api06: simplify exception handling and add exception handling to the diff

[rails.git] / lib / osm.rb

diff --git a/lib/osm.rb b/lib/osm.rb
index 916cf4d6a4ed757d3b2e436685ab4d19b959d23e..8798866e5dc918ab5fc63d94bbf217924cc5effd 100644 (file)
--- a/lib/osm.rb
+++ b/lib/osm.rb
@@ -1,13 +1,6 @@
+# The OSM module provides support functions for OSM.
 module OSM
 
-  # This piece of magic reads a GPX with SAX and spits out
-  # lat/lng and stuff
-  #
-  # This would print every latitude value:
-  #
-  # gpx = OSM::GPXImporter.new('somefile.gpx')
-  # gpx.points {|p| puts p['latitude']}
-
   require 'time'
   require 'rexml/parsers/sax2parser'
   require 'rexml/text'
@@ -15,36 +8,68 @@ module OSM
   require 'digest/md5'
   require 'RMagick'
 
+  # The base class for API Errors.
+  class APIError < RuntimeError
+    def render_opts { :text => "", :status => :internal_server_error } end
+  end
+
+  # Raised when an API object is not found.
+  class APINotFoundError < APIError
+  end
+
+  # Raised when a precondition to an API action fails sanity check.
+  class APIPreconditionFailedError < APIError
+    def render_opts { :text => "", :status => :precondition_failed } end
+  end
+
+  # Raised when to delete an already-deleted object.
+  class APIAlreadyDeletedError < APIError
+    def render_opts { :text => "", :status => :gone } end
+  end
+
+  # Raised when the provided version is not equal to the latest in the db.
+  class APIVersionMismatchError < APIError
+    def initialize(provided, latest)
+      @provided, @latest = provided, latest
+    end
+
+    attr_reader :provided, :latest
+
+    def render_opts
+      { :text => "Version mismatch: Provided " + ex.provided.to_s +
+       ", server had: " + ex.latest.to_s, :status => :bad_request }
+    end
+  end
+
+  # Helper methods for going to/from mercator and lat/lng.
   class Mercator
     include Math
 
-    def initialize(lat, lon, degrees_per_pixel, width, height)
-      #init me with your centre lat/lon, the number of degrees per pixel and the size of your image
-      @clat = lat
-      @clon = lon
-      @degrees_per_pixel = degrees_per_pixel
-      @degrees_per_pixel = 0.0000000001 if @degrees_per_pixel < 0.0000000001
+    #init me with your bounding box and the size of your image
+    def initialize(min_lat, min_lon, max_lat, max_lon, width, height)
+      xsize = xsheet(max_lon) - xsheet(min_lon)
+      ysize = ysheet(max_lat) - ysheet(min_lat)
+      xscale = xsize / width
+      yscale = ysize / height
+      scale = [xscale, yscale].max
+
+      xpad = width * scale - xsize
+      ypad = height * scale - ysize
+
       @width = width
       @height = height
-      @dlon = width / 2 * @degrees_per_pixel
-      @dlat = height / 2 * @degrees_per_pixel  * cos(@clat * PI / 180)
-
-      @tx = xsheet(@clon - @dlon)
-      @ty = ysheet(@clat - @dlat)
 
-      @bx = xsheet(@clon + @dlon)
-      @by = ysheet(@clat + @dlat)
+      @tx = xsheet(min_lon) - xpad / 2
+      @ty = ysheet(min_lat) - ypad / 2
 
+      @bx = xsheet(max_lon) + xpad / 2
+      @by = ysheet(max_lat) + ypad / 2
     end
 
     #the following two functions will give you the x/y on the entire sheet
 
-    def kilometerinpixels
-      return 40008.0  / 360.0 * @degrees_per_pixel
-    end
-
     def ysheet(lat)
-      log(tan(PI / 4 +  (lat  * PI / 180 / 2)))
+      log(tan(PI / 4 + (lat * PI / 180 / 2))) / (PI / 180)
     end
 
     def xsheet(lon)
@@ -63,14 +88,21 @@ module OSM
   end
 
 
+  # This piece of magic reads a GPX with SAX and spits out
+  # lat/lng and stuff
+  #
+  # This would print every latitude value:
+  #
+  # gpx = OSM::GPXImporter.new('somefile.gpx')
+  # gpx.points {|p| puts p['latitude']}
   class GPXImporter
     # FIXME swap REXML for libXML
     attr_reader :possible_points
     attr_reader :actual_points
     attr_reader :tracksegs
 
-    def initialize(filename)
-      @filename = filename
+    def initialize(file)
+      @file = file
     end
 
     def points
@@ -86,12 +118,16 @@ module OSM
       gotele = false
       gotdate = false
 
-      parser = REXML::Parsers::SAX2Parser.new(File.new(@filename))
+      @file.rewind
+
+      parser = REXML::Parsers::SAX2Parser.new(@file)
 
       parser.listen( :start_element,  %w{ trkpt }) do |uri,localname,qname,attributes| 
         lat = attributes['lat'].to_f
         lon = attributes['lon'].to_f
         gotlatlon = true
+        gotele = false
+        gotdate = false
         @possible_points += 1
       end
 
@@ -135,8 +171,7 @@ module OSM
       frames = 10
       width = 250
       height = 250
-      rat= Math.cos( ((max_lat + min_lat)/2.0) /  180.0 * 3.141592)
-      proj = OSM::Mercator.new((min_lat + max_lat) / 2, (max_lon + min_lon) / 2, (max_lat - min_lat) / width / rat, width, height)
+      proj = OSM::Mercator.new(min_lat, min_lon, max_lat, max_lon, width, height)
 
       linegc = Magick::Draw.new
       linegc.stroke_linejoin('miter')
@@ -211,8 +246,7 @@ module OSM
       #puts "getting icon for bbox #{min_lat},#{min_lon} - #{max_lat},#{max_lon}"
       width = 50
       height = 50
-      rat= Math.cos( ((max_lat + min_lat)/2.0) /  180.0 * 3.141592)
-      proj = OSM::Mercator.new((min_lat + max_lat) / 2, (max_lon + min_lon) / 2, (max_lat - min_lat) / width / rat, width, height)
+      proj = OSM::Mercator.new(min_lat, min_lon, max_lat, max_lon, width, height)
 
       gc = Magick::Draw.new
       gc.stroke_linejoin('miter')
@@ -278,7 +312,7 @@ module OSM
     def initialize(feed_title='OpenStreetMap GPS Traces', feed_description='OpenStreetMap GPS Traces', feed_url='http://www.openstreetmap.org/traces/')
       @doc = XML::Document.new
       @doc.encoding = 'UTF-8' 
-      
+
       rss = XML::Node.new 'rss'
       @doc.root = rss
       rss['version'] = "2.0"
@@ -423,4 +457,6 @@ module OSM
 
     return "#{tilesql} AND #{prefix}latitude BETWEEN #{minlat} AND #{maxlat} AND #{prefix}longitude BETWEEN #{minlon} AND #{maxlon}"
   end
+
+
 end