Unity png形式的图集拆除子图并把新的子png转换成sprite

　　/// <summary>
    /// 图集形式为.png形式  并在unity中有很多sprite的子图 
    /// </summary>
    private void AtlasSplit()
    {
        string guidStr = Selection.assetGUIDs[0];
        string path = AssetDatabase.GUIDToAssetPath(guidStr);
        Object[] spriteAtlas = AssetDatabase.LoadAllAssetsAtPath(path);
        string dirName = path.Substring(path.LastIndexOf("/") + 1).Replace(".png", "");

        string targetPath = $"Assets/{dirName}";
        if (!Directory.Exists(targetPath))
        {
            Directory.CreateDirectory(targetPath);
            AssetDatabase.Refresh();
        }

        for (int i = 0; i < spriteAtlas.Length; i++)
        {
            if (spriteAtlas[i] is Sprite sprite)
            {
                int spriteX = (int) sprite.rect.x;
                int spriteY = (int) sprite.rect.y;
                int spriteW = (int) sprite.rect.width;
                int spriteH = (int) sprite.rect.height;

                Texture2D texture2D = new Texture2D(spriteW, spriteH, TextureFormat.RGBA32, false);
                //sprite.texture 实际上是主图png的信息  所以直接在主图上取像素点
                texture2D.SetPixels(sprite.texture.GetPixels(spriteX, spriteY, spriteW, spriteH));
                string pngPath = $"{targetPath}/{sprite.name}.png"; 
                using (FileStream fs = new FileStream(pngPath, FileMode.Create, FileAccess.Write))
                {
                    byte[] bytes = texture2D.EncodeToPNG();
                    fs.Write(bytes, 0, bytes.Length);
                    fs.Flush();
                    fs.Close();
                    fs.Dispose();
                    AssetDatabase.Refresh();
                }

                TextureImporter textureImporter = AssetImporter.GetAtPath(pngPath) as TextureImporter;
                PngToSprite(textureImporter);
            }
        }
        AssetDatabase.Refresh();
    }
    /// <summary>
    /// png转成sprite
    /// </summary>
    /// <param name="textureImporter"></param>
    private void PngToSprite(TextureImporter textureImporter)
    {
        if (textureImporter != null && textureImporter.textureType != TextureImporterType.Sprite)
        {
            textureImporter.textureType = TextureImporterType.Sprite;
            textureImporter.spriteImportMode = SpriteImportMode.Single;
            textureImporter.spritePixelsPerUnit = 100;
            textureImporter.textureCompression = TextureImporterCompression.Compressed;
            textureImporter.SaveAndReimport();
        }
    }