Merged in ContentScrollSnapupdate (pull request #103)

ContentScrollSnapupdate

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;
@@ -185,12 +189,61 @@ namespace UnityEngine.UI.Extensions
             if (prevButton)
                 prevButton.GetComponent<Button>().onClick.AddListener(() => { PreviousItem(); });
 
+            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()
         {
@@ -469,11 +522,16 @@ namespace UnityEngine.UI.Extensions
         }
 
         public void OnEndDrag(PointerEventData ped)
+        {
+            if (IsScrollRectAvailable)
             {
                 StartCoroutine("SlideAndLerp");
             }
+        }
 
         private void Update()
+        {
+            if (IsScrollRectAvailable)
             {
                 if (_closestItem != ClosestItemIndex)
                 {
@@ -482,6 +540,7 @@ namespace UnityEngine.UI.Extensions
                     _closestItem = ClosestItemIndex;
                 }
             }
+        }
 
         private IEnumerator SlideAndLerp()
         {

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.
+        }
     }
 }