Unity editor extension - ReorderableList

I. Introduction

We define an array or list, which is displayed like this by default. This

display has several disadvantages
-the order of table elements cannot be changed
-if you add an element, you need to increase the value of the size
-if you want to delete one of the elements, it is very troublesome
ReorderableList can make the list or array display more humane in the Inspector panel

---

Two: use

First, you need to create a ReorderableList object, which has several callback functions
- drawElementCallback: the callback for drawing each element
- drawHeaderCallback: the callback for drawing the title -
elementHeightCallback: the callback for drawing the height of each element -
onAddCallback: when adding elements The callback
- onRemoveCallback: the callback when the element is removed,
and finally the DoLayoutList method is called for drawing

---

Three: Code implementation - simple case

using System.Collections.Generic;
using UnityEditor;
using UnityEngine;
using UnityEditorInternal;
using System;
using System.Linq;

public class Test : MonoBehaviour
{
    public List<string> list = new List<string>();
}

[CustomEditor(typeof(Test))]
public class TestEditor : Editor
{
    SerializedProperty m_list;

    ReorderableList reorderableList;

    private void OnEnable()
    {
        m_list = serializedObject.FindProperty("list");
        reorderableList = new ReorderableList(serializedObject, m_list, true, true, true, true);
    }

    public override void OnInspectorGUI()
    {
        serializedObject.Update();

        reorderableList.drawElementCallback = DrawElement;
        reorderableList.DoLayoutList();

        serializedObject.ApplyModifiedProperties();
    }

    void DrawElement(Rect rect, int index, bool isActive, bool isFocused)
    {
        SerializedProperty element = m_list.GetArrayElementAtIndex(index);
        EditorGUI.PropertyField(rect, element);
    }
}

---

Four: Code implementation - complex cases

using System.Collections.Generic;
using UnityEditor;
using UnityEngine;
using UnityEditorInternal;
using System;
using System.Linq;

public class Test : MonoBehaviour
{
    public List<TestChild> list = new List<TestChild>();
}

[Serializable]
public class TestChild
{
    public Sprite sprite;
    public string des;
    public int index;
}

[CustomEditor(typeof(Test))]
public class TestEditor : Editor
{
    SerializedProperty m_list;

    ReorderableList reorderableList;

    List<float> m_HeightCache = new List<float>();

    private void OnEnable()
    {
        m_list = serializedObject.FindProperty("list");
        reorderableList = new ReorderableList(serializedObject, m_list, true, true, true, true);
    }

    public override void OnInspectorGUI()
    {
        serializedObject.Update();

        reorderableList.onAddCallback = OnAdd;
        reorderableList.onRemoveCallback = OnRemove;
        reorderableList.onReorderCallback = OnReorder;
        reorderableList.onCanRemoveCallback = OnCanRemove;
        reorderableList.drawHeaderCallback = DrawHeader;
        reorderableList.drawElementCallback = DrawElement;
        reorderableList.onSelectCallback = OnSelect;
        reorderableList.onAddDropdownCallback = OnAddDropdown;
        reorderableList.elementHeightCallback = DrawElementHeight;
        reorderableList.DoLayoutList();

        serializedObject.ApplyModifiedProperties();
    }

    void DrawHeader(Rect rect)
    {
        EditorGUI.LabelField(rect, "Test List");
    }

    void DrawElement(Rect rect, int index, bool isActive, bool isFocused)
    {
        m_HeightCache[index] = isActive ? 100 : 50;

        SerializedProperty element = reorderableList.serializedProperty.GetArrayElementAtIndex(index);

        SerializedProperty serializedProperty_sprite = element.FindPropertyRelative("sprite");
        SerializedProperty serializedProperty_des = element.FindPropertyRelative("des");
        SerializedProperty serializedProperty_index = element.FindPropertyRelative("index");

        Rect rect_sprite;
        Rect rect_des;
        Rect rect_index;
        if (isActive)
        {
            rect_sprite = new Rect(rect.x, rect.y, 100, 100);
            rect_des = new Rect(rect.x + 120, rect.y, rect.width, 40);
            rect_index = new Rect(rect.x + 120, rect.y + 60, rect.width, 40);
        }
        else
        {
            rect_sprite = new Rect(rect.x, rect.y, 100, 50);
            rect_des = new Rect(rect.x + 120, rect.y, rect.width, 15);
            rect_index = new Rect(rect.x + 120, rect.y + 20, rect.width, 15);
        }

        EditorGUI.PropertyField(rect_sprite, serializedProperty_sprite, GUIContent.none);
        EditorGUI.PropertyField(rect_des, serializedProperty_des, GUIContent.none);
        EditorGUI.PropertyField(rect_index, serializedProperty_index, GUIContent.none);
    }

    float DrawElementHeight(int index)
    {
        if (m_HeightCache.Count > index)
        {
            return m_HeightCache[index];
        }
        else
        {
            m_HeightCache.Add(0);
            return m_HeightCache[index];
        }
    }

    void OnAdd(ReorderableList list)
    {
        if (EditorUtility.DisplayDialog("是否添加", "是否添加", "是", "否"))
        {
            ReorderableList.defaultBehaviours.DoAddButton(list);
            m_HeightCache.Add(0);
        }
    }

    void OnRemove(ReorderableList list)
    {
        if (EditorUtility.DisplayDialog("是否移除", "是否移除", "是", "否"))
        {
            ReorderableList.defaultBehaviours.DoRemoveButton(list);
            m_HeightCache.RemoveAt(list.count - 1);
        }
    }

    bool OnCanRemove(ReorderableList list)
    {
        return list.count >= 1;
    }

    void OnReorder(ReorderableList list)
    {
        Debug.Log("顺序改变后当前选择元素的index：" + list.index);
    }

    void OnSelect(ReorderableList list)
    {
        Debug.Log("当前选择元素的index：" + list.index);
    }

    void OnAddDropdown(Rect buttonRect, ReorderableList list)
    {
        var menu = new GenericMenu();
        menu.AddItem(new GUIContent("Add Default"), false, clickHandler,
            new TestContextParams() { des = "testDes", index = 1, });
        menu.ShowAsContext();
    }

    private void clickHandler(object target)
    {
        TestContextParams param = (TestContextParams)target;
        var index = m_list.arraySize;
        m_list.arraySize++;
        var element = m_list.GetArrayElementAtIndex(index);
        element.FindPropertyRelative("des").stringValue = param.des;
        element.FindPropertyRelative("index").intValue = param.index;
        serializedObject.ApplyModifiedProperties();

    }
    struct TestContextParams
    {
        public string des;
        public int index;
    }
}