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TWKB - port CartoDB implementation to mapnik 3.x.x

Browse source 
ref https://github.com/CartoDB/mapnik/blob/2.3.x.cartodb/plugins/input/postgis/postgis_utils.cpp
ref https://github.com/CartoDB/mapnik/tree/2.3.x.cartodb/plugins/input/postgis#23xcartodb
This commit is contained in:
artemp 2016-03-11 16:20:07 +01:00
parent f9397e7e66
commit 1f61aa3981
3 changed files with 393 additions and 3 deletions
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8
include/mapnik/wkb.hpp
View file

@ -60,9 +60,11 @@ class MAPNIK_DECL geometry_utils : private util::noncopyable
{
public:
static mapnik::geometry::geometry<double> from_wkb(const char* wkb,
std::size_t size,
wkbFormat format = wkbGeneric);
static geometry::geometry<double> from_wkb(char const* wkb,
std::size_t size,
wkbFormat format = wkbGeneric);
static geometry::geometry<double> from_twkb(char const* twkb, std::size_t size);
};
}

1
src/build.py
View file

@ -205,6 +205,7 @@ source = Split(
rule.cpp
save_map.cpp
wkb.cpp
twkb.cpp
projection.cpp
proj_transform.cpp
scale_denominator.cpp

387
src/twkb.cpp Normal file
View file

@ -0,0 +1,387 @@
/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2016 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
*
*****************************************************************************/
// mapnik
#include <mapnik/wkb.hpp>
#include <mapnik/feature.hpp>
#include <mapnik/geom_util.hpp>
#include <mapnik/util/noncopyable.hpp>
#include <mapnik/geometry_correct.hpp>
#include <cmath>
namespace mapnik { namespace detail {
struct twkb_reader : mapnik::util::noncopyable
{
private:
const char *twkb_;
size_t size_;
unsigned int pos_;
// Metadata on the geometry we are parsing
uint8_t twkb_type_;
uint8_t has_bbox_;
uint8_t has_size_;
uint8_t has_idlist_;
uint8_t has_z_;
uint8_t has_m_;
uint8_t is_empty_;
// Precision factors to convert ints to double
double factor_xy_;
double factor_z_;
double factor_m_;
// An array to keep delta values from 4 dimensions
int64_t coord_x_;
int64_t coord_y_;
int64_t coord_z_;
int64_t coord_m_;
public:
enum twkbGeometryType : std::uint8_t
{
twkbPoint = 1,
twkbLineString = 2,
twkbPolygon = 3,
twkbMultiPoint = 4,
twkbMultiLineString = 5,
twkbMultiPolygon = 6,
twkbGeometryCollection = 7
};
twkb_reader(char const* twkb, size_t size)
: twkb_(twkb), size_(size), pos_(0), twkb_type_(0), // Geometry type
has_bbox_(0), // Bounding box?
has_size_(0), // Size attribute?
has_idlist_(0), // Presence of X/Y
has_z_(0), // Presence of Z
has_m_(0), // Presence of M
is_empty_(0), // Empty?
factor_xy_(0.0), // Expansion factor for X/Y
factor_z_(0.0), // Expansion factor for Z
factor_m_(0.0) // Expansion factor for M
{}
mapnik::geometry::geometry<double> read()
{
mapnik::geometry::geometry<double> geom = mapnik::geometry::geometry_empty();
// Read the metadata bytes, populating all the
// information about optional fields, extended (z/m) dimensions
// expansion factors and so on
read_header();
// Each new read call has to reset the coordinate accumulators
coord_x_ = 0; // Accumulation register (x)
coord_y_ = 0; // Accumulation register (y)
coord_z_ = 0; // Accumulation register (z)
coord_m_ = 0; // Accumulation register (m)
// If the geometry is empty, add nothing to the paths array
if (is_empty_)
return geom;
// Read the [optional] size information
if (has_size_)
size_ = read_unsigned_integer();
// Read the [optional] bounding box information
if (has_bbox_) read_bbox();
switch (twkb_type_)
{
case twkbPoint:
geom = read_point();
break;
case twkbLineString:
geom = read_linestring();
break;
case twkbPolygon:
geom = read_polygon();
break;
case twkbMultiPoint:
geom = read_multipoint();
break;
case twkbMultiLineString:
geom = read_multilinestring();
break;
case twkbMultiPolygon:
geom = read_multipolygon();
break;
case twkbGeometryCollection:
geom = read_collection();
default:
break;
}
return geom;
}
private:
int64_t unzigzag64(uint64_t val)
{
if (val & 0x01)
return -1 * (int64_t)((val + 1) >> 1);
else
return (int64_t)(val >> 1);
}
int32_t unzigzag32(uint32_t val)
{
if (val & 0x01) return -1 * (int32_t)((val + 1) >> 1);
else return (int32_t)(val >> 1);
}
int8_t unzigzag8(uint8_t val)
{
if (val & 0x01) return -1 * (int8_t)((val + 1) >> 1);
else return (int8_t)(val >> 1);
}
// Read from signed 64bit varint
int64_t read_signed_integer() { return unzigzag64(read_unsigned_integer()); }
// Read from unsigned 64bit varint
uint64_t read_unsigned_integer()
{
uint64_t nVal = 0;
int nShift = 0;
uint8_t nByte;
// Check so we don't read beyond the twkb
while (pos_ < size_)
{
nByte = twkb_[pos_];
// We get here when there is more to read in the input varInt
// Here we take the least significant 7 bits of the read
// byte and put it in the most significant place in the result variable.
nVal |= ((uint64_t)(nByte & 0x7f)) << nShift;
// move the "cursor" of the input buffer step (8 bits)
pos_++;
// move the cursor in the resulting variable (7 bits)
nShift += 7;
// Hibit isn't set, so this is the last byte
if (!(nByte & 0x80)) {
return nVal;
}
}
return 0;
}
// Every TWKB geometry starts with a metadata header
//
// type_and_dims byte
// metadata_header byte
// [extended_dims] byte
// [size] uvarint
// [bounds] bbox
//
void read_header()
{
uint8_t type_precision = twkb_[pos_++];
uint8_t metadata = twkb_[pos_++];
twkb_type_ = type_precision & 0x0F;
int8_t precision = unzigzag8((type_precision & 0xF0) >> 4);
factor_xy_ = std::pow(10, static_cast<double>(precision));
has_bbox_ = metadata & 0x01;
has_size_ = (metadata & 0x02) >> 1;
has_idlist_ = (metadata & 0x04) >> 2;
uint8_t zm = (metadata & 0x08) >> 3;
is_empty_ = (metadata & 0x10) >> 4;
// Flag for higher dimensions means read a third byte
// of extended dimension information
if (zm)
{
zm = twkb_[pos_++];
// Strip Z/M presence and precision from ext byte
has_z_ = (zm & 0x01);
has_m_ = (zm & 0x02) >> 1;
// Convert the precision into factor
int8_t precision_z = (zm & 0x1C) >> 2;
int8_t precision_m = (zm & 0xE0) >> 5;
factor_z_ = pow(10, (double)precision_z);
factor_m_ = pow(10, (double)precision_m);
}
}
void read_bbox()
{
// we have nowhere to store this box information
// for now, so we'll just move the read head forward
// an appropriate number of times
if (has_bbox_)
{
read_signed_integer(); // uint64_t xmin
read_signed_integer(); // uint64_t xdelta
read_signed_integer(); // uint64_t ymin
read_signed_integer(); // uint64_t ydelta
if (has_z_)
{
read_signed_integer(); // uint64_t zmin
read_signed_integer(); // uint64_t zdelta
}
if (has_m_)
{
read_signed_integer(); // uint64_t mmin
read_signed_integer(); // uint64_t mdelta
}
}
}
void read_idlist(unsigned int num_ids)
{
// we have nowhere to store this id information
// for now, so we'll just move the read head
// forward an appropriate number of times
if (has_idlist_)
{
for (unsigned int i = 0; i < num_ids; ++i)
{
read_signed_integer(); // uint64_t id
}
}
}
template <typename Ring>
void read_coords(Ring & ring, std::size_t num_points)
{
for (std::size_t i = 0; i < num_points; ++i)
{
coord_x_ += read_signed_integer();
coord_y_ += read_signed_integer();
ring.emplace_back( coord_x_ / factor_xy_, coord_y_ / factor_xy_);
// Skip Z and M
if (has_z_) coord_z_ += read_signed_integer();
if (has_m_) coord_m_ += read_signed_integer();
}
}
mapnik::geometry::point<double> read_point()
{
coord_x_ += read_signed_integer();
coord_y_ += read_signed_integer();
double x = coord_x_ / factor_xy_;
double y = coord_y_ / factor_xy_;
return mapnik::geometry::point<double>(x, y);
}
mapnik::geometry::multi_point<double> read_multipoint()
{
mapnik::geometry::multi_point<double> multi_point;
unsigned int num_points = read_unsigned_integer();
if (has_idlist_) read_idlist(num_points);
if (num_points > 0)
{
multi_point.reserve(num_points);
for (unsigned int i = 0; i < num_points; ++i)
{
multi_point.emplace_back(read_point());
}
}
return multi_point;
}
mapnik::geometry::line_string<double> read_linestring()
{
mapnik::geometry::line_string<double> line;
unsigned int num_points = read_unsigned_integer();
if (num_points > 0)
{
line.reserve(num_points);
read_coords<mapnik::geometry::line_string<double>>(line, num_points);
}
return line;
}
mapnik::geometry::multi_line_string<double> read_multilinestring()
{
mapnik::geometry::multi_line_string<double> multi_line;
unsigned int num_lines = read_unsigned_integer();
if (has_idlist_) read_idlist(num_lines);
multi_line.reserve(num_lines);
for (unsigned int i = 0; i < num_lines; ++i)
{
multi_line.push_back(read_linestring());
}
return multi_line;
}
mapnik::geometry::polygon<double> read_polygon()
{
unsigned int num_rings = read_unsigned_integer();
mapnik::geometry::polygon<double> poly;
if (num_rings > 1)
{
poly.interior_rings.reserve(num_rings - 1);
}
for (unsigned int i = 0; i < num_rings; ++i)
{
mapnik::geometry::linear_ring<double> ring;
unsigned int num_points = read_unsigned_integer();
if (num_points > 0)
{
ring.reserve(num_points);
read_coords<mapnik::geometry::linear_ring<double>>(ring, num_points);
}
if ( i == 0) poly.set_exterior_ring(std::move(ring));
else poly.add_hole(std::move(ring));
}
return poly;
}
mapnik::geometry::multi_polygon<double> read_multipolygon()
{
mapnik::geometry::multi_polygon<double> multi_poly;
unsigned int num_polys = read_unsigned_integer();
if (has_idlist_) read_idlist(num_polys);
for (unsigned int i = 0; i < num_polys; ++i)
{
multi_poly.push_back(read_polygon());
}
return multi_poly;
}
mapnik::geometry::geometry_collection<double> read_collection()
{
unsigned int num_geometries = read_unsigned_integer();
mapnik::geometry::geometry_collection<double> collection;
if (has_idlist_) read_idlist(num_geometries);
for (unsigned int i = 0; i < num_geometries; ++i)
{
collection.push_back(read());
}
return collection;
}
};
} // namespace detail
mapnik::geometry::geometry<double> geometry_utils::from_twkb(const char* wkb, std::size_t size)
{
detail::twkb_reader reader(wkb, size);
mapnik::geometry::geometry<double> geom(reader.read());
// note: this will only be applied to polygons
mapnik::geometry::correct(geom);
return geom;
}
} // namespace mapnik