Swipe to delete callback

MainActivity.kt

private fun initRvActions() {
    rvCommands.layoutManager = LinearLayoutManager(this)
    rvCommands.adapter = AdapterCommands(model)
   rvCommands.addItemDecoration(DividerItemDecoration(this, DividerItemDecoration.VERTICAL))

    val swipeHandler = object : SwipeToDeleteCallback(this) {
        override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
            val adapter = rvCommands.adapter as AdapterCommands
            adapter.removeAt(viewHolder.adapterPosition)
        }
        override fun getMovementFlags(recyclerView: RecyclerView?,
                                          viewHolder: ViewHolder?): Int {
                Timber.d("jsp pos=${viewHolder?.adapterPosition}")
                // dont allow remove first element
                if (viewHolder?.adapterPosition == 0) return 0

                return (makeFlag(ACTION_STATE_IDLE, ItemTouchHelper.LEFT) or
                        makeFlag(ACTION_STATE_SWIPE, ItemTouchHelper.LEFT))
            }
    }
    val itemTouchHelper = ItemTouchHelper(swipeHandler)
    itemTouchHelper.attachToRecyclerView(rvCommands)
}

SwipeToDeleteCallback.kt

import android.content.Context
import android.graphics.Bitmap
import android.graphics.Bitmap.Config
import android.graphics.Canvas
import android.graphics.Color
import android.graphics.drawable.BitmapDrawable
import android.graphics.drawable.ColorDrawable
import android.provider.MediaStore
import android.support.v4.content.ContextCompat
import android.support.v7.widget.RecyclerView
import android.support.v7.widget.helper.ItemTouchHelper
import timber.log.Timber

abstract class SwipeToDeleteCallback(val context: Context) : ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {

    private val deleteIcon = ContextCompat.getDrawable(context, R.drawable.ic_delete_white_24)
    private val intrinsicWidth = deleteIcon!!.intrinsicWidth
    private val intrinsicHeight = deleteIcon!!.intrinsicHeight
    private val background = ColorDrawable()
    private val backgroundColor = Color.parseColor("#f44336")
    private val canvas = Canvas()

    override fun onMove(recyclerView: RecyclerView?,
                        viewHolder: RecyclerView.ViewHolder?,
                        target: RecyclerView.ViewHolder?): Boolean {
        return false
    }

    override fun onChildDraw(c: Canvas,
                             recyclerView: RecyclerView?,
                             viewHolder: RecyclerView.ViewHolder,
                             dX: Float,
                             dY: Float,
                             actionState: Int,
                             isCurrentlyActive: Boolean) {

        val itemView = viewHolder.itemView
        val itemHeight = itemView.bottom - itemView.top

        val backgroundWidth = -dX.toInt()
        val backgroundLeft = itemView.right + dX.toInt()

        // Calculate position of delete icon
        val deleteIconTop = itemView.top + (itemHeight - intrinsicHeight) / 2
        val deleteIconMargin = (itemHeight - intrinsicHeight) / 2
        val deleteIconLeft = itemView.right - deleteIconMargin - intrinsicWidth
        val deleteIconRight = itemView.right - deleteIconMargin
        val deleteIconBottom = deleteIconTop + intrinsicHeight

        val cCopy = Bitmap.createBitmap(c.width, c.height, Config.ARGB_4444)
        canvas.setBitmap(cCopy)

        // Draw the red delete background
        background.color = backgroundColor
        background.setBounds(backgroundLeft, itemView.top, itemView.right, itemView.bottom)
        background.draw(canvas)

        // Draw the delete icon
        deleteIcon!!.setBounds(deleteIconLeft, deleteIconTop, deleteIconRight, deleteIconBottom)
        deleteIcon!!.draw(canvas)

        val dr = BitmapDrawable(context.resources, cCopy)

        val allIconTop = itemView.top
        val allIconLeft = backgroundLeft
        val allIconRight = itemView.right
        val allIconBottom = itemView.bottom

        if (backgroundWidth > 0) {
            val hiddenAreaBmp = Bitmap.createBitmap(dr.bitmap, allIconLeft, allIconTop, backgroundWidth, itemHeight)
            val hidden = BitmapDrawable(context.resources, hiddenAreaBmp)
            hidden.setBounds(allIconLeft, allIconTop, allIconRight, allIconBottom)
            hidden.draw(c)
        }

        super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive)
    }

    private fun saveBitmap(bitmap: Bitmap,
                           name: String) {
        val s = context.packageName
        Timber.d("jsp bitmap is saved ")
        MediaStore.Images.Media.insertImage(context.contentResolver, bitmap, name, s);
    }
}