Added vector tile strategy

src/vector_tile_processor.ipp

@@ -50,6 +50,7 @@
 #include <string>
 #include <stdexcept>
 
+#include "vector_tile_strategy.hpp"
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wunused-parameter"
@@ -1249,19 +1250,13 @@ unsigned processor<T>::handle_geometry(mapnik::feature_impl const& feature,
                                        mapnik::proj_transform const& prj_trans,
                                        mapnik::box2d<double> const& buffered_query_ext)
 {
-    mapnik::proj_backward_strategy proj_strat(prj_trans);
-    mapnik::view_strategy view_strat(t_);
-    mapnik::geometry::scale_rounding_strategy scale_strat(backend_.get_path_multiplier());
-    using sg_type = mapnik::geometry::strategy_group<mapnik::proj_backward_strategy, 
-                                                     mapnik::view_strategy, 
-                                                     mapnik::geometry::scale_rounding_strategy >;
-    sg_type sg(proj_strat, view_strat, scale_strat);
+    vector_tile_strategy vs(prj_trans, t_, backend_.get_path_multiplier());
     mapnik::geometry::point<double> p1_min(buffered_query_ext.minx(), buffered_query_ext.miny());
     mapnik::geometry::point<double> p1_max(buffered_query_ext.maxx(), buffered_query_ext.maxy());
-    mapnik::geometry::point<std::int64_t> p2_min = mapnik::geometry::transform<std::int64_t>(p1_min, sg);
-    mapnik::geometry::point<std::int64_t> p2_max = mapnik::geometry::transform<std::int64_t>(p1_max, sg);
+    mapnik::geometry::point<std::int64_t> p2_min = mapnik::geometry::transform<std::int64_t>(p1_min, vs);
+    mapnik::geometry::point<std::int64_t> p2_max = mapnik::geometry::transform<std::int64_t>(p1_max, vs);
     box2d<int> bbox(p2_min.x, p2_min.y, p2_max.x, p2_max.y);
-    mapnik::geometry::geometry<std::int64_t> new_geom = mapnik::geometry::transform<std::int64_t>(geom, sg);
+    mapnik::geometry::geometry<std::int64_t> new_geom = mapnik::geometry::transform<std::int64_t>(geom, vs);
     encoder_visitor<T> encoder(backend_,feature,bbox, area_threshold_);
     if (simplify_distance_ > 0)
     {

src/vector_tile_strategy.hpp

@@ -0,0 +1,88 @@
+/*****************************************************************************
+ *
+ * This file is part of Mapnik (c++ mapping toolkit)
+ *
+ * Copyright (C) 2014 Artem Pavlenko
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ *****************************************************************************/
+
+#ifndef MAPNIK_VECTOR_TILE_STRATEGY_HPP
+#define MAPNIK_VECTOR_TILE_STRATEGY_HPP
+
+// mapnik
+#include <mapnik/config.hpp>
+#include <mapnik/util/noncopyable.hpp>
+#include <mapnik/proj_transform.hpp>
+#include <mapnik/view_transform.hpp>
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#pragma GCC diagnostic ignored "-Wunused-local-typedef"
+#include <boost/geometry/core/coordinate_type.hpp>
+#include <boost/geometry/core/access.hpp>
+#include <boost/numeric/conversion/cast.hpp>
+#pragma GCC diagnostic pop
+
+
+namespace mapnik {
+
+namespace vector_tile_impl {
+
+struct vector_tile_strategy
+{
+    vector_tile_strategy(proj_transform const& prj_trans,
+                         view_transform const& tr,
+                         double scaling)
+        : prj_trans_(prj_trans),
+          tr_(tr),
+          scaling_(scaling) {}
+
+    template <typename P1, typename P2>
+    inline bool apply(P1 const& p1, P2 & p2) const
+    {
+        using p2_type = typename boost::geometry::coordinate_type<P2>::type;
+        double x = boost::geometry::get<0>(p1);
+        double y = boost::geometry::get<1>(p1);
+        double z = 0.0;
+        if (!prj_trans_.backward(x, y, z)) return false;
+        tr_.forward(&x,&y);
+        x = x * scaling_;
+        y = y * scaling_;
+        x = std::floor(x + 0.5);
+        y = std::floor(y + 0.5);
+        boost::geometry::set<0>(p2, static_cast<p2_type>(x));
+        boost::geometry::set<1>(p2, static_cast<p2_type>(y));
+        return true;
+    }
+
+    template <typename P1, typename P2>
+    inline P2 execute(P1 const& p1, bool & status) const
+    {
+        P2 p2;
+        status = apply(p1, p2);
+        return p2;
+    }
+
+    proj_transform const& prj_trans_;
+    view_transform const& tr_;
+    double const scaling_;
+};
+
+}
+}
+
+#endif // MAPNIK_VECTOR_TILE_STRATEGY_HPP