There is no way to prevent ScrollView from automatically scrolling when TextView is focused?

Question

If I click text2 for the first time or whenever I click text2 after clicking text1, the ScrollView seems to be scrolling text2 to the top. If I put android:descendantFocusability="blocksDescendants" in the LinearLayout this scrolling does not happen, but I cannot select the text.

What I want is simple: I do not want this auto-scrolling. Is it IMPOSSIBLE to disable this behaviour of ScrollView and the I would have to create my own scroll view class from scratch? If it is impossible, please write that as an answer, so I could give it up.

<?xml version="1.0" encoding="utf-8"?>
<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="wrap_content">
            <TextView
                    android:text="I am text 1. Click me."
                    android:textColor="@color/black"
                    android:textIsSelectable="true"
                    android:background="#FF0000"
                    android:layout_width="match_parent"
                    android:layout_height="400dp"/>
            <TextView
                    android:text="I am text 2. Click me."
                    android:textIsSelectable="true"
                    android:background="#00FF00"
                    android:textColor="@color/black"
                    android:layout_width="match_parent"
                    android:layout_height="1000dp"/>
        </LinearLayout>
</ScrollView>

score 1 · Answer 1 · answered Jun 25 '21 at 07:13

1

android:descendantFocusability="blocksDescendants" will block its descendants from receiving focus.

Try adding a dummy view between your 2 text views and see.

<View
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:focusable="true"
    android:focusableInTouchMode="true" />

answered Jun 25 '21 at 07:13

Anju

9,379
14
55
94

My layout is scrollview > linearalayout > textview . Only putting android:descendantFocusability="afterDescendants" inside LinearLayout did the trick. Everything else blocked or had old unwanted behaviour – CaptainCrunch Nov 01 '22 at 14:16

score 1 · Accepted Answer · answered Jun 25 '21 at 08:16

You can make a subclass of ScrollView and override the protected method: computeScrollDeltaToGetChildRectOnScreen(Rect rect) and return 0 to disable the autoscrolling effect.

computeScrollDeltaToGetChildRectOnScreen

Compute the amount to scroll in the Y direction in order to get a rectangle completely on the screen (or, if taller than the screen, at least the first screen size chunk of it).

Kotlin Example:

class CustomScrollView : ScrollView {
    constructor(context: Context?) : super(context) {}
    constructor(context: Context?, attrs: AttributeSet?) : super(context, attrs) {}
    constructor(context: Context?, attrs: AttributeSet?, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {}

    override fun computeScrollDeltaToGetChildRectOnScreen(rect: Rect): Int {
        return 0
    }
}

Xml Usage:

<?xml version="1.0" encoding="utf-8"?>
<mypackagename.com.CustomScrollView
    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="wrap_content">
        <TextView
            android:text="I am text 1. Click me."
            android:textColor="@color/black"
            android:textIsSelectable="true"
            android:background="#FF0000"
            android:layout_width="match_parent"
            android:layout_height="400dp"/>
        <TextView
            android:text="I am text 2. Click me."
            android:textIsSelectable="true"
            android:background="#00FF00"
            android:textColor="@color/black"
            android:layout_width="match_parent"
            android:layout_height="1000dp"/>
    </LinearLayout>
</mypackagename.com.CustomScrollView>

There is no way to prevent ScrollView from automatically scrolling when TextView is focused?

2 Answers2