display some exif data on-screen

Program.cs

@@ -142,8 +142,14 @@ void main() {
 
 // FIXME: this should probably be IDisposable?
 public class Photo {
-  public bool Loaded = false;
   public string File;
+  public bool Loaded = false;
+  public string? CameraModel;
+  public string? LensModel;
+  public string FNumber = "<unk>";
+  public string ExposureTime = "<unk>";
+  public string IsoSpeed = "<unk>";
+
   private Texture texture;
   private Texture placeholder;
   private Image<Rgba32>? image = null;
@@ -158,11 +164,53 @@ public class Photo {
     image = await Image.LoadAsync<Rgba32>(File);
     ExifProfile? exifs = image.Metadata.ExifProfile;
     if (exifs != null) {
-      foreach (IExifValue exif in exifs.Values) {
-        if (exif.Tag.ToString() == "Model") {
-          Console.WriteLine($"{File} {exif.Tag}: {exif.GetValue()}");
+      Console.WriteLine("--------------------------------------");
+      // FIXME: handle Orientation
+      IExifValue<string>? model;
+      if (exifs.TryGetValue(ExifTag.Model, out model)) {
+        CameraModel = model.Value;
+      }
+      IExifValue<string>? lensModel;
+      if (exifs.TryGetValue(ExifTag.LensModel, out lensModel)) {
+        LensModel = lensModel.Value;
+      }
+
+      IExifValue<Rational>? fNumber;
+      if (exifs.TryGetValue(ExifTag.FNumber, out fNumber)) {
+        Rational r = fNumber.Value;
+        if (r.Denominator == 1) {
+          FNumber = $"f/{r.Numerator}";
+        } else {
+          // FIXME: assert that numerator is 10
+          if (r.Numerator % 10 == 0) {
+            FNumber = $"f/{r.Numerator / 10}";
+          } else {
+            FNumber= $"f/{r.Numerator / 10}.{r.Numerator % 10}";
+          }
         }
       }
+
+      IExifValue<Rational>? exposureTime;
+      if (exifs.TryGetValue(ExifTag.ExposureTime, out exposureTime)) {
+        Rational r = exposureTime.Value;
+        if (r.Numerator == 1) {
+          ExposureTime = $"1/{r.Denominator}";
+        } else if (r.Numerator == 10) {
+          ExposureTime = $"1/{r.Denominator / 10}";
+        } else {
+          Console.WriteLine("*** WARNING: unexpected ExposureTime numerator");
+          ExposureTime = r.ToString();
+        }
+      }
+
+      IExifValue<ushort[]>? isoSpeed;
+      if (exifs.TryGetValue(ExifTag.ISOSpeedRatings, out isoSpeed)) {
+        ushort[] iso = isoSpeed.Value;
+        IsoSpeed = $"ISO {iso[0]}";
+      }
+      foreach (IExifValue exif in exifs.Values) {
+        Console.WriteLine(exif.Tag.ToString() + " " + exif.GetValue().ToString());
+      }
     }
   }
 
@@ -175,6 +223,15 @@ public class Photo {
     }
     return texture;
   }
+
+  public string Description() {
+    if (Loaded) {
+      string shootingInfo = $"{FNumber} at {ExposureTime}, {IsoSpeed}";
+      return String.Format("{0,-30} {1,-50} {2}", shootingInfo, $"{CameraModel} {LensModel}", File);
+    } else {
+      return String.Format("{0,-81} {1}", "", File);
+    }
+  }
 }
 
 public class Texture : IDisposable {
@@ -293,7 +350,6 @@ public static class Util {
     image.Dispose();
     return texture;
   }
-
 }
 
 public class Game : GameWindow {
@@ -433,8 +489,8 @@ public class Game : GameWindow {
     GL.VertexAttribPointer(texCoordLocation, 2, VertexAttribPointerType.Float, false, 5 * sizeof(float), 3 * sizeof(float));
 
     // Load textures from JPEGs.
-    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\desktop\photos-test\");
+    string[] files = Directory.GetFiles(@"c:\users\colin\pictures\photos\2023\07\14\");
     // string[] files = Directory.GetFiles(@"C:\Users\colin\Pictures\photos\2018\06\23");
     // string[] files = Directory.GetFiles(@"C:\Users\colin\Desktop\Germany all\104D7000");
 
@@ -494,7 +550,7 @@ public class Game : GameWindow {
     }
 
     // Draw status box.
-    DrawText(activePhoto.File, geometry.StatusBox.Min.X + 80, geometry.StatusBox.Min.Y);
+    DrawText(activePhoto.Description(), geometry.StatusBox.Min.X + 80, geometry.StatusBox.Min.Y);
     if (activePhoto.Loaded) {
       DrawText($"{(scale * 100):F1}%", geometry.StatusBox.Min.X, geometry.StatusBox.Min.Y);
     }