Implements a basic swipe on recyclerview item

SwipeController.kt

package com.util

import android.graphics.Canvas
import android.graphics.Color
import android.graphics.Paint
import android.support.v7.widget.RecyclerView
import android.support.v7.widget.helper.ItemTouchHelper.Callback
import android.support.v7.widget.helper.ItemTouchHelper.*
import android.view.MotionEvent
import android.support.v7.widget.helper.ItemTouchHelper.ACTION_STATE_SWIPE
import android.view.View
import android.graphics.RectF
import timber.log.Timber


/*
Classe de gestion du Swipe sur RecyclerView
*/
internal class SwipeController : Callback() {

    override fun onSelectedChanged(viewHolder: RecyclerView.ViewHolder?, actionState: Int) {
        //Log.d("SwipeController", "onSelectedChanged")
        super.onSelectedChanged(viewHolder, actionState)
    }

    override fun getMovementFlags(recyclerView: RecyclerView, viewHolder: RecyclerView.ViewHolder): Int {
        //return makeMovementFlags(0, LEFT or RIGHT)
        return makeMovementFlags(0, LEFT)
    }

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

    override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
        // La ligne a été swipée
    }

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

        if (actionState == ACTION_STATE_SWIPE) {
            setTouchListener(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive)
        }

        // Dessiner les boutons arbitairement
        // TODO: Remplacer par des icônes ou fontes si possible
        drawButtons(c, viewHolder)

        val translationX: Float
        val itemViewWidth: Float = viewHolder.itemView.width.toFloat()
        if (dX > 0) {
            translationX = Math.min(-dX,  /*itemViewWidth / 2*/ buttonWidth*2)
        } else {
            translationX = Math.max(dX, -1 * /*itemViewWidth / 2*/ buttonWidth*2)
        }

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

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

        recyclerView.setOnTouchListener(object : View.OnTouchListener {
            override fun onTouch(v: View, event: MotionEvent): Boolean {
                //swipeBack = event.action == MotionEvent.ACTION_CANCEL || event.action == MotionEvent.ACTION_UP
                //Timber.d("onTouch")
                //Timber.d(event.toString())
                if (event.action == MotionEvent.ACTION_DOWN) {
                    Timber.d("ACTION_DOWN")
                    val x = event.getX()
                    val y = event.getY()
                    if (x>=deleteButton.left && x<=deleteButton.right && y>=deleteButton.top && y<=deleteButton.bottom) {
                        Timber.d("Delete button clicked")
                    } else if (x>=editButton.left && x<=editButton.right && y>=editButton.top && y<=editButton.bottom) {
                        Timber.d("Edit button clicked")
                    }
                }
                return false
            }
        })
    }

    val buttonWidth = 150f
    var buttonWidthWithoutPadding : Float = 0.0F

    lateinit var deleteButton : RectF
    lateinit var editButton : RectF
    private fun drawButtons(c: Canvas, viewHolder: RecyclerView.ViewHolder) {
        buttonWidthWithoutPadding = buttonWidth - 20
        val corners = 16f

        val itemView = viewHolder.itemView
        val p = Paint()

        deleteButton = RectF(itemView.right - buttonWidthWithoutPadding, itemView.top.toFloat(), itemView.right.toFloat(), itemView.bottom.toFloat())
        p.setColor(Color.RED)
        c.drawRoundRect(deleteButton, corners, corners, p)
        drawText("Suppr.", c, deleteButton, p)

        editButton = RectF(itemView.right - buttonWidthWithoutPadding, itemView.top.toFloat(), itemView.right - buttonWidthWithoutPadding * 2, itemView.bottom.toFloat())
        p.setColor(Color.GREEN)
        c.drawRoundRect(editButton, corners, corners, p)
        drawText("Editer", c, editButton, p)
    }

    private fun drawText(text: String, c: Canvas, button: RectF, p: Paint) {
        val textSize = 20f
        p.color = Color.WHITE
        p.isAntiAlias = true
        p.textSize = textSize

        val textWidth = p.measureText(text)
        c.drawText(text, button.centerX() - textWidth / 2, button.centerY() + textSize / 2, p)
    }

}