lib/gpx.rb

   1 module GPX
   2   class File
   3     require "libxml"
   4
   5     include LibXML
   6
   7     attr_reader :possible_points, :actual_points, :tracksegs
   8
   9     def initialize(file)
  10       @file = file
  11     end
  12
  13     def parse_file(reader)
  14       point = nil
  15
  16       while reader.read
  17         case reader.node_type
  18         when XML::Reader::TYPE_ELEMENT
  19           if reader.name == "trkpt"
  20             point = TrkPt.new(@tracksegs, reader["lat"].to_f, reader["lon"].to_f)
  21             @possible_points += 1
  22           elsif reader.name == "ele" && point
  23             point.altitude = reader.read_string.to_f
  24           elsif reader.name == "time" && point
  25             point.timestamp = Time.parse(reader.read_string)
  26           end
  27         when XML::Reader::TYPE_END_ELEMENT
  28           if reader.name == "trkpt" && point && point.valid?
  29             point.altitude ||= 0
  30             yield point
  31             @actual_points += 1
  32           elsif reader.name == "trkseg"
  33             @tracksegs += 1
  34           end
  35         end
  36       end
  37     end
  38
  39     def points(&block)
  40       return enum_for(:points) unless block_given?
  41
  42       @possible_points = 0
  43       @actual_points = 0
  44       @tracksegs = 0
  45
  46       begin
  47         Archive::Reader.open_filename(@file).each_entry_with_data do |_entry, data|
  48           parse_file(XML::Reader.string(data), &block)
  49         end
  50       rescue Archive::Error
  51         io = ::File.open(@file)
  52
  53         case MimeMagic.by_magic(io)&.type
  54         when "application/gzip" then io = Zlib::GzipReader.open(@file)
  55         when "application/x-bzip" then io = Bzip2::FFI::Reader.open(@file)
  56         end
  57
  58         parse_file(XML::Reader.io(io), &block)
  59       end
  60     end
  61
  62     def picture(min_lat, min_lon, max_lat, max_lon, num_points)
  63       nframes = 10
  64       width = 250
  65       height = 250
  66       delay = 50
  67
  68       points_per_frame = (num_points.to_f / nframes).ceil
  69
  70       proj = OSM::Mercator.new(min_lat, min_lon, max_lat, max_lon, width, height)
  71
  72       frames = []
  73
  74       (0...nframes).each do |n|
  75         frames[n] = GD2::Image::IndexedColor.new(width, height)
  76         black = frames[n].palette.allocate(GD2::Color[0, 0, 0])
  77         white = frames[n].palette.allocate(GD2::Color[255, 255, 255])
  78         grey = frames[n].palette.allocate(GD2::Color[187, 187, 187])
  79
  80         frames[n].draw do |pen|
  81           pen.color = white
  82           pen.rectangle(0, 0, width, height, true)
  83         end
  84
  85         frames[n].draw do |pen|
  86           pen.color = black
  87           pen.anti_aliasing = true
  88           pen.dont_blend = false
  89
  90           oldpx = 0.0
  91           oldpy = 0.0
  92
  93           first = true
  94
  95           points.each_with_index do |p, pt|
  96             px = proj.x(p.longitude)
  97             py = proj.y(p.latitude)
  98
  99             if (pt >= (points_per_frame * n)) && (pt <= (points_per_frame * (n + 1)))
 100               pen.thickness = 3
 101               pen.color = black
 102             else
 103               pen.thickness = 1
 104               pen.color = grey
 105             end
 106
 107             pen.line(px, py, oldpx, oldpy) unless first
 108             first = false
 109             oldpy = py
 110             oldpx = px
 111           end
 112         end
 113       end
 114
 115       image = GD2::AnimatedGif.new
 116       image.add(frames.first)
 117       frames.each do |frame|
 118         image.add(frame, :delay => delay)
 119       end
 120       image.end
 121
 122       output = StringIO.new
 123       image.export(output)
 124       output.read
 125     end
 126
 127     def icon(min_lat, min_lon, max_lat, max_lon)
 128       width = 50
 129       height = 50
 130       proj = OSM::Mercator.new(min_lat, min_lon, max_lat, max_lon, width, height)
 131
 132       image = GD2::Image::IndexedColor.new(width, height)
 133
 134       black = image.palette.allocate(GD2::Color[0, 0, 0])
 135       white = image.palette.allocate(GD2::Color[255, 255, 255])
 136
 137       image.draw do |pen|
 138         pen.color = white
 139         pen.rectangle(0, 0, width, height, true)
 140       end
 141
 142       image.draw do |pen|
 143         pen.color = black
 144         pen.anti_aliasing = true
 145         pen.dont_blend = false
 146
 147         oldpx = 0.0
 148         oldpy = 0.0
 149
 150         first = true
 151
 152         points do |p|
 153           px = proj.x(p.longitude)
 154           py = proj.y(p.latitude)
 155
 156           pen.line(px, py, oldpx, oldpy) unless first
 157
 158           first = false
 159           oldpy = py
 160           oldpx = px
 161         end
 162       end
 163
 164       image.gif
 165     end
 166   end
 167
 168   TrkPt = Struct.new(:segment, :latitude, :longitude, :altitude, :timestamp) do
 169     def valid?
 170       latitude && longitude && timestamp &&
 171         latitude >= -90 && latitude <= 90 &&
 172         longitude >= -180 && longitude <= 180
 173     end
 174   end
 175 end