Checkpoint in copying data from one tileset to another

Makefile

@@ -1,7 +1,7 @@
 PREFIX ?= /usr/local
 MANDIR ?= /usr/share/man/man1/
 
-all: tippecanoe enumerate decode
+all: tippecanoe enumerate decode tile-join
 
 docs: man/tippecanoe.1
 
@@ -33,6 +33,9 @@ enumerate: enumerate.o
 decode: decode.o vector_tile.pb.o projection.o
 	g++ $(PG) $(LIBS) -O3 -g -Wall -o $@ $^ -lm -lz -lprotobuf-lite -lsqlite3
 
+tile-join: tile-join.o vector_tile.pb.o projection.o pool.o
+	g++ $(PG) $(LIBS) -O3 -g -Wall -o $@ $^ -lm -lz -lprotobuf-lite -lsqlite3
+
 libjsonpull.a: jsonpull.o
 	ar rc $@ $^
 	ranlib $@

tile-join.cc

@@ -0,0 +1,172 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sqlite3.h>
+#include <string>
+#include <zlib.h>
+#include <math.h>
+#include "vector_tile.pb.h"
+
+extern "C" {
+#include "projection.h"
+#include "pool.h"
+}
+
+// https://github.com/mapbox/mapnik-vector-tile/blob/master/src/vector_tile_compression.hpp
+inline bool is_compressed(std::string const &data) {
+	return data.size() > 2 && (((uint8_t) data[0] == 0x78 && (uint8_t) data[1] == 0x9C) || ((uint8_t) data[0] == 0x1F && (uint8_t) data[1] == 0x8B));
+}
+
+// https://github.com/mapbox/mapnik-vector-tile/blob/master/src/vector_tile_compression.hpp
+inline int decompress(std::string const &input, std::string &output) {
+	z_stream inflate_s;
+	inflate_s.zalloc = Z_NULL;
+	inflate_s.zfree = Z_NULL;
+	inflate_s.opaque = Z_NULL;
+	inflate_s.avail_in = 0;
+	inflate_s.next_in = Z_NULL;
+	if (inflateInit2(&inflate_s, 32 + 15) != Z_OK) {
+		fprintf(stderr, "error: %s\n", inflate_s.msg);
+	}
+	inflate_s.next_in = (Bytef *) input.data();
+	inflate_s.avail_in = input.size();
+	size_t length = 0;
+	do {
+		output.resize(length + 2 * input.size());
+		inflate_s.avail_out = 2 * input.size();
+		inflate_s.next_out = (Bytef *) (output.data() + length);
+		int ret = inflate(&inflate_s, Z_FINISH);
+		if (ret != Z_STREAM_END && ret != Z_OK && ret != Z_BUF_ERROR) {
+			fprintf(stderr, "error: %s\n", inflate_s.msg);
+			return 0;
+		}
+
+		length += (2 * input.size() - inflate_s.avail_out);
+	} while (inflate_s.avail_out == 0);
+	inflateEnd(&inflate_s);
+	output.resize(length);
+	return 1;
+}
+
+int dezig(unsigned n) {
+	return (n >> 1) ^ (-(n & 1));
+}
+
+void handle(std::string message, int z, unsigned x, unsigned y, struct pool *file_keys) {
+	GOOGLE_PROTOBUF_VERIFY_VERSION;
+
+	// https://github.com/mapbox/mapnik-vector-tile/blob/master/examples/c%2B%2B/tileinfo.cpp
+	mapnik::vector::tile tile;
+	mapnik::vector::tile outtile;
+
+	if (is_compressed(message)) {
+		std::string uncompressed;
+		decompress(message, uncompressed);
+		if (!tile.ParseFromString(uncompressed)) {
+			fprintf(stderr, "Couldn't decompress tile %d/%u/%u\n", z, x, y);
+			exit(EXIT_FAILURE);
+		}
+	} else if (!tile.ParseFromString(message)) {
+		fprintf(stderr, "Couldn't parse tile %d/%u/%u\n", z, x, y);
+		exit(EXIT_FAILURE);
+	}
+
+	for (int l = 0; l < tile.layers_size(); l++) {
+		mapnik::vector::tile_layer layer = tile.layers(l);
+		mapnik::vector::tile_layer *outlayer = outtile.add_layers();
+
+		outlayer->set_name(layer.name());
+		outlayer->set_version(layer.version());
+		outlayer->set_extent(layer.extent());
+
+		for (int f = 0; f < layer.features_size(); f++) {
+			mapnik::vector::tile_feature feat = layer.features(f);
+			mapnik::vector::tile_feature *outfeature = outlayer->add_features();
+
+			outfeature->set_type(feat.type());
+
+			for (int g = 0; g < feat.geometry_size(); g++) {
+				outfeature->add_geometry(feat.geometry(g));
+			}
+		}
+	}
+}
+
+void decode(char *fname, char *map, struct pool *file_keys) {
+	sqlite3 *db;
+
+	if (sqlite3_open(fname, &db) != SQLITE_OK) {
+		fprintf(stderr, "%s: %s\n", fname, sqlite3_errmsg(db));
+		exit(EXIT_FAILURE);
+	}
+
+	const char *sql = "SELECT zoom_level, tile_column, tile_row, tile_data from tiles;";
+	sqlite3_stmt *stmt;
+	if (sqlite3_prepare_v2(db, sql, -1, &stmt, NULL) != SQLITE_OK) {
+		fprintf(stderr, "%s: select failed: %s\n", fname, sqlite3_errmsg(db));
+		exit(EXIT_FAILURE);
+	}
+
+	while (sqlite3_step(stmt) == SQLITE_ROW) {
+                long long zoom = sqlite3_column_int(stmt, 0);
+                long long x = sqlite3_column_int(stmt, 1);
+                long long y = sqlite3_column_int(stmt, 2);
+                y = (1LL << zoom) - 1 - y;
+
+		int len = sqlite3_column_bytes(stmt, 3);
+		const char *s = (const char *) sqlite3_column_blob(stmt, 3);
+
+		printf("found %lld/%lld/%lld\n", zoom, x, y);
+
+		handle(std::string(s, len), zoom, x, y, file_keys);
+	}
+
+	sqlite3_finalize(stmt);
+
+	if (sqlite3_close(db) != SQLITE_OK) {
+		fprintf(stderr, "%s: could not close database: %s\n", fname, sqlite3_errmsg(db));
+		exit(EXIT_FAILURE);
+	}
+}
+
+void usage(char **argv) {
+	fprintf(stderr, "Usage: %s [-f] -o new.mbtiles source.mbtiles map.csv\n", argv[0]);
+	exit(EXIT_FAILURE);
+}
+
+int main(int argc, char **argv) {
+	char *outfile = NULL;
+	int force = 0;
+
+	extern int optind;
+	extern char *optarg;
+	int i;
+
+	while ((i = getopt(argc, argv, "fo:")) != -1) {
+		switch (i) {
+			case 'o':
+				outfile = optarg;
+				break;
+
+			case 'f':
+				force = 1;
+				break;
+
+			default:
+				usage(argv);
+		}
+	}
+
+	if (argc != optind + 2 || outfile == NULL) {
+		usage(argv);
+	}
+
+	struct pool file_keys;
+	pool_init(&file_keys, 0);
+
+	decode(argv[optind], argv[optind + 1], &file_keys);
+
+	pool_free(&file_keys);
+
+	return 0;
+}