#125 Added background colours to text to make them more visible

Author: Dan Done

README.md

@@ -91,6 +91,7 @@ An example appsettings.json configuration file can be found [here](#example-apps
   * Off: Will not draw boundary boxes (note - this will speed up time between detection and notification as SynoAI will not have to manipulate the image)
 * DrawExclusions [optional] (Default: ```false```): Whether to draw the exclusion zone boundary boxes on the image. Useful for setting up the initial exclusion zones
 * BoxColor [optional] (Default: ```#FF0000```): The colour of the border of the boundary box
+* TextBoxColor [opional] (Default: ```#00FFFFFF``` aka ```transparent```): The colour of the box to draw behind the text to aid in making text more visible
 * ExclusionBoxColour [optional] (Default: ```#00FF00```): The colour of the border of the exclusion boundary box
 * StrokeWidth [optional] (Default: ```2```): The width, in pixels, of the border around the boundary box
 * Font [optional] (Default: ```Tahoma```): The font to use when labelling the boundary boxes on the output image

SynoAI/Config.cs

@@ -55,6 +55,10 @@ public static class Config
         /// The hex code of the colour to use for the exclusion boxes.
         /// </summary>
         public static string ExclusionBoxColor { get; private set; }
+        /// <summary>
+        /// The hex code of the colour to use behind the text on the image outputs.
+        /// </summary>
+        public static string TextBoxColor { get; private set; }
 
         /// <summary>
         ///The stroke width of the Box drawn around the objects.
@@ -192,6 +196,7 @@ public static void Generate(ILogger logger, IConfiguration configuration)
             BoxColor = configuration.GetValue<string>("BoxColor", SKColors.Green.ToString());
             FontColor = configuration.GetValue<string>("FontColor", SKColors.Green.ToString());
             ExclusionBoxColor = configuration.GetValue<string>("ExclusionBoxColor", SKColors.Red.ToString());
+            TextBoxColor = configuration.GetValue<string>("TextBoxColor", SKColors.Transparent.ToString());
 
             Font = configuration.GetValue<string>("Font", "Tahoma");
             FontSize = configuration.GetValue<int>("FontSize", 12);

SynoAI/Services/SnapshotManager.cs

@@ -92,20 +92,52 @@ public static ProcessedImage DressImage(Camera camera, byte[] snapshot, IEnumera
 
                         // Label positioning
                         int x = prediction.MinX + Config.TextOffsetX;
-                        int y = prediction.MinY + Config.FontSize + Config.TextOffsetY;
+                        int y = prediction.MinY + Config.FontSize + Config.TextOffsetY; // FontSize is added as text is drawn above the bottom co-ordinate
 
                         // Consider below box placement
                         if (Config.LabelBelowBox) 
                         {
                             y += prediction.SizeY;
                         }
-        
-                        // Draw the text
-                        SKFont font = new SKFont(SKTypeface.FromFamilyName(Config.Font), Config.FontSize);
-                        canvas.DrawText(label, x, y, font, new SKPaint 
+
+                        // Draw background box for the text if required
+                        SKTypeface typeface = SKTypeface.FromFamilyName(Config.Font);
+
+                        SKPaint paint = new SKPaint
                         {
-                            Color = GetColour(Config.FontColor)
-                        });   
+                            FilterQuality = SKFilterQuality.High,
+                            IsAntialias = true,
+                            Color = GetColour(Config.FontColor),
+                            TextSize = Config.FontSize,
+                            Typeface = typeface
+                        };
+
+                        string textBoxColor = Config.TextBoxColor;
+                        if (!string.IsNullOrWhiteSpace(textBoxColor) && !textBoxColor.Equals(SKColors.Transparent.ToString(), StringComparison.OrdinalIgnoreCase))
+                        {
+                            float textWidth = paint.MeasureText(label);
+                            float textBoxWidth = textWidth + (Config.TextOffsetX * 2);
+                            float textBoxHeight = Config.FontSize + (Config.TextOffsetY * 2);
+
+                            float textBoxX = prediction.MinX + Config.StrokeWidth;
+                            float textBoxY = prediction.MinY + Config.TextOffsetY;
+                            if (Config.LabelBelowBox)
+                            {
+                                textBoxY += prediction.SizeY;
+                            }
+
+                            SKRect textRectangle = SKRect.Create(textBoxX, textBoxY, textBoxWidth, textBoxHeight);
+                            canvas.DrawRect(textRectangle, new SKPaint
+                            {
+                                Style = SKPaintStyle.StrokeAndFill,
+                                Color = GetColour(textBoxColor),
+                                StrokeWidth = Config.StrokeWidth
+                            });
+                        }
+
+                        // Draw the text
+                        SKFont font = new SKFont(typeface, Config.FontSize);
+                        canvas.DrawText(label, x, y, paint);   
                     }
                 }
             }