put better caption in result image

Azaion.Common/Extensions/GraphicsExtensions.cs

@@ -0,0 +1,28 @@
+using System.Drawing;
+
+namespace Azaion.Common.Extensions;
+
+public static class GraphicsExtensions
+{
+    public static void DrawTextBox(this Graphics g, string text, PointF position, Brush background, Brush foreground)
+    {
+        using var textFont = new Font(FontFamily.GenericSerif, 14);
+        using var stringFormat = new StringFormat();
+        stringFormat.LineAlignment = StringAlignment.Near;
+        stringFormat.Alignment = StringAlignment.Center;
+
+        var padding = 1.0f;
+        var textSize = g.MeasureString(text, textFont);
+
+        var backgroundRect = new RectangleF(
+            position.X - textSize.Width / 2.0f - padding,
+            position.Y - padding,
+            textSize.Width + 2 * padding,
+            textSize.Height + 2 * padding
+        );
+
+        g.FillRectangle(background, backgroundRect);
+        g.DrawString(text, textFont, foreground, position, stringFormat);
+    }
+    
+}

Azaion.Common/Services/GalleryService.cs

@@ -278,8 +278,9 @@ public class GalleryService(
             var brush = new SolidBrush(Color.FromArgb(color.A, color.R, color.G, color.B));
             var det = new CanvasLabel(detection, new Size(originalImage.Width, originalImage.Height));
             g.DrawRectangle(new Pen(brush, width: 3), (float)det.X, (float)det.Y, (float)det.Width, (float)det.Height);
+
             var label  = detection.Confidence >= 0.995 ? detClass.UIName : $"{detClass.UIName}: {detection.Confidence * 100:F0}%";
-            g.DrawString(label, new Font(FontFamily.GenericSerif, 14), brush, new PointF((float)(det.X + det.Width / 2.0), (float)det.Y));
+            g.DrawTextBox(label, new PointF((float)(det.X + det.Width / 2.0), (float)(det.Y - 24)), brush, Brushes.Black);
         }
         originalImage.Save(Path.Combine(_dirConfig.ResultsDirectory, $"{annotation.Name}{Constants.RESULT_PREFIX}.jpg"), ImageFormat.Jpeg);
     }