Unity 基础 之 IDragHanlder 多种方法简单实现 UGUI 元素随着鼠标移动，拖动的效果
目录
Unity 基础 之 IDragHanlder 多种方法简单实现 UGUI 元素随着鼠标移动，拖动的效果
一、简单介绍
二、实现原理
三、注意实现
四、效果预览
五、实现步骤
六、多种方法实现拖拽 UI
方法一：RectTransformUtility.ScreenPointToWorldPointInRectangle
方法二 ：RectTransformUtility.ScreenPointToWorldPointInRectangle 并带位移 offset
方法三：RectTransformUtility.ScreenPointToLocalPointInRectangle 并带位移 Offset
方法四：Camera.WorldToScreenPoint 和 Camera.WorldToScreenPoint 并带位移 Offset
一、简单介绍
Unity中的一些基础知识点。
本节介绍，使用 IDraHandler ，简单的就实现 UGUI 元素，随着鼠标的移动而移动的效果。
二、实现原理
1、IBeginDragHandler, IDragHandler, IEndDragHandler 三个接口，进行实现拖拽的功能
2、RectTransformUtility.ScreenPointToWorldPointInRectangle 或者 RectTransformUtility.ScreenPointToLocalPointInRectangle
进行坐标转化，实现拖拽
3、必要的再结合 Camera.WorldToScreenPoint 和 Camera.ScreenToWorldPoint 一起实现拖拽移动效果
三、注意实现
1、根据 Canvas 的 Render Mode 不同的拖拽方法，移动的效果可能会略有不同，择需使用即可
四、效果预览
五、实现步骤
1、打开 Unity，新建一个空工程
2、在场景中搭建UI，布局如下
3、新建脚本，编辑方法移动 UI，把脚本对应赋值
六、多种方法实现拖拽 UI
方法一：RectTransformUtility.ScreenPointToWorldPointInRectangle
1、代码如下
using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.EventSystems;public class DragHandlerUGUI : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler{private RectTransform rectTransform;// Start is called before the first frame updatevoid Start(){rectTransform = GetComponent<RectTransform>();}public void OnBeginDrag(PointerEventData eventData){Debug.Log("开始拖拽");}public void OnDrag(PointerEventData eventData){Vector3 pos;RectTransformUtility.ScreenPointToWorldPointInRectangle(rectTransform, eventData.position, eventData.enterEventCamera, out pos);rectTransform.position = pos;}public void OnEndDrag(PointerEventData eventData){Debug.Log("结束拖拽");}}
2、效果如下
方法二 ：RectTransformUtility.ScreenPointToWorldPointInRectangle 并带位移 offset
1、代码如下
using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.EventSystems;public class DragHandlerUGUI : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler{private RectTransform rectTransform;private Vector3 pos; //控件初始位置private Vector3 mousePos; //鼠标初始位置private void Start(){rectTransform = GetComponent<RectTransform>();}public void OnBeginDrag(PointerEventData eventData){Debug.Log("开始拖拽"); pos = this.GetComponent<RectTransform>().position; RectTransformUtility.ScreenPointToWorldPointInRectangle(rectTransform, eventData.position, eventData.pressEventCamera, out mousePos);}public void OnDrag(PointerEventData eventData){Vector3 newVec;RectTransformUtility.ScreenPointToWorldPointInRectangle(rectTransform, eventData.position, eventData.pressEventCamera, out newVec);Vector3 offset = new Vector3(newVec.x - mousePos.x, newVec.y - mousePos.y, 0);rectTransform.position = pos + offset;}public void OnEndDrag(PointerEventData eventData){Debug.Log("结束拖拽");}}
2、效果如下
方法三：RectTransformUtility.ScreenPointToLocalPointInRectangle 并带位移 Offset
1、代码如下
using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.EventSystems;public class DragHandlerUGUI : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler{private Vector3 pos; //控件初始位置private Vector2 mousePos; //鼠标初始位置private RectTransform canvasRec;//控件所在画布private void Start(){canvasRec = this.GetComponentInParent<Canvas>().transform as RectTransform;}public void OnBeginDrag(PointerEventData eventData){Debug.Log("开始拖拽");//控件所在画布空间的初始位置pos = this.GetComponent<RectTransform>().anchoredPosition; //将屏幕空间鼠标位置eventData.position转换为鼠标在画布空间的鼠标位置RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRec, eventData.position, eventData.pressEventCamera, out mousePos);}public void OnDrag(PointerEventData eventData){Vector2 newVec;RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRec, eventData.position, eventData.pressEventCamera, out newVec);//鼠标移动在画布空间的位置增量Vector3 offset = new Vector3(newVec.x - mousePos.x, newVec.y - mousePos.y, 0);//原始位置增加位置增量即为现在位置(this.transform as RectTransform).anchoredPosition = pos + offset;}public void OnEndDrag(PointerEventData eventData){Debug.Log("结束拖拽");}}
2、效果如下
方法四：Camera.WorldToScreenPoint 和 Camera.WorldToScreenPoint 并带位移 Offset
1、代码如下
using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEngine.EventSystems;public class DragHandlerUGUI : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler{Vector3 uiScreenPosition;Vector3 mouseScreenPosition;Vector3 mScreenPosition;private Vector3 offset;Camera mCamera;// Start is called before the first frame updatevoid Start(){mCamera = Camera.main;}public void OnBeginDrag(PointerEventData eventData){Debug.Log("开始拖拽");//转换对象到当前屏幕位置uiScreenPosition = mCamera.WorldToScreenPoint(transform.position);mouseScreenPosition = mCamera.WorldToScreenPoint(eventData.position);//鼠标屏幕坐标mScreenPosition = new Vector3(mouseScreenPosition.x, mouseScreenPosition.y, uiScreenPosition.z);//获得鼠标和对象之间的偏移量,拖拽时相机应该保持不动offset = transform.position - mCamera.ScreenToWorldPoint(mScreenPosition);}public void OnDrag(PointerEventData eventData){mouseScreenPosition = mCamera.WorldToScreenPoint(eventData.position);//鼠标屏幕上新位置mScreenPosition = new Vector3(mouseScreenPosition.x, mouseScreenPosition.y, uiScreenPosition.z);// 对象新坐标transform.position = offset + mCamera.ScreenToWorldPoint(mScreenPosition);}public void OnEndDrag(PointerEventData eventData){Debug.Log("结束拖拽");}}
2、效果如下
