+ add support for background-image attribute

( background image is repeated both vertically
   and horizontally )

include/mapnik/map.hpp

@@ -74,6 +74,7 @@ private:
     std::string  srs_;
     int buffer_size_;
     boost::optional<color> background_;
+    boost::optional<std::string> background_image_;
     std::map<std::string,feature_type_style> styles_;
     std::map<std::string,metawriter_ptr> metawriters_;
     std::map<std::string,font_set> fontsets_;
@@ -306,6 +307,17 @@ public:
      */
     boost::optional<color> const& background() const;
     
+    /*! \brief Set the map background image filename.
+     *  @param c Background image filename.
+     */
+    void set_background_image(std::string const& image_filename);
+    
+    /*! \brief Get the map background image
+     *  @return Background image path as std::string
+     *  object
+     */
+    boost::optional<std::string> const& background_image() const;
+    
     /*! \brief Set buffer size 
      *  @param buffer_size Buffer size in pixels.
      */

src/agg/agg_renderer.cpp

@@ -120,8 +120,32 @@ agg_renderer<T>::agg_renderer(Map const& m, T & pixmap, double scale_factor, uns
       detector_(box2d<double>(-m.buffer_size(), -m.buffer_size(), m.width() + m.buffer_size() ,m.height() + m.buffer_size())),
       ras_ptr(new rasterizer)
 {
-    boost::optional<color> bg = m.background();
+    boost::optional<color> const& bg = m.background();
     if (bg) pixmap_.set_background(*bg);
+    
+    boost::optional<std::string> const& image_filename = m.background_image();
+    if (image_filename)
+    {
+        boost::optional<mapnik::image_ptr> bg_image = mapnik::image_cache::instance()->find(*image_filename,true);
+        if (bg_image)
+        {
+            int w = (*bg_image)->width();
+            int h = (*bg_image)->height();
+            if ( w > 0 && h > 0)
+            {
+                // repeat background-image in both x,y
+                unsigned x_steps = unsigned(std::ceil(width_/double(w)));
+                unsigned y_steps = unsigned(std::ceil(height_/double(h)));
+                for (unsigned x=0;x<x_steps;++x)
+                {
+                    for (unsigned y=0;y<y_steps;++y)
+                    {
+                        pixmap_.set_rectangle_alpha2(*(*bg_image), x*w, y*h, 1.0f);
+                    }
+                }
+            }
+        }
+    }
 #ifdef MAPNIK_DEBUG
     std::clog << "scale=" << m.scale() << "\n";
 #endif

src/load_map.cpp

@@ -171,10 +171,17 @@ void map_parser::parse_map( Map & map, ptree const & pt )
         try
         {
             optional<color> bgcolor = get_opt_attr<color>(map_node, "bgcolor");
-            if (bgcolor) {
+            if (bgcolor) 
+            {
                 map.set_background( * bgcolor );
             }
             
+            optional<std::string> image_filename = get_opt_attr<string>(map_node, "background-image");
+            if (image_filename)
+            {                
+                map.set_background_image(*image_filename);
+            }
+            
             map.set_srs( get_attr(map_node, "srs", map.srs() ));
 
             optional<unsigned> buffer_size = get_opt_attr<unsigned>(map_node,"buffer_size");

src/map.cpp

@@ -80,6 +80,7 @@ Map::Map(const Map& rhs)
       srs_(rhs.srs_),
       buffer_size_(rhs.buffer_size_),
       background_(rhs.background_),
+      background_image_(rhs.background_image_),
       styles_(rhs.styles_),
       metawriters_(rhs.metawriters_),
       layers_(rhs.layers_),
@@ -94,6 +95,7 @@ Map& Map::operator=(const Map& rhs)
     srs_=rhs.srs_;
     buffer_size_ = rhs.buffer_size_;
     background_=rhs.background_;
+    background_image_=rhs.background_image_;
     styles_=rhs.styles_;
     metawriters_ = rhs.metawriters_;
     layers_=rhs.layers_;
@@ -319,6 +321,16 @@ void Map::set_background(const color& c)
     background_ = c;
 }
    
+boost::optional<std::string> const& Map::background_image() const
+{
+    return background_image_;
+}
+   
+void Map::set_background_image(std::string const& image_filename)
+{
+    background_image_ = image_filename;
+}
+
 void Map::zoom(double factor)
 {
     coord2d center = currentExtent_.center();

src/save_map.cpp

@@ -699,12 +699,19 @@ void serialize_map(ptree & pt, Map const & map, bool explicit_defaults)
 
     set_attr( map_node, "srs", map.srs() );
 
-    optional<color> c = map.background();
+    optional<color> const& c = map.background();
     if ( c )
     {
         set_attr( map_node, "bgcolor", * c );
     }
 
+    optional<std::string> const& image_filename = map.background_image();
+    if ( image_filename )
+    {
+        set_attr( map_node, "background-image", *image_filename );
+    }
+    
+    
     unsigned buffer_size = map.buffer_size();
     if ( buffer_size || explicit_defaults)
     {