finally made the compass rose an optional overlay feature

ocitysmap.conf.dist

@@ -10,6 +10,7 @@ dbname=maposmatic
 # List of available stylesheets, each needs to be described by an eponymous
 # configuration section in this file.
 available_stylesheets: stylesheet_osm1, stylesheet_osm2
+available_overlays: scalebar, compass_rose, surveillance,
 
 # The default Mapnik stylesheet.
 [stylesheet_osm1]
@@ -22,3 +23,21 @@ path: /path/to/mapnik-osm/osm.xml
 name: AnotherOne
 description: Another OSM Stylesheet
 path: /path/to/another/osm.xml
+
+
+# Bundled overlay effect stylesheets
+[scalebar]
+name: Scale_Bar_overlay
+description: Scale bar
+path: internal:scalebar
+
+[compass_rose]
+name: Compass_Rose_overlay
+description: Compass Rose
+path: internal:compass_rose
+
+[surveillance]
+name: Surveillance_Overlay
+description: Surveillance Cameras
+path: internal:surveillance
+

ocitysmap/layoutlib/abstract_renderer.py

@@ -175,28 +175,6 @@ class Renderer:
         return Renderer._get_svg(ctx, logo_path, height)
 
 
-    @staticmethod
-    def _get_compass_rose(ctx, height):
-        """
-        Read the compass rose image and rescale it to fit within height.
-
-        Args:
-           ctx (cairo.Context): The cairo context to use to draw.
-           height (number): final height of the image (cairo units).
-
-        Return a tuple (cairo group object for the image, image width in
-                        cairo units).
-        """
-        logo_path = os.path.abspath(os.path.join(
-            os.path.dirname(__file__), '..', '..', 'images', 'compass-rose.svg'))
-        if not os.path.exists(logo_path):
-            logo_path = os.path.join(
-                sys.exec_prefix, 'share', 'images', 'ocitysmap',
-                'compass-rose.svg')
-
-        return Renderer._get_svg(ctx, logo_path, height)
-
-
     @staticmethod
     def _draw_labels(ctx, map_grid,
                      map_area_width_dots, map_area_height_dots,

ocitysmap/layoutlib/render_plugins/compass_rose/__init__.py

@@ -0,0 +1,33 @@
+import cairo
+import os
+import sys
+import logging
+from ocitysmap.layoutlib.commons import convert_pt_to_dots
+from ocitysmap.layoutlib.abstract_renderer import Renderer
+
+LOG = logging.getLogger('ocitysmap')
+
+def render(renderer, ctx):
+    svg_path = os.path.abspath(os.path.join(
+        os.path.dirname(__file__), '..', '..', '..', '..', 'images', 'compass-rose.svg'))
+
+    if not os.path.exists(svg_path):
+        logo_path = os.path.join(
+            sys.exec_prefix, 'share', 'images', 'ocitysmap', 'compass-rose.svg')
+
+    if not os.path.exists(svg_path):
+        LOG.warning("No compass rose image found")
+        return
+        
+    h = convert_pt_to_dots(renderer._title_margin_pt, renderer.dpi)
+    x = convert_pt_to_dots(renderer._map_coords[0], renderer.dpi)
+    y = convert_pt_to_dots(renderer._map_coords[1], renderer.dpi)
+        
+    ctx.save()   
+    ctx.translate(x + h/2, y + h/2)
+    rose_grp, rose_width = Renderer._get_svg(ctx, svg_path, h)
+    ctx.set_source(rose_grp)
+    ctx.paint_with_alpha(0.75)
+    ctx.stroke()
+    ctx.restore()
+

ocitysmap/layoutlib/single_page_renderers.py

@@ -646,17 +646,6 @@ class SinglePageRenderer(Renderer):
             ctx.restore()
 
 
-        # Draw compass rose
-        # TODO: proper positioning/scaling, move to abstract renderer
-        ctx.save()
-        ctx.translate(map_coords_dots[0] + title_margin_dots/2,
-                      map_coords_dots[1] + title_margin_dots/2)
-        rose_grp, rose_width = self._get_compass_rose(ctx, title_margin_dots)
-        ctx.set_source(rose_grp)
-        ctx.paint_with_alpha(0.75)
-        ctx.stroke()
-        ctx.restore()
-
         # Draw QR code
         if self.qrcode_text:
           ctx.save()