c-geohex3

GeoHex v3 implementation in C99.

VERSION: 1.50

What is GeoHex?

https://sites.google.com/site/geohexdocs/ http://geohex.net/

Synopsis

#include <geohex3.h>
#include <stdio.h>
#include <stdint.h>

int main (int argc, char *argv[]) {
  for (int i = 1; i < argc; i++) {
    printf("/********* geohex:%s **********/\n", argv[i]);
    const geohex_verify_result_t result = geohex_verify_code(argv[i]);
    switch (result) {
      case GEOHEX_VERIFY_RESULT_SUCCESS:
        {
          const geohex_t geohex = geohex_get_zone_by_code(argv[i]);
          printf("code  = %s\n", geohex.code);
          printf("level = %zu\n", geohex.level);
          printf("size  = %Lf\n", geohex.size);
          printf("[location]\n");
          printf("lat = %Lf\n", geohex.location.lat);
          printf("lng = %Lf\n", geohex.location.lng);
          printf("[coordinate]\n");
          printf("x = %ld\n", geohex.coordinate.x);
          printf("y = %ld\n", geohex.coordinate.y);
        }
        break;
      case GEOHEX_VERIFY_RESULT_INVALID_CODE:
        printf("code:%s is invalid.\n", argv[i]);
        break;
      case GEOHEX_VERIFY_RESULT_INVALID_LEVEL:
        printf("code:%s is invalid level. MAX_LEVEL:%d\n", argv[i], GEOHEX_MAX_LEVEL);
        break;
    }
  }
}

Dependencies

• picotest
• cmake
• prove

Cheat Sheet

SETUP

git clone https://github.com/karupanerura/c-geohex3.git
cd c-geohex3
git submodule update --init

BUILD

cmake .
make

TEST

make test

INSTALL

sudo -H make install

Types

SEE DETAIL: geohex3.h

Struct

geohex_location_t

Details of struct:

• lat: long double - latitude
• lng: long double - longitude

geohex_coordinate_t

Details of struct:

• x: int64_t
• y: int64_t

geohex_polygon_t

Details of struct:

• top:
  • left: geohex_location_t
  • right: geohex_location_t
• middle:
  • left: geohex_location_t
  • right: geohex_location_t
• bottom:
  • left: geohex_location_t
  • right: geohex_location_t

geohex_t

Details of struct:

• location: geohex_location_t
• coordinate: geohex_coordinate_t
• code: char *
• level: geohex_level_t
• size: long double

Enum

geohex_verify_result_t

Enum value. Result of verifing geohex's code.

• GEOHEX_VERIFY_RESULT_SUCCESS: Success to verify code.
• GEOHEX_VERIFY_RESULT_INVALID_CODE: Invalid code format.
• GEOHEX_VERIFY_RESULT_INVALID_LEVEL: Invalid geohex's level. (0-15 is valid.)

Others

geohex_level_t

Alias of size_t. Because geohex's level is defined as strlen(code) - 2.

Functions

SEE DETAIL: geohex3.h

Constructor

static inline geohex_coordinate_t geohex_coordinate(const int64_t x, const int64_t y);

Creates geohex_coordinate_t.

geohex_coordinate_t coordinate = geohex_coordinate(123L, 123L);

static inline geohex_location_t geohex_location(const double lat, const double lng);

Creates geohex_location_t.

geohex_location_t location = geohex_location(40.5814792855475L, 134.296601127877L);

geohex_t geohex_get_zone_by_location(const geohex_location_t location, geohex_level_t level);

Creates geohex_t by location.

geohex_t geohex = geohex_get_zone_by_location(geohex_location(40.5814792855475L, 134.296601127877L), 7);

geohex_t geohex_get_zone_by_coordinate(const geohex_coordinate_t coordinate, geohex_level_t level);

Creates geohex_t by coordinate.

geohex_t geohex = geohex_get_zone_by_coordinate(geohex_coordinate(123L, 123L), 7);

geohex_t geohex_get_zone_by_code(const char *code);

Creates geohex_t by geohex's code.

geohex_t geohex = geohex_get_zone_by_code("XE1234");

Utility

static inline long double geohex_hexsize(const geohex_level_t level);

Calculate geohex size.

static inline geohex_level_t geohex_calc_level_by_code(const char *code);

Calculate geohex level.

geohex_level_t level = geohex_calc_level_by_code("XE2345"); // => 4

geohex_verify_result_t geohex_verify_code(const char *code);

Verify geohex code.

const geohex_verify_result_t result = geohex_verify_code(geohex_code);
switch (result) {
case GEOHEX_VERIFY_RESULT_SUCCESS:
  ...;
  break;
case GEOHEX_VERIFY_RESULT_INVALID_CODE:
  ...;
  break;
case GEOHEX_VERIFY_RESULT_INVALID_LEVEL:
  ...;
  break;
}

Converter

geohex_coordinate_t geohex_location2coordinate(const geohex_location_t location);

Convert geohex_location_t to geohex_coordinate_t.

geohex_coordinate_t coordinate = geohex_location2coordinate(geohex_location(40.5814792855475L, 134.296601127877L));

geohex_location_t geohex_coordinate2location(const geohex_coordinate_t coordinate);

Convert geohex_coordinate_t to geohex_location_t.

geohex_coordinate_t coordinate = geohex_coordinate2location(geohex_coordinate(123L, 123L));

geohex_polygon_t geohex_get_hex_polygon(const geohex_t *geohex);

Convert geohex_t to geohex_polygon_t. (calc vertex location of geohex's polygon.)

geohex_t geohex = geohex_get_zone_by_code("XE1234");
geohex_polygon_t polygon = geohex_get_hex_polygon(&geohex);

LICENCE

MIT Licence. (GeoHex is MIT Licence too.)

AUTHOR

karupanerura