ExportPhotos(): add progress on statusbar, skip if already exporting

Program.cs

@@ -386,8 +386,8 @@ public class Game : GameWindow {
     geometry = new UiGeometry(nwSettings.Size, STAR_FILLED.Size.X);
   }
 
-  // private static string outputRoot = @"c:\users\colin\desktop\totte-output";
-  private static string outputRoot = @"c:\users\colin\pictures\photos";
+  private static string outputRoot = @"c:\users\colin\desktop\totte-output";
+  // private static string outputRoot = @"c:\users\colin\pictures\photos";
 
   private static Texture TEXTURE_WHITE = new(new Image<Rgba32>(1, 1, new Rgba32(255, 255, 255)));
   private static Texture TEXTURE_BLACK = new(new Image<Rgba32>(1, 1, new Rgba32(0, 0, 0)));
@@ -410,8 +410,7 @@ public class Game : GameWindow {
   int VertexBufferObject;
   int ElementBufferObject;
   int VertexArrayObject;
-  int numThumbnailsLoaded = 0;
-  readonly object numThumbnailsLoadedLock = new();
+
   List<Photo> allPhotos = new();
   List<Photo> photos = new();
   HashSet<Photo> loadedImages = new();
@@ -431,6 +430,15 @@ public class Game : GameWindow {
   float zoomLevel = 0f;
   double timeSinceEvent = 0;
 
+  // Variables that are protected by locks:
+  readonly object numThumbnailsLoadedLock = new();
+  int numThumbnailsLoaded = 0;
+
+  readonly object exportPhotosLock = new();  // locks the entire ExportPhotos() function.
+  int numPhotosToExport = 0;
+  readonly object numPhotosExportedLock = new();
+  int numPhotosExported = 0;
+
   protected override void OnUpdateFrame(FrameEventArgs e) {
     base.OnUpdateFrame(e);
     toast.Update(e.Time);
@@ -684,7 +692,7 @@ public class Game : GameWindow {
                            false, 5 * sizeof(float), 3 * sizeof(float));
 
     // Load photos from a directory.
-    string[] files = Directory.GetFiles(@"c:\users\colin\desktop\photos-test\");
+    // 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\23\");
     // string[] files = Directory.GetFiles(@"G:\DCIM\100EOSR6\");
@@ -692,7 +700,7 @@ public class Game : GameWindow {
     // string[] files = Directory.GetFiles(@"c:\users\colin\desktop\import");
     // 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\many-birds\");
+    string[] files = Directory.GetFiles(@"C:\Users\colin\Desktop\many-birds\");
 
     for (int i = 0; i < files.Count(); i++) {
       string file = files[i];
@@ -793,7 +801,7 @@ public class Game : GameWindow {
         p.LoadThumbnailAsync(geometry.ThumbnailSize);
         lock (numThumbnailsLoadedLock) {
           numThumbnailsLoaded++;
-          toast.Set($"Loading thumbnails: {numThumbnailsLoaded}/{allPhotos.Count}");
+          toast.Set($"[{numThumbnailsLoaded}/{allPhotos.Count}] Loading thumbnails");
         }
       }));
     }
@@ -802,13 +810,31 @@ public class Game : GameWindow {
 
   // To find the JPEG compression level of a file from the command line:
   // $ identify -verbose image.jpg | grep Quality:
-  // FIXME: don't ExportPhotos() if another export is already active.
-  // FIXME: show a progress bar or something.
   private async void ExportPhotos() {
-    JpegEncoder encoder = new JpegEncoder() { Quality = 100 };
-    foreach (Photo p in photos) {
-      await Task.Run( () => { p.SaveAsJpegAsync(outputRoot, encoder); });
+    List<Task> tasks = new();
+    lock (exportPhotosLock) {
+      // Don't ExportPhotos() if one is already active.
+      lock (numPhotosExportedLock) {
+        if (numPhotosToExport > 0 && numPhotosExported != numPhotosToExport) {
+          Console.WriteLine("ExportPhotos: skipping because another export is already in progress.");
+          return;
+        }
+      }
+
+      JpegEncoder encoder = new JpegEncoder() { Quality = 100 };
+      numPhotosToExport = photos.Count;
+      numPhotosExported = 0;
+      foreach (Photo p in photos) {
+        tasks.Add(Task.Run( () => {
+          p.SaveAsJpegAsync(outputRoot, encoder);
+          lock (numPhotosExportedLock) {
+            numPhotosExported++;
+            toast.Set($"[{numPhotosExported}/{numPhotosToExport}] Exported {outputRoot}/{p.Filename}");
+          }
+        }));
+      }
     }
+    await Task.WhenAll(tasks).ContinueWith(t => { toast.Set("Exporting photos: done!"); });
   }
 
   protected override void OnRenderFrame(FrameEventArgs e) {