Why does scrolling not work correctly when using WindowCompat.setDecorFitsSystemWindows(window, false)?

Question

It looks like when I add

WindowCompat.setDecorFitsSystemWindows(window, false)

to my Android app, scrolling through the content on the screen while the keyboard is open is broken. It does not allow you to scroll to the last item on the screen. Here is the code I am using.

package com.example.myapplication

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.core.view.WindowCompat
import com.example.myapplication.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        WindowCompat.setDecorFitsSystemWindows(window, false)
        super.onCreate(savedInstanceState)

        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

    }

}

<?xml version="1.0" encoding="utf-8"?>
<ScrollView 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/scrollView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.constraintlayout.widget.ConstraintLayout
        android:id="@+id/containerOfContainers"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:clipChildren="false"
        android:clipToPadding="false"
        android:orientation="vertical">

        <TextView
            android:id="@+id/titleText"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:focusable="true"
            android:focusableInTouchMode="true"
            android:gravity="center_horizontal"
            android:text="Title"
            android:textSize="40sp"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            tools:layout_constraintTop_creator="1"
            tools:layout_editor_absoluteX="@dimen/spark_gap_tiny">

            <requestFocus />
        </TextView>

        <EditText
            android:id="@+id/first"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:paddingTop="150dp"
            android:text="1"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/titleText" />


        <EditText
            android:id="@+id/second"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:paddingTop="150dp"
            android:text="2"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/first" />

        <EditText
            android:id="@+id/third"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:paddingTop="150dp"
            android:text="3"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/second" />

        <EditText
            android:id="@+id/fourth"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:paddingTop="150dp"
            android:text="4"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/third" />

        <EditText
            android:id="@+id/fifth"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:paddingTop="150dp"
            android:text="5"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/fourth" />

        <EditText
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:paddingTop="150dp"
            android:text="6"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toBottomOf="@+id/fifth" />
    </androidx.constraintlayout.widget.ConstraintLayout>
</ScrollView>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    package="com.example.myapplication">

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/Theme.MyApplication"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:label="@string/app_name"
            android:theme="@style/Theme.MyApplication">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Correct (I can scroll all the way down to 6 when the keyboard is open)

Wrong (I can only scroll to 4 when the keyboard is open)

What could be causing this? It seems like a pretty simple use case.

Answer 1

Figured it out. I need to update the insets when they change. See code.

package com.example.myapplication

import android.os.Bundle
import android.view.View
import android.view.ViewGroup
import android.view.WindowInsets
import androidx.appcompat.app.AppCompatActivity
import androidx.core.view.WindowCompat
import androidx.core.view.updateLayoutParams
import androidx.core.view.updateMargins
import com.example.myapplication.databinding.ActivityMainBinding


class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        WindowCompat.setDecorFitsSystemWindows(window, false)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)


        binding.root.setOnApplyWindowInsetsListener { _, _ ->
            applyKeyboardInsets(binding.root)
        }

    }


    private fun applyKeyboardInsets(root: View): WindowInsets {

        val insets = root.rootWindowInsets.getInsets(WindowInsets.Type.ime())
        root.updateLayoutParams<ViewGroup.MarginLayoutParams> {
            updateMargins(insets.left, insets.top, insets.right, insets.bottom)
        }
        return WindowInsets.Builder()
            .setInsets(WindowInsets.Type.ime(), insets)
            .build()
    }

}