[游戏开发]Unity编辑器扩展——进度条显示通用方法

在我们使用Unity编辑器扩展做一些批处理的工具时，通常会需要显示一个进度条，这样不会让Unity一直卡住不动，使得使用者不知道当前的进展。

那么如何显示进度条呢？涉及的相关API有：

EditorUtility.ClearProgressBar();
https://docs.unity3d.com/cn/2018.4/ScriptReference/EditorUtility.ClearProgressBar.html


带取消按钮的进度条
EditorUtility.DisplayCancelableProgressBar
https://docs.unity3d.com/cn/2018.4/ScriptReference/EditorUtility.DisplayCancelableProgressBar.html

不带取消按钮的进度条
EditorUtility.DisplayProgressBar
https://docs.unity3d.com/cn/current/ScriptReference/EditorUtility.DisplayProgressBar.html

一般使用我们都会使用带取消按钮的进度条去完成工具的编写，这样可交互性更强。

提供一个通用的进度条相关的类和方法：

using System;
using UnityEditor;
using UnityEngine;

namespace EditorHelp
{
    /// <summary>
    /// 编辑器辅助工具类
    /// </summary>
    public static class EditorUtilityHelp
    {
        private static void ClearUpdate(EditorApplication.CallbackFunction func)
        {
            EditorUtility.ClearProgressBar();
            if (func == null) return;
            EditorApplication.update -= func;
        }

        /// <summary>
        /// 显示操作进度
        /// </summary>
        /// <param name="title">标题</param>
        /// <param name="length">操作内容长度</param>
        /// <param name="onUpdate">逐个操作响应</param>
        /// <param name="onComplete">操作结束回调</param>
        public static EditorApplication.CallbackFunction ShowUpdate(string title, int length, Action<int> onUpdate,
            Action onComplete = null)
        {
            string[] tips = new string[length];
            for (int i = 0; i < tips.Length; i++)
            {
                tips[i] = "";
            }

            return ShowUpdate(title, tips, onUpdate, onComplete);
        }

        /// <summary>
        /// 显示操作进度
        /// </summary>
        /// <param name="title">标题</param>
        /// <param name="tips">操作提示数组</param>
        /// <param name="onUpdate">逐个操作响应</param>
        /// <param name="onComplete">操作结束回调</param>
        private static EditorApplication.CallbackFunction ShowUpdate(string title, object[] tips, Action<int> onUpdate,
            Action onComplete = null)
        {
            if (tips.Length == 0)
            {
                onComplete?.Invoke();
                return null;
            }

            int index = 0;
            EditorApplication.CallbackFunction func = null;
            func = () =>
            {
                string titleStr = $@"{title} [{index}/{tips.Length}]";
                bool isCancel = EditorUtility.DisplayCancelableProgressBar(titleStr, tips[index].ToString(),
                    (float) index / tips.Length);

                try
                {
                    onUpdate(index);
                }
                catch (Exception e)
                {
                    Debug.LogErrorFormat(@"【 {0} | {1} 】 {2}", title, tips[index], e);
                    ClearUpdate(func);
                    index = 0;
                }

                index++;
                if (isCancel)
                {
                    ClearUpdate(func);
                    index = 0;
                }
                else if (index >= tips.Length)
                {
                    ClearUpdate(func);
                    index = 0;
                    onComplete?.Invoke();
                }
            };
            EditorApplication.update += func;
            return func;
        }
    }
}