Fixes most Example svg renders

Author: mwagnerEE

Source/SVGImage/SVG/SVGRender.cs

@@ -3,6 +3,7 @@
 using System.Xml;
 using System.Linq;
 using System.Collections.Generic;
+using SVGImage.SVG.Utils;
 
 using System.Windows;
 using System.Windows.Media;

Source/SVGImage/SVG/Shapes/Shape.cs

@@ -125,6 +125,11 @@ public Stroke Stroke
         }
 
         protected virtual Fill DefaultFill()
+        {
+            return null;
+        }
+
+        protected virtual Fill GetParentFill()
         {
             var parent = this.Parent;
             while (parent != null)
@@ -141,7 +146,7 @@ protected virtual Fill DefaultFill()
 
         public Fill Fill
         {
-            get => m_fill ?? DefaultFill();
+            get => m_fill ?? GetParentFill() ?? DefaultFill();
             set => m_fill = value;
         }
 

Source/SVGImage/SVG/Utils/DrawingGroupSerializer.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Windows.Media;
+using System.Windows.Markup;
+using System.IO;
+using System.Xml;
+
+namespace SVGImage.SVG.Utils
+{
+    internal static class DrawingGroupSerializer
+    {
+        public static string SerializeToXaml(DrawingGroup drawingGroup)
+        {
+            if (drawingGroup is null)
+            {
+                throw new ArgumentNullException(nameof(drawingGroup));
+            }
+
+            // Freezing can help ensure serialization works without exceptions
+            if (drawingGroup.CanFreeze && !drawingGroup.IsFrozen)
+            {
+                drawingGroup.Freeze();
+            }
+
+            var settings = new XmlWriterSettings
+            {
+                Indent = true,
+                IndentChars = "  ",
+                OmitXmlDeclaration = true
+            };
+
+            using (var stringWriter = new StringWriter())
+            using (var xmlWriter = XmlWriter.Create(stringWriter, settings))
+            {
+                XamlWriter.Save(drawingGroup, xmlWriter);
+                return stringWriter.ToString();
+            }
+        }
+    }
+}