using System; using UnityEngine.Events; using UnityEngine.EventSystems; namespace UnityEngine.UI.Extensions { public class ScrollSnapBase : MonoBehaviour, IBeginDragHandler, IDragHandler { 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(); [Tooltip("The currently active page")] internal int _currentPage; internal int _previousPage; internal int _halfNoVisibleItems; private int _bottomItem, _topItem; [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(1, 8)] public float PageStep = 1; [Tooltip("The gameobject that contains toggles which suggest pagination. (optional)")] public GameObject Pagination; [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("Transition speed between pages. (optional)")] public float transitionSpeed = 7.5f; [Tooltip("Fast Swipe makes swiping page next / previous (optional)")] public Boolean UseFastSwipe = false; [Tooltip("How far 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 = 200; [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 arround Mask Area. (optional)")] public float MaskBuffer = 1; public int CurrentPage { get { return _currentPage; } internal set { if ((value != _currentPage && value >= 0 && value < _screensContainer.childCount) || (value == 0 && _screensContainer.childCount == 0)) { _previousPage = _currentPage; _currentPage = value; if(MaskArea) UpdateVisible(); if(!_lerp) ScreenChange(); ChangeBulletsInfo(_currentPage); } } } [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; } } // Use this for initialization void Awake() { _scroll_rect = gameObject.GetComponent<ScrollRect>(); if (_scroll_rect.horizontalScrollbar || _scroll_rect.verticalScrollbar) { Debug.LogWarning("Warning, using scrollbars with the Scroll Snap controls is not advised as it causes unpredictable results"); } if (StartingScreen < 0) { StartingScreen = 0; } _screensContainer = _scroll_rect.content; 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(); } else { InitialiseChildObjectsFromScene(); } if (NextButton) NextButton.GetComponent<Button>().onClick.AddListener(() => { NextScreen(); }); if (PrevButton) PrevButton.GetComponent<Button>().onClick.AddListener(() => { PreviousScreen(); }); } 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) { if (!_lerp) StartScreenChange(); _lerp = true; CurrentPage = _currentPage + 1; GetPositionforPage(_currentPage, ref _lerp_target); ScreenChange(); } } //Function for switching screens with buttons public void PreviousScreen() { if (_currentPage > 0) { if (!_lerp) StartScreenChange(); _lerp = true; 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> public void GoToScreen(int screenIndex) { if (screenIndex <= _screens - 1 && screenIndex >= 0) { if (!_lerp) 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((pos.y - _scrollStartPosition) / _childSize) : -(int)Math.Round((pos.x - _scrollStartPosition) / _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) { target.y = _childPos + _scrollStartPosition; } else { target.x = _childPos + _scrollStartPosition; } } /// <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.localPosition); GetPositionforPage(_currentPage, ref _lerp_target); ChangeBulletsInfo(_currentPage); } /// <summary> /// changes the bullets on the bottom of the page - pagination /// </summary> /// <param name="targetScreen"></param> internal 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; } } private void OnValidate() { var children = gameObject.GetComponent<ScrollRect>().content.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; } } /// <summary> /// Event fires when the user starts to change the page, either via swipe or button. /// </summary> internal void StartScreenChange() { 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() { OnSelectionChangeEndEvent.Invoke(_currentPage); _settled = true; } #region Interfaces /// <summary> /// Touch screen to start swiping /// </summary> /// <param name="eventData"></param> public void OnBeginDrag(PointerEventData eventData) { _pointerDown = true; _settled = false; StartScreenChange(); _startPosition = _screensContainer.localPosition; } /// <summary> /// While dragging do /// </summary> /// <param name="eventData"></param> public void OnDrag(PointerEventData eventData) { _lerp = false; } #endregion } }