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;
}
来源：CSDN
作者：zlQ_
链接：https://blog.csdn.net/zlQQhs/article/details/83383646