Rename method and move to Calculations module.

lib/geocoder/calculations.rb

@@ -147,6 +147,27 @@ module Geocoder
       to_degrees [lat, lon]
     end
 
+    ##
+    # Returns coordinates of the lower-left and upper-right corners of a box
+    # with the given point at its center. The radius is the shortest distance
+    # from the center point to any side of the box (the length of each side
+    # is twice the radius).
+    #
+    # This is useful for finding corner points of a map viewport, or for
+    # roughly limiting the possible solutions in a geo-spatial search
+    # (ActiveRecord queries use it thusly).
+    #
+    def bounding_box(latitude, longitude, radius, options = {})
+      units = options[:units] || :mi
+      radius = radius.to_f
+      [
+        latitude  - (radius / latitude_degree_distance(units)),
+        longitude - (radius / longitude_degree_distance(latitude, units)),
+        latitude  + (radius / latitude_degree_distance(units)),
+        longitude + (radius / longitude_degree_distance(latitude, units))
+      ]
+    end
+
     ##
     # Convert degrees to radians.
     # If an array (or multiple arguments) is passed,

lib/geocoder/orms/active_record.rb

@@ -172,9 +172,10 @@ module Geocoder::Orm
       def default_near_scope_options(latitude, longitude, radius, options)
         lat_attr = geocoder_options[:latitude]
         lon_attr = geocoder_options[:longitude]
+        b = Geocoder::Calculations.bounding_box(latitude, longitude, radius, options)
         conditions = \
           ["#{lat_attr} BETWEEN ? AND ? AND #{lon_attr} BETWEEN ? AND ?"] +
-          coordinate_bounds(latitude, longitude, radius)
+          [b[0], b[2], b[1], b[3]]
         if obj = options[:exclude]
           conditions[0] << " AND #{table_name}.id != ?"
           conditions << obj.id
@@ -187,21 +188,6 @@ module Geocoder::Orm
           :conditions => conditions
         }
       end
-
-      ##
-      # Get the rough high/low lat/long bounds for a geographic point and
-      # radius. Returns an array: <tt>[lat_lo, lat_hi, lon_lo, lon_hi]</tt>.
-      # Used to constrain search to a (radius x radius) square.
-      #
-      def coordinate_bounds(latitude, longitude, radius, units = :mi)
-        radius = radius.to_f
-        [
-          latitude  - (radius / Geocoder::Calculations.latitude_degree_distance(units)),
-          latitude  + (radius / Geocoder::Calculations.latitude_degree_distance(units)),
-          longitude - (radius / Geocoder::Calculations.longitude_degree_distance(latitude, units)),
-          longitude + (radius / Geocoder::Calculations.longitude_degree_distance(latitude, units))
-        ]
-      end
     end
 
     ##