Generates a sprite map from the files matching the glob pattern.
    Uses the keyword-style arguments passed in to control the placement.

def _sprite_map(g, **kwargs):
    """
    Generates a sprite map from the files matching the glob pattern.
    Uses the keyword-style arguments passed in to control the placement.
    """
    g = StringValue(g).value

    if not Image:
        raise Exception("Images manipulation require PIL")

    if g in sprite_maps:
        sprite_maps[glob]['*'] = datetime.datetime.now()
    elif '..' not in g:  # Protect against going to prohibited places...
        vertical = (kwargs.get('direction', 'vertical') == 'vertical')
        offset_x = NumberValue(kwargs.get('offset_x', 0))
        offset_y = NumberValue(kwargs.get('offset_y', 0))
        repeat = StringValue(kwargs.get('repeat', 'no-repeat'))
        position = NumberValue(kwargs.get('position', 0))
        dst_color = kwargs.get('dst_color')
        src_color = kwargs.get('src_color')
        if position and position > -1 and position < 1:
            position.units = {'%': _units_weights.get('%', 1), '_': '%'}
        spacing = kwargs.get('spacing', 0)
        if isinstance(spacing, ListValue):
            spacing = [int(NumberValue(v).value) for n, v in spacing.items()]
        else:
            spacing = [int(NumberValue(spacing).value)]
        spacing = (spacing * 4)[:4]

        if callable(STATIC_ROOT):
            rfiles = files = sorted(STATIC_ROOT(g))
        else:
            glob_path = os.path.join(STATIC_ROOT, g)
            files = glob.glob(glob_path)
            files = sorted((f, None) for f in files)
            rfiles = [(f[len(STATIC_ROOT):], s) for f, s in files]

        if not files:
            log.error("Nothing found at '%s'", glob_path)
            return StringValue(None)

        times = []
        for file, storage in files:
            try:
                d_obj = storage.modified_time(file)
                times.append(int(time.mktime(d_obj.timetuple())))
            except:
                times.append(int(os.path.getmtime(file)))

        map_name = os.path.normpath(
            os.path.dirname(g)).replace('\\', '_').replace('/', '_')
        key = list(zip(*files)[0]) + times + [repr(kwargs)]
        key = map_name + '-' + base64.urlsafe_b64encode(
            hashlib.md5(repr(key)).digest()).rstrip('=').replace('-', '_')
        asset_file = key + '.png'
        asset_path = os.path.join(ASSETS_ROOT, asset_file)

        if os.path.exists(asset_path + '.cache'):
            asset, map, sizes = pickle.load(open(asset_path + '.cache'))
            sprite_maps[asset] = map
        else:
            images = tuple(Image.open(storage.open(file)) if storage is not None else Image.open(file) for file, storage in files)
            names = tuple(os.path.splitext(
                os.path.basename(file))[0] for file, storage in files)
            positions = []
            spacings = []
            tot_spacings = []
            for name in names:
                name = name.replace('-', '_')
                _position = kwargs.get(name + '_position')
                if _position is None:
                    _position = position
                else:
                    _position = NumberValue(_position)
                    if _position and _position > -1 and _position < 1:
                        _position.units = {'%':
                                           _units_weights.get('%', 1), '_': '%'}
                positions.append(_position)
                _spacing = kwargs.get(name + '_spacing')
                if _spacing is None:
                    _spacing = spacing
                else:
                    if isinstance(_spacing, ListValue):
                        _spacing = [int(NumberValue(
                            v).value) for n, v in _spacing.items()]
                    else:
                        _spacing = [int(NumberValue(_spacing).value)]
                    _spacing = (_spacing * 4)[:4]
                spacings.append(_spacing)
                if _position and _position.unit != '%':
                    if vertical:
                        if _position > 0:
                            tot_spacings.append((_spacing[0], _spacing[
                                1], _spacing[2], _spacing[3] + _position))
                    else:
                        if _position > 0:
                            tot_spacings.append((_spacing[0] + _position,
                                                 _spacing[1], _spacing[2], _spacing[3]))
                else:
                    tot_spacings.append(_spacing)
            sizes = tuple(image.size for image in images)

            _spacings = zip(*tot_spacings)
            if vertical:
                width = max(
                    zip(*sizes)[0]) + max(_spacings[1]) + max(_spacings[3])
                height = sum(
                    zip(*sizes)[1]) + sum(_spacings[0]) + sum(_spacings[2])
            else:
                width = sum(
                    zip(*sizes)[0]) + sum(_spacings[1]) + sum(_spacings[3])
                height = max(
                    zip(*sizes)[1]) + max(_spacings[0]) + max(_spacings[2])

            new_image = Image.new(
                mode='RGBA',
                size=(width, height),
                color=(0, 0, 0, 0)
            )

            offsets_x = []
            offsets_y = []
            offset = 0
            for i, image in enumerate(images):
                spacing = spacings[i]
                position = positions[i]
                if vertical:
                    if position and position.unit == '%':
                        x = width * position.value - \
                            (spacing[3] + sizes[i][1] + spacing[1])
                    elif position.value < 0:
                        x = width + position.value - \
                            (spacing[3] + sizes[i][1] + spacing[1])
                    else:
                        x = position.value
                    offset += spacing[0]
                    new_image.paste(image, (int(x + spacing[3]), offset))
                    offsets_x.append(x)
                    offsets_y.append(offset - spacing[0])
                    offset += sizes[i][1] + spacing[2]
                else:
                    if position and position.unit == '%':
                        y = height * position.value - \
                            (spacing[0] + sizes[i][1] + spacing[2])
                    elif position.value < 0:
                        y = height + position.value - \
                            (spacing[0] + sizes[i][1] + spacing[2])
                    else:
                        y = position.value
                    offset += spacing[3]
                    new_image.paste(image, (offset, int(y + spacing[0])))
                    offsets_x.append(offset - spacing[3])
                    offsets_y.append(y)
                    offset += sizes[i][0] + spacing[1]

            if dst_color:
                src_color = ColorValue(
                    src_color).value[:3] if src_color else (0, 0, 0)
                dst_color = list(ColorValue(dst_color).value[:3])
                pixdata = new_image.load()
                for y in xrange(new_image.size[1]):
                    for x in xrange(new_image.size[0]):
                        if pixdata[x, y][:3] == src_color:
                            pixdata[x,
                                    y] = tuple(dst_color + [pixdata[x, y][3]])

            try:
                new_image.save(asset_path)
            except IOError:
                log.exception("Error while saving image")
            filetime = int(time.mktime(datetime.datetime.now().timetuple()))

            url = '%s%s?_=%s' % (ASSETS_URL, asset_file, filetime)
            asset = 'url("%s") %s' % (escape(url), repeat)
            # Use the sorted list to remove older elements (keep only 500
            # objects):
            if len(sprite_maps) > 1000:
                for a in sorted(sprite_maps, key=lambda a: sprite_maps[a]['*'], reverse=True)[500:]:
                    del sprite_maps[a]
            # Add the new object:
            map = dict(zip(names, zip(sizes, rfiles, offsets_x, offsets_y)))
            map['*'] = datetime.datetime.now()
            map['*f*'] = asset_file
            map['*k*'] = key
            map['*n*'] = map_name
            map['*t*'] = filetime
            pickle.dump((asset, map, zip(files, sizes)), open(
                asset_path + '.cache', 'w'))
            sprite_maps[asset] = map
        for file, size in sizes:
            sprite_images[file] = size
    ret = StringValue(asset)
    return ret