How to make a normal lines numbering in EditText?

Question

I am making a text editor for Android and I would like to show the number of every line in theEditText.

My solution was to make a TextView with lines numbers and place an EditText next to TextView. Like this

<LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:fillViewport="true">
        <TextView
            android:id="@+id/lines_numbering_view"
            android:layout_width="wrap_content"
            android:minWidth="10dp"
            android:layout_height="match_parent"
            android:textSize="18sp"
            android:text="1\n"/>
        <EditText
            <!--EditText options here-->
        />
    </LinearLayout>

This works fine but there is one fact... If the lines count is about 600, when TextView's onMeasure method is called, it makes the app to freeze for a 0.5 seconds.

So, what can I do to improve the performance of TextView or are there any good solutions of numbering lines?

Answer 1

The line number view can be seen and implemented as a ruler. All it needs as input is the line height. From there it can display increasing line numbers at the proper vertical positions. It need not know the number of lines in the content view.