Merge pull request #326 from BinaryKits/graphic-symbol

Update Graphic Symbol

Author: primo-ppcg

src/BinaryKits.Zpl.Label/Elements/ZplGraphicSymbol.cs

@@ -56,7 +56,7 @@ public override IEnumerable<string> Render(ZplRenderOptions context)
             //^GSo,h,w
             var result = new List<string>();
             result.AddRange(RenderPosition(context));
-            result.Add($"^GS{RenderFieldOrientation(FieldOrientation)},{context.Scale(Height)},{context.Scale(Width)}^FD{(char)Character}^FS");
+            result.Add($"^GS{RenderFieldOrientation(FieldOrientation)},{context.Scale(Height)},{context.Scale(Width)}^FD{(char?)Character}^FS");
 
             return result;
         }

src/BinaryKits.Zpl.Viewer/ElementDrawers/GraphicSymbolElementDrawer.cs

@@ -45,7 +45,7 @@ public override SKPoint Draw(ZplElementBase element, DrawerOptions options, SKPo
                     IsAntialias = options.Antialias
                 };
 
-                string displayText = $"{(char)graphicSymbol.Character}";
+                string displayText = $"{(char?)graphicSymbol.Character}";
                 float totalWidth = skFont.MeasureText(displayText, out SKRect textBounds);
 
                 using (new SKAutoCanvasRestore(this.skCanvas))