Extended the Marker start/mid/end getters with a function to return null if...

Extended the Marker start/mid/end getters with a function to return null if the property was set to none. This will prevent nullpointer issues when having none as one of the items.

Source/Basic Shapes/SvgLine.cs

@@ -4,6 +4,7 @@ using System.Text;
 using System.ComponentModel;
 using System.Drawing;
 using System.Drawing.Drawing2D;
+using Svg.ExtensionMethods;
 
 namespace Svg
 {
@@ -85,7 +86,7 @@ namespace Svg
         [SvgAttribute("marker-end")]
         public Uri MarkerEnd
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-end"); }
+            get { return this.Attributes.GetAttribute<Uri>("marker-end").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-end"] = value; }
         }
 
@@ -96,7 +97,7 @@ namespace Svg
         [SvgAttribute("marker-mid")]
         public Uri MarkerMid
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-mid"); }
+            get { return this.Attributes.GetAttribute<Uri>("marker-mid").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-mid"] = value; }
         }
 
@@ -107,7 +108,7 @@ namespace Svg
         [SvgAttribute("marker-start")]
         public Uri MarkerStart
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-start"); }
+	        get { return this.Attributes.GetAttribute<Uri>("marker-start").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-start"] = value; }
         }
 

Source/Basic Shapes/SvgPolygon.cs

@@ -4,6 +4,7 @@ using System.Text;
 using System.Drawing;
 using System.Drawing.Drawing2D;
 using System.Diagnostics;
+using Svg.ExtensionMethods;
 using Svg.Pathing;
 
 namespace Svg
@@ -32,7 +33,7 @@ namespace Svg
         [SvgAttribute("marker-end")]
         public Uri MarkerEnd
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-end"); }
+            get { return this.Attributes.GetAttribute<Uri>("marker-end").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-end"] = value; }
         }
 
@@ -43,7 +44,7 @@ namespace Svg
         [SvgAttribute("marker-mid")]
         public Uri MarkerMid
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-mid"); }
+            get { return this.Attributes.GetAttribute<Uri>("marker-mid").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-mid"] = value; }
         }
 
@@ -54,7 +55,7 @@ namespace Svg
         [SvgAttribute("marker-start")]
         public Uri MarkerStart
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-start"); }
+            get { return this.Attributes.GetAttribute<Uri>("marker-start").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-start"] = value; }
         }
 

Source/Basic Shapes/SvgPolyline.cs

@@ -4,6 +4,7 @@ using System.Text;
 using System.Drawing;
 using System.Drawing.Drawing2D;
 using System.Diagnostics;
+using Svg.ExtensionMethods;
 
 namespace Svg
 {
@@ -19,7 +20,7 @@ namespace Svg
         [SvgAttribute("marker-end")]
         public Uri MarkerEnd
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-end"); }
+            get { return this.Attributes.GetAttribute<Uri>("marker-end").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-end"] = value; }
         }
 
@@ -30,7 +31,7 @@ namespace Svg
         [SvgAttribute("marker-mid")]
         public Uri MarkerMid
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-mid"); }
+            get { return this.Attributes.GetAttribute<Uri>("marker-mid").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-mid"] = value; }
         }
 
@@ -41,7 +42,7 @@ namespace Svg
         [SvgAttribute("marker-start")]
         public Uri MarkerStart
         {
-            get { return this.Attributes.GetAttribute<Uri>("marker-start"); }
+            get { return this.Attributes.GetAttribute<Uri>("marker-start").ReplaceWithNullIfNone(); }
             set { this.Attributes["marker-start"] = value; }
         }
 

Source/ExtensionMethods/UriExtensions.cs

+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Svg.ExtensionMethods
+{
+	public static class UriExtensions
+	{
+		public static Uri ReplaceWithNullIfNone(this Uri uri)
+		{
+			if(uri == null) { return null; }
+			return string.Equals(uri.ToString(), "none", StringComparison.OrdinalIgnoreCase) ? null : uri;		
+		}
+	}
+}

Source/Paths/SvgPath.cs

@@ -6,6 +6,7 @@ using System.Drawing.Drawing2D;
 using System.Xml.Serialization;
 using System.Xml;
 using System.Diagnostics;
+using Svg.ExtensionMethods;
 using Svg.Pathing;
 using Svg.Transforms;
 
@@ -51,7 +52,7 @@ namespace Svg
         [SvgAttribute("marker-end", true)]
 		public Uri MarkerEnd
         {
-			get { return this.Attributes.GetAttribute<Uri>("marker-end"); }
+			get { return this.Attributes.GetAttribute<Uri>("marker-end").ReplaceWithNullIfNone(); }
 			set { this.Attributes["marker-end"] = value; }
 		}
 
@@ -62,7 +63,7 @@ namespace Svg
         [SvgAttribute("marker-mid", true)]
 		public Uri MarkerMid
 		{
-			get { return this.Attributes.GetAttribute<Uri>("marker-mid"); }
+			get { return this.Attributes.GetAttribute<Uri>("marker-mid").ReplaceWithNullIfNone(); }
 			set { this.Attributes["marker-mid"] = value; }
 		}
 
@@ -73,7 +74,7 @@ namespace Svg
         [SvgAttribute("marker-start", true)]
 		public Uri MarkerStart
 		{
-			get { return this.Attributes.GetAttribute<Uri>("marker-start"); }
+			get { return this.Attributes.GetAttribute<Uri>("marker-start").ReplaceWithNullIfNone(); }
 			set { this.Attributes["marker-start"] = value; }
 		}
 

Source/Svg.csproj

@@ -107,6 +107,7 @@
     <Compile Include="DataTypes\SvgTextPathSpacing.cs" />
     <Compile Include="DataTypes\XmlSpaceHandling.cs" />
     <Compile Include="Document Structure\SvgSymbol.cs" />
+    <Compile Include="ExtensionMethods\UriExtensions.cs" />
     <Compile Include="Filter Effects\ImageBuffer.cs" />
     <Compile Include="Painting\GenericBoundable.cs" />
     <Compile Include="Painting\SvgFallbackPaintServer .cs" />