75 lines
2.4 KiB
C#
75 lines
2.4 KiB
C#
using UnityEngine;
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using UnityEngine.EventSystems;
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using UnityEngine.UI;
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public class UIDragItem : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
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{
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private RectTransform rectTransform; // UI 图片的 RectTransform
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private CanvasGroup canvasGroup; // CanvasGroup 用于处理拖拽时的透明度
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private Vector2 startPosition; // 拖拽开始时的初始位置
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private Vector2 offset; // 鼠标相对于 UI 中心点的偏移量
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void Start()
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{
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// 获取 RectTransform 组件
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rectTransform = GetComponent<RectTransform>();
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// 添加 CanvasGroup 组件（如果不存在）
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canvasGroup = GetComponent<CanvasGroup>();
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if (canvasGroup == null)
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{
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canvasGroup = gameObject.AddComponent<CanvasGroup>();
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}
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}
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// 开始拖拽时调用
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public void OnBeginDrag(PointerEventData eventData)
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{
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// 记录初始位置
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startPosition = rectTransform.anchoredPosition;
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// 计算鼠标相对于 UI 中心点的偏移量
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Vector2 localPoint;
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if (RectTransformUtility.ScreenPointToLocalPointInRectangle(rectTransform, eventData.position, eventData.pressEventCamera, out localPoint))
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{
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offset = localPoint;
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}
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// 降低透明度，表示拖拽状态
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canvasGroup.alpha = 0.6f;
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// 禁用 Raycast 目标，防止拖拽时阻挡其他 UI 事件
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canvasGroup.blocksRaycasts = false;
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}
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// 拖拽过程中调用
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public void OnDrag(PointerEventData eventData)
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{
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// 将屏幕坐标转换为 UI 父对象的本地坐标
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Vector2 screenPoint = eventData.position;
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Vector2 localPoint;
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if (RectTransformUtility.ScreenPointToLocalPointInRectangle(
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rectTransform.parent as RectTransform, // 父对象（Canvas 或 Panel）
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screenPoint, // 屏幕坐标
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eventData.pressEventCamera, // 相机（Canvas 的渲染模式决定）
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out localPoint // 输出的本地坐标
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))
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{
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// 根据鼠标位置和偏移量更新 UI 的位置
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rectTransform.anchoredPosition = localPoint - offset;
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}
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}
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// 结束拖拽时调用
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public void OnEndDrag(PointerEventData eventData)
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{
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// 恢复透明度
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canvasGroup.alpha = 1.0f;
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// 启用 Raycast 目标
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canvasGroup.blocksRaycasts = true;
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// 如果需要，可以将 UI 图片重置到初始位置
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// rectTransform.anchoredPosition = startPosition;
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}
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} |