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# name: OpenStreetMap Onebox
# version: 0.2
# authors: Marcin Rataj
class Onebox::Engine::OpenStreetMapOnebox
include Onebox::Engine
# current embed defaults from openstreetmap.org
@@width = 425
@@height = 350
@@tile_size = 256
@@REGEX = /^https?:\/\/(?:www\.)openstreetmap\.org\/.*#map=([\d\.]+)\/([-\d\.]+)\/([-\d\.]+)/
# enable oneboxing permalinks (http://wiki.openstreetmap.org/wiki/Permalink) into iframes
matches_regexp(@@REGEX)
def to_html
zoom, lat, lon = @url.match(@@REGEX).captures
iframe_url = "//www.openstreetmap.org/export/embed.html?bbox=#{get_bbox(lat.to_f, lon.to_f, zoom.to_i)}"
if marker = @url.match(/mlat=([-\d\.]+).+mlon=([-\d\.]+)/)
mlat, mlon = marker.captures
iframe_url = "#{iframe_url}&marker=#{mlat}%2C#{mlon}"
end
if layers = @url.match(/layers=(\w+)/)
iframe_url = "#{iframe_url}&layers=#{layers.captures[0]}"
end
"<iframe src='#{iframe_url}' style='border: 0' width='#{@@width}' height='#{@@height}' frameborder='0' scrolling='no'></iframe>"
end
private
# http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#Lon..2Flat._to_tile_numbers_3
# note: it is slightly modified as fractional part is not discarded (http://goo.gl/oNtQ5g)
def get_tile_number(lat_deg, lng_deg, zoom)
lat_rad = lat_deg/180 * Math::PI
n = 2.0 ** zoom
x = (lng_deg + 180.0) / 360.0 * n
y = (1.0 - Math::log(Math::tan(lat_rad) + (1 / Math::cos(lat_rad))) / Math::PI) / 2.0 * n
if !y.infinite?.nil?
y = x
end
[x, y]
end
# http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#Tile_numbers_to_lon..2Flat._3
def get_lat_lng_for_number(xtile, ytile, zoom)
n = 2.0 ** zoom
lon_deg = xtile / n * 360.0 - 180.0
lat_rad = Math::atan(Math::sinh(Math::PI * (1 - 2 * ytile / n)))
lat_deg = 180.0 * (lat_rad / Math::PI)
[lat_deg, lon_deg]
end
# http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#Lon..2Flat._to_bbox
def get_bbox(lat, lon, zoom)
xtile, ytile = get_tile_number(lat, lon, zoom)
xtile_s = (xtile * @@tile_size - @@width/2.0) / @@tile_size
ytile_s = (ytile * @@tile_size - @@height/2.0) / @@tile_size
xtile_e = (xtile * @@tile_size + @@width/2.0) / @@tile_size
ytile_e = (ytile * @@tile_size + @@height/2.0) / @@tile_size
lat_s, lon_s = get_lat_lng_for_number(xtile_s, ytile_s, zoom)
lat_e, lon_e = get_lat_lng_for_number(xtile_e, ytile_e, zoom)
"#{lon_s}%2C#{lat_s}%2C#{lon_e}%2C#{lat_e}"
end
end
# vim:ts=2:sw=2:et:
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