Unity,UI拖拽（跟随手指移动）_unity ugui canvas 手指拖拽-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_43282959/article/details/118331218

本文介绍了一个Unity中自定义UI拖拽组件的实现方法。通过继承MonoBehaviour并实现IPointerDownHandler等接口，文章详细展示了如何响应鼠标按下、拖动及释放事件，并利用RectTransformUtility将屏幕坐标转换为UI坐标，实现UI元素的平滑拖拽。

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public class UIDrag : MonoBehaviour, IPointerDownHandler, IDragHandler, IEndDragHandler
{

#region 字段
public RectTransform canvas;
private RectTransform imgRect;
Vector2 offest = new Vector2();
#endregion

private void Start()
{
imgRect = this.GetComponent<RectTransform>();
canvas = this.transform.parent.GetComponent<RectTransform>();
}

#region 接口
public void OnDrag(PointerEventData eventData)
{
Vector2 mouseDrag = eventData.position;
Vector2 uguiPos = new Vector2();

//RectTransformUtility.ScreenPointToLocalPointInRectangle() 把屏幕坐标转换成UI坐标
//canvas 为当前物体的父物体的RectTransform
bool isRect = RectTransformUtility.ScreenPointToLocalPointInRectangle(canvas,mouseDrag,eventData.enterEventCamera,out uguiPos);
if (isRect)
{
imgRect.anchoredPosition = offest + uguiPos;
}
}

public void OnEndDrag(PointerEventData eventData)
{
offest = Vector2.zero;
}

public void OnPointerDown(PointerEventData eventData)
{
Debug.Log("按下");
Vector2 mouseDown = eventData.position; //鼠标按下时的屏幕坐标
Vector2 mouseUguiPos = new Vector2(); //返回的UGUI坐标
bool isRect = RectTransformUtility.ScreenPointToLocalPointInRectangle(canvas,mouseDown,eventData.enterEventCamera,out mouseUguiPos);
if (isRect)
{
offest = imgRect.anchoredPosition - mouseUguiPos; //计算点击在UI上但是没点击在UI正中心
Debug.Log(offest);
}
}

#endregion
}