FlashPunk resizable tilemap

        public function resize(width:int, height:int):void
        {
            if (usePositions)
            {
                width /= _tile.width;
                height /= _tile.height;
            }

            _temp = _map.clone();
            _map = new BitmapData(width, height, false, 0);
            _map.copyPixels(_temp, _map.rect, FP.zero);
            _temp = new BitmapData(width, height, false, 0);
            resizeCanvas(width * _tile.width, height * _tile.height);
            updateAll();

            _columns = width;
            _rows = height;
        }

//Then on canvas you modify:

        public function Canvas(width:uint, height:uint)
        {
            resizeCanvas(width, height);
        }

        public function resizeCanvas(width:uint, height:uint):void
        {
            _width = width;
            _height = height;
            _refWidth = Math.ceil(width / _maxWidth);
            _refHeight = Math.ceil(height / _maxHeight);
            _ref = new BitmapData(_refWidth, _refHeight, false, 0);
            var x:uint, y:uint, w:uint, h:uint, i:uint,
            ww:uint = _width % _maxWidth,
                hh:uint = _height % _maxHeight;
            if (!ww) ww = _maxWidth;
            if (!hh) hh = _maxHeight;
            while (y < _refHeight)
            {
                h = y < _refHeight - 1 ? _maxHeight : hh;
                while (x < _refWidth)
                {
                    w = x < _refWidth - 1 ? _maxWidth : ww;
                    _ref.setPixel(x, y, i);
                    _buffers[i] = new BitmapData(w, h, true, 0);
                    i ++; x ++;
                }
                x = 0; y ++;
            }
        }