tippecanoe/tile.cc

#include <iostream>
#include <fstream>
#include <string>
#include <stdio.h>
#include <unistd.h>
#include <zlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <math.h>
#include "vector_tile.pb.h"

extern "C" {
	#include "tile.h"
}

#define CMD_BITS 3

// https://github.com/mapbox/mapnik-vector-tile/blob/master/src/vector_tile_compression.hpp
static inline int compress(std::string const& input, std::string& output) {
	z_stream deflate_s;
	deflate_s.zalloc = Z_NULL;
	deflate_s.zfree = Z_NULL;
	deflate_s.opaque = Z_NULL;
	deflate_s.avail_in = 0;
	deflate_s.next_in = Z_NULL;
	deflateInit(&deflate_s, Z_DEFAULT_COMPRESSION);
	deflate_s.next_in = (Bytef *)input.data();
	deflate_s.avail_in = input.size();
	size_t length = 0;
	do {
		size_t increase = input.size() / 2 + 1024;
		output.resize(length + increase);
		deflate_s.avail_out = increase;
		deflate_s.next_out = (Bytef *)(output.data() + length);
		int ret = deflate(&deflate_s, Z_FINISH);
		if (ret != Z_STREAM_END && ret != Z_OK && ret != Z_BUF_ERROR) {
			return -1;
		}
		length += (increase - deflate_s.avail_out);
	} while (deflate_s.avail_out == 0);
	deflateEnd(&deflate_s);
	output.resize(length);
	return 0;
}

int draw(char **meta, mapnik::vector::tile_feature *feature, int z, unsigned tx, unsigned ty, int detail) {
	int px = 0, py = 0;
	int cmd_idx = -1;
	int cmd = -1;
	int length = 0;
	int drew = 0;

	while (1) {
		int op;
		deserialize_int(meta, &op);

		if (op == VT_END) {
			break;
		}

		if (op != cmd) {
			if (cmd_idx >= 0) {
				if (feature != NULL) {
					feature->set_geometry(cmd_idx, (length << CMD_BITS) | (cmd & ((1 << CMD_BITS) - 1)));
				}
			}

			cmd = op;
			length = 0;

			if (feature != NULL) {
				cmd_idx = feature->geometry_size();
				feature->add_geometry(0);
			}
		}

		if (op == VT_MOVETO || op == VT_LINETO) {
			int wx, wy;
			deserialize_int(meta, &wx);
			deserialize_int(meta, &wy);

			long long wwx = (unsigned) wx;
			long long wwy = (unsigned) wy;

			if (z != 0) {
				wwx -= tx << (32 - z);
				wwy -= ty << (32 - z);
			}

			wwx >>= (32 - detail - z);
			wwy >>= (32 - detail - z);

			int dx = wwx - px;
			int dy = wwy - py;

			if (dx != 0 || dy != 0 || length == 0) {
				if (feature != NULL) {
					feature->add_geometry((dx << 1) ^ (dx >> 31));
					feature->add_geometry((dy << 1) ^ (dy >> 31));
				}

				px = wwx;
				py = wwy;
				length++;

				if (op == VT_LINETO && (dx != 0 || dy != 0)) {
					drew = 1;
				}
			}
		} else if (op == VT_CLOSEPATH) {
			length++;
		}
	}

	if (cmd_idx >= 0) {
		if (feature != NULL) {
			feature->set_geometry(cmd_idx, (length << CMD_BITS) | (cmd & ((1 << CMD_BITS) - 1)));
		}
	}

	return drew;
}


void write_tile(struct index *start, struct index *end, char *metabase, unsigned *file_bbox, int z, unsigned tx, unsigned ty, int detail, int basezoom, struct pool *file_keys) {
	GOOGLE_PROTOBUF_VERIFY_VERSION;

	mapnik::vector::tile tile;
	mapnik::vector::tile_layer *layer = tile.add_layers();

	layer->set_name("name");
	layer->set_version(1);

	layer->set_extent(1 << detail);

	struct pool keys;
	keys.n = 0;
	keys.vals = NULL;
	keys.head = NULL;
	keys.tail = NULL;

	struct pool values;
	values.n = 0;
	values.vals = NULL;
	values.head = NULL;
	values.tail = NULL;

	struct pool dup;
	dup.n = 1;
	dup.vals = NULL;
	dup.head = NULL;
	dup.tail = NULL;

	double interval = 1;
	double seq = 0;

	if (z < basezoom) {
		interval = exp(log(2.5) * (basezoom - z));
	}

	struct index *i;
	for (i = start; i < end; i++) {
		int t;

		char *meta = metabase + i->fpos;
		deserialize_int(&meta, &t);

		if (t == VT_POINT) {
			seq++;

			if (seq >= 0) {
				seq -= interval;
			} else {
				continue;
			}
		}

		if (t == VT_POINT || draw(&meta, NULL, z, tx, ty, detail)) {
			struct pool_val *pv = pool_long_long(&dup, &i->fpos, 0);
			if (pv->n == 0) {
				continue;
			}
			pv->n = 0;

			meta = metabase + i->fpos;
			deserialize_int(&meta, &t);

			mapnik::vector::tile_feature *feature = layer->add_features();

			if (t == VT_POINT) {
				feature->set_type(mapnik::vector::tile::Point);
			} else if (t == VT_LINE) {
				feature->set_type(mapnik::vector::tile::LineString);
			} else if (t == VT_POLYGON) {
				feature->set_type(mapnik::vector::tile::Polygon);
			} else {
				feature->set_type(mapnik::vector::tile::Unknown);
			}

			draw(&meta, feature, z, tx, ty, detail);

			int m;
			deserialize_int(&meta, &m);

			int i;
			for (i = 0; i < m; i++) {
				int t;
				deserialize_int(&meta, &t);
				struct pool_val *key = deserialize_string(&meta, &keys, VT_STRING);
				struct pool_val *value = deserialize_string(&meta, &values, t);

				feature->add_tags(key->n);
				feature->add_tags(value->n);

				// Dup to retain after munmap
				pool(file_keys, strdup(key->s), t);
			}
		}
	}

	struct pool_val *pv;
	for (pv = keys.head; pv != NULL; pv = pv->next) {
		layer->add_keys(pv->s, strlen(pv->s));
	}
	for (pv = values.head; pv != NULL; pv = pv->next) {
		mapnik::vector::tile_value *tv = layer->add_values();

		if (pv->type == VT_NUMBER) {
			tv->set_double_value(atof(pv->s));
		} else {
			tv->set_string_value(pv->s);
		}
	}
	pool_free(&keys);
	pool_free(&values);
	pool_free(&dup);

	std::string s;
	std::string compressed;

	tile.SerializeToString(&s);
	compress(s, compressed);

	if (compressed.size() > 500000) {
		fprintf(stderr, "tile %d/%u/%u size is %lld, >500000\n", z, tx, ty, (long long) compressed.size());
		exit(EXIT_FAILURE);
	}

	const char *prefix = "tiles";
	char path[strlen(prefix) + 200];

	mkdir(prefix, 0777);

	sprintf(path, "%s/%d", prefix, z);
	mkdir(path, 0777);

	sprintf(path, "%s/%d/%u", prefix, z, tx);
	mkdir(path, 0777);

	sprintf(path, "%s/%d/%u/%u.pbf", prefix, z, tx, ty);
	FILE *f = fopen(path, "wb");
	fwrite(compressed.data(), 1, compressed.size(), f);
	fclose(f);
}