+ point symbolizer opacity patch from Brian (openstreetmap@brian.quinion.co.uk)

bindings/python/mapnik_point_symbolizer.cpp

@@ -36,5 +36,8 @@ void export_point_symbolizer()
         .add_property("allow_overlap",
               &point_symbolizer::get_allow_overlap,
               &point_symbolizer::set_allow_overlap)
+        .add_property("opacity",
+              &point_symbolizer::get_opacity,
+              &point_symbolizer::set_opacity)
         ;
 }

include/mapnik/point_symbolizer.hpp

@@ -40,8 +40,17 @@ namespace mapnik
         point_symbolizer(point_symbolizer const& rhs);
         void set_allow_overlap(bool overlap);
         bool get_allow_overlap() const;
+        void set_opacity(float opacity)
+        {
+            opacity_ = opacity;
+        }
+        float get_opacity() const
+        {
+            return opacity_;
+        }
         
     private:
+        float opacity_;
         bool overlap_;
     };
 }

src/agg_renderer.cpp

@@ -442,7 +442,7 @@ namespace mapnik
             if (sym.get_allow_overlap() || 
                 detector_.has_placement(label_ext))
             {    
-               pixmap_.set_rectangle_alpha(px,py,*data);
+               pixmap_.set_rectangle_alpha2(*data,px,py,sym.get_opacity());
                detector_.insert(label_ext);
             }
          }

src/load_map.cpp

@@ -524,6 +524,8 @@ namespace mapnik
             optional<std::string> type =  get_opt_attr<string>(sym, "type"); 
             optional<boolean> allow_overlap = 
                 get_opt_attr<boolean>(sym, "allow_overlap");
+            optional<float> opacity = 
+                get_opt_attr<float>(sym, "opacity");
 
             optional<unsigned> width = get_opt_attr<unsigned>(sym, "width"); 
             optional<unsigned> height = get_opt_attr<unsigned>(sym, "height"); 
@@ -545,6 +547,10 @@ namespace mapnik
                    {
                       symbol.set_allow_overlap( * allow_overlap );
                    }
+                   if (opacity)
+                   {
+                      symbol.set_opacity( * opacity );
+                   }			
                    rule.append(symbol);
                 }
                 catch (ImageReaderException const & ex )

src/point_symbolizer.cpp

@@ -35,7 +35,8 @@ namespace mapnik
 {
     point_symbolizer::point_symbolizer()
         : symbolizer_with_image(boost::shared_ptr<ImageData32>(new ImageData32(4,4))),
-          overlap_(false)
+          overlap_(false),
+          opacity_(1.0)
     {
         //default point symbol is black 4x4px square
         image_->set(0xff000000);
@@ -45,12 +46,14 @@ namespace mapnik
                                        std::string const& type,
                                        unsigned width,unsigned height) 
         : symbolizer_with_image(file, type, width, height),
-          overlap_(false)
+          overlap_(false),
+          opacity_(1.0)
     { }
     
     point_symbolizer::point_symbolizer(point_symbolizer const& rhs)
         : symbolizer_with_image(rhs),
-          overlap_(rhs.overlap_)
+          overlap_(rhs.overlap_),
+          opacity_(rhs.opacity_)
     {}
     
     void point_symbolizer::set_allow_overlap(bool overlap)