Fix #176: Blurry text when overlapped with colored background

Samples/SVGViewer/DebugRenderer.cs

@@ -93,7 +93,11 @@ namespace SVGViewer
             _transform.Translate(dx, dy, order);
         }
 
-
+        public CompositingMode CompositingMode
+        {
+          get { return System.Drawing.Drawing2D.CompositingMode.SourceOver; /* default value */ }
+          set { /* Do Nothing */ }
+        }
 
         public SmoothingMode SmoothingMode
         {

Source/Rendering/ISvgRenderer.cs

@@ -19,6 +19,7 @@ namespace Svg
         void ScaleTransform(float sx, float sy, MatrixOrder order = MatrixOrder.Append);
         void SetBoundable(ISvgBoundable boundable);
         void SetClip(Region region, CombineMode combineMode = CombineMode.Replace);
+        CompositingMode CompositingMode { get; set; }
         SmoothingMode SmoothingMode { get; set; }
         Matrix Transform { get; set; }
         void TranslateTransform(float dx, float dy, MatrixOrder order = MatrixOrder.Append);

Source/Rendering/SvgRenderer.cs

@@ -79,7 +79,11 @@ namespace Svg
             this._innerGraphics.TranslateTransform(dx, dy, order);
         }
         
-
+        public CompositingMode CompositingMode
+        {
+          get { return this._innerGraphics.CompositingMode; }
+          set { this._innerGraphics.CompositingMode = value; }
+        }
 
         public SmoothingMode SmoothingMode
         {

Source/Text/SvgTextBase.cs

@@ -259,6 +259,11 @@ namespace Svg
                     renderer.SmoothingMode = SmoothingMode.AntiAlias;
                 }
 
+                // If text color blends with background color, text will be rendered blurry
+                // To avoid it, we set SourceCopy which overwrite background color
+                var compositingMode = renderer.CompositingMode;
+                renderer.CompositingMode = CompositingMode.SourceCopy;
+
                 this.RenderFill(renderer);
                 this.RenderStroke(renderer);
                 this.RenderChildren(renderer);
@@ -269,6 +274,8 @@ namespace Svg
                     renderer.SmoothingMode = SmoothingMode.Default;
                 }
 
+                renderer.CompositingMode = compositingMode;
+
                 this.ResetClip(renderer);
                 this.PopTransforms(renderer);
             }