Unity 编辑器扩展十一 DecoratorDrawer

RhinoFreak

Unity Editor 基础篇（八）：Decorator Drawers
Unity Editor 实践 ： 自定义小工具
一、示例


在Scripts文件夹下添加
using System.Collections;using System.Collections.Generic;using UnityEngine;public class DrawerImageAttribute : PropertyAttribute{    public DrawerImageAttribute()    {    }}//using System.Collections;using System.Collections.Generic;using UnityEngine;public class TestImageAttribute : MonoBehaviour{    [DrawerImage]    public float ff;}
在Editor文件夹下添加
using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEditor;[CustomPropertyDrawer(typeof(DrawerImageAttribute))]public class DrawerImageAttributeDrawer : DecoratorDrawer{    private Texture2D image;    public override void OnGUI(Rect position)    {        Debug.Log("DrawerImageAttributeDrawer OnGUI");        if (image == null)        {            image = Resources.Load<Texture2D>("gold");        }        GUI.DrawTexture(position, image);    }    public override float GetHeight()    {        return base.GetHeight();    }}
如下图，金币图绘制产生变形，需要修改GetHeight() 方法

image.png

2.

using System.Collections;using System.Collections.Generic;using UnityEngine;public class DrawerImageAttribute : PropertyAttribute{    public int height;    public DrawerImageAttribute()    {    }    public DrawerImageAttribute(int _height)    {        height = _height;    }}using System.Collections;using System.Collections.Generic;using UnityEngine;using UnityEditor;[CustomPropertyDrawer(typeof(DrawerImageAttribute))]public class DrawerImageAttributeDrawer : DecoratorDrawer{    private Texture2D image;    private DrawerImageAttribute _attribute;    public override void OnGUI(Rect position)    {        Debug.Log("DrawerImageAttributeDrawer OnGUI");        if (image == null)        {            image = Resources.Load<Texture2D>("gold");        }        _attribute = (DrawerImageAttribute)attribute;        GUI.DrawTexture(position, image);    }    public override float GetHeight()    {        return base.GetHeight() + _attribute.height;    }}public class TestImageAttribute : MonoBehaviour{    [DrawerImage(150)]    public float ff;}
报错了：
NullReferenceException: Object reference not set to an instance of an objectDrawerImageAttributeDrawer.GetHeight () (at Assets/Editor/DrawerImageAttributeDrawer.cs:25)
脚本先调用的是 GetHeight() 方法，因此当我们在 GetHeight() 方法中使用 _attribute.height 的时候便会报空指针的错误，因为此时的 _attribute 还没有初始化，因此让我们添加如下代码：
...    private Texture2D image;    private DrawerImageAttribute _attribute = new DrawerImageAttribute();

image.png