tile-conv.js

#!/usr/bin/env node
var tilelive = require('tilelive');
var path = require('path');
var fs = require("fs");
var zlib = require("zlib");

const
MAX_ZOOM = 14;

require('tilelive-bridge').registerProtocols(tilelive);

var args = process.argv;
args.splice(0, 2); // Remove 'node' and the name of the script

var recursive = false;
var compress = false;
var outputPrefix = null;

// Check for flags
while (args.length > 0) {
	if (args[0] == '-r') { // Recursive mode
		recursive = true;
		args.splice(0, 1);
	} else if (args[0] == '-p') { // Output prefix
		outputPrefix = args[1];
		args.splice(0, 2);
	} else if (args[0] == '-c') { // Compression
		compress = true;
		args.splice(0, 1);
	} else {
		break; // Done processing flags
	}
}

if (args.length < 4) {
	console.error('Usage tile-conv <mapnik xlm file> <z> <x> <y>');
	process.exit(1);
}

var mapFile = path.resolve(__dirname, args[0]);
var originZ = args[1];
var originX = args[2];
var originY = args[3];

if (outputPrefix == null) {
	outputPrefix =  path.parse(mapFile).name;
}

var counter = 0;
var zoomLevels = MAX_ZOOM - originZ;
var totalCount = 0;
if (recursive) {
	while (zoomLevels >= 0) {
		totalCount += Math.pow(4, zoomLevels);
		zoomLevels--;
	}
} else {
	totalCount = 1;
}

console.log('Loading data from ' + mapFile);

tilelive.load("bridge://" + mapFile, function(err, source) {
	if (err)
		throw err;
	if (recursive) {
		processTileRecursive(source, originZ, originX, originY, function() {
			console.log('Done!');
			process.exit(0);
		});
	} else {
		processTile(source, originZ, originX, originY, function() {
			console.log('Done!');
			process.exit(0);
		});
	}
});

function processTileRecursive(source, z, x, y, callback) {
	processTile(source, z, x, y, function(empty) {
		if (z == MAX_ZOOM || empty) {
			callback();
			return;
		}
		var nextZ = ++z;
		var nextX = x * 2;
		var nextY = y * 2;
		// Process the four sub quads
		processTileRecursive(source, nextZ, nextX, nextY, function() {
			processTileRecursive(source, nextZ, nextX + 1, nextY, function() {
				processTileRecursive(source, nextZ, nextX, nextY + 1, function() {
					processTileRecursive(source, nextZ, nextX + 1, nextY + 1, function() {
						callback();
					});
				});
			});
		});
	});
}

function processTile(source, z, x, y, callback) {
	console.log('Processing tile ' + z + ' ' + x + ' ' + y);
	// Interface is in XYZ/Google coordinates.
	// Use `y = (1 << z) - 1 - y` to flip TMS coordinates.
	source.getTile(z, x, y, function(err, tile, headers) {
		if (err) {
			counter++;
			callback(true);
			return;
		}
		var fileName = 'out/' + outputPrefix + '-' + z + '-' + x + '-' + y + '.pbf';
		if (compress) {
			fileName += '.gz';
		}
		var finishedCallback = function() {
			counter++;
			console.log('Completed ' + counter + '/' + totalCount);
			callback(false);
		};
		if (compress) {
			writeFile(fileName, tile, finishedCallback);
		} else {
			zlib.gunzip(tile, function(err, decompressed) {
				writeFile(fileName, decompressed, finishedCallback);
			});
		}
	});
}

function writeFile(fileName, data, callback) {
	var out = fs.createWriteStream(fileName);
	out.on('finish', function() {
		callback();
	});
	out.write(data);
	out.end();
}