shape.input - add support for reading offset/record_length from *.shx in shape_featureset (no *.index) - ref #3126

plugins/input/shape/shape_featureset.cpp

@@ -22,7 +22,7 @@
 
 // stl
 #include <iostream>
-
+#include <cassert>
 // mapnik
 #include <mapnik/debug.hpp>
 #include <mapnik/feature_factory.hpp>
@@ -54,7 +54,8 @@ shape_featureset<filterT>::shape_featureset(filterT const& filter,
       ctx_(std::make_shared<mapnik::context_type>())
 {
     shape_.shp().skip(100);
-    setup_attributes(ctx_, attribute_names, shape_name, shape_,attr_ids_);
+    shape_.shx().skip(100);
+    setup_attributes(ctx_, attribute_names, shape_name, shape_, attr_ids_);
 }
 
 template <typename filterT>
@@ -64,12 +65,13 @@ feature_ptr shape_featureset<filterT>::next()
     {
         return feature_ptr();
     }
-
-
-    while (shape_.shp().pos() < std::streampos(file_length_ * 2))
+    while  (!shape_.shx().is_eof())
     {
-        shape_.move_to(shape_.shp().pos());
-        shape_file::record_type record(shape_.reclength_ * 2);
+        int offset = shape_.shx().read_xdr_integer();
+        int record_length = shape_.shx().read_xdr_integer();
+        shape_.move_to(2*offset);
+        assert(record_length == shape_.reclength_);
+        shape_file::record_type record(record_length * 2);
         shape_.shp().read_record(record);
         int type = record.read_ndr_integer();
 
@@ -136,13 +138,11 @@ feature_ptr shape_featureset<filterT>::next()
         if (attr_ids_.size())
         {
             shape_.dbf().move_to(shape_.id_);
-            std::vector<int>::const_iterator itr = attr_ids_.begin();
-            std::vector<int>::const_iterator end = attr_ids_.end();
             try
             {
-                for (; itr != end; ++itr)
+                for (auto id : attr_ids_)
                 {
-                    shape_.dbf().add_attribute(*itr, *tr_, *feature); //TODO optimize!!!
+                    shape_.dbf().add_attribute(id, *tr_, *feature); //TODO optimize!!!
                 }
             }
             catch (...)

plugins/input/shape/shape_io.cpp

@@ -31,18 +31,20 @@
 
 using mapnik::datasource_exception;
 const std::string shape_io::SHP = ".shp";
+const std::string shape_io::SHX = ".shx";
 const std::string shape_io::DBF = ".dbf";
 const std::string shape_io::INDEX = ".index";
 
 shape_io::shape_io(std::string const& shape_name, bool open_index)
     : type_(shape_null),
       shp_(shape_name + SHP),
+      shx_(shape_name + SHX),
       dbf_(shape_name + DBF),
       reclength_(0),
       id_(0)
 {
     bool ok = (shp_.is_open() && dbf_.is_open());
-    if (! ok)
+    if (!ok)
     {
         throw datasource_exception("Shape Plugin: cannot read shape file '" + shape_name + "'");
     }
@@ -58,6 +60,10 @@ shape_io::shape_io(std::string const& shape_name, bool open_index)
             MAPNIK_LOG_WARN(shape) << "shape_io: Could not open index=" << shape_name << INDEX;
         }
     }
+    if  (!index_ && !shx_.is_open())
+    {
+        throw datasource_exception("Shape Plugin: cannot read shape index file '" + shape_name + ".shx'");
+    }
 }
 
 shape_io::~shape_io() {}
@@ -74,6 +80,11 @@ shape_file& shape_io::shp()
     return shp_;
 }
 
+shape_file& shape_io::shx()
+{
+    return shx_;
+}
+
 dbf_file& shape_io::dbf()
 {
     return dbf_;

plugins/input/shape/shape_io.hpp

@@ -61,6 +61,7 @@ public:
     ~shape_io();
 
     shape_file& shp();
+    shape_file& shx();
     dbf_file& dbf();
 
     inline boost::optional<shape_file&> index()
@@ -81,6 +82,7 @@ public:
 
     shapeType type_;
     shape_file shp_;
+    shape_file shx_;
     dbf_file   dbf_;
     std::unique_ptr<shape_file> index_;
     unsigned reclength_;
@@ -88,6 +90,7 @@ public:
     box2d<double> cur_extent_;
 
     static const std::string SHP;
+    static const std::string SHX;
     static const std::string DBF;
     static const std::string INDEX;
 };