360 lines
12 KiB
C#
360 lines
12 KiB
C#
/// Credit setchi (https://github.com/setchi)
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/// Sourced from - https://github.com/setchi/FancyScrollView
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using System;
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using UnityEngine.EventSystems;
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using UnityEngine.UI.Extensions.EasingCore;
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namespace UnityEngine.UI.Extensions
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{
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public class Scroller : UIBehaviour, IBeginDragHandler, IEndDragHandler, IDragHandler
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{
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[SerializeField] RectTransform viewport = default;
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[SerializeField] ScrollDirection directionOfRecognize = ScrollDirection.Vertical;
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[SerializeField] MovementType movementType = MovementType.Elastic;
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[SerializeField] float elasticity = 0.1f;
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[SerializeField] float scrollSensitivity = 1f;
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[SerializeField] bool inertia = true;
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[SerializeField] float decelerationRate = 0.03f;
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[SerializeField] Snap snap = new Snap {
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Enable = true,
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VelocityThreshold = 0.5f,
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Duration = 0.3f,
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Easing = Ease.InOutCubic
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};
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readonly AutoScrollState autoScrollState = new AutoScrollState();
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Action<float> onValueChanged;
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Action<int> onSelectionChanged;
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Vector2 pointerStartLocalPosition;
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float dragStartScrollPosition;
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float prevScrollPosition;
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float currentScrollPosition;
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int totalCount;
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bool dragging;
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float velocity;
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enum ScrollDirection
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{
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Vertical,
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Horizontal,
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}
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public enum MovementType
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{
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Unrestricted = ScrollRect.MovementType.Unrestricted,
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Elastic = ScrollRect.MovementType.Elastic,
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Clamped = ScrollRect.MovementType.Clamped
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}
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[Serializable]
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class Snap
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{
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public bool Enable;
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public float VelocityThreshold;
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public float Duration;
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public Ease Easing;
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}
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static readonly Func<float, float> DefaultEasingFunction = EasingFunction.Get(Ease.OutCubic);
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class AutoScrollState
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{
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public bool Enable;
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public bool Elastic;
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public float Duration;
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public Func<float, float> EasingFunction;
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public float StartTime;
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public float EndScrollPosition;
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public Action OnComplete;
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public void Reset()
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{
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Enable = false;
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Elastic = false;
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Duration = 0f;
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StartTime = 0f;
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EasingFunction = DefaultEasingFunction;
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EndScrollPosition = 0f;
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OnComplete = null;
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}
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public void Complete()
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{
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OnComplete?.Invoke();
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Reset();
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}
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}
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public void OnValueChanged(Action<float> callback) => onValueChanged = callback;
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public void OnSelectionChanged(Action<int> callback) => onSelectionChanged = callback;
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public void SetTotalCount(int totalCount) => this.totalCount = totalCount;
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public void ScrollTo(int index, float duration, Action onComplete = null) => ScrollTo(index, duration, Ease.OutCubic, onComplete);
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public void ScrollTo(int index, float duration, Ease easing, Action onComplete = null) => ScrollTo(index, duration, EasingFunction.Get(easing), onComplete);
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public void ScrollTo(int index, float duration, Func<float, float> easingFunction, Action onComplete = null)
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{
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if (duration <= 0f)
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{
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JumpTo(index);
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return;
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}
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autoScrollState.Reset();
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autoScrollState.Enable = true;
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autoScrollState.Duration = duration;
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autoScrollState.EasingFunction = easingFunction ?? DefaultEasingFunction;
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autoScrollState.StartTime = Time.unscaledTime;
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autoScrollState.EndScrollPosition = CalculateDestinationIndex(index);
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autoScrollState.OnComplete = onComplete;
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velocity = 0f;
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dragStartScrollPosition = currentScrollPosition;
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UpdateSelection(Mathf.RoundToInt(CircularPosition(autoScrollState.EndScrollPosition, totalCount)));
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}
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public void JumpTo(int index)
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{
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autoScrollState.Reset();
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velocity = 0f;
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dragging = false;
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index = CalculateDestinationIndex(index);
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UpdateSelection(index);
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UpdatePosition(index);
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}
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void IBeginDragHandler.OnBeginDrag(PointerEventData eventData)
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{
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if (eventData.button != PointerEventData.InputButton.Left)
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{
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return;
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}
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pointerStartLocalPosition = Vector2.zero;
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RectTransformUtility.ScreenPointToLocalPointInRectangle(
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viewport,
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eventData.position,
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eventData.pressEventCamera,
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out pointerStartLocalPosition);
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dragStartScrollPosition = currentScrollPosition;
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dragging = true;
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autoScrollState.Reset();
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}
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void IDragHandler.OnDrag(PointerEventData eventData)
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{
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if (eventData.button != PointerEventData.InputButton.Left)
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{
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return;
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}
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if (!dragging)
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{
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return;
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}
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if (!RectTransformUtility.ScreenPointToLocalPointInRectangle(
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viewport,
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eventData.position,
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eventData.pressEventCamera,
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out var localCursor))
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{
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return;
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}
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var pointerDelta = localCursor - pointerStartLocalPosition;
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var position = (directionOfRecognize == ScrollDirection.Horizontal ? -pointerDelta.x : pointerDelta.y)
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/ ViewportSize
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* scrollSensitivity
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+ dragStartScrollPosition;
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var offset = CalculateOffset(position);
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position += offset;
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if (movementType == MovementType.Elastic)
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{
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if (offset != 0f)
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{
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position -= RubberDelta(offset, scrollSensitivity);
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}
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}
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UpdatePosition(position);
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}
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void IEndDragHandler.OnEndDrag(PointerEventData eventData)
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{
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if (eventData.button != PointerEventData.InputButton.Left)
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{
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return;
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}
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dragging = false;
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}
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float ViewportSize => directionOfRecognize == ScrollDirection.Horizontal
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? viewport.rect.size.x
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: viewport.rect.size.y;
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float CalculateOffset(float position)
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{
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if (movementType == MovementType.Unrestricted)
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{
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return 0f;
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}
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if (position < 0f)
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{
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return -position;
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}
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if (position > totalCount - 1)
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{
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return totalCount - 1 - position;
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}
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return 0f;
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}
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void UpdatePosition(float position)
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{
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currentScrollPosition = position;
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onValueChanged?.Invoke(currentScrollPosition);
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}
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void UpdateSelection(int index) => onSelectionChanged?.Invoke(index);
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float RubberDelta(float overStretching, float viewSize) =>
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(1 - 1 / (Mathf.Abs(overStretching) * 0.55f / viewSize + 1)) * viewSize * Mathf.Sign(overStretching);
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void Update()
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{
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var deltaTime = Time.unscaledDeltaTime;
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var offset = CalculateOffset(currentScrollPosition);
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if (autoScrollState.Enable)
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{
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var position = 0f;
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if (autoScrollState.Elastic)
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{
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position = Mathf.SmoothDamp(currentScrollPosition, currentScrollPosition + offset, ref velocity,
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elasticity, Mathf.Infinity, deltaTime);
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if (Mathf.Abs(velocity) < 0.01f)
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{
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position = Mathf.Clamp(Mathf.RoundToInt(position), 0, totalCount - 1);
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velocity = 0f;
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autoScrollState.Complete();
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}
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}
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else
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{
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var alpha = Mathf.Clamp01((Time.unscaledTime - autoScrollState.StartTime) /
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Mathf.Max(autoScrollState.Duration, float.Epsilon));
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position = Mathf.LerpUnclamped(dragStartScrollPosition, autoScrollState.EndScrollPosition,
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autoScrollState.EasingFunction(alpha));
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if (Mathf.Approximately(alpha, 1f))
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{
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autoScrollState.Complete();
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}
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}
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UpdatePosition(position);
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}
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else if (!dragging && (!Mathf.Approximately(offset, 0f) || !Mathf.Approximately(velocity, 0f)))
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{
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var position = currentScrollPosition;
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if (movementType == MovementType.Elastic && !Mathf.Approximately(offset, 0f))
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{
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autoScrollState.Reset();
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autoScrollState.Enable = true;
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autoScrollState.Elastic = true;
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UpdateSelection(Mathf.Clamp(Mathf.RoundToInt(position), 0, totalCount - 1));
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}
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else if (inertia)
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{
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velocity *= Mathf.Pow(decelerationRate, deltaTime);
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if (Mathf.Abs(velocity) < 0.001f)
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{
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velocity = 0f;
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}
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position += velocity * deltaTime;
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if (snap.Enable && Mathf.Abs(velocity) < snap.VelocityThreshold)
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{
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ScrollTo(Mathf.RoundToInt(currentScrollPosition), snap.Duration, snap.Easing);
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}
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}
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else
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{
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velocity = 0f;
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}
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if (!Mathf.Approximately(velocity, 0f))
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{
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if (movementType == MovementType.Clamped)
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{
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offset = CalculateOffset(position);
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position += offset;
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if (Mathf.Approximately(position, 0f) || Mathf.Approximately(position, totalCount - 1f))
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{
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velocity = 0f;
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UpdateSelection(Mathf.RoundToInt(position));
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}
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}
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UpdatePosition(position);
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}
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}
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if (!autoScrollState.Enable && dragging && inertia)
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{
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var newVelocity = (currentScrollPosition - prevScrollPosition) / deltaTime;
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velocity = Mathf.Lerp(velocity, newVelocity, deltaTime * 10f);
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}
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prevScrollPosition = currentScrollPosition;
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}
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int CalculateDestinationIndex(int index) => movementType == MovementType.Unrestricted
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? CalculateClosestIndex(index)
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: Mathf.Clamp(index, 0, totalCount - 1);
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int CalculateClosestIndex(int index)
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{
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var diff = CircularPosition(index, totalCount)
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- CircularPosition(currentScrollPosition, totalCount);
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if (Mathf.Abs(diff) > totalCount * 0.5f)
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{
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diff = Mathf.Sign(-diff) * (totalCount - Mathf.Abs(diff));
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}
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return Mathf.RoundToInt(diff + currentScrollPosition);
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}
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float CircularPosition(float p, int size) => size < 1 ? 0 : p < 0 ? size - 1 + (p + 1) % size : p % size;
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}
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}
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