[游戏开发]Unity CustomPropertyDrawer自定义显示属性

1.对于ScriptableObject 的属性 自定义显示，需要使用CustomPropertyDrawer

2.实现规程

需要自定义属性的脚本：

[System.Serializable]
public class TargetElementFinder
{
    public FindTargetType Type;
    public string Id;
    public Coordinate SelfRange;
    public List<Coordinate> TileRange;//集合
}

用到的类型脚本：

public enum FindTargetType
{
    Self=0,
    Target=1,
    Player=2,
    Range=3,
    Global=4,
    SelfRange=5,
}

[System.Serializable]
public struct Coordinate
{
    public int X;
    public int Y;
}

CustomPropertyDrawer 编辑器实现：

using System;
using UnityEditor;
using UnityEngine;

[CustomPropertyDrawer(typeof(TargetElementFinder))]
public class TargetElementFinder_ParamEditor : PropertyDrawer
{
    private const int HeightOneLine = 20;//定义一行的高
    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
    {
        //position: 在Inspector面板的位置、大小  property: 待绘制的属性  label: 值的字段名
        if (!property.isExpanded)//属性是否展开
        {
            EditorGUI.PropertyField(position, property, new GUIContent("TargetElementFinder"), true);//显示展开的位置和名字
            return;
        }
        //设置关闭的位置和名字
        var headPosition = new Rect(position.x, position.y, position.width, HeightOneLine);
        EditorGUI.PropertyField(headPosition, property, new GUIContent("TargetElementFinder"), false);

        EditorGUI.indentLevel += 2;//缩进加2
        var typeProperty = property.FindPropertyRelative("Type");//找到属性名为Type的属性
        var typePosition = new Rect(position.x, position.y + HeightOneLine, position.width, HeightOneLine);//定义属性显示的位置
        //显示枚举类型的属性
        typeProperty.enumValueIndex = EditorGUI.Popup(typePosition, "Type", typeProperty.enumValueIndex, typeProperty.enumDisplayNames);

        var keyValueType = (FindTargetType) Enum.GetValues(typeof(FindTargetType)).GetValue(typeProperty.enumValueIndex);
        switch (keyValueType)
        {
            case FindTargetType.Self:
            case FindTargetType.Target:
            case FindTargetType.Player://这些类型 没有参数
                break;
            case FindTargetType.Range:
            case FindTargetType.Global://这些类型有两个参数
                //显示字符串参数
                var idProperty = property.FindPropertyRelative("Id");
                var idPosition = new Rect(typePosition.x, typePosition.y + HeightOneLine, typePosition.width, HeightOneLine);
                idProperty.stringValue = EditorGUI.TextField(idPosition, "Id", idProperty.stringValue);

                //显示集合参数
                var tileRangeProperty = property.FindPropertyRelative("TileRange");
                var tileRangePosition = new Rect(idPosition.x, idPosition.y + HeightOneLine, idPosition.width, HeightOneLine);
                EditorGUI.PropertyField(tileRangePosition, tileRangeProperty, new GUIContent("TileRange"), true);
                break;
            case FindTargetType.SelfRange://显示类参数
                var selfRangeProperty = property.FindPropertyRelative("SelfRange");
                var selfRangePosition = new Rect(typePosition.x, typePosition.y + HeightOneLine, typePosition.width, HeightOneLine);
                EditorGUI.PropertyField(selfRangePosition, selfRangeProperty);
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }
        EditorGUI.indentLevel -= 2;//恢复缩进

    }

    //返回属性的高度 由UnityEditor自动调用
    public override float GetPropertyHeight(SerializedProperty property, GUIContent label)
    {
        if (!property.isExpanded) return HeightOneLine;//属性没有展开 高度是一行的高度
        
        var typeProperty = property.FindPropertyRelative("Type");
        var keyValueType = (FindTargetType)Enum.GetValues(typeof(FindTargetType)).GetValue(typeProperty.enumValueIndex);
        switch (keyValueType)
        {
            case FindTargetType.Self:
            case FindTargetType.Target:
            case FindTargetType.Player://属性展开了，由于没有参数，只有一个属性和变量名 高度=一行高度*2
                return HeightOneLine*2;
            case FindTargetType.Range:
            case FindTargetType.Global:
                var tileRangeProperty = property.FindPropertyRelative("TileRange");
                if (tileRangeProperty.isExpanded)//展开
                {
                    var arayCount = tileRangeProperty.arraySize;
                    return HeightOneLine * (5 + arayCount);//根据元素的个数设置属性高度
                }
                else
                    return HeightOneLine * 4;
            case FindTargetType.SelfRange://一共3行属性的显示 高度就*3
                return HeightOneLine * 3;
            default:
                throw new ArgumentOutOfRangeException();
        }
    }
}

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