Create BounceTouchListener class in the project and use it to add a Bouncy effect to the Transactions items when the user tries to overscroll.

app/src/main/java/cy/agorise/bitsybitshareswallet/fragments/TransactionsFragment.kt

@@ -1,17 +1,20 @@
 package cy.agorise.bitsybitshareswallet.fragments
 
+import android.graphics.Point
 import android.os.Bundle
 import android.preference.PreferenceManager
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
+import androidx.fragment.app.FragmentActivity
 import androidx.lifecycle.Observer
 import androidx.lifecycle.ViewModelProviders
 import androidx.recyclerview.widget.LinearLayoutManager
 import cy.agorise.bitsybitshareswallet.R
 import cy.agorise.bitsybitshareswallet.adapters.TransfersDetailsAdapter
 import cy.agorise.bitsybitshareswallet.database.joins.TransferDetail
+import cy.agorise.bitsybitshareswallet.utils.BounceTouchListener
 import cy.agorise.bitsybitshareswallet.utils.Constants
 import cy.agorise.bitsybitshareswallet.viewmodels.TransferDetailViewModel
 import kotlinx.android.synthetic.main.fragment_transactions.*
@@ -20,6 +23,11 @@ class TransactionsFragment : Fragment() {
 
     private lateinit var mTransferDetailViewModel: TransferDetailViewModel
 
+    /** Variables used for the RecyclerView pull springy animation  */
+    private var bounceTouchListener: BounceTouchListener? = null
+    private var pivotY1: Float = 0.toFloat()
+    private var pivotY2:Float = 0.toFloat()
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
@@ -45,6 +53,45 @@ class TransactionsFragment : Fragment() {
         mTransferDetailViewModel.getAll(userId).observe(this, Observer<List<TransferDetail>> { transfersDetails ->
             transfersDetailsAdapter.replaceAll(transfersDetails)
         })
+
+        rvTransactions.pivotX = getScreenWidth(activity) * 0.5f
+
+        pivotY1 = 0f
+        pivotY2 = getScreenHeight(activity) * .5f
+
+        bounceTouchListener =
+                BounceTouchListener.create(rvTransactions, object : BounceTouchListener.OnTranslateListener {
+                    override fun onTranslate(translation: Float) {
+                        if (translation > 0) {
+                            bounceTouchListener?.setMaxAbsTranslation(-99)
+                            rvTransactions.pivotY = pivotY1
+                            val scale = 2 * translation / rvTransactions.measuredHeight + 1
+                            rvTransactions.scaleY = Math.pow(scale.toDouble(), .6).toFloat()
+                        } else {
+                            bounceTouchListener?.setMaxAbsTranslation((pivotY2 * .33f).toInt())
+                            rvTransactions.pivotY = pivotY2
+                            val scale = 2 * translation / rvTransactions.measuredHeight + 1
+                            rvTransactions.scaleY = Math.pow(scale.toDouble(), .5).toFloat()
+                        }
+                    }
+                })
+
+        // Sets custom touch listener to handle bounce/stretch effect
+        rvTransactions.setOnTouchListener(bounceTouchListener)
+    }
+
+    private fun getScreenWidth(activity: FragmentActivity?): Int {
+        val display = activity?.windowManager?.defaultDisplay
+        val size = Point()
+        display?.getSize(size)
+        return size.x
+    }
+
+    private fun getScreenHeight(activity: FragmentActivity?): Int {
+        val display = activity?.windowManager?.defaultDisplay
+        val size = Point()
+        display?.getSize(size)
+        return size.y
     }
 
 //    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {

app/src/main/java/cy/agorise/bitsybitshareswallet/utils/BounceTouchListener.kt

@@ -0,0 +1,340 @@
+package cy.agorise.bitsybitshareswallet.utils
+
+import android.animation.Animator
+import android.animation.AnimatorListenerAdapter
+import android.animation.ValueAnimator
+import android.view.MotionEvent
+import android.view.View
+import android.view.ViewGroup
+import android.view.animation.DecelerateInterpolator
+import android.widget.ListView
+import android.widget.ScrollView
+import androidx.annotation.IdRes
+import androidx.core.view.MotionEventCompat
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import androidx.recyclerview.widget.StaggeredGridLayoutManager
+
+class BounceTouchListener private constructor(
+    private val mMainView: View,
+    contentResId: Int,
+    private val onTranslateListener: OnTranslateListener?
+) :
+    View.OnTouchListener {
+
+    private var downCalled = false
+    private val mContent: View
+    private var mDownY: Float = 0.toFloat()
+    private var mSwipingDown: Boolean = false
+    private var mSwipingUp: Boolean = false
+    private val mInterpolator = DecelerateInterpolator(3f)
+    private val swipUpEnabled = true
+    private var mActivePointerId = -99
+    private var mLastTouchY = -99f
+    private var mMaxAbsTranslation = -99
+
+
+    init {
+        mContent = if (contentResId == -1) mMainView else mMainView.findViewById(contentResId)
+    }
+
+    override fun onTouch(view: View, motionEvent: MotionEvent): Boolean {
+        val action = MotionEventCompat.getActionMasked(motionEvent)
+
+        when (action) {
+            MotionEvent.ACTION_DOWN -> {
+                run {
+                    onDownMotionEvent(motionEvent)
+                    view.onTouchEvent(motionEvent)
+                    downCalled = true
+                    if (mContent.translationY == 0f) {
+                        return false
+                    }
+                }
+                run {
+                    if (mActivePointerId == -99) {
+                        onDownMotionEvent(motionEvent)
+                        downCalled = true
+                    }
+                    val pointerIndex = MotionEventCompat.findPointerIndex(motionEvent, mActivePointerId)
+                    val y = MotionEventCompat.getY(motionEvent, pointerIndex)
+
+                    if (!hasHitTop() && !hasHitBottom() || !downCalled) {
+                        if (!downCalled) {
+                            downCalled = true
+                        }
+                        mDownY = y
+                        view.onTouchEvent(motionEvent)
+                        return false
+                    }
+
+                    val deltaY = y - mDownY
+                    if (Math.abs(deltaY) > 0 && hasHitTop() && deltaY > 0) {
+                        mSwipingDown = true
+                        sendCancelEventToView(view, motionEvent)
+                    }
+                    if (swipUpEnabled) {
+                        if (Math.abs(deltaY) > 0 && hasHitBottom() && deltaY < 0) {
+                            mSwipingUp = true
+                            sendCancelEventToView(view, motionEvent)
+                        }
+                    }
+                    if (mSwipingDown || mSwipingUp) {
+                        if (deltaY <= 0 && mSwipingDown || deltaY >= 0 && mSwipingUp) {
+                            mDownY = 0f
+                            mSwipingDown = false
+                            mSwipingUp = false
+                            downCalled = false
+                            val downEvent = MotionEvent.obtain(motionEvent)
+                            downEvent.action = MotionEvent.ACTION_DOWN or
+                                    (MotionEventCompat.getActionIndex(motionEvent) shl MotionEventCompat.ACTION_POINTER_INDEX_SHIFT)
+                            view.onTouchEvent(downEvent)
+                        }
+                        var translation =
+                            (deltaY / Math.abs(deltaY) * Math.pow(Math.abs(deltaY).toDouble(), .8)).toInt()
+                        if (mMaxAbsTranslation > 0) {
+                            if (translation < 0) {
+                                translation = Math.max(-mMaxAbsTranslation, translation)
+                            } else {
+                                translation = Math.min(mMaxAbsTranslation, translation)
+                            }
+                        }
+                        mContent.translationY = translation.toFloat()
+                        onTranslateListener?.onTranslate(mContent.translationY)
+
+                        return true
+                    }
+                }
+            }
+            MotionEvent.ACTION_MOVE -> {
+                if (mActivePointerId == -99) {
+                    onDownMotionEvent(motionEvent)
+                    downCalled = true
+                }
+                val pointerIndex = MotionEventCompat.findPointerIndex(motionEvent, mActivePointerId)
+                val y = MotionEventCompat.getY(motionEvent, pointerIndex)
+                if (!hasHitTop() && !hasHitBottom() || !downCalled) {
+                    if (!downCalled) {
+                        downCalled = true
+                    }
+                    mDownY = y
+                    view.onTouchEvent(motionEvent)
+                    return false
+                }
+                val deltaY = y - mDownY
+                if (Math.abs(deltaY) > 0 && hasHitTop() && deltaY > 0) {
+                    mSwipingDown = true
+                    sendCancelEventToView(view, motionEvent)
+                }
+                if (swipUpEnabled) {
+                    if (Math.abs(deltaY) > 0 && hasHitBottom() && deltaY < 0) {
+                        mSwipingUp = true
+                        sendCancelEventToView(view, motionEvent)
+                    }
+                }
+                if (mSwipingDown || mSwipingUp) {
+                    if (deltaY <= 0 && mSwipingDown || deltaY >= 0 && mSwipingUp) {
+                        mDownY = 0f
+                        mSwipingDown = false
+                        mSwipingUp = false
+                        downCalled = false
+                        val downEvent = MotionEvent.obtain(motionEvent)
+                        downEvent.action = MotionEvent.ACTION_DOWN or
+                                (MotionEventCompat.getActionIndex(motionEvent) shl MotionEventCompat.ACTION_POINTER_INDEX_SHIFT)
+                        view.onTouchEvent(downEvent)
+                    }
+                    var translation = (deltaY / Math.abs(deltaY) * Math.pow(Math.abs(deltaY).toDouble(), .8)).toInt()
+                    if (mMaxAbsTranslation > 0) {
+                        if (translation < 0) {
+                            translation = Math.max(-mMaxAbsTranslation, translation)
+                        } else {
+                            translation = Math.min(mMaxAbsTranslation, translation)
+                        }
+                    }
+                    mContent.translationY = translation.toFloat()
+                    onTranslateListener?.onTranslate(mContent.translationY)
+                    return true
+                }
+            }
+
+            MotionEvent.ACTION_UP -> {
+                mActivePointerId = -99
+                // cancel
+                mContent.animate()
+                    .setInterpolator(mInterpolator)
+                    .translationY(0f)
+                    .setDuration(DEFAULT_ANIMATION_TIME)
+                    .setListener(object : AnimatorListenerAdapter() {
+                        override fun onAnimationStart(animation: Animator) {
+                            (animation as ValueAnimator).addUpdateListener {
+                                onTranslateListener?.onTranslate(mContent.translationY)
+                            }
+                            super.onAnimationStart(animation)
+                        }
+                    })
+
+                mDownY = 0f
+                mSwipingDown = false
+                mSwipingUp = false
+                downCalled = false
+            }
+
+            MotionEvent.ACTION_CANCEL -> {
+                mActivePointerId = -99
+            }
+
+            MotionEvent.ACTION_POINTER_UP -> {
+                val pointerIndex = MotionEventCompat.getActionIndex(motionEvent)
+                val pointerId = MotionEventCompat.getPointerId(motionEvent, pointerIndex)
+
+                if (pointerId == mActivePointerId) {
+                    val newPointerIndex = if (pointerIndex == 0) 1 else 0
+                    mLastTouchY = MotionEventCompat.getY(motionEvent, newPointerIndex)
+                    mActivePointerId = MotionEventCompat.getPointerId(motionEvent, newPointerIndex)
+
+                    if (mContent.translationY > 0) {
+                        mDownY = mLastTouchY - Math.pow(mContent.translationY.toDouble(), (10f / 8f).toDouble()).toInt()
+                        mContent.animate().cancel()
+                    } else if (mContent.translationY < 0) {
+                        mDownY = mLastTouchY +
+                                Math.pow((-mContent.translationY).toDouble(), (10f / 8f).toDouble()).toInt()
+                        mContent.animate().cancel()
+                    }
+                }
+            }
+        }
+        return false
+    }
+
+    private fun sendCancelEventToView(view: View, motionEvent: MotionEvent) {
+        (view as ViewGroup).requestDisallowInterceptTouchEvent(true)
+        val cancelEvent = MotionEvent.obtain(motionEvent)
+        cancelEvent.action = MotionEvent.ACTION_CANCEL or
+                (MotionEventCompat.getActionIndex(motionEvent) shl MotionEventCompat.ACTION_POINTER_INDEX_SHIFT)
+        view.onTouchEvent(cancelEvent)
+    }
+
+    private fun onDownMotionEvent(motionEvent: MotionEvent) {
+        val pointerIndex = MotionEventCompat.getActionIndex(motionEvent)
+        mLastTouchY = MotionEventCompat.getY(motionEvent, pointerIndex)
+        mActivePointerId = MotionEventCompat.getPointerId(motionEvent, 0)
+
+        if (mContent.translationY > 0) {
+            mDownY = mLastTouchY - Math.pow(mContent.translationY.toDouble(), (10f / 8f).toDouble()).toInt()
+            mContent.animate().cancel()
+        } else if (mContent.translationY < 0) {
+            mDownY = mLastTouchY + Math.pow((-mContent.translationY).toDouble(), (10f / 8f).toDouble()).toInt()
+            mContent.animate().cancel()
+        } else {
+            mDownY = mLastTouchY
+        }
+    }
+
+    private fun hasHitBottom(): Boolean {
+        if (mMainView is ScrollView) {
+            val scrollView = mMainView
+            val view = scrollView.getChildAt(scrollView.childCount - 1)
+            val diff = view.bottom - (scrollView.height + scrollView.scrollY)// Calculate the scrolldiff
+            return diff == 0
+        } else if (mMainView is ListView) {
+            val listView = mMainView
+            if (listView.adapter != null) {
+                if (listView.adapter.count > 0) {
+                    return listView.lastVisiblePosition == listView.adapter.count - 1 && listView.getChildAt(listView.childCount - 1).bottom <= listView.height
+                }
+            }
+        } else if (mMainView is RecyclerView) {
+            val recyclerView = mMainView
+            if (recyclerView.adapter != null && recyclerView.layoutManager != null) {
+                val adapter = recyclerView.adapter
+                if (adapter!!.itemCount > 0) {
+                    val layoutManager = recyclerView.layoutManager
+                    if (layoutManager is LinearLayoutManager) {
+                        val linearLayoutManager = layoutManager as LinearLayoutManager?
+                        return linearLayoutManager!!.findLastCompletelyVisibleItemPosition() == adapter.itemCount - 1
+                    } else if (layoutManager is StaggeredGridLayoutManager) {
+                        val staggeredGridLayoutManager = layoutManager as StaggeredGridLayoutManager?
+                        val checks = staggeredGridLayoutManager!!.findLastCompletelyVisibleItemPositions(null)
+                        for (check in checks) {
+                            if (check == adapter.itemCount - 1)
+                                return true
+                        }
+                    }
+                }
+            }
+        }
+        return false
+    }
+
+    private fun hasHitTop(): Boolean {
+        if (mMainView is ScrollView) {
+            return mMainView.scrollY == 0
+        } else if (mMainView is ListView) {
+            val listView = mMainView
+            if (listView.adapter != null) {
+                if (listView.adapter.count > 0) {
+                    return listView.firstVisiblePosition == 0 && listView.getChildAt(0).top >= 0
+                }
+            }
+        } else if (mMainView is RecyclerView) {
+            val recyclerView = mMainView
+            if (recyclerView.adapter != null && recyclerView.layoutManager != null) {
+                val adapter = recyclerView.adapter
+                if (adapter!!.itemCount > 0) {
+                    val layoutManager = recyclerView.layoutManager
+                    if (layoutManager is LinearLayoutManager) {
+                        val linearLayoutManager = layoutManager as LinearLayoutManager?
+                        return linearLayoutManager!!.findFirstCompletelyVisibleItemPosition() == 0
+                    } else if (layoutManager is StaggeredGridLayoutManager) {
+                        val staggeredGridLayoutManager = layoutManager as StaggeredGridLayoutManager?
+                        val checks = staggeredGridLayoutManager!!.findFirstCompletelyVisibleItemPositions(null)
+                        for (check in checks) {
+                            if (check == 0)
+                                return true
+                        }
+                    }
+                }
+            }
+        }
+
+        return false
+    }
+
+    fun setMaxAbsTranslation(maxAbsTranslation: Int) {
+        this.mMaxAbsTranslation = maxAbsTranslation
+    }
+
+    interface OnTranslateListener {
+        fun onTranslate(translation: Float)
+    }
+
+    companion object {
+        private val DEFAULT_ANIMATION_TIME = 600L
+
+        /**
+         * Creates a new BounceTouchListener
+         *
+         * @param mainScrollableView  The main view that this touch listener is attached to
+         * @param onTranslateListener To perform action on translation, can be null if not needed
+         * @return A new BounceTouchListener attached to the given scrollable view
+         */
+        fun create(mainScrollableView: View, onTranslateListener: OnTranslateListener?): BounceTouchListener {
+            return create(mainScrollableView, -1, onTranslateListener)
+        }
+
+        /**
+         * Creates a new BounceTouchListener
+         *
+         * @param mainView            The main view that this touch listener is attached to
+         * @param contentResId        Resource Id of the scrollable view
+         * @param onTranslateListener To perform action on translation, can be null if not needed
+         * @return A new BounceTouchListener attached to the given scrollable view
+         */
+        fun create(
+            mainView: View, @IdRes contentResId: Int,
+            onTranslateListener: OnTranslateListener?
+        ): BounceTouchListener {
+            return BounceTouchListener(mainView, contentResId, onTranslateListener)
+        }
+    }
+}

app/src/main/res/layout/fragment_transactions.xml

@@ -1,18 +1,12 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout
+<androidx.recyclerview.widget.RecyclerView
-    xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools"
+    xmlns:android="http://schemas.android.com/apk/res/android"
-    android:orientation="vertical"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/rvTransactions"
     android:layout_width="match_parent"
-    android:layout_height="match_parent">
+    android:layout_height="match_parent"
-
+    android:padding="@dimen/card_margin"
-    <androidx.recyclerview.widget.RecyclerView
+    android:clipToPadding="false"
-        android:id="@+id/rvTransactions"
+    tools:listitem="@layout/item_transaction"
-        android:layout_width="match_parent"
+    tools:itemCount="6"
-        android:layout_height="wrap_content"
+    android:layoutAnimation="@anim/layout_animation_from_bottom"/>
-        android:padding="@dimen/card_margin"
-        android:clipToPadding="false"
-        tools:listitem="@layout/item_transaction"
-        tools:itemCount="6"
-        android:layoutAnimation="@anim/layout_animation_from_bottom"/>
-
-</LinearLayout>