add first new-world putTile() function

lib/mbtiles.js

@@ -29,14 +29,20 @@ function MBTiles(uri, callback) {
     if (typeof uri === 'string') uri = url.parse(uri);
 
     this.filename = uri.pathname;
-    this.db = new sqlite3.cached.Database(mbtiles.filename, function(err) {
+    Step(function() {
+        mbtiles.db = new sqlite3.cached.Database(mbtiles.filename, this)
+    }, function(err) {
         if (err) return callback(err);
-        else fs.stat(mbtiles.filename, function(err, stat) {
-            if (err) return callback(err);
-            mbtiles.stat = stat;
-            callback(null, mbtiles);
-        });
-    });
+        fs.stat(mbtiles.filename, this);
+    }, function(err, stat) {
+        if (err) return callback(err);
+        mbtiles.stat = stat;
+        mbtiles.exists('map', this);
+    }, function(err, exists) {
+        if (err) return callback(err);
+        else if (!exists) mbtiles.setup(this);
+        else this(null);
+    }, callback);
 };
 
 // Finds all mbtiles file in the filepath and returns their tilesource URI.
@@ -154,7 +160,17 @@ MBTiles.prototype.insertMetadata = function(data, callback) {
     this.insert('metadata', metadata, callback);
 };
 
-// Insert a set of tiles into an mbtiles database.
+// Insert a tile. Scheme is XYZ.
+MBTiles.prototype.putTile = function(z, x, y, data, callback) {
+    if (typeof callback !== 'function') callback = noop;
+
+    // Flip Y coordinate because MBTiles files are TMS.
+    y = Math.pow(2, z) - 1 - y;
+
+    this.insertTiles([ { z: z, x: x, y: y, data: data }], callback);
+};
+
+// Insert a set of tiles into an mbtiles database. Scheme is TMS.
 //
 // - @param {Array} renders array of images to be inserted. Each item should
 //   be an object of the form { z: z, x: x, y: y, data: [Image buffer] }.