From fc6ea6089d4c494b1c1c62334b51db75f0519410 Mon Sep 17 00:00:00 2001
From: Simon Jackson <darkside@zenithmoon.com>
Date: Sat, 23 Apr 2022 21:01:37 +0100
Subject: [PATCH] Fixes issue #398 where the Next / Previous buttons filed to
 work if the ScrollSnap was previously scrolling.

Also renamed the Extension Methods scripts and added a new function.

Resolves: #398
---
 Runtime/Scripts/Layout/ScrollSnapBase.cs      | 14 +++++-------
 ...xtentionMethods.cs => ExtensionMethods.cs} | 22 +++++++++++++++++++
 ...thods.cs.meta => ExtensionMethods.cs.meta} |  0
 3 files changed, 28 insertions(+), 8 deletions(-)
 rename Runtime/Scripts/Utilities/{ExtentionMethods.cs => ExtensionMethods.cs} (57%)
 rename Runtime/Scripts/Utilities/{ExtentionMethods.cs.meta => ExtensionMethods.cs.meta} (100%)

diff --git a/Runtime/Scripts/Layout/ScrollSnapBase.cs b/Runtime/Scripts/Layout/ScrollSnapBase.cs
index abee12c..3d570c7 100644
--- a/Runtime/Scripts/Layout/ScrollSnapBase.cs
+++ b/Runtime/Scripts/Layout/ScrollSnapBase.cs
@@ -5,6 +5,7 @@
 using System;
 using UnityEngine.Events;
 using UnityEngine.EventSystems;
+using UnityEngine.UI.Extensions;
 
 namespace UnityEngine.UI.Extensions
 {
@@ -314,6 +315,8 @@ namespace UnityEngine.UI.Extensions
         //Function for switching screens with buttons
         public void NextScreen()
         {
+            _scroll_rect.velocity = Vector2.zero;
+
             if (_currentPage < _screens - 1 || _isInfinite)
             {
                 if (!_lerp) StartScreenChange();
@@ -336,6 +339,8 @@ namespace UnityEngine.UI.Extensions
         //Function for switching screens with buttons
         public void PreviousScreen()
         {
+            _scroll_rect.velocity = Vector2.zero;
+
             if (_currentPage > 0 || _isInfinite)
             {
                 if (!_lerp) StartScreenChange();
@@ -515,15 +520,8 @@ namespace UnityEngine.UI.Extensions
                 MaskBuffer = 1;
             }
 
-            if (PageStep < 0)
-            {
-                PageStep = 0;
-            }
+            PageStep.Clamp(0, 9);
 
-            if (PageStep > 8)
-            {
-                PageStep = 9;
-            }
             var infiniteScroll = GetComponent<UI_InfiniteScroll>();
             if (ChildObjects != null && ChildObjects.Length > 0 && infiniteScroll != null && !infiniteScroll.InitByUser)
             {
diff --git a/Runtime/Scripts/Utilities/ExtentionMethods.cs b/Runtime/Scripts/Utilities/ExtensionMethods.cs
similarity index 57%
rename from Runtime/Scripts/Utilities/ExtentionMethods.cs
rename to Runtime/Scripts/Utilities/ExtensionMethods.cs
index 07da566..4193c3c 100644
--- a/Runtime/Scripts/Utilities/ExtentionMethods.cs
+++ b/Runtime/Scripts/Utilities/ExtensionMethods.cs
@@ -29,5 +29,27 @@ namespace UnityEngine.UI.Extensions
                 !gameObject.hideFlags.HasFlag(HideFlags.HideInHierarchy);
                     // I don't care about GameObjects *inside* prefabs, just the overall prefab.
         }
+
+        /// <summary>
+        /// Generic clamp method to limt a value between a range of values
+        /// </summary>
+        /// <typeparam name="T"><see cref="IComparable"/> data type</typeparam>
+        /// <param name="value">Value to clamp</param>
+        /// <param name="min">Minimum value</param>
+        /// <param name="max">Maximum value</param>
+        /// <returns></returns>
+        public static T Clamp<T>(this T value, T min, T max) where T : IComparable<T>
+        {
+            if (value.CompareTo(min) < 0)
+            {
+                value = min;
+            }
+            if (value.CompareTo(max) > 0)
+            {
+                value =  max;
+            }
+
+            return value;
+        }
     }
 }
diff --git a/Runtime/Scripts/Utilities/ExtentionMethods.cs.meta b/Runtime/Scripts/Utilities/ExtensionMethods.cs.meta
similarity index 100%
rename from Runtime/Scripts/Utilities/ExtentionMethods.cs.meta
rename to Runtime/Scripts/Utilities/ExtensionMethods.cs.meta