Unity--EditorGUI.ObjectField实现

记录下，以后可以有个参考

绘制UI使用的是style.Draw(position, gUIContent, id, DragAndDrop.activeControlID == id);

这个style其实就是EditorStyles.objectField

有ObjectSelector.get.Show(obj, objType, property, allowSceneObjects);的

码块是后面那个圈圈的点击事件，点击后弹出对象选择面板

拖拽处理在EventType.DragUpdated，EventType.DragPerform的case块代码中

public static Object ObjectField(Rect position, GUIContent label, Object obj, Type objType, bool allowSceneObjects)
{
	int controlID = GUIUtility.GetControlID(EditorGUI.s_ObjectFieldHash, FocusType.Keyboard, position);
	position = EditorGUI.PrefixLabel(position, controlID, label);
	if (EditorGUIUtility.HasObjectThumbnail(objType) && position.height > 16f)
	{
		float num = Mathf.Min(position.width, position.height);
		position.height = num;
		position.xMin = position.xMax - num;
	}
	return EditorGUI.DoObjectField(position, position, controlID, obj, objType, null, null, allowSceneObjects);
}

internal static Object DoObjectField(Rect position, Rect dropRect, int id, Object obj, Type objType, SerializedProperty property, EditorGUI.ObjectFieldValidator validator, bool allowSceneObjects)
{
	return EditorGUI.DoObjectField(position, dropRect, id, obj, objType, property, validator, allowSceneObjects, EditorStyles.objectField);
}

internal static Object DoObjectField(Rect position, Rect dropRect, int id, Object obj, Type objType, SerializedProperty property, EditorGUI.ObjectFieldValidator validator, bool allowSceneObjects, GUIStyle style)
{
	if (validator == null)
	{
		if (EditorGUI.<>f__mg$cache5 == null)
		{
			EditorGUI.<>f__mg$cache5 = new EditorGUI.ObjectFieldValidator(EditorGUI.ValidateObjectFieldAssignment);
		}
		validator = EditorGUI.<>f__mg$cache5;
	}
	Event current = Event.current;
	EventType eventType = current.type;
	if (!GUI.enabled && GUIClip.enabled && Event.current.rawType == EventType.MouseDown)
	{
		eventType = Event.current.rawType;
	}
	bool flag = EditorGUIUtility.HasObjectThumbnail(objType);
	EditorGUI.ObjectFieldVisualType objectFieldVisualType = EditorGUI.ObjectFieldVisualType.IconAndText;
	if (flag && position.height <= 18f && position.width <= 32f)
	{
		objectFieldVisualType = EditorGUI.ObjectFieldVisualType.MiniPreview;
	}
	else
	{
		if (flag && position.height > 16f)
		{
			objectFieldVisualType = EditorGUI.ObjectFieldVisualType.LargePreview;
		}
	}
	Vector2 iconSize = EditorGUIUtility.GetIconSize();
	if (objectFieldVisualType == EditorGUI.ObjectFieldVisualType.IconAndText)
	{
		EditorGUIUtility.SetIconSize(new Vector2(12f, 12f));
	}
	else
	{
		if (objectFieldVisualType == EditorGUI.ObjectFieldVisualType.LargePreview)
		{
			EditorGUIUtility.SetIconSize(new Vector2(64f, 64f));
		}
	}
	Object result;
	switch (eventType)
	{
	case EventType.KeyDown:
		if (GUIUtility.keyboardControl == id)
		{
			if (current.keyCode == KeyCode.Backspace || current.keyCode == KeyCode.Delete)
			{
				if (property != null)
				{
					property.objectReferenceValue = null;
				}
				else
				{
					obj = null;
				}
				GUI.changed = true;
				current.Use();
			}
			if (current.MainActionKeyForControl(id))
			{
				ObjectSelector.get.Show(obj, objType, property, allowSceneObjects);
				ObjectSelector.get.objectSelectorID = id;
				current.Use();
				GUIUtility.ExitGUI();
			}
		}
		goto IL_664;
	case EventType.KeyUp:
	case EventType.ScrollWheel:
	case EventType.Layout:
		IL_119:
		if (eventType != EventType.ExecuteCommand)
		{
			if (eventType == EventType.DragExited)
			{
				if (GUI.enabled)
				{
					HandleUtility.Repaint();
				}
				goto IL_664;
			}
			if (eventType != EventType.MouseDown)
			{
				goto IL_664;
			}
			if (Event.current.button != 0)
			{
				goto IL_664;
			}
			if (position.Contains(Event.current.mousePosition))
			{
				Rect rect;
				switch (objectFieldVisualType)
				{
				case EditorGUI.ObjectFieldVisualType.IconAndText:
				case EditorGUI.ObjectFieldVisualType.MiniPreview:
					rect = new Rect(position.xMax - 15f, position.y, 15f, position.height);
					break;
				case EditorGUI.ObjectFieldVisualType.LargePreview:
					rect = new Rect(position.xMax - 36f, position.yMax - 14f, 36f, 14f);
					break;
				default:
					throw new ArgumentOutOfRangeException();
				}
				EditorGUIUtility.editingTextField = false;
				if (rect.Contains(Event.current.mousePosition))
				{
					if (GUI.enabled)
					{
						GUIUtility.keyboardControl = id;
						ObjectSelector.get.Show(obj, objType, property, allowSceneObjects);
						ObjectSelector.get.objectSelectorID = id;
						current.Use();
						GUIUtility.ExitGUI();
					}
				}
				else
				{
					Object @object = (property == null) ? obj : property.objectReferenceValue;
					Component component = @object as Component;
					if (component)
					{
						@object = component.gameObject;
					}
					if (EditorGUI.showMixedValue)
					{
						@object = null;
					}
					if (Event.current.clickCount == 1)
					{
						GUIUtility.keyboardControl = id;
						EditorGUI.PingObjectOrShowPreviewOnClick(@object, position);
						current.Use();
					}
					else
					{
						if (Event.current.clickCount == 2)
						{
							if (@object)
							{
								AssetDatabase.OpenAsset(@object);
								GUIUtility.ExitGUI();
							}
							current.Use();
						}
					}
				}
			}
			goto IL_664;
		}
		else
		{
			string commandName = current.commandName;
			if (commandName == "ObjectSelectorUpdated" && ObjectSelector.get.objectSelectorID == id && GUIUtility.keyboardControl == id && (property == null || !property.isScript))
			{
				result = EditorGUI.AssignSelectedObject(property, validator, objType, current);
				return result;
			}
			if (!(commandName == "ObjectSelectorClosed") || ObjectSelector.get.objectSelectorID != id || GUIUtility.keyboardControl != id || property == null || !property.isScript)
			{
				goto IL_664;
			}
			if (ObjectSelector.get.GetInstanceID() == 0)
			{
				current.Use();
				goto IL_664;
			}
			result = EditorGUI.AssignSelectedObject(property, validator, objType, current);
			return result;
		}
		break;
	case EventType.Repaint:
	{
		GUIContent gUIContent;
		if (EditorGUI.showMixedValue)
		{
			gUIContent = EditorGUI.s_MixedValueContent;
		}
		else
		{
			if (property != null)
			{
				gUIContent = EditorGUIUtility.TempContent(property.objectReferenceStringValue, AssetPreview.GetMiniThumbnail(property.objectReferenceValue));
				obj = property.objectReferenceValue;
				if (obj != null)
				{
					Object[] references = new Object[]
					{
						obj
					};
					if (EditorSceneManager.preventCrossSceneReferences && EditorGUI.CheckForCrossSceneReferencing(obj, property.serializedObject.targetObject))
					{
						if (!EditorApplication.isPlaying)
						{
							gUIContent = EditorGUI.s_SceneMismatch;
						}
						else
						{
							gUIContent.text += string.Format(" ({0})", EditorGUI.GetGameObjectFromObject(obj).scene.name);
						}
					}
					else
					{
						if (validator(references, objType, property, EditorGUI.ObjectFieldValidatorOptions.ExactObjectTypeValidation) == null)
						{
							gUIContent = EditorGUI.s_TypeMismatch;
						}
					}
				}
			}
			else
			{
				gUIContent = EditorGUIUtility.ObjectContent(obj, objType);
			}
		}
		switch (objectFieldVisualType)
		{
		case EditorGUI.ObjectFieldVisualType.IconAndText:
			EditorGUI.BeginHandleMixedValueContentColor();
			style.Draw(position, gUIContent, id, DragAndDrop.activeControlID == id);
			EditorGUI.EndHandleMixedValueContentColor();
			break;
		case EditorGUI.ObjectFieldVisualType.LargePreview:
			EditorGUI.DrawObjectFieldLargeThumb(position, id, obj, gUIContent);
			break;
		case EditorGUI.ObjectFieldVisualType.MiniPreview:
			EditorGUI.DrawObjectFieldMiniThumb(position, id, obj, gUIContent);
			break;
		default:
			throw new ArgumentOutOfRangeException();
		}
		goto IL_664;
	}
	case EventType.DragUpdated:
	case EventType.DragPerform:
		if (dropRect.Contains(Event.current.mousePosition) && GUI.enabled)
		{
			Object[] objectReferences = DragAndDrop.objectReferences;
			Object object2 = validator(objectReferences, objType, property, EditorGUI.ObjectFieldValidatorOptions.None);
			if (object2 != null)
			{
				if (!allowSceneObjects && !EditorUtility.IsPersistent(object2))
				{
					object2 = null;
				}
			}
			if (object2 != null)
			{
				DragAndDrop.visualMode = DragAndDropVisualMode.Generic;
				if (eventType == EventType.DragPerform)
				{
					if (property != null)
					{
						property.objectReferenceValue = object2;
					}
					else
					{
						obj = object2;
					}
					GUI.changed = true;
					DragAndDrop.AcceptDrag();
					DragAndDrop.activeControlID = 0;
				}
				else
				{
					DragAndDrop.activeControlID = id;
				}
				Event.current.Use();
			}
		}
		goto IL_664;
	}
	goto IL_119;
	IL_664:
	EditorGUIUtility.SetIconSize(iconSize);
	result = obj;
	return result;
}