* [o] Optimizes the touch relative offsets

* [m] Increases the height of first page elements to showcase long items

Author: shahsurajk

recyclerviewfastscroller/src/main/java/com/qtalk/recyclerviewfastscroller/RecyclerViewFastScroller.kt

@@ -43,7 +43,6 @@ import androidx.core.content.ContextCompat
 import androidx.core.widget.TextViewCompat
 import androidx.recyclerview.widget.LinearLayoutManager
 import androidx.recyclerview.widget.RecyclerView
-import kotlin.math.abs
 import kotlin.math.max
 import kotlin.math.min
 import kotlin.math.roundToInt
@@ -310,33 +309,24 @@ class RecyclerViewFastScroller @JvmOverloads constructor(
 
             // getting the position of this view on the screen, getting absolute X and Y coordinates
             getLocationInWindow(locationArray)
+            val yAbsPosition: Int = locationArray[1]
 
-            // this offset is to nullify the difference in the height between the handle and touch's relative value
-            var touchRelativeOffset = 0f
             val touchListener = OnTouchListener { _, motionEvent ->
 
-                val yAbsPosition: Int = locationArray[1]
-                // val xAbsPosition : Int = locationArray[0]
-
                 val touchAction = motionEvent.action.and(motionEvent.actionMasked)
                 log("Touch Action: $touchAction")
+
                 when (touchAction) {
                     MotionEvent.ACTION_MOVE, MotionEvent.ACTION_DOWN -> {
+
                         // disallow parent to spy on touch events
                         requestDisallowInterceptTouchEvent(true)
+
                         if (motionEvent.action == MotionEvent.ACTION_DOWN) {
                             if (!adapterDataObserver.isInitialized()) {
                                 registerDataObserver()
                             }
 
-                            // compute relative touch offset only on DOWN and use the same for MOVE events
-                            touchRelativeOffset =
-                                motionEvent.rawY - yAbsPosition - handleImageView.y
-
-                            // check if offset is in bounds
-                            if (abs(touchRelativeOffset) > handleImageView.height) touchRelativeOffset =
-                                0f
-
                             // set the engaged flag to prevent the handle from scrolling again as the OnScrolled event in the ScrollListener is called even for programmatic scrolls
                             isEngaged = true
 
@@ -346,12 +336,17 @@ class RecyclerViewFastScroller @JvmOverloads constructor(
                                 popupTextView.animateVisibility()
                             }
                         }
+
                         //
                         // ------------- Common methods to Move and Down events -------------------
                         // calculate relative Y position internal to the view, from motion absolute px touch value and absolute start point of the view
                         //
+
+                        // subtract the handle height offset
+                        val handleHeightOffset = handleImageView.height / 2
+
                         val currentRelativeYPos =
-                            motionEvent.rawY - yAbsPosition - touchRelativeOffset
+                            motionEvent.rawY - yAbsPosition - handleHeightOffset
 
                         // move the handle only if fastScrolled, else leave the translation of the handle to the onScrolled method on the listener
 

sample/src/main/res/layout/recycler_view_list_item_center.xml

@@ -1,13 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="wrap_content"
+    android:layout_height="400dp"
     xmlns:app="http://schemas.android.com/apk/res-auto">
     <TextView
         app:layout_constraintTop_toTopOf="parent"
         android:id="@+id/text_view"
         android:layout_width="match_parent"
-        android:layout_height="wrap_content"
+        android:layout_height="match_parent"
         android:textSize="18sp"
         android:gravity="center"
         android:padding="@dimen/text_view_padding"/>