Class: ServerSideGoogleMaps::Path

Inherits:
Object
  • Object
show all
Defined in:
lib/server-side-google-maps/path.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(points) ⇒ Path

Returns a new instance of Path.

Raises:

  • (ArgumentError) 


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# File 'lib/server-side-google-maps/path.rb', line 10

def initialize(points)
  raise ArgumentError.new('path must be an Enumerable') unless Enumerable === points
  raise ArgumentError.new('path must have one or more points') unless points.length > 0
  i = 0
  @points = points.collect do |pt|
    raise ArgumentError.new("path element #{i} must have .latitude and .longitude") unless pt.respond_to?(:latitude)
    pt
  end
end

Instance Attribute Details

#points ⇒ Object (readonly)

Returns the value of attribute points.



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# File 'lib/server-side-google-maps/path.rb', line 3

def points
  @points
end

Class Method Details

.get_elevations(params) ⇒ Object 



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# File 'lib/server-side-google-maps/path.rb', line 5

def self.get_elevations(params)
  server = Server.new
  server.get('/maps/api/elevation', {:sensor => false}.merge(params))
end

Instance Method Details

#calculate_distances ⇒ Object

Sets .distance on every Point in the Path

Yes, this is a hack: it assumes all the Points will only belong to this Path. It’s here because it’s convenient.



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# File 'lib/server-side-google-maps/path.rb', line 43

def calculate_distances
  total_distance = 0
  last_point = nil
  points.each do |point|
    if last_point
      distance_piece = last_point.distance(point)
      total_distance += distance_piece
    end
    point.distance_along_path = total_distance
    last_point = point
  end
end

#elevations(n) ⇒ Object

Returns a new Path with n equidistant Points along this Path, complete with .elevation



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# File 'lib/server-side-google-maps/path.rb', line 21

def elevations(n)
  results = self.class.get_elevations(:path => "enc:#{encoded_path}", :samples => n)

  i = -1
  total_distance = points.last.distance_along_path

  points = results['results'].collect do |r|
    i += 1
    Point.new(
      r['location']['lat'].to_f,
      r['location']['lng'].to_f,
      :elevation => r['elevation'].to_f,
      :distance_along_path => total_distance && (total_distance.to_f * i / (n - 1)).to_i
    )
  end
  Path.new(points)
end

#interpolate(n) ⇒ Object

Returns a Path that approximates this one, with n points



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# File 'lib/server-side-google-maps/path.rb', line 57

def interpolate(n)
  calculate_distances unless points[0].distance_along_path

  total_distance = points[-1].distance_along_path - points[0].distance_along_path
  distance_step = 1.0 * total_distance / (n - 1)

  ret = []
  ret << create_interpolated_point(points[0], points[0], 0.0, :distance_along_path => points[0].distance_along_path)

  j = 0
  current_distance = points[0].distance_along_path
  (1...(n - 1)).each do |i|
    current_distance += distance_step if i > 0
    while j < (points.length - 2) && points[j + 1].distance_along_path < current_distance #&& points[j].distance_along_path == points[j + 1].distance_along_path
      j += 1
    end

    point_before = points[j]
    point_after = points[j + 1]
    point_segment_length = point_after.distance_along_path - point_before.distance_along_path

    fraction_after = (1.0 * current_distance - point_before.distance_along_path) / point_segment_length

    ret << create_interpolated_point(point_before, point_after, fraction_after, :distance_along_path => current_distance.to_i)
  end

  ret << create_interpolated_point(points[-1], points[-1], 0.0, :distance_along_path => points[-1].distance_along_path)

  Path.new(ret)
end

#simplify(latlng_error2) ⇒ Object 



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# File 'lib/server-side-google-maps/path.rb', line 88

def simplify(latlng_error2)
  simplified_points = douglas_peucker(points, latlng_error2)
  Path.new(simplified_points)
end