Applies default values of 50% for radial gradient cx,cy and r. This prevents...

Applies default values of 50% for radial gradient cx,cy and r. This prevents an OutOfMemory exception when loading svg files without these parameters specified.

Source/Painting/SvgRadialGradientServer.cs

@@ -49,6 +49,10 @@ namespace Svg
         /// </summary>
         public SvgRadialGradientServer()
         {
+            //Apply default values of 50% to cX,cY and r
+            CenterX = new SvgUnit(SvgUnitType.Percentage, 50);
+            CenterY = new SvgUnit(SvgUnitType.Percentage, 50);
+            Radius = new SvgUnit(SvgUnitType.Percentage, 50);
         }
 
         public override Brush GetBrush(SvgVisualElement renderingElement, float opacity)
@@ -59,7 +63,9 @@ namespace Svg
             float radius = this.Radius.ToDeviceValue(renderingElement);
             RectangleF boundingBox = (this.GradientUnits == SvgCoordinateUnits.ObjectBoundingBox) ? renderingElement.Bounds : renderingElement.OwnerDocument.GetDimensions();
 
-            path.AddEllipse(left-radius, top-radius, radius*2, radius*2);
+            if (radius > 0)
+            {
+                path.AddEllipse(left - radius, top - radius, radius * 2, radius * 2);
 
                 PathGradientBrush brush = new PathGradientBrush(path);
                 ColorBlend blend = base.GetColourBlend(renderingElement, opacity);
@@ -69,5 +75,8 @@ namespace Svg
 
                 return brush;
             }
+            
+            return null;            
+        }
     }
 }
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