unity/C# 反射

• 下面例子通过反射功能调用TextureImporter对象中的GetWidthAndHeight方法，在纹理导入之前就能得到纹理的宽高。

  using UnityEditor;
  using System.Reflection;
  using UnityEngine;
  
  public class SpriteSheetPostprocessor:AssetPostprocessor{
      private void OnPreprocessTexture(){
          TextureImporter importer=assetImporter as TextureImporter;
          object[] parameters=new object[2]{0,0};
          //MethodInfo methodInfo=typeof(TextureImporter).GetMethod("GetWidthAndHeight",BindingFlags.NonPublic|BindingFlags.Instance);
          MethodInfo methodInfo=importer.GetType().GetMethod("GetWidthAndHeight",BindingFlags.NonPublic|BindingFlags.Instance);
          methodInfo.Invoke(importer,parameters);
          Debug.LogFormat("width:{0} height:{1}",parameters[0],parameters[1]);
      }
  }
  

• 下面示例使用反射调用 UnityEditor.dll 中的私有类的方法 UnityEditor.PackageExport.ShowExportPackage()，显示导出包窗口

  PackageExport 类的源码开源地址：https://github.com/Unity-Technologies/UnityCsReference/blob/master/Editor/Mono/GUI/PackageExport.cs#L74

  #if UNITY_EDITOR
  using System;
  using System.Reflection;
  using UnityEditor;
  using UnityEngine;
  
  public class EditorTest : Editor {
  
      [MenuItem("Tools/EditorTest", true)]
      private static bool ValidateMenuItem() {
          return !EditorApplication.isPlaying;
      }
  
      [MenuItem("Tools/EditorTest")]
      private static void Test() {
          if (EditorApplication.isPlaying) return;
          Debug.Log("== Tools/EditorTest ==");
          
          Type t = Assembly.Load("UnityEditor").GetType("UnityEditor.PackageExport");
          MethodInfo showExportPackageMethodInfo = t.GetMethod("ShowExportPackage", BindingFlags.Static | BindingFlags.NonPublic);
          showExportPackageMethodInfo.Invoke(t, null);
  
      }
  }
  #endif
  

• 示例，在拽时 ScrollRect 不触发按钮点击

  using System.Reflection;
  using UnityEngine;
  using UnityEngine.EventSystems;
  using UnityEngine.UI;
  
  public class ScrollRectButton : MonoBehaviour, IPointerUpHandler {
  
      private readonly FieldInfo m_scrollRectDraggingFieldInfo = typeof(ScrollRect).GetField("m_Dragging", BindingFlags.NonPublic | BindingFlags.Instance);
      private ScrollRect m_scrollRect;
      
      
      /// <summary>
      /// 通过反射获取私有字段 scrollRect.m_Dragging
      /// </summary>
      private bool IsDragingScrollRect() {
          //var info = m_scrollRect.GetType().GetField("m_Dragging", BindingFlags.NonPublic | BindingFlags.Instance);
          //return (bool)info.GetValue(m_scrollRect);
          return (bool)m_scrollRectDraggingFieldInfo.GetValue(m_scrollRect);
      }
  
      void IPointerUpHandler.OnPointerUp(PointerEventData eventData) {
          // 非拽 scrollRect 时，则视为点击
          if (!IsDragingScrollRect()) {
              OnPointerClick(eventData);
          }
      }
  
      private void OnPointerClick(PointerEventData eventData) {
          Debug.Log("OnPointerClick");
      }
  
      private void Awake() {
          m_scrollRect = GetComponentInParent<ScrollRect>();
      }
  }