From b6f4e5a144a337ec83474b14a98d6dbe8f0c78ab Mon Sep 17 00:00:00 2001
From: "Simon (darkside) Jackson" <none@none>
Date: Sat, 17 Oct 2015 16:16:23 +0100
Subject: [PATCH] Updated ScrollSnap with fixes from author

--HG--
branch : develop_4.6
---
 Scripts/Layout/ScrollSnap.cs | 335 +++++++++++++++++++++--------------
 1 file changed, 199 insertions(+), 136 deletions(-)

diff --git a/Scripts/Layout/ScrollSnap.cs b/Scripts/Layout/ScrollSnap.cs
index 849f521..ff193e3 100644
--- a/Scripts/Layout/ScrollSnap.cs
+++ b/Scripts/Layout/ScrollSnap.cs
@@ -9,23 +9,23 @@
 ///   if you dont wish to use this auto resize turn of autoLayoutItems
 /// - fixed current page made it independant from pivot
 /// - replaced pagination with delegate function
-
 using System;
 using UnityEngine.EventSystems;
 
 namespace UnityEngine.UI.Extensions
 {
 	[ExecuteInEditMode]
-    [RequireComponent(typeof(ScrollRect))]
-    [AddComponentMenu("UI/Extensions/Scroll Snap")]
-    public class ScrollSnap : MonoBehaviour, IBeginDragHandler, IEndDragHandler, IDragHandler
+	[RequireComponent(typeof(ScrollRect))]
+	[AddComponentMenu("UI/Extensions/Scroll Snap")]
+	public class ScrollSnap : MonoBehaviour, IBeginDragHandler, IEndDragHandler, IDragHandler
 	{
 		// needed becouse of reversed behavior of axis Y compared to X
 		// (positions of children lower in children list in horizontal directions grows when in vertical it gets smaller)
-		public enum ScrollDirection {
+		public enum ScrollDirection
+		{
 			Horizontal,
 			Vertical
-		};
+		}
 
 		public delegate void PageSnapChange(int page);
 
@@ -34,11 +34,12 @@ namespace UnityEngine.UI.Extensions
 		public ScrollDirection direction = ScrollDirection.Horizontal;
 
 		protected ScrollRect scrollRect;
-		protected RectTransform scrollRectTransform;
-		protected Transform listContainerTransform;
-		protected RectTransform rectTransform;
 
-		protected int items = 0;
+		protected RectTransform scrollRectTransform;
+
+		protected Transform listContainerTransform;
+
+		protected RectTransform rectTransform;
 
 		int pages;
 
@@ -46,22 +47,31 @@ namespace UnityEngine.UI.Extensions
 
 		// anchor points to lerp to to see child on certain indexes
 		protected Vector3[] pageAnchorPositions;
+
 		protected Vector3 lerpTarget;
+
 		protected bool lerp;
 
 		// item list related
 		protected float listContainerMinPosition;
+
 		protected float listContainerMaxPosition;
+
 		protected float listContainerSize;
+
 		protected RectTransform listContainerRectTransform;
+
 		protected Vector2 listContainerCachedSize;
 
 		protected float itemSize;
+		
+		protected int itemsCount = 0;
 
-        [Tooltip("Button to go to the next page. (optional)")]
-        public GameObject nextButton;
-        [Tooltip("Button to go to the previous page. (optional)")]
-		public GameObject prevButton;
+		[Tooltip("Button to go to the next page. (optional)")]
+		public Button nextButton;
+
+		[Tooltip("Button to go to the previous page. (optional)")]
+		public Button prevButton;
 		
 		[Tooltip("Number of items visible in one page of scroll frame.")]
 		[RangeAttribute(1,100)]
@@ -72,74 +82,97 @@ namespace UnityEngine.UI.Extensions
 		
 		[Tooltip("If you wish to update scrollbar numberOfSteps to number of active children on list.")]
 		public bool linkScrolbarSteps = false;
+		
+		[Tooltip("If you wish to update scrollrect sensitivity to size of list element.")]
+		public bool linkScrolrectScrollSensitivity = false;
 
-        public Boolean useFastSwipe = true;
-        public int fastSwipeThreshold = 100;
+		public Boolean useFastSwipe = true;
+
+		public int fastSwipeThreshold = 100;
 
 		// drag related
 		protected bool startDrag = true;
+
 		protected Vector3 positionOnDragStart = new Vector3();
+
 		protected int pageOnDragStart;
 		
 		protected bool fastSwipeTimer = false;
+
 		protected int fastSwipeCounter = 0;
+
 		protected int fastSwipeTarget = 10;
 
-        // Use this for initialization
-		void Start()
+		// Use this for initialization
+		void Awake()
 		{
 			lerp = false;
 
-			scrollRect = gameObject.GetComponent<ScrollRect> ();
-			scrollRectTransform = gameObject.GetComponent<RectTransform> ();
+			scrollRect = gameObject.GetComponent<ScrollRect>();
+			scrollRectTransform = gameObject.GetComponent<RectTransform>();
 			listContainerTransform = scrollRect.content;
-			listContainerRectTransform = listContainerTransform.GetComponent<RectTransform> ();
+			listContainerRectTransform = listContainerTransform.GetComponent<RectTransform>();
 
-			rectTransform = listContainerTransform.gameObject.GetComponent<RectTransform> ();
+			rectTransform = listContainerTransform.gameObject.GetComponent<RectTransform>();
 			UpdateListItemsSize();
 			UpdateListItemPositions();
 
-			ChangePage (CurrentPage ());
+			ChangePage(CurrentPage());
 
 			if (nextButton)
 			{
-				nextButton.GetComponent<Button> ().onClick.AddListener (() => { NextScreen (); });
+				nextButton.GetComponent<Button>().onClick.AddListener(() => {
+					NextScreen(); });
 			}
 
-            if (prevButton)
+			if (prevButton)
 			{
-				prevButton.GetComponent<Button> ().onClick.AddListener (() => { PreviousScreen (); });
+				prevButton.GetComponent<Button>().onClick.AddListener(() => {
+					PreviousScreen(); });
 			}
 		}
 
+		void Start()
+		{
+			Awake();
+		}
+
 		public void UpdateListItemsSize()
 		{
 			float size = 0;
+			float currentSize = 0;
 			if (direction == ScrollSnap.ScrollDirection.Horizontal)
 			{
 				size = scrollRectTransform.rect.width / itemsVisibleAtOnce;
+				currentSize = listContainerRectTransform.rect.width / itemsCount;
 			}
 			else
 			{
 				size = scrollRectTransform.rect.height / itemsVisibleAtOnce;
+				currentSize = listContainerRectTransform.rect.height / itemsCount;
 			}
 
 			itemSize = size;
 
-			if (autoLayoutItems && size != itemSize)
+			if (linkScrolrectScrollSensitivity)
+			{
+				scrollRect.scrollSensitivity = itemSize;
+			}
+
+			if (autoLayoutItems && currentSize != size && itemsCount > 0)
 			{
 				if (direction == ScrollSnap.ScrollDirection.Horizontal)
 				{
 					foreach (var tr in listContainerTransform)
 					{
-						GameObject child = ((Transform)tr).gameObject;
+						GameObject child = ((Transform) tr).gameObject;
 						if (child.activeInHierarchy)
 						{
-							var childLayout = child.GetComponent<LayoutElement> ();
+							var childLayout = child.GetComponent<LayoutElement>();
 							
 							if (childLayout == null)
 							{
-								childLayout = child.AddComponent<LayoutElement> ();
+								childLayout = child.AddComponent<LayoutElement>();
 							}
 							
 							childLayout.minWidth = itemSize;
@@ -150,14 +183,14 @@ namespace UnityEngine.UI.Extensions
 				{
 					foreach (var tr in listContainerTransform)
 					{
-						GameObject child = ((Transform)tr).gameObject;
+						GameObject child = ((Transform) tr).gameObject;
 						if (child.activeInHierarchy)
 						{
-							var childLayout = child.GetComponent<LayoutElement> ();
+							var childLayout = child.GetComponent<LayoutElement>();
 							
 							if (childLayout == null)
 							{
-								childLayout = child.AddComponent<LayoutElement> ();
+								childLayout = child.AddComponent<LayoutElement>();
 							}
 							
 							childLayout.minHeight = itemSize;
@@ -174,22 +207,25 @@ namespace UnityEngine.UI.Extensions
 				// checking how many children of list are active
 				int activeCount = 0;
 				
-				foreach (var tr in listContainerTransform) {
-					if (((Transform)tr).gameObject.activeInHierarchy) {
+				foreach (var tr in listContainerTransform)
+				{
+					if (((Transform) tr).gameObject.activeInHierarchy)
+					{
 						activeCount++;
 					}
 				}
 
 				// if anything changed since last check reinitialize anchors list
-				items = 0;
+				itemsCount = 0;
 				Array.Resize(ref pageAnchorPositions, activeCount);
-				
+
 				if (activeCount > 0)
 				{
-					pages = Mathf.Max (activeCount - itemsVisibleAtOnce + 1, 1);
+					pages = Mathf.Max(activeCount - itemsVisibleAtOnce + 1, 1);
 
 					if (direction == ScrollDirection.Horizontal)
 					{
+						//Debug.Log ("-------------looking for list spanning range----------------");
 						// looking for list spanning range min/max
 						scrollRect.horizontalNormalizedPosition = 0;
 						listContainerMaxPosition = listContainerTransform.localPosition.x;
@@ -197,6 +233,8 @@ namespace UnityEngine.UI.Extensions
 						listContainerMinPosition = listContainerTransform.localPosition.x;
 						
 						listContainerSize = listContainerMaxPosition - listContainerMinPosition;
+						//itemSize = pages > 1 ? listContainerSize / (float)(pages - 1) : listContainerSize / activeCount;
+						//itemSize *= (pages + itemsVisibleAtOnce) / (pages + 1);
 
 						for (var i = 0; i < pages; i ++)
 						{
@@ -206,9 +244,12 @@ namespace UnityEngine.UI.Extensions
 								listContainerTransform.localPosition.z
 							);
 						}
+						
+						//Debug.Log (String.Format("min:{0:0.0}, max:{1:0.0}, pages: {2:0}, width: {3:0}", listContainerMinPosition, listContainerMaxPosition, pages, listContainerSize/pages));
 					}
 					else
 					{
+						//Debug.Log ("-------------looking for list spanning range----------------");
 						// looking for list spanning range
 						scrollRect.verticalNormalizedPosition = 1;
 						listContainerMinPosition = listContainerTransform.localPosition.y;
@@ -216,6 +257,8 @@ namespace UnityEngine.UI.Extensions
 						listContainerMaxPosition = listContainerTransform.localPosition.y;
 						
 						listContainerSize = listContainerMaxPosition - listContainerMinPosition;
+						//itemSize = pages > 1 ? listContainerSize / (float)(pages - 1) : listContainerSize / activeCount;
+						//itemSize *= (pages + itemsVisibleAtOnce) / (pages + 1);
 
 						for (var i = 0; i < pages; i ++)
 						{
@@ -224,22 +267,24 @@ namespace UnityEngine.UI.Extensions
 								listContainerMinPosition + itemSize * i,
 								listContainerTransform.localPosition.z
 							);
-						}
-						
-						foreach (var tr in listContainerTransform) {
-							if (((Transform)tr).gameObject.activeInHierarchy) {
-								activeCount++;
-							}
+							//Debug.Log (String.Format("pos[{0:0}]={1} {2:0%}", i, pageAnchorPositions[i], pages > 1 ? i/(float)(pages-1) : (float)i));
 						}
 
+						//Debug.Log (String.Format("min:{0:0.0}, max:{1:0.0}, pages: {2:0}, width: {3:0}", listContainerMinPosition, listContainerMaxPosition, pages, listContainerSize/pages));
 					}
 
 					UpdateScrollbar(linkScrolbarSteps);
 					startingPage = Mathf.Min(startingPage, pages);
 					ResetPage();
 				}
-				items = activeCount;
-				listContainerCachedSize.Set (listContainerRectTransform.rect.size.x, listContainerRectTransform.rect.size.y); 
+
+				if (itemsCount != activeCount)
+				{
+					ChangePage(CurrentPage());
+				}
+
+				itemsCount = activeCount;
+				listContainerCachedSize.Set(listContainerRectTransform.rect.size.x, listContainerRectTransform.rect.size.y); 
 			}
 
 		}
@@ -248,11 +293,11 @@ namespace UnityEngine.UI.Extensions
 		{
 			if (direction == ScrollDirection.Horizontal)
 			{
-				scrollRect.horizontalNormalizedPosition = pages > 1 ? (float)startingPage / (float)(pages - 1) : 0;
+				scrollRect.horizontalNormalizedPosition = pages > 1 ? (float) startingPage / (float) (pages - 1) : 0;
 			}
 			else
 			{
-				scrollRect.verticalNormalizedPosition = pages > 1 ? (float)(pages - startingPage - 1) / (float)(pages - 1) : 0;
+				scrollRect.verticalNormalizedPosition = pages > 1 ? (float) (pages - startingPage - 1) / (float) (pages - 1) : 0;
 			}
 		}
 
@@ -294,7 +339,7 @@ namespace UnityEngine.UI.Extensions
 			}
 		}
 
-        void Update()
+		void LateUpdate()
 		{
 			UpdateListItemsSize();
 			UpdateListItemPositions();
@@ -303,7 +348,7 @@ namespace UnityEngine.UI.Extensions
 			{
 				UpdateScrollbar(false);
 
-                listContainerTransform.localPosition = Vector3.Lerp(listContainerTransform.localPosition, lerpTarget, 7.5f * Time.deltaTime);
+				listContainerTransform.localPosition = Vector3.Lerp(listContainerTransform.localPosition, lerpTarget, 7.5f * Time.deltaTime);
                 
 				if (Vector3.Distance(listContainerTransform.localPosition, lerpTarget) < 0.001f)
 				{
@@ -311,83 +356,87 @@ namespace UnityEngine.UI.Extensions
 					lerp = false;
 					
 					UpdateScrollbar(linkScrolbarSteps);
-                }
+					
+					//Debug.Log(String.Format("Lerp: {0}/{1} page: {2:0}", lerpTarget, listContainerTransform.localPosition, CurrentPage()));
+				}
 
-                //change the info bullets at the bottom of the screen. Just for visual effect
-                if (Vector3.Distance(listContainerTransform.localPosition, lerpTarget) < 10f)
+				//change the info bullets at the bottom of the screen. Just for visual effect
+				if (Vector3.Distance(listContainerTransform.localPosition, lerpTarget) < 10f)
 				{
-                    ChangePage(CurrentPage());
-                }
-            }
-
-            if (fastSwipeTimer)
-			{
-                fastSwipeCounter++;
+					ChangePage(CurrentPage());
+				}
 			}
-        }
 
-        private bool fastSwipe = false; //to determine if a fast swipe was performed
+			if (fastSwipeTimer)
+			{
+				fastSwipeCounter++;
+			}
+			
+			//Debug.Log(String.Format("Update: {0}", listContainerTransform.localPosition));
+		}
+
+		private bool fastSwipe = false; //to determine if a fast swipe was performed
 
 
-        //Function for switching screens with buttons
-        public void NextScreen()
+		//Function for switching screens with buttons
+		public void NextScreen()
 		{
-			UpdateListItemPositions ();
+			UpdateListItemPositions();
 
 			if (CurrentPage() < pages - 1)
 			{
-                lerp = true;
-                lerpTarget = pageAnchorPositions[CurrentPage() + 1];
+				lerp = true;
+				lerpTarget = pageAnchorPositions[CurrentPage() + 1];
 
-                ChangePage(CurrentPage() + 1);
-            }
-        }
+				ChangePage(CurrentPage() + 1);
+			}
+		}
 
-        //Function for switching screens with buttons
-        public void PreviousScreen()
+		//Function for switching screens with buttons
+		public void PreviousScreen()
 		{
-			UpdateListItemPositions ();
+			UpdateListItemPositions();
 
 			if (CurrentPage() > 0)
 			{
-                lerp = true;
-                lerpTarget = pageAnchorPositions[CurrentPage() - 1];
+				lerp = true;
+				lerpTarget = pageAnchorPositions[CurrentPage() - 1];
 
-                ChangePage(CurrentPage() - 1);
-            }
-        }
+				ChangePage(CurrentPage() - 1);
+			}
+		}
 
-        //Because the CurrentScreen function is not so reliable, these are the functions used for swipes
-        private void NextScreenCommand()
-        {
+		//Because the CurrentScreen function is not so reliable, these are the functions used for swipes
+		private void NextScreenCommand()
+		{
 			if (pageOnDragStart < pages - 1)
 			{
 				int targetPage = Mathf.Min(pages - 1, pageOnDragStart + itemsVisibleAtOnce);
-                lerp = true;
+				lerp = true;
 
 				lerpTarget = pageAnchorPositions[targetPage];
 
 				ChangePage(targetPage);
-            }
-        }
+			}
+		}
 
-        //Because the CurrentScreen function is not so reliable, these are the functions used for swipes
-        private void PrevScreenCommand()
+		//Because the CurrentScreen function is not so reliable, these are the functions used for swipes
+		private void PrevScreenCommand()
 		{
 			if (pageOnDragStart > 0)
 			{
 				int targetPage = Mathf.Max(0, pageOnDragStart - itemsVisibleAtOnce);
-                lerp = true;
+				lerp = true;
 
 				lerpTarget = pageAnchorPositions[targetPage];
 
 				ChangePage(targetPage);
-            }
-        }
+			}
+		}
 
 
-        //returns the current screen that the is seeing
-        public int CurrentPage()
+		//returns the current screen that the is seeing
+		public int CurrentPage()
 		{
 			float pos;
 
@@ -404,35 +453,49 @@ namespace UnityEngine.UI.Extensions
 
 			float page = pos / itemSize;
 
-			return Mathf.Clamp(Mathf.RoundToInt(page), 0, pages);
-        }
+			//Debug.Log (String.Format("min:{0:0.0}, max:{1:0.0}, current:{2:0.0}/{4:0.0}, page:{3:0.0}, target:{5}", listContainerMinPosition, listContainerMaxPosition, pos, page, listContainerTransform.localPosition.x, pageAnchorPositions[Mathf.RoundToInt(page)]));
 
-        //changes the bullets on the bottom of the page - pagination
-        private void ChangePage(int currentPage)
-        {
+			return Mathf.Clamp(Mathf.RoundToInt(page), 0, pages);
+		}
+
+		//changes the bullets on the bottom of the page - pagination
+		private void ChangePage(int currentPage)
+		{
 			startingPage = currentPage;
 
+			if (nextButton)
+			{
+				nextButton.interactable = currentPage < pages - 1;
+			}
+			
+			if (prevButton)
+			{
+				prevButton.interactable = currentPage > 0;
+			}
+
 			if (onPageChange != null)
 			{
 				onPageChange(currentPage);
 			}
-        }
+		}
 
         #region Interfaces
-        public void OnBeginDrag(PointerEventData eventData)
-        {
+		public void OnBeginDrag(PointerEventData eventData)
+		{
 			UpdateScrollbar(false);
 
 			fastSwipeCounter = 0;
 			fastSwipeTimer = true;
 
 			positionOnDragStart = eventData.position;
-            pageOnDragStart = CurrentPage();
-        }
+			pageOnDragStart = CurrentPage();
 
-        public void OnEndDrag(PointerEventData eventData)
-        {
-            startDrag = true;
+			//Debug.Log (String.Format("pageOnDragStart:{0:0}", pageOnDragStart));
+		}
+
+		public void OnEndDrag(PointerEventData eventData)
+		{
+			startDrag = true;
 			float change = 0;
 
 			if (direction == ScrollDirection.Horizontal)
@@ -444,20 +507,20 @@ namespace UnityEngine.UI.Extensions
 				change = -positionOnDragStart.y + eventData.position.y;
 			}
 
-            if (useFastSwipe)
-            {
-                fastSwipe = false;
-                fastSwipeTimer = false;
+			if (useFastSwipe)
+			{
+				fastSwipe = false;
+				fastSwipeTimer = false;
 
-                if (fastSwipeCounter <= fastSwipeTarget)
-                {
-                    if (Math.Abs(change) > fastSwipeThreshold)
-                    {
-                        fastSwipe = true;
-                    }
-                }
-                if (fastSwipe)
-                {
+				if (fastSwipeCounter <= fastSwipeTarget)
+				{
+					if (Math.Abs(change) > fastSwipeThreshold)
+					{
+						fastSwipe = true;
+					}
+				}
+				if (fastSwipe)
+				{
 					if (change > 0)
 					{
 						NextScreenCommand();
@@ -466,30 +529,30 @@ namespace UnityEngine.UI.Extensions
 					{
 						PrevScreenCommand();
 					}
-                }
-                else
-                {
-                    lerp = true;
+				}
+				else
+				{
+					lerp = true;
 					lerpTarget = pageAnchorPositions[CurrentPage()];
-                }
-            }
-            else
-            {
-                lerp = true;
+				}
+			}
+			else
+			{
+				lerp = true;
 				lerpTarget = pageAnchorPositions[CurrentPage()];
-            }
-        }
+			}
+		}
 
-        public void OnDrag(PointerEventData eventData)
-        {
+		public void OnDrag(PointerEventData eventData)
+		{
 			lerp = false;
 
 			if (startDrag)
-            {
-                OnBeginDrag(eventData);
-                startDrag = false;
-            }
-        }
+			{
+				OnBeginDrag(eventData);
+				startDrag = false;
+			}
+		}
         #endregion
-    }
+	}
 }
\ No newline at end of file