Update to allow more settings for font, color, position

- copyright_text_font: a system or user font name, or absolute path to
.ttf file
- copyright_text_font_size: font size used when
copyright_text_font is set
- copyright_text_color: text color
- copyright_text_position: a 2 tuple (x,y) specifying coordinates of top-left corner of
text

sigal/plugins/copyright.py

@@ -5,13 +5,19 @@
 Settings:
 
 - ``copyright``: the copyright text.
-
-TODO: Add more settings (font, size, ...)
+- ``copyright_text_font``: the copyright text font - either system/user font-name or absolute path to font.tff file.
+                           If no font is specified, or specified font is not found, default font is used.
+- ``copyright_text_font_size``: the copyright text font-size. If no font is specified, this setting is ignored.
+- ``copyright_text_color``: the copyright text color in 3 tuple (R, G, B) Decimal RGB code.
+                            e.g. (255, 255, 255) is White.
+- ``copyright_text_position``: the copyright text position in 2 tuple (left, top).
+                               By default text would be positioned at bottom-left corner.
 
 """
 
 import logging
 from PIL import ImageDraw
+from PIL import ImageFont
 from sigal import signals
 
 logger = logging.getLogger(__name__)
@@ -20,7 +26,24 @@ logger = logging.getLogger(__name__)
 def add_copyright(img, settings=None):
     logger.debug('Adding copyright to %r', img)
     draw = ImageDraw.Draw(img)
-    draw.text((5, img.size[1] - 15), settings['copyright'])
+    text = settings['copyright']
+    font = settings.get('copyright_text_font', None)
+    font_size = settings.get('copyright_text_font_size', 10)
+    assert font_size >= 0
+    color = settings.get('copyright_text_color', (0, 0, 0))
+    bottom_margin = 3   # bottom margin for text
+    text_height = bottom_margin + 12    # default text height (of 15) for default font
+    if font:
+        try:
+            font = ImageFont.truetype(font, font_size)
+            text_height = font.getsize(text)[1] + bottom_margin
+        except:     # load default font in case of any exception
+            logger.debug("Exception: Couldn't locate font %s, using default font", font)
+            font = ImageFont.load_default()
+    else:
+        font = ImageFont.load_default()
+    left, top = settings.get('copyright_text_position', (5, img.size[1] - text_height))
+    draw.text((left, top), text, fill=color, font=font)
     return img