gistfile1.txt

package de.check24.techtalk.recyclerview.bigtosmall

import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import de.check24.techtalk.common.BaseActivity
import de.check24.techtalk.databinding.ActivityRecyclerviewBigToSmallBinding
import de.check24.techtalk.recyclerview.bigtosmall.adapter.RecyclerViewBigToSmallAdapter

/**
 * Created by kevin.toerpsch on 01.03.2021
 * RecyclerAdapterActivity
 */
class RecyclerBigToSmallActivity : BaseActivity<ActivityRecyclerviewBigToSmallBinding>() {

    override val bindingInflater: (LayoutInflater) -> ActivityRecyclerviewBigToSmallBinding
        get() = ActivityRecyclerviewBigToSmallBinding::inflate

    private var actualScrollTo: Int = 0

    private val bigRecyclerViewAdapter by lazy { RecyclerViewBigToSmallAdapter(true) }
    private val smallRecyclerViewAdapter by lazy { RecyclerViewBigToSmallAdapter(false) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        binding?.apply {
            recyclerViewBig.apply {
                layoutManager = LinearLayoutManager(context, RecyclerView.HORIZONTAL, false)
                adapter = bigRecyclerViewAdapter
                setOnScrollChangeListener { _, _, _, _, _ ->
                    val firstView = findFirstVisibleView(recyclerViewBig.layoutManager as LinearLayoutManager)
                    val position = firstView?.let { recyclerViewBig.getChildAdapterPosition(it) }
                    val scrollTo = (recyclerViewBig.computeHorizontalScrollOffset() * getRecyclerViewScrollSize(recyclerViewSmall)) / getRecyclerViewScrollSize(recyclerViewBig)
                    firstView?.let {
                        val offset: Float = (-firstView.x) / firstView.measuredWidth
                        Log.d("Nurs","ofset = ${recyclerViewBig.computeHorizontalScrollOffset()} postipon = ${position}" +
                                " smalpos = ${offset} diff =  ${scrollTo - actualScrollTo}")
                        if (position != null) {
                            recyclerViewSmall.getChildAt(position-3)?.apply {
                                scaleY = ((1-offset)/2)
                            }
                            recyclerViewSmall.getChildAt(position -2)?.apply {
                                scaleY = 1-offset
                            }
                            recyclerViewSmall.getChildAt(position -1)?.apply {
                                scaleY = 1f
                            }
                            recyclerViewSmall.getChildAt(position)?.apply {
                                scaleY = 1f
                            }
                            recyclerViewSmall.getChildAt(position+1)?.apply {
                                scaleY = 1f
                            }
                            recyclerViewSmall.getChildAt(position+2)?.apply {
                                scaleY = offset
                            }
                            recyclerViewSmall.getChildAt(position+3)?.apply {
                                scaleY = (offset/2)
                            }
                        }
                        scrollSmallToPos(scrollTo,offset)
                    }
                    if (scrollTo>actualScrollTo){

                    }else{

                    }

                }
            }
            recyclerViewSmall.apply {
                layoutManager = LinearLayoutManager(context, RecyclerView.HORIZONTAL, false)
                adapter = smallRecyclerViewAdapter
            }
        }
    }
    private fun findFirstVisibleView(layoutManager: LinearLayoutManager): View? {
        val childCount = layoutManager.childCount
        if (childCount == 0) {
            return null
        }
        var closestChild: View? = null
        var firstVisibleChild = Int.MAX_VALUE
        for (i in 0 until childCount) {
            val child = layoutManager.getChildAt(i)
            val childStart = child!!.x.toInt()
            if (childStart + child.measuredWidth < firstVisibleChild) {
                firstVisibleChild = childStart
                closestChild = child
            }
        }
        return closestChild
    }
    private fun scrollSmallToPos(scrollTo: Int,offset:Float) {
        binding?.recyclerViewSmall?.scrollBy(scrollTo - actualScrollTo, 0)
        this@RecyclerBigToSmallActivity.actualScrollTo = scrollTo
    }

    private fun getRecyclerViewScrollSize(recyclerView: RecyclerView): Int = recyclerView.computeHorizontalScrollRange() - recyclerView.computeHorizontalScrollExtent()

}