Draw Line in recycler view and fill space below | Android | Kotlin

Question

I have made Item decorator for drawing line in recycler view it works well. Now I want to fill everything below the line. Also I want to make line connection more smooth, I have tried increasing the PATH_CORNER_RADIUS_IN_DP but seems not working well, maybe I'm missing something

package com.meteosolutions.vojvodinameteo.recyclers

import android.content.Context
import android.content.res.Resources
import android.graphics.Canvas
import android.graphics.CornerPathEffect
import android.graphics.Paint
import androidx.core.content.ContextCompat
import androidx.recyclerview.widget.RecyclerView
import com.meteosolutions.vojvodinameteo.R
import com.meteosolutions.vojvodinameteo.model.data.fragmentMain.HourlyForecastData
import kotlin.math.roundToInt


private const val STROKE_WIDTH = 7f
private const val PATH_CORNER_RADIUS_IN_DP = 60
private const val CHILD_HEADER_OR_FOOTER_HEIGHT_IN_DP = 278

internal class TemperatureLineItemDecorator(temperatureList: List<HourlyForecastData>, context: Context) :
    RecyclerView.ItemDecoration() {

    private val drawPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
        strokeWidth = STROKE_WIDTH
        style = Paint.Style.STROKE
        strokeJoin = Paint.Join.ROUND
        strokeCap = Paint.Cap.ROUND
        color = ContextCompat.getColor(context, R.color.white)
        pathEffect = CornerPathEffect(PATH_CORNER_RADIUS_IN_DP.dpToPx)
    }

    private val normalizedTemperatureValues = normalizeValues(temperatureList)

    override fun onDraw(canvas: Canvas, parent: RecyclerView, state: RecyclerView.State) {
        super.onDraw(canvas, parent, state)

        for (childIndex in 0 until parent.childCount) {
            val childView = parent.getChildAt(childIndex)
            val dataIndex = parent.getChildAdapterPosition(childView)
            val childViewHeight = childView.height

            canvas.drawLine(
                childView.left.toFloat(),
                calculateYValue(dataIndex, childViewHeight),
                childView.right.toFloat(),
                calculateYValue(getDataIndexOfNextChild(dataIndex), childViewHeight),
                drawPaint
            )
        }
    }

    private fun getDataIndexOfNextChild(currentChildDataIndex: Int): Int {
        val nextChildDataIndex = currentChildDataIndex + 1
        return if (nextChildDataIndex >= normalizedTemperatureValues.size) {
            currentChildDataIndex
        } else {
            nextChildDataIndex
        }
    }

    private fun calculateYValue(dataIndex: Int, childViewHeight: Int): Float {
        val graphHeight = childViewHeight - (CHILD_HEADER_OR_FOOTER_HEIGHT_IN_DP / 2).dpToPx
        val graphStartHeightDelta = CHILD_HEADER_OR_FOOTER_HEIGHT_IN_DP.dpToPx

        return ((1 - normalizedTemperatureValues[dataIndex] * graphHeight + graphStartHeightDelta))
    }

    private fun normalizeValues(hourlyForecastData: List<HourlyForecastData>): List<Float> {
        val minTemperature = hourlyForecastData.minBy { it.temp.roundToInt() }
        val maxTemperature = hourlyForecastData.maxBy { it.temp.roundToInt() }

        if (minTemperature.temp.roundToInt() >= maxTemperature.temp.roundToInt()) {
            return hourlyForecastData.map { 0.5f }
        }

        val range = maxTemperature.temp - minTemperature.temp
        return hourlyForecastData.map {
            val relativeValue = it.temp - minTemperature.temp
            return@map (relativeValue / range).toFloat()
        }
    }
}

val Int.dpToPx: Float
    get() = (this * Resources.getSystem().displayMetrics.density)