Optionally output JSON data with pixel coordinates.

include/mapnik/metawriter.hpp

@@ -81,7 +81,7 @@ public:
      * \param box Area (in pixel coordinates)
      * \param feature The feature being processed
      * \param prj_trans Projection transformation
-     * \param t Cooridnate transformation
+     * \param t Coordinate transformation
      * \param properties List of properties to output
      */
     virtual void add_box(box2d<double> const& box, Feature const& feature,
@@ -107,7 +107,6 @@ public:
      * \param properties metawriter_property_map object with userdefined values.
      *        Useful for setting filename etc.
      */
-    
     virtual void start(metawriter_property_map const& properties) 
     {
         boost::ignore_unused_variable_warning(properties);
@@ -122,7 +121,7 @@ public:
      */
     void set_size(int width, int height) { width_ = width; height_ = height; }
     /** Set Map object's srs. */
-    virtual void set_map_srs(projection const& proj) = 0;
+    virtual void set_map_srs(projection const& proj) { /* Not required when working with image coordinates. */ }
     /** Return the list of default properties. */
     metawriter_properties const& get_default_properties() const { return dflt_properties_;}
 protected:

include/mapnik/metawriter_inmem.hpp

@@ -80,8 +80,6 @@ public:
           metawriter_properties const& properties);
   
   virtual void start(metawriter_property_map const& properties);
-  virtual void stop();
-  virtual void set_map_srs(projection const& proj);
 
   /**
    * An instance of a rendered feature. The box represents the image

include/mapnik/metawriter_json.hpp

@@ -70,6 +70,8 @@ public:
     void set_output_empty(bool output_empty) { output_empty_ = output_empty; }
     /** See set_output_empty(). */
     bool get_output_empty() { return output_empty_; }
+    void set_pixel_coordinates(bool on) { pixel_coordinates_ = on; }
+    bool get_pixel_coordinates() { return pixel_coordinates_; }
     virtual void set_map_srs(projection const& proj);
 protected:
     enum {
@@ -80,6 +82,7 @@ protected:
     /** Features written. */
     int count_;
     bool output_empty_;
+    bool pixel_coordinates_;
     /** Transformation from map srs to output srs. */
     proj_transform *trans_;
     projection output_srs_;
@@ -94,15 +97,17 @@ protected:
         if (count_ == HEADER_NOT_WRITTEN) write_header();
         if (count_++) *f_ << ",\n";
 
-        *f_  << "{ \"type\": \"Feature\",\n  \"geometry\": { \"type\": \""<<type<<"\",\n    \"coordinates\":";
+        *f_  << "{ \"type\": \"Feature\",\n  \"geometry\": { \"type\": \"" << type << "\",\n    \"coordinates\":";
     }
     void write_properties(Feature const& feature, metawriter_properties const& properties);
     inline void write_point(CoordTransform const& t, double x, double y, bool last = false)
     {
         double z = 0.0;
-        t.backward(&x, &y);
-        trans_->forward(x, y, z);
-        *f_ << "["<<x<<","<<y<<"]";
+        if (!pixel_coordinates_) {
+            t.backward(&x, &y);
+            trans_->forward(x, y, z);
+        }
+        *f_ << "[" << x << "," << y << "]";
         if (!last) {
             *f_ << ",";
         }

src/metawriter.cpp

@@ -104,7 +104,7 @@ void metawriter_json_stream::write_properties(Feature const& feature, metawriter
 {
     *f_ << "}," << //Close coordinates object
             "\n  \"properties\": {";
-    std::map<std::string, value> fprops = feature.props();
+    std::map<std::string, value> const &fprops = feature.props();
     int i = 0;
     BOOST_FOREACH(std::string p, properties)
     {
@@ -143,14 +143,21 @@ void metawriter_json_stream::add_box(box2d<double> const &box, Feature const& fe
 {
     /* Check if feature is in bounds. */
     if (box.maxx() < 0 || box.maxy() < 0 || box.minx() > width_ || box.miny() > height_) return;
+    double minx, miny, maxx, maxy;
+    if (pixel_coordinates_) {
+        minx = box.minx();
+        miny = box.miny();
+        maxx = box.maxx();
+        maxy = box.maxy();
+    } else {
+        //t_ coord transform has transform for box2d combined with proj_transform
+        box2d<double> transformed = t.backward(box, *trans_);
 
-    //t_ coord transform has transform for box2d combined with proj_transform
-    box2d<double> transformed = t.backward(box, *trans_);
-
-    double minx = transformed.minx();
-    double miny = transformed.miny();
-    double maxx = transformed.maxx();
-    double maxy = transformed.maxy();
+        minx = transformed.minx();
+        miny = transformed.miny();
+        maxx = transformed.maxx();
+        maxy = transformed.maxy();
+    }
 
     write_feature_header("Polygon");
 

src/metawriter_factory.cpp

@@ -41,9 +41,9 @@ metawriter_create(const boost::property_tree::ptree &pt) {
   metawriter_ptr writer;
   string type = get_attr<string>(pt, "type");
 
+  optional<string> properties = get_opt_attr<string>(pt, "default-output");
   if (type == "json") {
     string file = get_attr<string>(pt, "file");
-    optional<string> properties = get_opt_attr<string>(pt, "default-output");
     metawriter_json_ptr json = metawriter_json_ptr(new metawriter_json(properties, parse_path(file)));
     optional<boolean> output_empty = get_opt_attr<boolean>(pt, "output-empty");
     if (output_empty) {
@@ -52,10 +52,8 @@ metawriter_create(const boost::property_tree::ptree &pt) {
     writer = json;
     
   } else if (type == "inmem") {
-    optional<string> properties = get_opt_attr<string>(pt, "default-output");
     metawriter_inmem_ptr inmem = metawriter_inmem_ptr(new metawriter_inmem(properties));
     writer = inmem;
-    
   } else {
     throw config_error(string("Unknown type '") + type + "'");
   }

src/metawriter_inmem.cpp

@@ -57,7 +57,6 @@ namespace mapnik {
 
 metawriter_inmem::metawriter_inmem(metawriter_properties dflt_properties) 
   : metawriter(dflt_properties) {
-  // ???
 }
 
 metawriter_inmem::~metawriter_inmem() {
@@ -130,16 +129,6 @@ metawriter_inmem::start(metawriter_property_map const& /*properties*/) {
   instances_.clear();
 }
 
-void 
-metawriter_inmem::stop() {
-}
-
-void 
-metawriter_inmem::set_map_srs(projection const& /*proj*/) {
-  // currently unused, since the inmem metawriter keeps everything in
-  // image coordinates.
-}
-
 const std::list<metawriter_inmem::meta_instance> &
 metawriter_inmem::instances() const {
   return instances_;