Decorator

package some.package

import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.graphics.Rect
import android.support.v7.widget.RecyclerView
import android.view.View

class ItemDecorator : RecyclerView.ItemDecoration() {

    private val paint = Paint(Color.WHITE)

    private val rectHeight = 20

    override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView, state: RecyclerView.State) {
        if (needDrawBottomDelimiter(parent, view)) {
            outRect.bottom = rectHeight
        } else {
            super.getItemOffsets(outRect, view, parent, state)
        }
    }

    private fun needDrawBottomDelimiter(parent: RecyclerView, view: View): Boolean {
        val viewPosition = parent.getChildAdapterPosition(view)
        val lastItem = if (parent.adapter != null) parent.adapter!!.itemCount - 1 else 0
        return viewPosition == 0 || viewPosition == lastItem
    }

    override fun onDraw(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
        val dividerStart = parent.paddingStart
        val dividerEnd = parent.width - parent.paddingEnd
        val endIndex = parent.adapter?.itemCount ?: 0
        for (index in 0 until endIndex) {
            val currentChild = parent.getChildAt(index)
            if (needDrawBottomDelimiter(parent, currentChild)) {
                val params = currentChild.layoutParams as RecyclerView.LayoutParams
                val bottomView = currentChild.bottom + params.bottomMargin
                val startX = dividerStart.toFloat()
                val startY = bottomView.toFloat()
                val endX = dividerEnd.toFloat()
                val endY = startY + rectHeight
                c.drawRect(startX, startY, endX, endY, paint)
            }
        }
    }

}