Module: EasyMapTiles

Defined in:
lib/easy_map_tiles.rb,
lib/easy_map_tiles/version.rb

Constant Summary collapse

TO_DEG = 
Rational(180.0, Math::PI)
TO_RAD = 
Rational(Math::PI, 180)
TILE_SIZE =

in px

256.0
EARTH_RADIUS =

in meters

6378137.0
PX_PER_RAD = 
Rational(TILE_SIZE, (2 * Math::PI))
VERSION = 
"0.0.1"

Class Method Summary collapse

Class Method Details

.most_fitting_zoom_level(lat_deg, lon_deg, zoom_levels) ⇒ Object 



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# File 'lib/easy_map_tiles.rb', line 35

def most_fitting_zoom_level(lat_deg, lon_deg, zoom_levels)
  Array(zoom_levels).min_by do |zoom|
    to_world_px(lat_deg, lon_deg, zoom).reduce(0){|s,e| s += (TILE_SIZE / 2 - (e % TILE_SIZE)).abs}
  end
end

.tile_div(lat_deg, lon_deg, zoom_levels, opts = {}) ⇒ Object 



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# File 'lib/easy_map_tiles.rb', line 41

def tile_div(lat_deg, lon_deg, zoom_levels, opts={})
  satellite = opts[:satellite] || false
  marker = opts[:marker] || false
  zoom = most_fitting_zoom_level(lat_deg, lon_deg, zoom_levels)
  if marker
    px,py = to_world_px(lat_deg, lon_deg, zoom).map{|e| (e % TILE_SIZE) / TILE_SIZE}
    styles = [
      "left: #{(px*100).round(3)}%",
      "top: #{(py*100).round(3)}%"
    ]
    styles += [
      'border-radius: 50%',
      'background: rgba(255,50,50,0.9)',
      'width: 12px',
      'height: 12px',
      'position: absolute',
      'box-shadow: 0px 0px 6px 2px rgba(255,50,50,0.9)'
    ] unless opts[:marker_styles] == false
    marker_div = "<div class='emt-marker' style='#{styles.join(';')}'></div>"
  end

  styles = [
    "background-image: url(\"#{tile_url(lat_deg, lon_deg, zoom, satellite)}\")"
  ]
  styles += [
    'background-size: cover',
    'position: relative',
    'display: inline-block',
    'width: 256px',
    'height: 256px'
  ] unless opts[:tile_styles] == false
  "<div class='emt-tile' style='#{styles.join(';')}'>#{marker_div}</div>"
end

.tile_url(lat_deg, lon_deg, zoom, satellite = false) ⇒ Object 



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# File 'lib/easy_map_tiles.rb', line 25

def tile_url(lat_deg, lon_deg, zoom, satellite=false)
  px,py = to_world_px(lat_deg, lon_deg, zoom)
  x, y = Rational(px, TILE_SIZE).to_i, Rational(py, TILE_SIZE).to_i
  if satellite
    "https://khms#{rand(0..3)}.google.com/kh/v=131&x=#{x}&y=#{y}&z=#{zoom}"
  else
    "http://mt#{rand(0..3)}.google.com/vt/hl=en&x=#{x}&y=#{y}&z=#{zoom}"
  end
end

.to_world_px(lat_deg, lon_deg, zoom) ⇒ Object

returns the pixel coordinates at the given zoom level on the world map



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# File 'lib/easy_map_tiles.rb', line 14

def to_world_px(lat_deg, lon_deg, zoom)
  # scale the latitude via mercator projections
  # see http://en.wikipedia.org/wiki/Mercator_projection#Derivation_of_the_Mercator_projection
  lat_scaled_rad = Math.log( Math.tan( Rational(Math::PI, 4) + Rational(TO_RAD * lat_deg, 2) ))
  # https://developers.google.com/maps/documentation/javascript/examples/map-coordinates
  wx = (TILE_SIZE / 2) + PX_PER_RAD * (TO_RAD * lon_deg)
  wy = (TILE_SIZE / 2) - PX_PER_RAD * lat_scaled_rad
  tiles_count = 2**zoom
  [(wx * tiles_count).to_i, (wy * tiles_count).to_i]
end