Support for top bar rendering.

BarcodeStandard/BarcodeLib.cs

@@ -167,7 +167,7 @@ public Barcode(string data, Type iType)
 
         /// <summary>
         /// Mode when rendering guard bars for barcodes that support them (EAN-8/EAN-13/UPC-A/UPC-E)
-        /// 
+        ///
         /// Functionality not implemented for codes other than EAN-13
         /// </summary>
         public GuardBarsMode GuardBarsMode { get; set; }
@@ -228,6 +228,15 @@ public byte[] EncodedImageBytes
         /// </summary>
         public bool DisableEan13CountryException { get; set; } = false;
 
+        /// <summary>
+        /// Enable rendering of top bar when rendering code.
+        ///
+        /// Top bar is typically used when printing codes on thermal printers
+        /// to detect damaged print head dots. Damage dots would create missing bars that
+        /// could cause the barcode to be invalid/unreadable.
+        /// </summary>
+        public bool IncludeTopBar { get; set; }
+
         #endregion Properties
 
         #region General Encode
@@ -563,7 +572,9 @@ private SKBitmap Generate_Image()
                         }//using
 
                         if (IncludeLabel)
+                        {
                             Labels.Label_ITF14(this, bitmap);
+                        }
 
                         break;
                     }//case
@@ -590,6 +601,7 @@ private SKBitmap Generate_Image()
                         //draw image
                         var pos = 0;
                         var halfBarWidth = (int)(iBarWidth * 0.5);
+                        var totalBarcodeWidth = EncodedValue.Length * iBarWidth;
 
                         using (var canvas = new SKCanvas(bitmap))
                         {
@@ -617,7 +629,19 @@ private SKBitmap Generate_Image()
 
                         if (IncludeLabel)
                         {
-                            Labels.Label_UPCA(this, bitmap);
+                            if (GuardBarsMode != GuardBarsMode.Disabled)
+                            {
+                                Labels.Label_UPCA(this, bitmap);
+                            }
+                            else
+                            {
+                                Labels.Label_Generic(this, bitmap, totalBarcodeWidth);
+                            }
+                        }
+
+                        if (IncludeTopBar)
+                        {
+                            Labels.TopBar(this, bitmap, shiftAdjustment, totalBarcodeWidth, iBarWidth);
                         }
 
                         break;
@@ -696,6 +720,11 @@ private SKBitmap Generate_Image()
                             }
                         }
 
+                        if (IncludeTopBar)
+                        {
+                            Labels.TopBar(this, bitmap, shiftAdjustment, totalBarcodeWidth, iBarWidth);
+                        }
+
                         break;
                     }//case
                 default:
@@ -768,6 +797,11 @@ private SKBitmap Generate_Image()
                             Labels.Label_Generic(this, bitmap, totalBarcodeWidth);
                         }//if
 
+                        if (IncludeTopBar)
+                        {
+                            Labels.TopBar(this, bitmap, shiftAdjustment, totalBarcodeWidth, iBarWidth);
+                        }
+
                         break;
                     }//switch
             }//switch

BarcodeStandard/Labels.cs

@@ -346,5 +346,25 @@ private static int GetFontSize(Barcode barcode, int wid, int hgt, string lbl)
 
             return fontSize;
         }
+
+        internal static void TopBar(Barcode barcode, SKBitmap img, int shiftAdjustment, int barcodeWidth, int iBarWidth)
+        {
+            using (var g = new SKCanvas(img))
+            using (var foreBrush = new SKPaint())
+            using (var backBrush = new SKPaint())
+            {
+                foreBrush.ColorF = barcode.ForeColor;
+                foreBrush.IsAntialias = true;
+                foreBrush.StrokeWidth = iBarWidth;
+                backBrush.ColorF = barcode.BackColor;
+                backBrush.IsAntialias = true;
+
+                // Clear area under top bar
+                g.DrawRect(new SKRect(0, 0, img.Width, iBarWidth * 3), backBrush);
+
+                // Draw the top bar
+                g.DrawLine(new SKPoint(shiftAdjustment, iBarWidth * 1.5f), new SKPoint(shiftAdjustment + barcodeWidth, iBarWidth * 1.5f), foreBrush); 
+            }
+        }
     }
 }

BarcodeStandardExample/TestApp.cs

@@ -42,6 +42,7 @@ private void btnEncode_Click(object sender, EventArgs e)
             var w = Convert.ToInt32(txtWidth.Text.Trim());
             var h = Convert.ToInt32(txtHeight.Text.Trim());
             _b.Alignment = AlignmentPositions.Center;
+            _b.IncludeTopBar = chkTopBar.Checked;
 
             //barcode alignment
             switch (cbBarcodeAlign.SelectedItem.ToString().Trim().ToLower())