From 93e36943a221d0731ddc662f79a226b444b21048 Mon Sep 17 00:00:00 2001
From: "Simon (darkside) Jackson" <darkside@zenithmoon.com>
Date: Fri, 23 Oct 2020 12:04:11 +0100
Subject: [PATCH 1/2] Refactored and extended the ContentScrollSnap control

* Added protection against errors and empty scrollrect content
* Added new SetNewItems function to add children programmatically to the control and reset accordingly
---
 .../Layout/ContentScrollSnapHorizontal.cs     | 75 ++++++++++++++++---
 Runtime/Scripts/Utilities/ExtentionMethods.cs | 20 ++++-
 2 files changed, 84 insertions(+), 11 deletions(-)

diff --git a/Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs b/Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs
index 7a65c69..8f732ca 100644
--- a/Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs
+++ b/Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs
@@ -185,11 +185,60 @@ namespace UnityEngine.UI.Extensions
             if (prevButton)
                 prevButton.GetComponent<Button>().onClick.AddListener(() => { PreviousItem(); });
 
-            SetupDrivenTransforms();
-            SetupSnapScroll();
-            scrollRect.horizontalNormalizedPosition = 0;
-            _closestItem = 0;
-            GoTo(startInfo);
+            if (IsScrollRectAvailable)
+            {
+                SetupDrivenTransforms();
+                SetupSnapScroll();
+                scrollRect.horizontalNormalizedPosition = 0;
+                _closestItem = 0;
+                GoTo(startInfo);
+            }
+        }
+
+        public void SetNewItems(ref List<Transform> newItems)
+        {
+            if (scrollRect && contentTransform)
+            {
+                for (int i = scrollRect.content.childCount - 1; i >= 0; i--)
+                {
+                    Transform child = contentTransform.GetChild(i);
+                    child.SetParent(null);
+                    GameObject.DestroyImmediate(child.gameObject);
+                }
+
+                foreach (Transform item in newItems)
+                {
+                    GameObject newItem = item.gameObject;
+                    if (newItem.IsPrefab())
+                    {
+                        newItem = Instantiate(item.gameObject, contentTransform);
+                    }
+                    else
+                    {
+                        newItem.transform.SetParent(contentTransform);
+                    }
+                }
+
+                SetupDrivenTransforms();
+                SetupSnapScroll();
+                scrollRect.horizontalNormalizedPosition = 0;
+                _closestItem = 0;
+                GoTo(startInfo);
+            }
+        }
+
+        private bool IsScrollRectAvailable
+        {
+            get
+            {
+                if (scrollRect &&
+                    contentTransform &&
+                    contentTransform.childCount > 0)
+                {
+                    return true;
+                }
+                return false;
+            }
         }
 
         private void OnDisable()
@@ -470,16 +519,22 @@ namespace UnityEngine.UI.Extensions
 
         public void OnEndDrag(PointerEventData ped)
         {
-            StartCoroutine("SlideAndLerp");
+            if (IsScrollRectAvailable)
+            {
+                StartCoroutine("SlideAndLerp");
+            }
         }
 
         private void Update()
         {
-            if (_closestItem != ClosestItemIndex)
+            if (IsScrollRectAvailable)
             {
-                CurrentItemChanged.Invoke(ClosestItemIndex);
-                ChangePaginationInfo(ClosestItemIndex);
-                _closestItem = ClosestItemIndex;
+                if (_closestItem != ClosestItemIndex)
+                {
+                    CurrentItemChanged.Invoke(ClosestItemIndex);
+                    ChangePaginationInfo(ClosestItemIndex);
+                    _closestItem = ClosestItemIndex;
+                }
             }
         }
 
diff --git a/Runtime/Scripts/Utilities/ExtentionMethods.cs b/Runtime/Scripts/Utilities/ExtentionMethods.cs
index cb39962..07da566 100644
--- a/Runtime/Scripts/Utilities/ExtentionMethods.cs
+++ b/Runtime/Scripts/Utilities/ExtentionMethods.cs
@@ -1,4 +1,6 @@
-namespace UnityEngine.UI.Extensions
+using System;
+
+namespace UnityEngine.UI.Extensions
 {
     public static class ExtentionMethods
     {
@@ -11,5 +13,21 @@
             }
             return result;
         }
+
+        public static bool IsPrefab(this GameObject gameObject)
+        {
+            if (gameObject == null)
+            {
+                throw new ArgumentNullException(nameof(gameObject));
+            }
+
+            return
+                !gameObject.scene.IsValid() &&
+                !gameObject.scene.isLoaded &&
+                gameObject.GetInstanceID() >= 0 &&
+                // I noticed that ones with IDs under 0 were objects I didn't recognize
+                !gameObject.hideFlags.HasFlag(HideFlags.HideInHierarchy);
+                    // I don't care about GameObjects *inside* prefabs, just the overall prefab.
+        }
     }
 }

From 5a3621a4641182893f6f57b7fc284ac4deccc3c0 Mon Sep 17 00:00:00 2001
From: "Simon (darkside) Jackson" <darkside@zenithmoon.com>
Date: Fri, 23 Oct 2020 12:41:14 +0100
Subject: [PATCH 2/2] Added header

---
 Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs b/Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs
index 8f732ca..9b242c4 100644
--- a/Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs
+++ b/Runtime/Scripts/Layout/ContentScrollSnapHorizontal.cs
@@ -1,4 +1,8 @@
-using System.Collections;
+/// Credit Beka Westberg 
+/// Sourced from - https://bitbucket.org/UnityUIExtensions/unity-ui-extensions/pull-requests/28
+/// Updated by SimonDarksideJ - Added some exception management and a SetNewItems to replace the content programmatically
+
+using System.Collections;
 using System.Collections.Generic;
 using UnityEngine.EventSystems;
 using UnityEngine.Events;