add ExposureBiasValue to the statusbar

Photo.cs

@@ -104,6 +104,7 @@ public class Photo {
   public string FNumber = "<unk>";
   public string ExposureTime = "<unk>";
   public string IsoSpeed = "<unk>";
+  public string ExposureBiasValue = "<unk>";
   public int Rating = 0;
   public ushort Orientation = 1;
   public GpsInfo? Gps = null;
@@ -370,6 +371,15 @@ public class Photo {
       DateTimeOriginal = DateTimeOriginal.AddSeconds(fractionalSeconds);
     }
 
+    IExifValue<SignedRational>? exposureBiasValue;
+    if (exifs.TryGetValue(ExifTag.ExposureBiasValue, out exposureBiasValue)) {
+      SignedRational r = exposureBiasValue.Value;
+      ExposureBiasValue = r.ToString();
+      if (r.Numerator >= 0) {
+        ExposureBiasValue = "+" + ExposureBiasValue;
+      }
+    }
+
     Gps = GpsInfo.ParseExif(exifs);
   }
 
@@ -416,7 +426,7 @@ public class Photo {
   public string Description() {
     string date = DateTimeOriginal.ToString("yyyy-MM-dd HH:mm:ss.ff");
     return String.Format(
-        "{0,6}  {1,-5}  {2,-7} {3,-10} {7,4}x{8,-4} {4}    {5,-20}    {6}",
-        FocalLength, FNumber, ExposureTime, IsoSpeed, date, ShortLensModel, Filename, Size.X, Size.Y);
+        "{0,6}  {1,-5}  {2,-7} {3,-10} {9,-4} {7,4}x{8,-4} {4}    {5,-20}    {6}",
+        FocalLength, FNumber, ExposureTime, IsoSpeed, date, ShortLensModel, Filename, Size.X, Size.Y, ExposureBiasValue);
   }
 }