com.unity.uiextensions.nosa.../Scripts/Layout/FancyScrollView/Core/FancyScrollView.cs

136 lines
4.7 KiB
C#

/// Credit setchi (https://github.com/setchi)
/// Sourced from - https://github.com/setchi/FancyScrollView
using System.Collections.Generic;
namespace UnityEngine.UI.Extensions
{
public abstract class FancyScrollView<TItemData, TContext> : MonoBehaviour where TContext : class, new()
{
[SerializeField, Range(1e-2f, 1f)] protected float cellInterval = 0.2f;
[SerializeField, Range(0f, 1f)] protected float scrollOffset = 0.5f;
[SerializeField] protected bool loop = false;
[SerializeField] protected Transform cellContainer = default;
readonly IList<FancyScrollViewCell<TItemData, TContext>> pool =
new List<FancyScrollViewCell<TItemData, TContext>>();
protected float currentPosition;
protected abstract GameObject CellPrefab { get; }
protected IList<TItemData> ItemsSource { get; set; } = new List<TItemData>();
protected TContext Context { get; } = new TContext();
/// <summary>
/// Updates the contents.
/// </summary>
/// <param name="itemsSource">Items source.</param>
protected virtual void UpdateContents(IList<TItemData> itemsSource)
{
ItemsSource = itemsSource;
Refresh();
}
/// <summary>
/// Refreshes the cells.
/// </summary>
protected virtual void Refresh() => UpdatePosition(currentPosition, true);
/// <summary>
/// Updates the scroll position.
/// </summary>
/// <param name="position">Position.</param>
protected virtual void UpdatePosition(float position) => UpdatePosition(position, false);
protected void UpdatePosition(float position, bool forceRefresh)
{
currentPosition = position;
var p = position - scrollOffset / cellInterval;
var firstIndex = Mathf.CeilToInt(p);
var firstPosition = (Mathf.Ceil(p) - p) * cellInterval;
if (firstPosition + pool.Count * cellInterval < 1f)
{
ResizePool(firstPosition);
}
UpdateCells(firstPosition, firstIndex, forceRefresh);
}
void ResizePool(float firstPosition)
{
Debug.Assert(CellPrefab != null);
Debug.Assert(cellContainer != null);
var addCount = Mathf.CeilToInt((1f - firstPosition) / cellInterval) - pool.Count;
for (var i = 0; i < addCount; i++)
{
var cell = Instantiate(CellPrefab, cellContainer).GetComponent<FancyScrollViewCell<TItemData, TContext>>();
if (cell == null)
{
throw new MissingComponentException(
$"FancyScrollViewCell<{typeof(TItemData).FullName}, {typeof(TContext).FullName}> " +
$"component not found in {CellPrefab.name}.");
}
cell.SetupContext(Context);
cell.SetVisible(false);
pool.Add(cell);
}
}
void UpdateCells(float firstPosition, int firstIndex, bool forceRefresh)
{
for (var i = 0; i < pool.Count; i++)
{
var index = firstIndex + i;
var position = firstPosition + i * cellInterval;
var cell = pool[CircularIndex(index, pool.Count)];
if (loop)
{
index = CircularIndex(index, ItemsSource.Count);
}
if (index < 0 || index >= ItemsSource.Count || position > 1f)
{
cell.SetVisible(false);
continue;
}
if (forceRefresh || cell.Index != index || !cell.IsVisible)
{
cell.Index = index;
cell.SetVisible(true);
cell.UpdateContent(ItemsSource[index]);
}
cell.UpdatePosition(position);
}
}
int CircularIndex(int i, int size) => size < 1 ? 0 : i < 0 ? size - 1 + (i + 1) % size : i % size;
#if UNITY_EDITOR
bool cachedLoop;
float cachedCellInterval, cachedScrollOffset;
void LateUpdate()
{
if (cachedLoop != loop || cachedCellInterval != cellInterval || cachedScrollOffset != scrollOffset)
{
cachedLoop = loop;
cachedCellInterval = cellInterval;
cachedScrollOffset = scrollOffset;
UpdatePosition(currentPosition);
}
}
#endif
}
public sealed class FancyScrollViewNullContext { }
public abstract class FancyScrollView<TItemData> : FancyScrollView<TItemData, FancyScrollViewNullContext> { }
}