Add anchor parameter for symbol drawer, so symbol image can be centered.

yagicard/__init__.py

@@ -45,11 +45,12 @@ class Images ():
         self.images[key] = value
 
 class SymbolDrawer ():
-    def __init__ (self, size, direction="ltr"):
+    def __init__ (self, size, direction="ltr", anchor="la"):
         self.direction = direction
         self.symbols = []
         self.symbol_pos = (0, 0)
         self.size = (0, 0)
+        self.anchor = anchor
 
     def add_symbol (self, symbol):
         if isinstance(symbol, str):
@@ -67,6 +68,17 @@ class SymbolDrawer ():
         image = Image.new("RGBA", self.size)
         for symbol in self.symbols:
             image.paste(symbol[0], symbol[1])
+
+        if self.anchor[0] == "m":
+            dest = (dest[0] - int(self.size[0] / 2), dest[1])
+        elif self.anchor[0] == "r":
+            dest = (dest[0] - self.size[0], dest[1])
+
+        if self.anchor[1] == "m":
+            dest = (dest[0], dest[1] - int(self.size[1] / 2))
+        elif self.anchor[1] == "b":
+            dest = (dest[0], dest[1] - self.size[1])
+
         target_image.alpha_composite(image, dest)
 
 images  = Images(IMAGES_DIRECTORY)