ImageLoader.cs

using System.Collections.Generic;
using System.IO;
using ProtoTurtle.BitmapDrawing;
using TMPro;
using UnityEngine;

public class ImageLoader : MonoBehaviour
{
    public class NewImageEventArgs { public Texture2D Tex2D; public string FilePath; public bool InitialLoad; };
    public delegate void NewImageEventHandler(NewImageEventArgs onNewImageEventArgs);
    public NewImageEventHandler NewImage;

    public class ImageRemovedEventArgs { public string FilePath; };
    public delegate void ImageRemovedEventHandler(ImageRemovedEventArgs onImageRemovedEventArgs);
    public ImageRemovedEventHandler ImageRemoved;

    [SerializeField] TextMeshProUGUI _tmp;

    [SerializeField] private string _imageFolderPath;
    [SerializeField] private float _loadNextImageCooldown = 1f;
    
    private List<string> _loadedImagePaths = new List<string>();
    private float _loadNextImageCountdown = 0;
 
    private void Start()
    {
        Log($"Looking for images in {_imageFolderPath}");
        LoadImages(true);
        _loadNextImageCountdown = _loadNextImageCooldown;
    }

    private void Update()
    {
        _loadNextImageCountdown -= Time.deltaTime;
        if (_loadNextImageCountdown < 0)
        {
            _loadNextImageCountdown = _loadNextImageCooldown;
            LoadImages(false);
        }
    }

    private void Log(string s)
    {
        _tmp.text = _tmp.text + "\n" + s;
    }
 
    private void LoadImages(bool loadAll)
    {
        List<string> filePaths = new List<string>(Directory.GetFiles(_imageFolderPath, "*.png"));

        foreach (string filePath in filePaths)
        {
            if (!_loadedImagePaths.Contains(filePath))
            {
                _loadedImagePaths.Add(filePath);
                Log($"Found new image at {filePath}");

                byte[] pngBytes = System.IO.File.ReadAllBytes(filePath);
        
                Texture2D tex = new Texture2D(2, 2);
                tex.LoadImage(pngBytes);
                tex.FloodClear(5, 5);
        
                NewImage?.Invoke(new NewImageEventArgs{Tex2D = tex, FilePath = filePath, InitialLoad = loadAll});

                if (!loadAll) return;
            }
        }

        List<string> removedImages = new();
        foreach (string loadedImagePath in _loadedImagePaths)
        {
            if (!filePaths.Contains(loadedImagePath))
            {
                removedImages.Add(loadedImagePath);
            }
        }
        foreach (string removedImage in removedImages)
        {
            ImageRemoved?.Invoke(new ImageRemovedEventArgs{FilePath = removedImage});
            _loadedImagePaths.Remove(removedImage);
        }
    }
}