tippecanoe/geojson.c

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <string.h>
#include <fcntl.h>
#include <ctype.h>
#include <errno.h>
#include <limits.h>
#include "jsonpull.h"

#define GEOM_POINT 0                /* array of positions */
#define GEOM_MULTIPOINT 1           /* array of arrays of positions */
#define GEOM_LINESTRING 2           /* array of arrays of positions */
#define GEOM_MULTILINESTRING 3      /* array of arrays of arrays of positions */
#define GEOM_POLYGON 4              /* array of arrays of arrays of positions */
#define GEOM_MULTIPOLYGON 5         /* array of arrays of arrays of arrays of positions */
#define GEOM_TYPES 6

#define MB_GEOM_POINT 1
#define MB_GEOM_LINE 2
#define MB_GEOM_POLYGON 3

#define OP_MOVETO 1
#define OP_LINETO 2
#define OP_CLOSEPATH 7

char *geometry_names[GEOM_TYPES] = {
	"Point",
	"MultiPoint",
	"LineString",
	"MultiLineString",
	"Polygon",
	"MultiPolygon",
};

int geometry_within[GEOM_TYPES] = {
	-1,                /* point */
	GEOM_POINT,        /* multipoint */
	GEOM_POINT,        /* linestring */
	GEOM_LINESTRING,   /* multilinestring */
	GEOM_LINESTRING,   /* polygon */
	GEOM_POLYGON,      /* multipolygon */
};

int mb_geometry[GEOM_TYPES] = {
	MB_GEOM_POINT,
	MB_GEOM_POINT,
	MB_GEOM_LINE,
	MB_GEOM_LINE,
	MB_GEOM_POLYGON,
	MB_GEOM_POLYGON,
};

/* XXX */
#define META_STRING JSON_STRING
#define META_INTEGER JSON_NUMBER
#define META_BOOLEAN JSON_TRUE

// http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
void latlon2tile(double lat, double lon, int zoom, unsigned int *x, unsigned int *y) {
	double lat_rad = lat * M_PI / 180;
	unsigned long long n = 1LL << zoom;

	*x = n * ((lon + 180) / 360);
	*y = n * (1 - (log(tan(lat_rad) + 1/cos(lat_rad)) / M_PI)) / 2;
}

void parse_geometry(int t, json_object *j, unsigned *bbox, int *n, unsigned **out, int op) {
	if (j == NULL || j->type != JSON_ARRAY) {
		fprintf(stderr, "expected array for type %d\n", t);
		return;
	}

	int within = geometry_within[t];
	if (within >= 0) {
		printf("[");
		int i;
		for (i = 0; i < j->length; i++) {
			if (within == GEOM_POINT) {
				if (i == 0 || t == GEOM_MULTIPOINT) {
					op = OP_MOVETO;
				} else {
					op = OP_LINETO;
				}
			}

			parse_geometry(within, j->array[i], bbox, n, out, op);
		}
		printf("]");
	} else {
		if (j->length == 2 && j->array[0]->type == JSON_NUMBER && j->array[1]->type == JSON_NUMBER) {
			if (out != NULL || bbox != NULL) {
				unsigned x, y;
				double lon = j->array[0]->number;
				double lat = j->array[1]->number;
				latlon2tile(lat, lon, 32, &x, &y);

				if (bbox != NULL) {
					if (x < bbox[0]) {
						bbox[0] = x;
					}
					if (y < bbox[1]) {
						bbox[1] = y;
					}
					if (x > bbox[2]) {
						bbox[2] = x;
					}
					if (y > bbox[3]) {
						bbox[3] = y;
					}
				}
				if (out != NULL) {
					(*out)[0] = op;
					(*out)[1] = x;
					(*out)[2] = y;
					(*out) += 3;
				}
				if (n != NULL) {
					*n += 3;
				}
			}

			printf(" %d %f,%f ", op, j->array[0]->number, j->array[1]->number);
		} else {
			fprintf(stderr, "malformed point");
		}
	}

	if (t == GEOM_POLYGON) {
		if (out != NULL) {
			(*out)[0] = OP_CLOSEPATH;
			(*out) += 1;
		}
		if (n != NULL) {
			*n += 1;
		}
		printf(" closepath ");
	}
}

void read_json(FILE *f) {
	json_pull *jp = json_begin_file(f);

	while (1) {
		json_object *j = json_read(jp);
		if (j == NULL) {
			if (jp->error != NULL) {
				fprintf(stderr, "%d: %s\n", jp->line, jp->error);
			}

			json_free(jp->root);
			break;
		}

		json_object *type = json_hash_get(j, "type");
		if (type == NULL || type->type != JSON_STRING || strcmp(type->string, "Feature") != 0) {
			continue;
		}

		json_object *geometry = json_hash_get(j, "geometry");
		if (geometry == NULL) {
			fprintf(stderr, "%d: feature with no geometry\n", jp->line);
			goto next_feature;
		}

		json_object *geometry_type = json_hash_get(geometry, "type");
		if (geometry_type == NULL || geometry_type->type != JSON_STRING) {
			fprintf(stderr, "%d: geometry without type string\n", jp->line);
			goto next_feature;
		}

		json_object *properties = json_hash_get(j, "properties");
		if (properties == NULL || properties->type != JSON_HASH) {
			fprintf(stderr, "%d: feature without properties hash\n", jp->line);
			goto next_feature;
		}

		json_object *coordinates = json_hash_get(geometry, "coordinates"); 
		if (coordinates == NULL || coordinates->type != JSON_ARRAY) {
			fprintf(stderr, "%d: feature without coordinates array\n", jp->line);
			goto next_feature;
		}

		int t;
		for (t = 0; t < GEOM_TYPES; t++) {
			if (strcmp(geometry_type->string, geometry_names[t]) == 0) {
				break;
			}
		}
		if (t >= GEOM_TYPES) {
			fprintf(stderr, "%d: Can't handle geometry type %s\n", jp->line, geometry_type->string);
			goto next_feature;
		}

		/* scope for variable-length arrays */
		{
			char *metakey[properties->length];
			char *metaval[properties->length];
			int metatype[properties->length];
			int m = 0;

			int i;
			for (i = 0; i < properties->length; i++) {
				if (properties->keys[i]->type == JSON_STRING) {
					metakey[m] = properties->keys[i]->string;

					if (properties->values[i] != NULL && properties->values[i]->type == JSON_STRING) {
						metatype[m] = META_STRING;
						metaval[m] = properties->values[i]->string;
						m++;
					} else if (properties->values[i] != NULL && properties->values[i]->type == JSON_NUMBER) {
						metatype[m] = META_INTEGER;
						metaval[m] = properties->values[i]->string;
						m++;
					} else if (properties->values[i] != NULL && (properties->values[i]->type == JSON_TRUE || properties->values[i]->type == JSON_FALSE)) {
						metatype[m] = META_BOOLEAN;
						metaval[m] = properties->values[i]->string;
						m++;
					} else {
						fprintf(stderr, "%d: Unsupported meta type\n", jp->line);
						goto next_feature;
					}
				}
			}

			unsigned bbox[] = { UINT_MAX, UINT_MAX, 0, 0 };
			int n = 0;

			printf("%d: ", mb_geometry[t]);
			parse_geometry(t, coordinates, bbox, &n, NULL, OP_MOVETO);
			printf("\n");

			unsigned out[n];
			unsigned *end = out;
			parse_geometry(t, coordinates, NULL, NULL, &end, OP_MOVETO);
			printf("\n-> ");
			for (i = 0; i < n; i++) {
				printf("%x ", out[i]);
			}
			printf("\n");
			
			printf("%d elements, bbox %x %x %x %x\n", n, bbox[0], bbox[1], bbox[2], bbox[3]);
		}

next_feature:
		json_free(j);

		/* XXX check for any non-features in the outer object */
	}

	json_end(jp);
}

int main(int argc, char **argv) {
	if (argc > 1) {
		int i;
		for (i = 1; i < argc; i++) {
			FILE *f = fopen(argv[i], "r");
			if (f == NULL) {
				fprintf(stderr, "%s: %s: %s\n", argv[0], argv[i], strerror(errno));
			} else {
				read_json(f);
				fclose(f);
			}
		}
	} else {
		read_json(stdin);
	}
	return 0;
}