unload Photos by least-recently-used

Program.cs

@@ -172,6 +172,7 @@ void main() {
 public class Photo {
   public string Filename;
   public bool Loaded = false;
+  public long LastTouch = 0;
   public Vector2i Size;
   public DateTime DateTimeOriginal;
   public string CameraModel = "";
@@ -183,6 +184,7 @@ public class Photo {
   public int Rating = 0;
   public ushort Orientation = 1;
 
+  private static long touchCounter = 0;
   private Texture texture;
   private Texture placeholder;
   private Image<Rgba32>? image = null;
@@ -204,6 +206,7 @@ public class Photo {
     // We don't assign to this.image until Load() is done, because we might
     // edit the image due to rotation (etc) and don't want to try generating
     // a texture for it until that's already happened.
+    LastTouch = touchCounter++;
     Image<Rgba32> tmp = await Image.LoadAsync<Rgba32>(Filename);
     Util.RotateImageFromExif(tmp, Orientation);
     image = tmp;
@@ -348,6 +351,7 @@ public class Photo {
   }
 
   public Texture Texture() {
+    LastTouch = touchCounter++;
     if (texture == placeholder && image != null) {
       // The texture needs to be created on the GL thread, so we instantiate
       // it here (since this is called from OnRenderFrame), as long as the
@@ -371,6 +375,9 @@ public class Texture : IDisposable {
   public int Handle;
   public Vector2i Size;
 
+  private static int maxHandle = -1;
+  private bool disposedValue = false;
+
   public Texture(Image<Rgba32> image) {
     Size = new Vector2i(image.Width, image.Height);
     byte[] pixelBytes = new byte[Size.X * Size.Y * Unsafe.SizeOf<Rgba32>()];
@@ -395,9 +402,6 @@ public class Texture : IDisposable {
     //GL.GenerateMipmap(GenerateMipmapTarget.Texture2D);
   }
 
-  private static int maxHandle = -1;
-  private bool disposedValue = false;
-
   protected virtual void Dispose(bool disposing) {
     if (!disposedValue) {
       GL.DeleteTexture(Handle);
@@ -565,7 +569,7 @@ public class Game : GameWindow {
   int VertexArrayObject;
   List<Photo> allPhotos = new();
   List<Photo> photos = new();
-  HashSet<string> loadedImages = new();
+  HashSet<Photo> loadedImages = new();
   int photoIndex = 0;
   int ribbonIndex = 0;
   Shader shader = new();
@@ -711,6 +715,7 @@ public class Game : GameWindow {
   void FilterByRating(int rating) {
     Console.WriteLine("filter to " + rating);
     photos = allPhotos.Where(p => p.Rating >= rating).ToList();
+    // TODO: put this closest to wherever the previously active photo was.
     photoIndex = 0;
   }
 
@@ -752,10 +757,10 @@ public class Game : GameWindow {
 
     // Load photos from a directory.
     // string[] files = Directory.GetFiles(@"c:\users\colin\desktop\photos-test\");
-    string[] files = Directory.GetFiles(@"c:\users\colin\pictures\photos\2023\07\14\");
+    // string[] files = Directory.GetFiles(@"c:\users\colin\pictures\photos\2023\07\14\");
     // string[] files = Directory.GetFiles(@"G:\DCIM\100EOSR6\");
     // string[] files = Directory.GetFiles(@"C:\Users\colin\Pictures\photos\2018\06\23");
-    // string[] files = Directory.GetFiles(@"C:\Users\colin\Desktop\Germany all\104D7000");
+    string[] files = Directory.GetFiles(@"C:\Users\colin\Desktop\Germany all\104D7000");
     // string[] files = Directory.GetFiles(@"C:\Users\colin\Desktop\many-birds\");
 
     for (int i = 0; i < files.Count(); i++) {
@@ -785,28 +790,31 @@ public class Game : GameWindow {
   }
 
   private async void LoadAndUnloadImagesAsync() {
-    int minUnloadedImage = Math.Max(0, photoIndex - 20);
-    int maxUnloadedImage = Math.Min(photoIndex + 30, photos.Count - 1);
-    int minLoadedImage = Math.Max(0, photoIndex - 10);
+    int minLoadedImage = Math.Max(0, photoIndex - 20);
     int maxLoadedImage = Math.Min(photoIndex + 20, photos.Count - 1);
-    // First, unload images that are far outside our window.
-    // FIXME: also cancel any in-progress loading tasks that have moved outside our window.
+    // First, unload images that haven't been touched in a while.
+    // FIXME: also cancel any of these if they still have an in-progress loading task -- I suspect this is the source of a memory leak.
     // FIXME: keep around thumbnail-sized textures?
-    // FIXME: turn unloading back on, using an LRU cache for evicting images.
-    /*
-    foreach (int i in loadedImages) {
-      if (i < minUnloadedImage || i > maxUnloadedImage) {
-        // Console.WriteLine("unloading " + i);
-        loadedImages.Remove(i);
-        photos[i].UnloadAsync();
+    while (loadedImages.Count > 60) {
+      long earliestTime = long.MaxValue;
+      Photo? earliest = null;
+      foreach (Photo photo in loadedImages) {
+        if (photo.LastTouch < earliestTime) {
+          earliest = photo;
+          earliestTime = photo.LastTouch;
+        }
+      }
+      if (earliest != null) {
+        Console.WriteLine($"loadedImages.Count: {loadedImages.Count}, evicting {earliest.Filename} @ {earliestTime}");
+        earliest.UnloadAsync();
+        loadedImages.Remove(earliest);
       }
     }
-    */
-    // Then, start loading any images that aren't in our window.
+    // Then, start loading any images that are in our window but not yet loaded.
     for (int i = minLoadedImage; i <= maxLoadedImage; i++) {
-      if (!loadedImages.Contains(photos[i].Filename)) {
-        // Console.WriteLine("loading " + i);
-        loadedImages.Add(photos[i].Filename);
+      if (!loadedImages.Contains(photos[i])) {
+        Console.WriteLine("loading " + i);
+        loadedImages.Add(photos[i]);
         await Task.Run( () => { photos[i].LoadAsync(); });
       }
     }