Can update the street index label according to the grid's location.

With this patch, the street index should now have its labels A1-B2
correct for the location of streets. The street indexer has a new
method apply_grid() that calls item.update_location_str(grid) so that
all the items have their location_str field correct. The items are
updated in-place: beware if multiple threads are manipulating a
StreetIndex object...

ocitysmap2/grid.py

@@ -53,6 +53,7 @@ class Grid:
         """
 
         self._bbox = bounding_box
+        self.rtl   = rtl
         self._height_m, self._width_m = bounding_box.spheric_sizes()
 
         l.info('Laying out grid on %.1fx%.1fm area...' %
@@ -67,28 +68,27 @@ class Grid:
                 Grid.GRID_COUNT_TRESHOLD):
                 break
 
-        self._horiz_angle = (abs(self._bbox.get_top_left()[1] -
-                                 self._bbox.get_bottom_right()[1]) /
-                             self.horiz_count)
-        self._vert_angle  = (abs(self._bbox.get_top_left()[0] -
-                                 self._bbox.get_bottom_right()[0]) /
-                             self.vert_count)
+        self._horiz_angle_span = abs(self._bbox.get_top_left()[1] -
+                                     self._bbox.get_bottom_right()[1])
+        self._vert_angle_span  = abs(self._bbox.get_top_left()[0] -
+                                     self._bbox.get_bottom_right()[0])
 
-        self._horizontal_lines = [self._bbox.get_top_left()[0] -
-                                  (x+1) * self._vert_angle for x in xrange(
-                                      int(math.floor(self.vert_count)))]
-        self._vertical_lines   = [self._bbox.get_top_left()[1] +
-                                  (x+1) * self._horiz_angle for x in xrange(
-                                      int(math.floor(self.horiz_count)))]
+        self._horiz_unit_angle = (self._horiz_angle_span / self.horiz_count)
+        self._vert_unit_angle  = (self._vert_angle_span / self.vert_count)
+
+        self._horizontal_lines = [ ( self._bbox.get_top_left()[0] -
+                                    (x+1) * self._vert_unit_angle)
+                                  for x in xrange(int(math.floor(self.vert_count)))]
+        self._vertical_lines   = [ (self._bbox.get_top_left()[1] +
+                                    (x+1) * self._horiz_unit_angle)
+                                   for x in xrange(int(math.floor(self.horiz_count)))]
 
         self.horizontal_labels = map(self._gen_horizontal_square_label,
                                       xrange(int(math.ceil(self.horiz_count))))
-        if rtl:
-            self.horizontal_labels.reverse()
         self.vertical_labels = map(self._gen_vertical_square_label,
                                    xrange(int(math.ceil(self.vert_count))))
 
-        l.info('Using %dx%dm grid (%dx%d squares).' %
+        l.info('Using %sx%sm grid (%sx%s squares).' %
                (self.grid_size_m, self.grid_size_m,
                 self.horiz_count, self.vert_count))
 
@@ -120,6 +120,9 @@ class Grid:
             28 -> AB
             ...
         """
+        if self.rtl:
+            x = len(self._vertical_lines) - x
+
         label = ''
         while x != -1:
             label = chr(ord('A') + x % 26) + label
@@ -131,6 +134,22 @@ class Grid:
         number. Since we put numbers verticaly, this is simply x+1."""
         return str(x + 1)
 
+    def get_location_str(self, lattitude, longitude):
+        """
+        Translate the given lattitude/longitude (EPSG:4326) into a
+        string of the form "CA42"
+        """
+        hdelta = min(abs(longitude - self._bbox.get_top_left()[1]),
+                     self._horiz_angle_span)
+        hlabel = self.horizontal_labels[int(hdelta / self._horiz_unit_angle)]
+
+        vdelta = min(abs(lattitude - self._bbox.get_top_left()[0]),
+                     self._vert_angle_span)
+        vlabel = self.vertical_labels[int(vdelta / self._vert_unit_angle)]
+
+        return "%s%s" % (hlabel, vlabel)
+
+
 if __name__ == "__main__":
     logging.basicConfig(level=logging.DEBUG)
     grid = Grid(coords.BoundingBox(44.4883, -1.0901, 44.4778, -1.0637))

ocitysmap2/index/__init__.py

@@ -35,6 +35,7 @@ if __name__ == '__main__':
 
     from ocitysmap2 import i18n, coords
     from ocitysmap2.index import commons
+    from ocitysmap2.grid import Grid
 
     import render
 
@@ -72,6 +73,10 @@ if __name__ == '__main__':
 
     surface = cairo.PDFSurface('/tmp/myindex.pdf', width, height)
 
+    # Map index to grid
+    grid = Grid(bbox, rtl = False)
+    street_index.apply_grid(grid)
+
     index = render.StreetIndexRenderer(i18nMock(False),
                                        street_index.categories)
 
@@ -107,6 +112,14 @@ if __name__ == '__main__':
     _render('width', 'right')
     surface.show_page()
 
+    ##
+    ## Now demo with RTL = True
+    ##
+
+    # Map index to grid
+    grid = Grid(bbox, rtl = True)
+    street_index.apply_grid(grid)
+
     index = render.StreetIndexRenderer(i18nMock(True),
                                        street_index.categories)
     _render('height', 'top')

ocitysmap2/index/commons.py

@@ -90,6 +90,7 @@ class IndexCategory:
     def get_all_item_squares(self):
         return [x.squares for x in self.items]
 
+
 class IndexItem:
     """
     An IndexItem represents one item in the index (a street or a POI). It
@@ -161,6 +162,41 @@ class IndexItem:
                                     line_end - line_start - fheight/2)
         ctx.restore()
 
+    def update_location_str(self, grid):
+        """
+        Update the location_str field from the given Grid object.
+
+        Args:
+           grid (ocitysmap2.Grid): the Grid object from which we
+           compute the location strings
+
+        Returns:
+           Nothing, but the location_str field will have been altered
+        """
+        if self.endpoint1 is not None:
+            ep1_label = grid.get_location_str( * self.endpoint1.get_latlong())
+        else:
+            ep1_label = None
+        if self.endpoint2 is not None:
+            ep2_label = grid.get_location_str( * self.endpoint2.get_latlong())
+        else:
+            ep2_label = None
+        if ep1_label is None:
+            ep1_label = ep2_label
+        if ep2_label is None:
+            ep2_label = ep1_label
+
+        if ep1_label == ep2_label:
+            if ep1_label is None:
+                self.location_str = "???"
+            self.location_str = ep1_label
+        elif grid.rtl:
+            self.location_str = "%s-%s" % (max(ep1_label, ep2_label),
+                                           min(ep1_label, ep2_label))
+        else:
+            self.location_str = "%s-%s" % (min(ep1_label, ep2_label),
+                                           max(ep1_label, ep2_label))
+
 
 if __name__ == "__main__":
     import cairo

ocitysmap2/index/indexer.py

@@ -64,6 +64,23 @@ class StreetIndex:
     def categories(self):
         return self._categories
 
+    def apply_grid(self, grid):
+        """
+        Fix the label location_str field by mapping the streets to the
+        given grid.
+
+        Args:
+           grid (ocitysmap2.Grid): the Grid object from which we
+           compute the location strings
+
+        Returns:
+           Nothing, but self._categories will have been modified !
+        """
+        for category in self._categories:
+            for item in category.items:
+                item.update_location_str(grid)
+
+
     def write_to_csv(self, title, output_filename):
         # TODO: implement writing the index to CSV
         try:

ocitysmap2/index/render.py

@@ -96,7 +96,7 @@ class StreetIndexRenderingArea:
 
 class StreetIndexRenderer:
     """
-    The StreetIndex class encapsulate all the logic related to the querying and
+    The StreetIndex class encapsulates all the logic related to the querying and
     rendering of the street index.
     """