTopOf="@ id/button_update"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_chainStyle="spread_inside">

        <TextView
            android:id="@ id/event_log"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="@string/empty_log"
            android:textSize="48sp" />
    </ScrollView>

    <Button
        android:id="@ id/button_update"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/update"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@ id/button_send"
        app:layout_constraintHorizontal_chainStyle="spread"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@ id/scroller" />

    <Button
        android:id="@ id/button_send"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/send"
        app:layout_constraintEnd_toStartOf="@ id/button_clear"
        app:layout_constraintStart_toEndOf="@ id/button_update"
        app:layout_constraintTop_toTopOf="@id/button_update" />

    <Button
        android:id="@ id/button_clear"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/clear"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toEndOf="@ id/button_send"
        app:layout_constraintTop_toTopOf="@id/button_update" />

</androidx.constraintlayout.widget.ConstraintLayout>