python plugin: remove Shapely dependency from tests

Remove the Shapely dependency by generating the output features directly in WKT format. Update the expected output image
because the circles are now generated directly as 72-sided polygons rather than by buffering a point.

tests/python_tests/python_plugin_test.py

@@ -8,13 +8,6 @@ import sys
 from utilities import execution_path
 from nose.tools import *
 
-try:
-    from shapely.geometry import Point
-    have_shapely = True
-except ImportError:
-    print('Shapely is required for python data source test.')
-    have_shapely = False
-
 def setup():
     # All of the paths used are relative, if we run the tests
     # from another directory we need to chdir()
@@ -27,18 +20,14 @@ class PointDatasource(mapnik.PythonDatasource):
         )
 
     def features(self, query):
-        return mapnik.PythonDatasource.wkb_features(
+        return mapnik.PythonDatasource.wkt_features(
             keys = ('label',), 
             features = (
-                ( Point(5,6).wkb, { 'label': 'foo-bar'} ), 
-                ( Point(60,50).wkb, { 'label': 'buzz-quux'} ), 
+                ( 'POINT (5 6)', { 'label': 'foo-bar'} ), 
+                ( 'POINT (60 50)', { 'label': 'buzz-quux'} ), 
             )
         )
 
-def box2d_to_shapely(box):
-    import shapely.geometry
-    return shapely.geometry.box(box.minx, box.miny, box.maxx, box.maxy)
-
 class ConcentricCircles(object):
     def __init__(self, centre, bounds, step=1):
         self.centre = centre
@@ -53,20 +42,31 @@ class ConcentricCircles(object):
             bounds = self.container.bounds
             step = self.container.step
 
-            if centre.within(bounds):
-                self.radius = step
-            else:
-                self.radius = math.ceil(centre.distance(bounds) / float(step)) * step
+            self.radius = step
 
         def next(self):
-            circle = self.container.centre.buffer(self.radius)
-            self.radius += self.container.step
+            points = []
+            for alpha in xrange(0, 361, 5):
+                x = math.sin(math.radians(alpha)) * self.radius + self.container.centre[0]
+                y = math.cos(math.radians(alpha)) * self.radius + self.container.centre[1]
+                points.append('%s %s' % (x,y))
+            circle = 'POLYGON ((' + ','.join(points) + '))'
 
             # has the circle grown so large that the boundary is entirely within it?
-            if circle.contains(self.container.bounds):
+            tl = (self.container.bounds.maxx, self.container.bounds.maxy)
+            tr = (self.container.bounds.maxx, self.container.bounds.maxy)
+            bl = (self.container.bounds.minx, self.container.bounds.miny)
+            br = (self.container.bounds.minx, self.container.bounds.miny)
+            def within_circle(p):
+                delta_x = p[0] - self.container.centre[0]
+                delta_y = p[0] - self.container.centre[0]
+                return delta_x*delta_x + delta_y*delta_y < self.radius*self.radius
+
+            if all(within_circle(p) for p in (tl,tr,bl,br)):
                 raise StopIteration()
 
-            return ( circle.wkb, { } )
+            self.radius += self.container.step
+            return ( circle, { } )
 
     def __iter__(self):
         return ConcentricCircles.Iterator(self)
@@ -87,16 +87,14 @@ class CirclesDatasource(mapnik.PythonDatasource):
         self.step = step
 
     def features(self, query):
-        # Get the query bounding-box as a shapely bounding box
-        bounding_box = box2d_to_shapely(query.bbox)
-        centre = Point(self.centre_x, self.centre_y)
+        centre = (self.centre_x, self.centre_y)
 
-        return mapnik.PythonDatasource.wkb_features(
+        return mapnik.PythonDatasource.wkt_features(
             keys = (),
-            features = ConcentricCircles(centre, bounding_box, self.step)
+            features = ConcentricCircles(centre, query.bbox, self.step)
         )
 
-if 'python' in mapnik.DatasourceCache.instance().plugin_names() and have_shapely:
+if 'python' in mapnik.DatasourceCache.instance().plugin_names():
     # make sure we can load from ourself as a module
     sys.path.append(execution_path('.'))