githubmirror/omim

map/ge0_parser.cpp
155 строк4 KB
Mikhail Gorbushin
[geometry] Get rid of MercatorBounds, refactor to namespace mercator
01 ноя 2019, 11:09
01 ноя 2019, 11:096f5d401
#include "map/ge0_parser.hpp"

#include "map/mwm_url.hpp"

#include "api/internal/c/api-client-internals.h"

#include "geometry/mercator.hpp"

#include "coding/url_encode.hpp"

#include "base/math.hpp"
#include "base/string_utils.hpp"

#include <algorithm>

using namespace std;

namespace url_scheme
{
Ge0Parser::Ge0Parser()
{
  for (size_t i = 0; i < 256; ++i)
    m_base64ReverseCharTable[i] = 255;
  for (uint8_t i = 0; i < 64; ++i)
  {
    char c = MapsWithMe_Base64Char(i);
    m_base64ReverseCharTable[static_cast<uint8_t>(c)] = i;
  }
}

bool Ge0Parser::Parse(string const & url, url_scheme::ApiPoint & outPoint, double & outZoomLevel)
{
  // URL format:
  //
  //       +------------------  1 byte: zoom level
  //       |+-------+---------  9 bytes: lat,lon
  //       ||       | +--+----  Variable number of bytes: point name
  //       ||       | |  |
  // ge0://ZCoordba64/Name

  const int ZOOM_POSITION = 6;
  const int LATLON_POSITION = ZOOM_POSITION + 1;
  const int NAME_POSITON_IN_URL = 17;
  const int LATLON_LENGTH = NAME_POSITON_IN_URL - LATLON_POSITION - 1;
  const size_t MAX_NAME_LENGTH = 256;

  if (url.size() < 16 || !strings::StartsWith(url, "ge0://"))
    return false;

  uint8_t const zoomI = DecodeBase64Char(url[ZOOM_POSITION]);
  if (zoomI > 63)
    return false;
  outZoomLevel = DecodeZoom(zoomI);

  DecodeLatLon(url.substr(LATLON_POSITION, LATLON_LENGTH), outPoint.m_lat, outPoint.m_lon);

  ASSERT(mercator::ValidLon(outPoint.m_lon), (outPoint.m_lon));
  ASSERT(mercator::ValidLat(outPoint.m_lat), (outPoint.m_lat));

  if (url.size() >= NAME_POSITON_IN_URL)
  {
    outPoint.m_name = DecodeName(
        url.substr(NAME_POSITON_IN_URL, min(url.size() - NAME_POSITON_IN_URL, MAX_NAME_LENGTH)));
  }
  return true;
}

uint8_t Ge0Parser::DecodeBase64Char(char const c)
{
  return m_base64ReverseCharTable[static_cast<uint8_t>(c)];
}

double Ge0Parser::DecodeZoom(uint8_t const zoomByte)
{
  // Coding zoom -  int newZoom = ((oldZoom - 4) * 4)
  return static_cast<double>(zoomByte) / 4 + 4;
}

void Ge0Parser::DecodeLatLon(string const & url, double & lat, double & lon)
{
  int latInt = 0, lonInt = 0;
  DecodeLatLonToInt(url, latInt, lonInt, url.size());
  lat = DecodeLatFromInt(latInt, (1 << MAPSWITHME_MAX_COORD_BITS) - 1);
  lon = DecodeLonFromInt(lonInt, (1 << MAPSWITHME_MAX_COORD_BITS) - 1);
}

void Ge0Parser::DecodeLatLonToInt(string const & url, int & lat, int & lon, size_t const bytes)
{
  int shift = MAPSWITHME_MAX_COORD_BITS - 3;
  for (size_t i = 0; i < bytes; ++i, shift -= 3)
  {
    const uint8_t a = DecodeBase64Char(url[i]);
    const int lat1 = (((a >> 5) & 1) << 2 | ((a >> 3) & 1) << 1 | ((a >> 1) & 1));
    const int lon1 = (((a >> 4) & 1) << 2 | ((a >> 2) & 1) << 1 | (a & 1));
    lat |= lat1 << shift;
    lon |= lon1 << shift;
  }
  const double middleOfSquare = 1 << (3 * (MAPSWITHME_MAX_POINT_BYTES - bytes) - 1);
  lat += middleOfSquare;
  lon += middleOfSquare;
}

double Ge0Parser::DecodeLatFromInt(int const lat, int const maxValue)
{
  return static_cast<double>(lat) / maxValue * 180 - 90;
}

double Ge0Parser::DecodeLonFromInt(int const lon, int const maxValue)
{
  return static_cast<double>(lon) / (maxValue + 1.0) * 360.0 - 180;
}

string Ge0Parser::DecodeName(string name)
{
  ValidateName(name);
  name = UrlDecode(name);
  SpacesToUnderscore(name);
  return name;
}

void Ge0Parser::SpacesToUnderscore(string & name)
{
  for (size_t i = 0; i < name.size(); ++i)
  {
    if (name[i] == ' ')
      name[i] = '_';
    else if (name[i] == '_')
      name[i] = ' ';
  }
}

void Ge0Parser::ValidateName(string & name)
{
  if (name.empty())
    return;
  for (size_t i = 0; i + 2 < name.size(); ++i)
  {
    if (name[i] == '%' && (!IsHexChar(name[i + 1]) || !IsHexChar(name[i + 2])))
    {
      name.resize(i);
      return;
    }
  }
  if (name[name.size() - 1] == '%')
    name.resize(name.size() - 1);
  else if (name.size() > 1 && name[name.size() - 2] == '%')
    name.resize(name.size() - 2);
}

bool Ge0Parser::IsHexChar(char const a)
{
  return ((a >= '0' && a <= '9') || (a >= 'A' && a <= 'F') || (a >= 'a' && a <= 'f'));
}

}  // namespace url_scheme