2 patches for HSS/VSS

* Added new overload to AddChild, allows to set WorldPositionStays for added childen
* New RemoveAllChildren function

--HG--
branch : develop_5.3

Scripts/Layout/HorizontalScrollSnap.cs

@@ -92,9 +92,19 @@ namespace UnityEngine.UI.Extensions
         /// </summary>
         /// <param name="GO">GameObject to add to the ScrollSnap</param>
         public void AddChild(GameObject GO)
+        {
+            AddChild(GO, false);
+        }
+
+        /// <summary>
+        /// Add a new child to this Scroll Snap and recalculate it's children
+        /// </summary>
+        /// <param name="GO">GameObject to add to the ScrollSnap</param>
+        /// <param name="WorldPositionStays">Should the world position be updated to it's parent transform?</param>
+        public void AddChild(GameObject GO, bool WorldPositionStays)
         {
             _scroll_rect.horizontalNormalizedPosition = 0;
-            GO.transform.SetParent(_screensContainer);
+            GO.transform.SetParent(_screensContainer, WorldPositionStays);
             DistributePages();
             if (MaskArea) UpdateVisible();
 
@@ -131,6 +141,28 @@ namespace UnityEngine.UI.Extensions
             SetScrollContainerPosition();
         }
 
+        /// <summary>
+        /// Remove all children from this ScrollSnap
+        /// </summary>
+        /// <param name="ChildrenRemoved"></param>
+        public void RemoveAllChildren(out GameObject[] ChildrenRemoved)
+        {
+            var _screenCount = _screensContainer.childCount;
+            ChildrenRemoved = new GameObject[_screenCount];
+
+            for (int i = _screenCount - 1; i >= 0; i--)
+            {
+                ChildrenRemoved[i] = _screensContainer.GetChild(i).gameObject;
+                ChildrenRemoved[i].transform.SetParent(null);
+            }
+
+            _scroll_rect.horizontalNormalizedPosition = 0;
+            CurrentPage = 0;
+            InitialiseChildObjectsFromScene();
+            DistributePages();
+            if (MaskArea) UpdateVisible();
+        }
+
         private void SetScrollContainerPosition()
         {
             _scrollStartPosition = _screensContainer.localPosition.x;

Scripts/Layout/ScrollSnapBase.cs

@@ -78,7 +78,7 @@ namespace UnityEngine.UI.Extensions
             }
             internal set
             {
-                if (value != _currentPage && value >= 0 && value < _screensContainer.childCount)
+                if ((value != _currentPage && value >= 0 && value < _screensContainer.childCount) || (value == 0 && _screensContainer.childCount == 0))
                 {
                     _previousPage = _currentPage;
                     _currentPage = value;
@@ -190,7 +190,10 @@ namespace UnityEngine.UI.Extensions
         internal void UpdateVisible()
         {
             //If there are no objects in the scene or a mask, exit
-            if (!MaskArea && (ChildObjects == null || ChildObjects.Length < 1 || _screensContainer.childCount < 1)) return;
+            if (!MaskArea || ChildObjects == null || ChildObjects.Length < 1 || _screensContainer.childCount < 1)
+            {
+                return;
+            }
 
             _maskSize = _isVertical ? MaskArea.rect.height : MaskArea.rect.width;
             _halfNoVisibleItems = (int)Math.Round(_maskSize / (_childSize * MaskBuffer), MidpointRounding.AwayFromZero) / 2;

Scripts/Layout/VerticalScrollSnap.cs

@@ -87,9 +87,19 @@ namespace UnityEngine.UI.Extensions
         /// </summary>
         /// <param name="GO">GameObject to add to the ScrollSnap</param>
         public void AddChild(GameObject GO)
+        {
+            AddChild(GO, false);
+        }
+
+        /// <summary>
+        /// Add a new child to this Scroll Snap and recalculate it's children
+        /// </summary>
+        /// <param name="GO">GameObject to add to the ScrollSnap</param>
+        /// <param name="WorldPositionStays">Should the world position be updated to it's parent transform?</param>
+        public void AddChild(GameObject GO, bool WorldPositionStays)
         {
             _scroll_rect.verticalNormalizedPosition = 0;
-            GO.transform.SetParent(_screensContainer);
+            GO.transform.SetParent(_screensContainer, WorldPositionStays);
             InitialiseChildObjectsFromScene();
             DistributePages();
             if (MaskArea) UpdateVisible();
@@ -127,6 +137,28 @@ namespace UnityEngine.UI.Extensions
             SetScrollContainerPosition();
         }
 
+        /// <summary>
+        /// Remove all children from this ScrollSnap
+        /// </summary>
+        /// <param name="ChildrenRemoved"></param>
+        public void RemoveAllChildren(out GameObject[] ChildrenRemoved)
+        {
+            var _screenCount = _screensContainer.childCount;
+            ChildrenRemoved = new GameObject[_screenCount];
+
+            for (int i = _screenCount - 1; i >= 0; i--)
+            {
+                ChildrenRemoved[i] = _screensContainer.GetChild(i).gameObject;
+                ChildrenRemoved[i].transform.SetParent(null);
+            }
+
+            _scroll_rect.verticalNormalizedPosition = 0;
+            CurrentPage = 0;
+            InitialiseChildObjectsFromScene();
+            DistributePages();
+            if (MaskArea) UpdateVisible();
+        }
+
         private void SetScrollContainerPosition()
         {
             _scrollStartPosition = _screensContainer.localPosition.y;