/// Credit BinaryX
/// Sourced from - http://forum.unity3d.com/threads/scripts-useful-4-6-scripts-collection.264161/page-2#post-1945602
/// Updated by simonDarksideJ - removed dependency on a custom ScrollRect script. Now implements drag interfaces and standard Scroll Rect.
using System;
using UnityEngine.Events;
using UnityEngine.EventSystems;
namespace UnityEngine.UI.Extensions
{
public class ScrollSnapBase : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler, IScrollSnap, IPointerClickHandler
{
internal Rect panelDimensions;
internal RectTransform _screensContainer;
internal bool _isVertical;
internal int _screens = 1;
internal float _scrollStartPosition;
internal float _childSize;
private float _childPos, _maskSize;
internal Vector2 _childAnchorPoint;
internal ScrollRect _scroll_rect;
internal Vector3 _lerp_target;
internal bool _lerp;
internal bool _pointerDown = false;
internal bool _settled = true;
internal Vector3 _startPosition = new Vector3();
internal int _currentPage;
internal int _previousPage;
internal int _halfNoVisibleItems;
internal bool _isInfinite; // Is a UI Infinite scroller attached to the control
internal int _infiniteWindow; // The infinite window the control is in
internal float _infiniteOffset; // How much to offset a repositioning
private int _bottomItem, _topItem;
internal bool _startEventCalled = false;
internal bool _endEventCalled = false;
internal bool _suspendEvents = false;
[Serializable]
public class SelectionChangeStartEvent : UnityEvent { }
[Serializable]
public class SelectionPageChangedEvent : UnityEvent<int> { }
[Serializable]
public class SelectionChangeEndEvent : UnityEvent<int> { }
[Tooltip("The screen / page to start the control on\n*Note, this is a 0 indexed array")]
[SerializeField]
public int StartingScreen = 0;
[Tooltip("The distance between two pages based on page height, by default pages are next to each other")]
[SerializeField]
[Range(0, 8)]
public float PageStep = 1;
[Tooltip("The gameobject that contains toggles which suggest pagination. (optional)")]
public GameObject Pagination;
[Tooltip("Button to go to the previous page. (optional)")]
public GameObject PrevButton;
[Tooltip("Button to go to the next page. (optional)")]
public GameObject NextButton;
[Tooltip("Transition speed between pages. (optional)")]
public float transitionSpeed = 7.5f;
[Tooltip("Hard Swipe forces to swiping to the next / previous page (optional)")]
public bool UseHardSwipe = false;
[Tooltip("Fast Swipe makes swiping page next / previous (optional)")]
public bool UseFastSwipe = false;
[Tooltip("Swipe Delta Threshold looks at the speed of input to decide if a swipe will be initiated (optional)")]
public bool UseSwipeDeltaThreshold = false;
[Tooltip("Offset for how far a swipe has to travel to initiate a page change (optional)")]
public int FastSwipeThreshold = 100;
[Tooltip("Speed at which the ScrollRect will keep scrolling before slowing down and stopping (optional)")]
public int SwipeVelocityThreshold = 100;
[Tooltip("Threshold for swipe speed to initiate a swipe, below threshold will return to closest page (optional)")]
public float SwipeDeltaThreshold = 5.0f;
[Tooltip("Use time scale instead of unscaled time (optional)")]
public bool UseTimeScale = true;
[Tooltip("The visible bounds area, controls which items are visible/enabled. *Note Should use a RectMask. (optional)")]
public RectTransform MaskArea;
[Tooltip("Pixel size to buffer around Mask Area. (optional)")]
public float MaskBuffer = 1;
public int CurrentPage
{
get
{
return _currentPage;
}
internal set
{
if (_isInfinite)
{
//Work out which infinite window we are in
float infWindow = (float)value / (float)_screensContainer.childCount;
if (infWindow < 0)
{
_infiniteWindow = (int)(Math.Floor(infWindow));
}
else
{
_infiniteWindow = value / _screensContainer.childCount;
}
//Invert the value if negative and differentiate from Window 0
_infiniteWindow = value < 0 ? (-_infiniteWindow) : _infiniteWindow;
//Calculate the page within the child count range
value = value % _screensContainer.childCount;
if (value < 0)
{
value = _screensContainer.childCount + value;
}
else if (value > _screensContainer.childCount - 1)
{
value = value - _screensContainer.childCount;
}
}
if ((value != _currentPage && value >= 0 && value < _screensContainer.childCount) || (value == 0 && _screensContainer.childCount == 0))
{
_previousPage = _currentPage;
_currentPage = value;
if (MaskArea) UpdateVisible();
if (!_lerp) ScreenChange();
OnCurrentScreenChange(_currentPage);
}
}
}
[Tooltip("By default the container will lerp to the start when enabled in the scene, this option overrides this and forces it to simply jump without lerping")]
public bool JumpOnEnable = false;
[Tooltip("By default the container will return to the original starting page when enabled, this option overrides this behaviour and stays on the current selection")]
public bool RestartOnEnable = false;
[Tooltip("(Experimental)\nBy default, child array objects will use the parent transform\nHowever you can disable this for some interesting effects")]
public bool UseParentTransform = true;
[Tooltip("Scroll Snap children. (optional)\nEither place objects in the scene as children OR\nPrefabs in this array, NOT BOTH")]
public GameObject[] ChildObjects;
[SerializeField]
[Tooltip("Event fires when a user starts to change the selection")]
private SelectionChangeStartEvent m_OnSelectionChangeStartEvent = new SelectionChangeStartEvent();
public SelectionChangeStartEvent OnSelectionChangeStartEvent { get { return m_OnSelectionChangeStartEvent; } set { m_OnSelectionChangeStartEvent = value; } }
[SerializeField]
[Tooltip("Event fires as the page changes, while dragging or jumping")]
private SelectionPageChangedEvent m_OnSelectionPageChangedEvent = new SelectionPageChangedEvent();
public SelectionPageChangedEvent OnSelectionPageChangedEvent { get { return m_OnSelectionPageChangedEvent; } set { m_OnSelectionPageChangedEvent = value; } }
[SerializeField]
[Tooltip("Event fires when the page settles after a user has dragged")]
private SelectionChangeEndEvent m_OnSelectionChangeEndEvent = new SelectionChangeEndEvent();
public SelectionChangeEndEvent OnSelectionChangeEndEvent { get { return m_OnSelectionChangeEndEvent; } set { m_OnSelectionChangeEndEvent = value; } }
void Awake()
{
if (_scroll_rect == null)
{
_scroll_rect = gameObject.GetComponent<ScrollRect>();
}
if (_scroll_rect.horizontalScrollbar && _scroll_rect.horizontal)
{
var hscroll = _scroll_rect.horizontalScrollbar.gameObject.AddComponent<ScrollSnapScrollbarHelper>();
hscroll.ss = this;
}
if (_scroll_rect.verticalScrollbar && _scroll_rect.vertical)
{
var vscroll = _scroll_rect.verticalScrollbar.gameObject.AddComponent<ScrollSnapScrollbarHelper>();
vscroll.ss = this;
}
panelDimensions = gameObject.GetComponent<RectTransform>().rect;
if (StartingScreen < 0)
{
StartingScreen = 0;
}
_screensContainer = _scroll_rect.content;
InitialiseChildObjects();
if (NextButton)
NextButton.GetComponent<Button>().onClick.AddListener(() => { NextScreen(); });
if (PrevButton)
PrevButton.GetComponent<Button>().onClick.AddListener(() => { PreviousScreen(); });
_isInfinite = GetComponent<UI_InfiniteScroll>() != null;
}
internal void InitialiseChildObjects()
{
if (ChildObjects != null && ChildObjects.Length > 0)
{
if (_screensContainer.transform.childCount > 0)
{
Debug.LogError("ScrollRect Content has children, this is not supported when using managed Child Objects\n Either remove the ScrollRect Content children or clear the ChildObjects array");
return;
}
InitialiseChildObjectsFromArray();
if (GetComponent<UI_InfiniteScroll>() != null)
{
GetComponent<UI_InfiniteScroll>().Init();
}
}
else
{
InitialiseChildObjectsFromScene();
}
}
internal void InitialiseChildObjectsFromScene()
{
int childCount = _screensContainer.childCount;
ChildObjects = new GameObject[childCount];
for (int i = 0; i < childCount; i++)
{
ChildObjects[i] = _screensContainer.transform.GetChild(i).gameObject;
if (MaskArea && ChildObjects[i].activeSelf)
{
ChildObjects[i].SetActive(false);
}
}
}
internal void InitialiseChildObjectsFromArray()
{
int childCount = ChildObjects.Length;
RectTransform childRect;
GameObject child;
for (int i = 0; i < childCount; i++)
{
child = GameObject.Instantiate(ChildObjects[i]);
//Optionally, use original GO transform when initialising, by default will use parent RectTransform position/rotation
if (UseParentTransform)
{
childRect = child.GetComponent<RectTransform>();
childRect.rotation = _screensContainer.rotation;
childRect.localScale = _screensContainer.localScale;
childRect.position = _screensContainer.position;
}
child.transform.SetParent(_screensContainer.transform);
ChildObjects[i] = child;
if (MaskArea && ChildObjects[i].activeSelf)
{
ChildObjects[i].SetActive(false);
}
}
}
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;
}
_maskSize = _isVertical ? MaskArea.rect.height : MaskArea.rect.width;
_halfNoVisibleItems = (int)Math.Round(_maskSize / (_childSize * MaskBuffer), MidpointRounding.AwayFromZero) / 2;
_bottomItem = _topItem = 0;
//work out how many items below the current page can be visible
for (int i = _halfNoVisibleItems + 1; i > 0; i--)
{
_bottomItem = _currentPage - i < 0 ? 0 : i;
if (_bottomItem > 0) break;
}
//work out how many items above the current page can be visible
for (int i = _halfNoVisibleItems + 1; i > 0; i--)
{
_topItem = _screensContainer.childCount - _currentPage - i < 0 ? 0 : i;
if (_topItem > 0) break;
}
//Set the active items active
for (int i = CurrentPage - _bottomItem; i < CurrentPage + _topItem; i++)
{
try
{
ChildObjects[i].SetActive(true);
}
catch
{
Debug.Log("Failed to setactive child [" + i + "]");
}
}
//Deactivate items out of visibility at the bottom of the ScrollRect Mask (only on scroll)
if (_currentPage > _halfNoVisibleItems) ChildObjects[CurrentPage - _bottomItem].SetActive(false);
//Deactivate items out of visibility at the top of the ScrollRect Mask (only on scroll)
if (_screensContainer.childCount - _currentPage > _topItem) ChildObjects[CurrentPage + _topItem].SetActive(false);
}
//Function for switching screens with buttons
public void NextScreen()
{
if (_currentPage < _screens - 1 || _isInfinite)
{
if (!_lerp) StartScreenChange();
_lerp = true;
if (_isInfinite)
{
CurrentPage = GetPageforPosition(_screensContainer.anchoredPosition) + 1;
}
else
{
CurrentPage = _currentPage + 1;
}
GetPositionforPage(_currentPage, ref _lerp_target);
ScreenChange();
}
}
//Function for switching screens with buttons
public void PreviousScreen()
{
if (_currentPage > 0 || _isInfinite)
{
if (!_lerp) StartScreenChange();
_lerp = true;
if (_isInfinite)
{
CurrentPage = GetPageforPosition(_screensContainer.anchoredPosition) - 1;
}
else
{
CurrentPage = _currentPage - 1;
}
GetPositionforPage(_currentPage, ref _lerp_target);
ScreenChange();
}
}
/// <summary>
/// Function for switching to a specific screen
/// *Note, this is based on a 0 starting index - 0 to x
/// </summary>
/// <param name="screenIndex">0 starting index of page to jump to</param>
/// <param name="pagination">Override the screen movement if driven from a pagination control</param>
public void GoToScreen(int screenIndex, bool pagination = false)
{
if (screenIndex <= _screens - 1 && screenIndex >= 0)
{
if (!_lerp || pagination) StartScreenChange();
_lerp = true;
CurrentPage = screenIndex;
GetPositionforPage(_currentPage, ref _lerp_target);
ScreenChange();
}
}
/// <summary>
/// Gets the closest page for the current Scroll Rect container position
/// </summary>
/// <param name="pos">Position to test, normally the Scroll Rect container Local position</param>
/// <returns>Closest Page number (zero indexed array value)</returns>
internal int GetPageforPosition(Vector3 pos)
{
return _isVertical ?
(int)Math.Round((_scrollStartPosition - pos.y) / _childSize) :
(int)Math.Round((_scrollStartPosition - pos.x) / _childSize);
}
/// <summary>
/// Validates if the current Scroll Rect container position is within the bounds for a page
/// </summary>
/// <param name="pos">Position to test, normally the Scroll Rect container Local position</param>
/// <returns>True / False, is the position in the bounds of a page</returns>
internal bool IsRectSettledOnaPage(Vector3 pos)
{
return _isVertical ?
-((pos.y - _scrollStartPosition) / _childSize) == -(int)Math.Round((pos.y - _scrollStartPosition) / _childSize) :
-((pos.x - _scrollStartPosition) / _childSize) == -(int)Math.Round((pos.x - _scrollStartPosition) / _childSize);
}
/// <summary>
/// Returns the local position for a child page based on the required page number
/// </summary>
/// <param name="page">Page that the position is required for (Zero indexed array value)</param>
/// <param name="target">Outputs the local position for the selected page</param>
internal void GetPositionforPage(int page, ref Vector3 target)
{
_childPos = -_childSize * page;
if (_isVertical)
{
_infiniteOffset = _screensContainer.anchoredPosition.y < 0 ? -_screensContainer.sizeDelta.y * _infiniteWindow : _screensContainer.sizeDelta.y * _infiniteWindow;
_infiniteOffset = _infiniteOffset == 0 ? 0 : _infiniteOffset < 0 ? _infiniteOffset - _childSize * _infiniteWindow : _infiniteOffset + _childSize * _infiniteWindow;
target.y = _childPos + _scrollStartPosition + _infiniteOffset;
}
else
{
_infiniteOffset = _screensContainer.anchoredPosition.x < 0 ? -_screensContainer.sizeDelta.x * _infiniteWindow : _screensContainer.sizeDelta.x * _infiniteWindow;
_infiniteOffset = _infiniteOffset == 0 ? 0 : _infiniteOffset < 0 ? _infiniteOffset - _childSize * _infiniteWindow : _infiniteOffset + _childSize * _infiniteWindow;
target.x = _childPos + _scrollStartPosition + _infiniteOffset;
}
}
/// <summary>
/// Updates the _Lerp target to the closest page and updates the pagination bullets. Each control's update loop will then handle the move.
/// </summary>
internal void ScrollToClosestElement()
{
_lerp = true;
CurrentPage = GetPageforPosition(_screensContainer.anchoredPosition);
GetPositionforPage(_currentPage, ref _lerp_target);
OnCurrentScreenChange(_currentPage);
}
/// <summary>
/// notifies pagination indicator and navigation buttons of a screen change
/// </summary>
internal void OnCurrentScreenChange(int currentScreen)
{
ChangeBulletsInfo(currentScreen);
ToggleNavigationButtons(currentScreen);
}
/// <summary>
/// changes the bullets on the bottom of the page - pagination
/// </summary>
/// <param name="targetScreen"></param>
private void ChangeBulletsInfo(int targetScreen)
{
if (Pagination)
{
for (int i = 0; i < Pagination.transform.childCount; i++)
{
Pagination.transform.GetChild(i).GetComponent<Toggle>().isOn = (targetScreen == i) ? true : false;
}
}
}
// Make a lock function for pagination, to prevent event leaking
/// <summary>
/// disables the page navigation buttons when at the first or last screen
/// </summary>
/// <param name="targetScreen"></param>
private void ToggleNavigationButtons(int targetScreen)
{
//If this is using an Infinite Scroll, then don't disable
if (!_isInfinite)
{
if (PrevButton)
{
PrevButton.GetComponent<Button>().interactable = targetScreen > 0;
}
if (NextButton)
{
NextButton.GetComponent<Button>().interactable = targetScreen < _screensContainer.transform.childCount - 1;
}
}
}
private void OnValidate()
{
if (_scroll_rect == null)
{
_scroll_rect = GetComponent<ScrollRect>();
}
if (!_scroll_rect.horizontal && !_scroll_rect.vertical)
{
Debug.LogError("ScrollRect has to have a direction, please select either Horizontal OR Vertical with the appropriate control.");
}
if (_scroll_rect.horizontal && _scroll_rect.vertical)
{
Debug.LogError("ScrollRect has to be unidirectional, only use either Horizontal or Vertical on the ScrollRect, NOT both.");
}
var ScrollRectContent = gameObject.GetComponent<ScrollRect>().content;
if (ScrollRectContent != null)
{
var children = ScrollRectContent.childCount;
if (children != 0 || ChildObjects != null)
{
var childCount = ChildObjects == null || ChildObjects.Length == 0 ? children : ChildObjects.Length;
if (StartingScreen > childCount - 1)
{
StartingScreen = childCount - 1;
}
if (StartingScreen < 0)
{
StartingScreen = 0;
}
}
}
if (MaskBuffer <= 0)
{
MaskBuffer = 1;
}
if (PageStep < 0)
{
PageStep = 0;
}
if (PageStep > 8)
{
PageStep = 9;
}
var infiniteScroll = GetComponent<UI_InfiniteScroll>();
if (ChildObjects != null && ChildObjects.Length > 0 && infiniteScroll != null && !infiniteScroll.InitByUser)
{
Debug.LogError($"[{gameObject.name}]When using procedural children with a ScrollSnap (Adding Prefab ChildObjects) and the Infinite Scroll component\nYou must set the 'InitByUser' option to true, to enable late initialising");
}
}
/// <summary>
/// Event fires when the user starts to change the page, either via swipe or button.
/// </summary>
public void StartScreenChange()
{
if (!_startEventCalled)
{
_suspendEvents = true;
_startEventCalled = true;
_endEventCalled = false;
OnSelectionChangeStartEvent.Invoke();
}
}
/// <summary>
/// Event fires when the currently viewed page changes, also updates while the scroll is moving
/// </summary>
internal void ScreenChange()
{
OnSelectionPageChangedEvent.Invoke(_currentPage);
}
/// <summary>
/// Event fires when control settles on a page, outputs the new page number
/// </summary>
internal void EndScreenChange()
{
if (!_endEventCalled)
{
_suspendEvents = false;
_endEventCalled = true;
_startEventCalled = false;
_settled = true;
OnSelectionChangeEndEvent.Invoke(_currentPage);
}
}
/// <summary>
/// Returns the Transform of the Current page
/// </summary>
/// <returns>Currently selected Page Transform</returns>
public Transform CurrentPageObject()
{
return _screensContainer.GetChild(CurrentPage);
}
/// <summary>
/// Returns the Transform of the Current page in an out parameter for performance
/// </summary>
/// <param name="returnObject">Currently selected Page Transform</param>
public void CurrentPageObject(out Transform returnObject)
{
returnObject = _screensContainer.GetChild(CurrentPage);
}
#region Drag Interfaces
/// <summary>
/// Touch screen to start swiping
/// </summary>
/// <param name="eventData"></param>
public void OnBeginDrag(PointerEventData eventData)
{
_pointerDown = true;
_settled = false;
StartScreenChange();
_startPosition = _screensContainer.anchoredPosition;
}
/// <summary>
/// While dragging do
/// </summary>
/// <param name="eventData"></param>
public void OnDrag(PointerEventData eventData)
{
_lerp = false;
}
public virtual void OnEndDrag(PointerEventData eventData) { }
#endregion
#region IScrollSnap Interface
/// <summary>
/// Added to provide a uniform interface for the ScrollBarHelper
/// </summary>
int IScrollSnap.CurrentPage()
{
return CurrentPage = GetPageforPosition(_screensContainer.anchoredPosition);
}
/// <summary>
/// Added to provide a uniform interface for the ScrollBarHelper
/// </summary>
public void SetLerp(bool value)
{
_lerp = value;
}
/// <summary>
/// Added to provide a uniform interface for the ScrollBarHelper
/// </summary>
public void ChangePage(int page)
{
GoToScreen(page);
}
public void OnPointerClick(PointerEventData eventData)
{
var position = _screensContainer.anchoredPosition;
}
#endregion
}
}