Fixed handling of default values for radial gradients

- added possibility for class-specific default attribute values
- fixes load/save of W3C example pservers-grad-06-b
- fixes #397

Source/SvgDefinitionDefaults.cs

@@ -10,49 +10,93 @@ namespace Svg
     /// </summary>
     public static class SvgDefaults
     {
-        //internal dictionary for the defaults
-        private static readonly Dictionary<string, string> _defaults = new Dictionary<string, string>();
+        // defaults that are specific to some elements
+        private static Dictionary<string, Dictionary<string, string>> _propDefaults = 
+            new Dictionary<string, Dictionary<string, string>>
+            {
+                { "SvgRadialGradientServer", new Dictionary<string, string>
+                { { "cx", "50%" }, { "cy", "50%" }, { "r", "50%" } } },
+                { "SvgLinearGradientServer", new Dictionary<string, string>
+                { { "x1", "0%" }, { "x2", "100%" }, { "y1", "0%" }, { "y2", "100%" }  } },
+            };
 
-        static SvgDefaults()
+        // common defaults
+        private static readonly Dictionary<string, string> _defaults =
+            new Dictionary<string, string>()
             {
-            _defaults["d"] = "";
+                { "d", "" },
+                { "viewBox", "0, 0, 0, 0" },
+                { "visibility", "visible" },
+                { "display", "inline" },
+                { "enable-background", "accumulate" },
+                { "opacity", "1" },
+                { "clip", "auto" },
+                { "clip-rule", "nonzero" },
+                { "clipPathUnits", "userSpaceOnUse" },
+                { "x", "0" },
+                { "y", "0" },
+                { "transform", "" },
+
+                // line
+                { "x1", "0" },
+                { "x2", "0" },
+                { "y1", "0" },
+                { "y2", "0" },
 
-            _defaults["viewBox"] = "0, 0, 0, 0";
+                // circle, ellipse
+                { "cx", "0" },
+                { "cy", "0" },
 
-            _defaults["visibility"] = "visible";
-            _defaults["opacity"] = "1";
-            _defaults["clip-rule"] = "nonzero";
+                { "fill", "" },
+                { "fill-opacity", "1" },
+                { "fill-rule", "nonzero" },
 
-            _defaults["transform"] = "";
-            _defaults["rx"] = "0";
-            _defaults["ry"] = "0";
-            _defaults["cx"] = "0";
-            _defaults["cy"] = "0";
+                { "stop-color", "black" },
+                { "stop-opacity", "1" },
 
-            _defaults["fill"] = "";
-            _defaults["fill-opacity"] = "1";
-            _defaults["fill-rule"] = "nonzero";
+                { "stroke", "none" },
+                { "stroke-opacity", "1" },
+                { "stroke-width", "1" },
+                { "stroke-miterlimit", "4" },
+                { "stroke-linecap", "butt" },
+                { "stroke-linejoin", "miter" },
+                { "stroke-dasharray", "none" },
+                { "stroke-dashoffset", "0" },
 
-            _defaults["stroke"] = "none";
-            _defaults["stroke-opacity"] = "1";
-            _defaults["stroke-width"] = "1";
-            _defaults["stroke-miterlimit"] = "4";
-            _defaults["stroke-linecap"] = "butt";
-            _defaults["stroke-linejoin"] = "miter";
-            _defaults["stroke-dasharray"] = "none";
-            _defaults["stroke-dashoffset"] = "0";
+                // marker
+                { "markerUnits", "strokeWidth" },
+                { "refX", "0" },
+                { "refY", "0" },
+                { "markerWidth", "3" },
+                { "markerHeight", "3" },
+                { "orient", "0" }
+            };
+
+
+        static SvgDefaults()
+        {
         }
 
         /// <summary>
         /// Checks whether the property value is the default value of the svg definition.
         /// </summary>
         /// <param name="attributeName">Name of the svg attribute</param>
+        /// <param name="componentType">Class name of the svg element</param>
         /// <param name="value">.NET value of the attribute</param>
-        public static bool IsDefault(string attributeName, string value)
+        public static bool IsDefault(string attributeName, string componentType, string value)
+        {
+            Console.WriteLine(componentType + ": " + attributeName);
+            if (_propDefaults.ContainsKey(componentType))
+            {
+                if (_propDefaults[componentType].ContainsKey(attributeName))
                 {
+                    return _propDefaults[componentType][attributeName] == value;
+                }
+            }
+
             if (_defaults.ContainsKey(attributeName))
             {
-                if (_defaults[attributeName] == value) return true;
+                return _defaults[attributeName] == value;
             }
             return false;
         }

Source/SvgElement.cs

@@ -600,7 +600,7 @@ namespace Svg
                         var type = propertyValue.GetType();
                         
                         //Only write the attribute's value if it is not the default value, not null/empty, or we're forcing the write.
-                        if ((!string.IsNullOrEmpty(value) && !SvgDefaults.IsDefault(attr.Attribute.Name, value)) || forceWrite)
+                        if ((!string.IsNullOrEmpty(value) && !SvgDefaults.IsDefault(attr.Attribute.Name, attr.Property.ComponentType.Name, value)) || forceWrite)
                         {
                             if (writeStyle)
                             {