save rating in XMP data. also change default window size

Program.cs

@@ -15,6 +15,7 @@ using SixLabors.ImageSharp.Formats.Jpeg;
 using System;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
+using System.Text;
 using System.Xml.Linq;
 
 namespace SemiColinGames;
@@ -199,8 +200,8 @@ public class Photo {
     DateTimeOriginal = creationTime;
     ImageInfo info = Image.Identify(filename);
     Size = new(info.Size.Width, info.Size.Height);
+    Rating = ParseRating(info.Metadata.XmpProfile);
     ParseExif(info.Metadata.ExifProfile);
-    TryParseRating(info.Metadata.XmpProfile, out Rating);
   }
 
   public async void LoadAsync() {
@@ -221,7 +222,7 @@ public class Photo {
     }
   }
 
-  public async void SaveAsJpeg(string outputRoot, JpegEncoder encoder) {
+  public async void SaveAsJpegAsync(string outputRoot, JpegEncoder encoder) {
     // FIXME: if nothing was changed about this image, just copy the file bytes directly, possibly with metadata changed?
     string directory = System.IO.Path.Combine(
         outputRoot,
@@ -231,7 +232,7 @@ public class Photo {
     Directory.CreateDirectory(directory);
     string filename = System.IO.Path.Combine(directory, System.IO.Path.GetFileName(Filename));
     Console.WriteLine("saving " + filename);
-    // FIXME: update Rating data.
+    // FIXME: what if we also saved Exif rating?
     // FIXME: add comments / captions as ImageDescription?
     // FIXME: strip some Exif tags for privacy reasons?
     // FIXME: warn if the file already exists?
@@ -249,31 +250,50 @@ public class Photo {
         now.Year, now.Month, now.Day, now.Hour, now.Minute, now.Second);
       exif.SetValue<string>(ExifTag.DateTime, datetime);
 
+      image.Metadata.XmpProfile = UpdateXmp(image.Metadata.XmpProfile);
+
       await image.SaveAsync(filename, encoder);
     }
   }
 
-  private bool TryParseRating(XmpProfile? xmp, out int rating) {
+  private XElement? GetXmpRoot(XmpProfile? xmp) {
-    rating = 0;
     if (xmp == null) {
-      return false;
+      return null;
     }
     XDocument? doc = xmp.GetDocument();
     if (doc == null) {
-      return false;
+      return null;
     }
-    XElement? root = doc.Root;
+    return doc.Root;
+  }
+
+  private int ParseRating(XmpProfile? xmp) {
+    XElement? root = GetXmpRoot(xmp);
     if (root == null) {
-      return false;
+      return 0;
     }
     foreach (XElement elt in root.Descendants()) {
       if (elt.Name == "{http://ns.adobe.com/xap/1.0/}Rating") {
+        int rating = 0;
         if (int.TryParse(elt.Value, out rating)) {
-          return true;
+          return rating;
         }
       }
     }
-    return false;
+    return 0;
+  }
+
+  private XmpProfile? UpdateXmp(XmpProfile? xmp) {
+    if (xmp == null) {
+      return null;
+    }
+    string xmlIn = Encoding.UTF8.GetString(xmp.ToByteArray());
+    int index = xmlIn.IndexOf("</xmp:Rating>");
+    if (index == -1) {
+      return xmp;
+    }
+    string xmlOut = xmlIn.Substring(0, index - 1) + Rating.ToString() + xmlIn.Substring(index);
+    return new XmpProfile(Encoding.UTF8.GetBytes(xmlOut));
   }
 
   // Exif (and other image metadata) reference, from the now-defunct Metadata Working Group:
@@ -627,6 +647,7 @@ public class Game : GameWindow {
     bool ctrlIsDown = input.IsKeyDown(Keys.LeftControl) || input.IsKeyDown(Keys.RightControl);
 
     // FIXME: add a confirm dialog before closing. (Also for the window-close button.)
+    // FIXME: don't quit if there's pending file-write operations.
     // Close when Escape is pressed.
     if (input.IsKeyPressed(Keys.Escape)) {
       Close();
@@ -826,7 +847,7 @@ public class Game : GameWindow {
     // 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(@"G:\DCIM\100EOSR6\");
-    // string[] files = Directory.GetFiles(@"c:\users\colin\desktop\totte-output\2023\07\28");
+    // string[] files = Directory.GetFiles(@"c:\users\colin\desktop\totte-output\2023\07\31");
     // 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\");
@@ -913,9 +934,10 @@ public class Game : GameWindow {
   // FIXME: show a progress bar or something.
   private async void ExportPhotos() {
     JpegEncoder encoder = new JpegEncoder() { Quality = 100 };
-    string outputRoot = @"c:\users\colin\pictures\photos\";
+    string outputRoot = @"c:\users\colin\desktop\totte-output";
+    // string outputRoot = @"c:\users\colin\pictures\photos";
     foreach (Photo p in photos) {
-      await Task.Run( () => { p.SaveAsJpeg(outputRoot, encoder); });
+      await Task.Run( () => { p.SaveAsJpegAsync(outputRoot, encoder); });
     }
   }
 
@@ -1088,7 +1110,8 @@ static class Program {
     nwSettings.WindowState = WindowState.Normal;
     nwSettings.CurrentMonitor = bestMonitor.Handle;
     nwSettings.Location = new Vector2i(bestMonitor.WorkArea.Min.X + 1, bestMonitor.WorkArea.Min.Y + 31);
-    nwSettings.Size = new Vector2i(bestMonitor.WorkArea.Size.X - 2, bestMonitor.WorkArea.Size.Y - 32);
+    // nwSettings.Size = new Vector2i(bestMonitor.WorkArea.Size.X - 2, bestMonitor.WorkArea.Size.Y - 32);
+    nwSettings.Size = new Vector2i(1600, 900);
     nwSettings.MinimumSize = UiGeometry.MIN_WINDOW_SIZE;
     nwSettings.Title = "Totte";
     nwSettings.IsEventDriven = false;