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using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
/// <summary>
/// 自动吸附的滑动列表
/// </summary>
public class AutoAdsorbScrollView : MonoBehaviour, IBeginDragHandler, IEndDragHandler
{
private ScrollRect scrollRect;//滑动框组件
private RectTransform content;//滑动框的Content
private GridLayoutGroup layout;//布局组件
private int totalPage; //总页数
private int curPage; //当前页的下标
private float[] eachPageNUPos; //每页的NormalizedPositon的值
private float targetNUPos; //目标页的NormalizedPositon的值
private Vector2 beginMousePos; //鼠标开始按下的位置
private Vector2 endMousePos; //鼠标结束按下的位置
private bool isDrag; //是否在拖拽
[Header("是否可以滑动多页")]
public bool sliderMultPage;
[Header("视为滑动一页的距离")]
[Space(25)]
public float sliderOnePageDis;
[Header("视为滑动多页的距离")]
public float sliderMultPageDis;
[Header("缓动到目标页的持续时间")]
public float duration;
#region Init
private void Awake()
{
scrollRect = GetComponent<ScrollRect>();
content = scrollRect.content;
layout = content.GetComponent<GridLayoutGroup>();
Init();//初始化
}
/// <summary>
/// 初始化
/// </summary>
private void Init()
{
totalPage = content.childCount;
SetContentSize();//设置Content大小
CalcEachPageNUPos();//计算每一页的NormalizedPositon值
SetLayout();//设置布局
}
/// <summary>
/// 设置Content大小
/// </summary>
private void SetContentSize()
{
content.sizeDelta = new Vector2
(
layout.padding.right + layout.padding.left + (totalPage - 1) * (layout.cellSize.x + layout.spacing.x) - layout.spacing.x,
content.sizeDelta.y
); ;
}
/// <summary>
/// 计算每一页的NormalizedPositon值
/// </summary>
private void CalcEachPageNUPos()
{
float tempNUPos = 0;
eachPageNUPos = new float[totalPage];
for (int i = 0; i < totalPage; i++)
{
eachPageNUPos[i] = tempNUPos;
tempNUPos += 1f / (totalPage - 1);
}
}
/// <summary>
/// 设置布局
/// </summary>
private void SetLayout()
{
scrollRect.horizontal = true;
scrollRect.vertical = false;
layout.padding.right = layout.padding.left;
layout.startCorner = GridLayoutGroup.Corner.UpperLeft;
layout.childAlignment = TextAnchor.MiddleCenter;
layout.constraintCount = 1;
}
#endregion
#region Main
/// <summary>
/// 拖拽开始
/// </summary>
public void OnBeginDrag(PointerEventData eventData)
{
isDrag = true;
beginMousePos = Input.mousePosition;
}
/// <summary>
/// 拖拽结束
/// </summary>
/// <param name="eventData"></param>
public void OnEndDrag(PointerEventData eventData)
{
isDrag = false;
coe = 0;
endMousePos = Input.mousePosition;
Vector2 offset = endMousePos - beginMousePos;
Debug.Log("滑动距离为：" + offset);
if (sliderMultPage)
{
//单页滑动
if (Mathf.Abs(offset.x) >= sliderOnePageDis && Mathf.Abs(offset.x) < sliderMultPageDis)
{
float tempHorizontalNUPos = scrollRect.horizontalNormalizedPosition;
FindNearlyPage(tempHorizontalNUPos);
}
//多页滑动
else if (Mathf.Abs(offset.x) >= sliderMultPageDis)
{
if (offset.x > 0)
{
curPage = 0;
}
else if (offset.x < 0)
{
curPage = totalPage - 1;
}
}
}
else
{
//单页滑动
if (Mathf.Abs(offset.x) >= sliderOnePageDis)
{
float tempHorizontalNUPos = scrollRect.horizontalNormalizedPosition;
FindNearlyPage(tempHorizontalNUPos);
}
}
targetNUPos = eachPageNUPos[curPage];
}
private float coe;//比例系数
private void Update()
{
if (isDrag)
{
return;
}
coe += Time.deltaTime / duration;
scrollRect.horizontalNormalizedPosition = Mathf.Lerp(scrollRect.horizontalNormalizedPosition, targetNUPos, coe);
}
#endregion
#region Tool
/// <summary>
/// 寻找距离当前NormalizedPositon最近的页
/// </summary>
private void FindNearlyPage(float tempHorizontalNUPos)
{
float minOffset = Mathf.Abs(eachPageNUPos[0] - tempHorizontalNUPos);
for (int i = 0; i < totalPage; i++)
{
float tempHorizontalOffset = Mathf.Abs(eachPageNUPos[i] - tempHorizontalNUPos);
if (tempHorizontalOffset <= minOffset)
{
minOffset = tempHorizontalOffset;
curPage = i;
}
}
}
#endregion
}
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