IconRecorder.cs

using Cysharp.Threading.Tasks;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using UnityEditor;
using UnityEditor.Recorder;
using UnityEditor.Recorder.Input;
using UnityEngine;

[DefaultExecutionOrder(-50)]
public class IconRecorder : MonoBehaviour
{
    #region Properties

    [field: SerializeField]
    private string ProjectDestinationDir { get; set; }

    [field: Range(32, 8192)]
    [field: SerializeField]
    private int RenderResolution { get; set; }

    [field: Range(32, 2048)]
    [field: SerializeField]
    private int OutputResolution { get; set; }

    #endregion

    #region Methods

    private static void DestroyBehaviours<T>(GameObject gObj) where T : Object
    {
        var cmps = gObj.GetComponentsInChildren<T>();
        for (var i = cmps.Length - 1; i >= 0; i--)
        {
            var cmp = cmps[i];
            DestroyImmediate(cmp);
        }
    }

    [SuppressMessage("ReSharper", "Unity.IncorrectMethodSignature")]
    private async UniTaskVoid Awake()
    {
        foreach (Transform child in transform)
        {
            var childObj = child.gameObject;
            childObj.SetActive(false);
            DestroyBehaviours<MonoBehaviour>(childObj);
        }

        var outputDir = Path.Combine(Path.GetTempPath(), "RecorderOutput");
        if (Directory.Exists(outputDir))
        {
            Directory.Delete(outputDir, true);
        }

        Directory.CreateDirectory(outputDir);

        // Setup recorder
        var controllerSettings = ScriptableObject.CreateInstance<RecorderControllerSettings>();
        var recorderController = new RecorderController(controllerSettings);
        var imageRecorder = ScriptableObject.CreateInstance<ImageRecorderSettings>();
        imageRecorder.name = "Icon Recorder";
        imageRecorder.Enabled = true;
        imageRecorder.OutputFormat = ImageRecorderSettings.ImageRecorderOutputFormat.PNG;
        imageRecorder.CaptureAlpha = true;
        imageRecorder.imageInputSettings = new RenderTextureSamplerSettings
        {
            OutputWidth = OutputResolution,
            OutputHeight = OutputResolution,
            CameraTag = "MainCamera",
            RecordTransparency = true,
            RenderHeight = RenderResolution,
            RenderWidth = RenderResolution
        };
        controllerSettings.SetRecordModeToSingleFrame(0);
        controllerSettings.AddRecorderSettings(imageRecorder);

        // Delay a few frames to allow recorder to setup
        await UniTask.DelayFrame(2);

        foreach (Transform child in transform)
        {
            imageRecorder.OutputFile = Path.Combine(outputDir, child.name);

            // Record
            child.gameObject.SetActive(true);
            recorderController.PrepareRecording();
            recorderController.StartRecording();

            // Need an additional frame to allow recorder to do its thing
            await UniTask.DelayFrame(2);

            // Stop recording
            recorderController.StopRecording();
            child.gameObject.SetActive(false);
        }

        // Copy to project directory
        var fixedProjectDestinationDir = ProjectDestinationDir;
        if (fixedProjectDestinationDir.StartsWith("Assets/"))
        {
            fixedProjectDestinationDir = fixedProjectDestinationDir.Substring(7);
        }

        foreach (var srcFilePath in Directory.EnumerateFiles(outputDir, "*.png"))
        {
            var filename = Path.GetFileName(srcFilePath);
            var dstFilePath = Path.Combine(Application.dataPath, fixedProjectDestinationDir, filename);
            File.Copy(srcFilePath, dstFilePath, true);
        }

        EditorApplication.delayCall += AssetDatabase.Refresh;
        EditorApplication.isPlaying = false;
    }

    private void Reset()
    {
        RenderResolution = 32;
        OutputResolution = 32;
    }

    private void OnValidate()
    {
        RenderResolution = Mathf.Max(32, Mathf.ClosestPowerOfTwo(RenderResolution));
        OutputResolution = Mathf.Max(32, Mathf.ClosestPowerOfTwo(OutputResolution));
        ProjectDestinationDir = ProjectDestinationDir.Replace('\\', '/');
    }

    #endregion
}