Updated FastSwipe logic to measure the distance of a swipe against the container width (with threshold offset) rather than using velocity (which was messy)

Resolves #130

Examples/HSS-VSS-ScrollSnap/ScrollSnapManagedTests.unity

@@ -311,12 +311,12 @@ MonoBehaviour:
   m_Name: 
   m_EditorClassIdentifier: 
   StartingScreen: 0
-  PageStep: 2
+  PageStep: 2.7
   Pagination: {fileID: 266467291}
   PrevButton: {fileID: 1112321044}
   NextButton: {fileID: 803284189}
   transitionSpeed: 7.5
-  UseFastSwipe: 0
+  UseFastSwipe: 1
   FastSwipeThreshold: 100
   SwipeVelocityThreshold: 200
   MaskArea: {fileID: 0}
@@ -1892,7 +1892,7 @@ RectTransform:
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
   m_AnchorMin: {x: 1, y: 1}
   m_AnchorMax: {x: 1, y: 1}
-  m_AnchoredPosition: {x: -113.9, y: -183.2}
+  m_AnchoredPosition: {x: -113.899994, y: -183.2}
   m_SizeDelta: {x: 150, y: 30}
   m_Pivot: {x: 0.5, y: 0.5}
 --- !u!114 &803284191

Scripts/Layout/HorizontalScrollSnap.cs

@@ -72,7 +72,6 @@ namespace UnityEngine.UI.Extensions
 
             int _offset = 0;
             float _dimension = 0;
-            Rect panelDimensions = gameObject.GetComponent<RectTransform>().rect;
             float currentXPosition = 0;
             var pageStepValue = _childSize = (int)panelDimensions.width * ((PageStep == 0) ? 3 : PageStep);
 
@@ -88,7 +87,7 @@ namespace UnityEngine.UI.Extensions
 
             _dimension = currentXPosition + _offset * -1;
 
-            _screensContainer.GetComponent<RectTransform>().offsetMax = new Vector2(_dimension, 0f);
+            _screensContainer.offsetMax = new Vector2(_dimension, 0f);
         }
 
         /// <summary>
@@ -214,25 +213,17 @@ namespace UnityEngine.UI.Extensions
 
             if (_scroll_rect.horizontal)
             {
-                if (UseFastSwipe)
+                var distance = Vector3.Distance(_startPosition, _screensContainer.localPosition);
+                if (UseFastSwipe && distance < panelDimensions.width + FastSwipeThreshold)
                 {
-                    //If using fastswipe - then a swipe does page next / previous
+                    _scroll_rect.velocity = Vector3.zero;
-                    if ((_scroll_rect.velocity.x > 0 &&_scroll_rect.velocity.x > FastSwipeThreshold) ||
+                    if (_startPosition.x - _screensContainer.localPosition.x > 0)
-                        _scroll_rect.velocity.x < 0 && _scroll_rect.velocity.x < -FastSwipeThreshold)
                     {
-                        _scroll_rect.velocity = Vector3.zero;
+                        NextScreen();
-                        if (_startPosition.x - _screensContainer.localPosition.x > 0)
-                        {
-                            NextScreen();
-                        }
-                        else
-                        {
-                            PreviousScreen();
-                        }
                     }
                     else
                     {
-                        ScrollToClosestElement();
+                        PreviousScreen();
                     }
                 }
             }

Scripts/Layout/ScrollSnapBase.cs

@@ -10,6 +10,7 @@ namespace UnityEngine.UI.Extensions
 {
     public class ScrollSnapBase : MonoBehaviour, IBeginDragHandler, IDragHandler, IScrollSnap
     {
+        internal Rect panelDimensions;
         internal RectTransform _screensContainer;
         internal bool _isVertical;
 
@@ -29,8 +30,8 @@ namespace UnityEngine.UI.Extensions
         internal int _currentPage;
         internal int _previousPage;
         internal int _halfNoVisibleItems;
+        internal bool _moveStarted;
         private int _bottomItem, _topItem;
-        private bool _moveStarted;
 
         [Serializable]
         public class SelectionChangeStartEvent : UnityEvent { }
@@ -63,7 +64,7 @@ namespace UnityEngine.UI.Extensions
         [Tooltip("Fast Swipe makes swiping page next / previous (optional)")]
         public Boolean UseFastSwipe = false;
 
-        [Tooltip("How far swipe has to travel to initiate a page change (optional)")]
+        [Tooltip("Offset for how far a swipe has to travel to initiate a page change (optional)\nDefault is the panel dimensions")]
         public int FastSwipeThreshold = 100;
 
         [Tooltip("Speed at which the ScrollRect will keep scrolling before slowing down and stopping (optional)")]
@@ -139,7 +140,8 @@ namespace UnityEngine.UI.Extensions
                 var vscroll = _scroll_rect.verticalScrollbar.gameObject.AddComponent<ScrollSnapScrollbarHelper>();
                 vscroll.ss = this;
             }
-
+            panelDimensions = gameObject.GetComponent<RectTransform>().rect;
+            
             if (StartingScreen < 0)
             {
                 StartingScreen = 0;

Scripts/Layout/VerticalScrollSnap.cs

@@ -214,25 +214,17 @@ namespace UnityEngine.UI.Extensions
 
             if (_scroll_rect.vertical)
             {
-                if (UseFastSwipe)
+                var distance = Vector3.Distance(_startPosition, _screensContainer.localPosition);
+                if (UseFastSwipe && distance < panelDimensions.height + FastSwipeThreshold)
                 {
-                    //If using fastswipe - then a swipe does page next / previous
+                    _scroll_rect.velocity = Vector3.zero;
-                    if ((_scroll_rect.velocity.y > 0 && _scroll_rect.velocity.y > FastSwipeThreshold) ||
+                    if (_startPosition.y - _screensContainer.localPosition.y > 0)
-                        _scroll_rect.velocity.y < 0 && _scroll_rect.velocity.y < -FastSwipeThreshold)
                     {
-                        _scroll_rect.velocity = Vector3.zero;
+                        NextScreen();
-                        if (_startPosition.y - _screensContainer.localPosition.y > 0)
-                        {
-                            NextScreen();
-                        }
-                        else
-                        {
-                            PreviousScreen();
-                        }
                     }
                     else
                     {
-                        ScrollToClosestElement();
+                        PreviousScreen();
                     }
                 }
             }