Class: EncodedPolyline

Inherits:
Object
  • Object
show all
Defined in:
lib/encoded_polyline/core.rb,
lib/encoded_polyline/version.rb

Constant Summary collapse

VERSION = 
"0.0.2"

Class Method Summary collapse

Class Method Details

.decode(str, precision = 5) ⇒ Object 



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# File 'lib/encoded_polyline/core.rb', line 26

def self.decode(str, precision=5)
  self.decode_arr(str.split(//), precision)
end

.decode_arr(arr, precision = 5) ⇒ Object 



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# File 'lib/encoded_polyline/core.rb', line 14

def self.decode_arr(arr, precision=5)
  num = 0
  arr[0..-2].each_with_index do |elem, i|
    num = (num | (((elem[0].ord - 63) ^ 0x20) << (i * 5)))
  end
  num = (num | ((arr.last[0].ord - 63) << ((arr.size-1) * 5)))
  num = ~num if ((num & 0x1) == 1)
  num = num >> 1
  num = num.to_f * (10 ** -precision)
  return num
end

.decode_points(str, precision = 5) ⇒ Object 



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# File 'lib/encoded_polyline/core.rb', line 44

def self.decode_points(str, precision=5)
  decoded_points = []
  point_chars = []

  str.each_char do |char|
    point_chars << char
    if ((char[0].ord - 63) & 0x20).zero?
      decoded_points << decode_arr(point_chars, precision)
      point_chars = []
    end
  end

  coordinates = [[decoded_points.shift, decoded_points.shift]]
   while decoded_points.any?
     coordinates << [
       coordinates.last[0] + decoded_points.shift,
       coordinates.last[1] + decoded_points.shift
     ]
   end
  return coordinates
end

.encode(number, precision = 5) ⇒ Object 



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# File 'lib/encoded_polyline/core.rb', line 2

def self.encode(number, precision=5)
  number = (number * (10 ** precision)).round
  n = number << 1
  n = ~n if number < 0
  str = ""
  while n >= 0x20 do
      str << ((0x20 | (n & 0x1f)) + 63).chr
      n = n >> 5
  end
  return str << (n + 63).chr
end

.encode_points(coordinates, precision = 5) ⇒ Object 



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# File 'lib/encoded_polyline/core.rb', line 30

def self.encode_points(coordinates, precision=5)
  output = ""
  output << encode(coordinates.first[0], precision)
  output << encode(coordinates.first[1], precision)

  (1..coordinates.size-1).each do |i|
    previous = coordinates[i-1]
    current = coordinates[i]
    output << encode(current[0] - previous[0], precision)
    output << encode(current[1] - previous[1], precision)
  end
  return output
end