add option to collect the total extent of all placement bboxs to enable passing along to metawriters - modified patch from kevin.kreaiser - closes #755

include/mapnik/placement_finder.hpp

@@ -76,6 +76,8 @@ struct placement : boost::noncopyable
     bool allow_overlap;
     std::pair<double, double> dimensions;
     int text_size;
+    bool collect_extents;
+    box2d<double> extents;
 };
 
 
@@ -101,7 +103,7 @@ public:
     void update_detector(placement & p);
 
     void clear();
-
+    
 private:
     ///Helpers for find_line_placement
 

src/agg/process_text_symbolizer.cpp

@@ -88,6 +88,8 @@ void agg_renderer<T>::process(text_symbolizer const& sym,
         string_info info(text);
 
         faces->get_string_info(info);
+        metawriter_with_properties writer = sym.get_metawriter();
+
         unsigned num_geom = feature.num_geometries();
         for (unsigned i=0; i<num_geom; ++i)
         {
@@ -97,6 +99,9 @@ void agg_renderer<T>::process(text_symbolizer const& sym,
             {
                 placement text_placement(info, sym, placement_options, scale_factor_);
                 text_placement.avoid_edges = sym.get_avoid_edges();
+                if (writer.first)
+                    text_placement.collect_extents =true; // needed for inmem metawriter
+
                 if (sym.get_label_placement() == POINT_PLACEMENT ||
                         sym.get_label_placement() == INTERIOR_PLACEMENT)
                 {
@@ -121,7 +126,6 @@ void agg_renderer<T>::process(text_symbolizer const& sym,
                                                 angle, sym.get_vertical_alignment(),sym.get_line_spacing(),
                                                 sym.get_character_spacing(),sym.get_horizontal_alignment(),
                                                 sym.get_justify_alignment());
-
                     finder.update_detector(text_placement);
                 }
                 else if ( geom.num_points() > 1 && sym.get_label_placement() == LINE_PLACEMENT)
@@ -141,7 +145,6 @@ void agg_renderer<T>::process(text_symbolizer const& sym,
                     ren.render(x,y);
                 }
 
-                metawriter_with_properties writer = sym.get_metawriter();
                 if (writer.first) writer.first->add_text(text_placement, faces, feature, t_, writer.second);
             }
         }

src/metawriter_inmem.cpp

@@ -79,20 +79,10 @@ metawriter_inmem::add_text(placement const& p,
                            Feature const& feature,
                            CoordTransform const& /*t*/,
                            metawriter_properties const& properties) {
-  // there's more than one bbox for the text (one for each char), so keeping it
-  // simple for the moment and merging them all together...
-  if (p.envelopes.size() > 0) {
-    // stupid queue - doesn't expose begin() and end(), so forced to iterate by
-    // taking a copy...
-    std::queue<box2d<double> > env_copy = p.envelopes;
+  if (p.extents.valid()) {
     meta_instance inst;
-    box2d<double> box = env_copy.front();
-    while (env_copy.size() > 1) {
-      env_copy.pop();
-      box.expand_to_include(env_copy.front());
-    }
     inst.properties = intersect_properties(feature, properties);
-    inst.box = box;
+    inst.box = p.extents;
     instances_.push_back(inst);
   }
 }

src/placement_finder.cpp

@@ -72,7 +72,9 @@ placement::placement(string_info & info_,
       has_dimensions(has_dimensions_),
       allow_overlap(false),
       dimensions(std::make_pair(w,h)),
-      text_size(placement_options->text_size)
+      text_size(placement_options->text_size),
+      collect_extents(false),
+      extents()
 {}
 
 placement::placement(string_info & info_,
@@ -97,7 +99,9 @@ placement::placement(string_info & info_,
       has_dimensions(false),
       allow_overlap(sym.get_allow_overlap()),
       dimensions(),
-      text_size(placement_options->text_size)
+      text_size(placement_options->text_size),
+      collect_extents(false),
+      extents()
 {}
 
 
@@ -960,11 +964,27 @@ void placement_finder<DetectorT>::find_line_circle_intersection(
 template <typename DetectorT>
 void placement_finder<DetectorT>::update_detector(placement & p)
 {
+    bool first = true;
+
+    // add the bboxes to the detector and remove from the placement
     while (!p.envelopes.empty())
     {
         box2d<double> e = p.envelopes.front();
         detector_.insert(e, p.info.get_string());
         p.envelopes.pop();
+
+        if (p.collect_extents)
+        {
+            if(first)
+            {
+                first = false;
+                p.extents = e;
+            }
+            else
+            {
+                p.extents.expand_to_include(e);
+            }
+        }
     }
 }
 
@@ -974,7 +994,6 @@ void placement_finder<DetectorT>::clear()
     detector_.clear();
 }
 
-
 typedef coord_transform2<CoordTransform,geometry_type> PathType;
 typedef label_collision_detector4 DetectorType;