Line count mechanism in JTextArea

TextAreaLineCounter.kt

package lt.linecounter

import java.awt.Font
import java.awt.FontMetrics
import java.awt.Insets
import java.awt.font.LineBreakMeasurer
import java.awt.font.TextAttribute
import java.text.AttributedString
import java.text.BreakIterator
import javax.swing.JTextArea

class TextAreaLineCounter(
    private val textArea: JTextArea
) {

    private val font: Font
        get() = textArea.font
    private val fontMetrics: FontMetrics
        get() = textArea.getFontMetrics(font)
    private val insets: Insets
        get() = textArea.insets
    private val formatWidth: Float
        get() = (textArea.width - insets.left - insets.right).toFloat()

    fun countLines(): Int {
        return countLinesInParagraphs(
            textRaw = textArea.text,
            font = font,
            fontMetrics = fontMetrics,
            formatWidth = formatWidth
        )
    }

    private fun countLinesInParagraphs(
        textRaw: String,
        font: Font,
        fontMetrics: FontMetrics,
        formatWidth: Float
    ): Int {
        val paragraphs: List<String> = textRaw.split("\n")
        val lineCount = paragraphs.fold(0) { acc: Int, sentence: String ->
            val newCount = acc + countLinesInSentence(sentence, font, fontMetrics, formatWidth)
            newCount
        }
        return lineCount
    }

    private fun countLinesInSentence(
        textRaw: String,
        font: Font,
        fontMetrics: FontMetrics,
        formatWidth: Float
    ): Int {
        val text = AttributedString(textRaw)
        text.addAttribute(TextAttribute.FONT, font)
        val frc = fontMetrics.fontRenderContext
        val charIt = text.iterator
        val lineMeasurer = LineBreakMeasurer(
            charIt,
            BreakIterator.getWordInstance(),
            frc
        )
        lineMeasurer.position = charIt.beginIndex
        var noLines = 0
        while (lineMeasurer.position < charIt.endIndex) {
            lineMeasurer.nextLayout(formatWidth)
            noLines++
        }
        return noLines
    }
}