Add Mapnik store

tilecloud/store/mapnik_utils.py

@@ -0,0 +1,66 @@
+from json import dumps
+
+from tilecloud import TileStore
+
+try:
+    import mapnik2 as mapnik
+except:
+    import mapnik
+
+
+class MapnikTileStore(TileStore):
+    """
+    Tiles stored to render with Mapnik
+
+    requires mapnik2: http://pypi.python.org/pypi/mapnik2
+    """
+
+    def __init__(self, tilegrid, mapfile, data_buffer=128, image_buffer=0, output_format='png256', resolution=2, layers_fields={}, **kwargs):
+        """
+        Conastructs a MapnikTileStore
+
+        :param tilegrid: the tilegrid.
+        :param mapfile: the file used to render the tiles.
+        :param buffer_size: the image buffer size default is 128.
+        :param output_format: the output format,
+            possible values 'jpeg', 'png', 'png256', 'grid',
+            default is 'png256'
+        :param layers: the layers and fields used in the grid generation,
+            example: { 'my_layer': ['my_first_field', 'my_segonf_field']},
+            default is {}.
+        :param **kwargs: for extended class.
+        """
+
+        TileStore.__init__(self, **kwargs)
+        self.tilegrid = tilegrid
+        self.buffer = image_buffer
+        self.output_format = output_format
+        self.resolution = resolution
+        self.layers_fields = layers_fields
+
+        self.mapnik = mapnik.Map(tilegrid.tile_size, tilegrid.tile_size)
+        mapnik.load_map(self.mapnik, mapfile, True)
+        self.mapnik.buffer_size = data_buffer
+
+    def get_one(self, tile):
+        bbox = self.tilegrid.extent(tile.tilecoord, self.buffer)
+        bbox2d = mapnik.Box2d(bbox[0], bbox[1], bbox[2], bbox[3])
+
+        size = tile.tilecoord.n * self.tilegrid.tile_size + 2 * self.buffer
+        self.mapnik.resize(size, size)
+        self.mapnik.zoom_to_box(bbox2d)
+
+        if self.output_format == 'grid':
+            grid = mapnik.Grid(self.tilegrid.tile_size, self.tilegrid.tile_size)
+            for n, l in enumerate(self.mapnik.layers):
+                if l.name in self.layers_fields:
+                    mapnik.render_layer(self.mapnik, grid, layer=n, fields=self.layers_fields[l.name])
+
+            tile.data = dumps(grid.encode('utf', resolution=self.resolution))
+        else:
+            # Render image with default Agg renderer
+            im = mapnik.Image(size, size)
+            mapnik.render(self.mapnik, im)
+            tile.data = im.tostring(self.output_format)
+
+        return tile