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Diffstat (limited to 'lib/python2.7/site-packages/django/contrib/gis/maps/google/zoom.py')
| -rw-r--r-- | lib/python2.7/site-packages/django/contrib/gis/maps/google/zoom.py | 162 |
1 files changed, 0 insertions, 162 deletions
diff --git a/lib/python2.7/site-packages/django/contrib/gis/maps/google/zoom.py b/lib/python2.7/site-packages/django/contrib/gis/maps/google/zoom.py deleted file mode 100644 index c93cf4e..0000000 --- a/lib/python2.7/site-packages/django/contrib/gis/maps/google/zoom.py +++ /dev/null @@ -1,162 +0,0 @@ -from django.contrib.gis.geos import GEOSGeometry, LinearRing, Polygon, Point -from django.contrib.gis.maps.google.gmap import GoogleMapException -from django.utils.six.moves import xrange -from math import pi, sin, log, exp, atan - -# Constants used for degree to radian conversion, and vice-versa. -DTOR = pi / 180. -RTOD = 180. / pi - -class GoogleZoom(object): - """ - GoogleZoom is a utility for performing operations related to the zoom - levels on Google Maps. - - This class is inspired by the OpenStreetMap Mapnik tile generation routine - `generate_tiles.py`, and the article "How Big Is the World" (Hack #16) in - "Google Maps Hacks" by Rich Gibson and Schuyler Erle. - - `generate_tiles.py` may be found at: - http://trac.openstreetmap.org/browser/applications/rendering/mapnik/generate_tiles.py - - "Google Maps Hacks" may be found at http://safari.oreilly.com/0596101619 - """ - - def __init__(self, num_zoom=19, tilesize=256): - "Initializes the Google Zoom object." - # Google's tilesize is 256x256, square tiles are assumed. - self._tilesize = tilesize - - # The number of zoom levels - self._nzoom = num_zoom - - # Initializing arrays to hold the parameters for each one of the - # zoom levels. - self._degpp = [] # Degrees per pixel - self._radpp = [] # Radians per pixel - self._npix = [] # 1/2 the number of pixels for a tile at the given zoom level - - # Incrementing through the zoom levels and populating the parameter arrays. - z = tilesize # The number of pixels per zoom level. - for i in xrange(num_zoom): - # Getting the degrees and radians per pixel, and the 1/2 the number of - # for every zoom level. - self._degpp.append(z / 360.) # degrees per pixel - self._radpp.append(z / (2 * pi)) # radians per pixel - self._npix.append(z / 2) # number of pixels to center of tile - - # Multiplying `z` by 2 for the next iteration. - z *= 2 - - def __len__(self): - "Returns the number of zoom levels." - return self._nzoom - - def get_lon_lat(self, lonlat): - "Unpacks longitude, latitude from GEOS Points and 2-tuples." - if isinstance(lonlat, Point): - lon, lat = lonlat.coords - else: - lon, lat = lonlat - return lon, lat - - def lonlat_to_pixel(self, lonlat, zoom): - "Converts a longitude, latitude coordinate pair for the given zoom level." - # Setting up, unpacking the longitude, latitude values and getting the - # number of pixels for the given zoom level. - lon, lat = self.get_lon_lat(lonlat) - npix = self._npix[zoom] - - # Calculating the pixel x coordinate by multiplying the longitude value - # with with the number of degrees/pixel at the given zoom level. - px_x = round(npix + (lon * self._degpp[zoom])) - - # Creating the factor, and ensuring that 1 or -1 is not passed in as the - # base to the logarithm. Here's why: - # if fac = -1, we'll get log(0) which is undefined; - # if fac = 1, our logarithm base will be divided by 0, also undefined. - fac = min(max(sin(DTOR * lat), -0.9999), 0.9999) - - # Calculating the pixel y coordinate. - px_y = round(npix + (0.5 * log((1 + fac)/(1 - fac)) * (-1.0 * self._radpp[zoom]))) - - # Returning the pixel x, y to the caller of the function. - return (px_x, px_y) - - def pixel_to_lonlat(self, px, zoom): - "Converts a pixel to a longitude, latitude pair at the given zoom level." - if len(px) != 2: - raise TypeError('Pixel should be a sequence of two elements.') - - # Getting the number of pixels for the given zoom level. - npix = self._npix[zoom] - - # Calculating the longitude value, using the degrees per pixel. - lon = (px[0] - npix) / self._degpp[zoom] - - # Calculating the latitude value. - lat = RTOD * ( 2 * atan(exp((px[1] - npix)/ (-1.0 * self._radpp[zoom]))) - 0.5 * pi) - - # Returning the longitude, latitude coordinate pair. - return (lon, lat) - - def tile(self, lonlat, zoom): - """ - Returns a Polygon corresponding to the region represented by a fictional - Google Tile for the given longitude/latitude pair and zoom level. This - tile is used to determine the size of a tile at the given point. - """ - # The given lonlat is the center of the tile. - delta = self._tilesize / 2 - - # Getting the pixel coordinates corresponding to the - # the longitude/latitude. - px = self.lonlat_to_pixel(lonlat, zoom) - - # Getting the lower-left and upper-right lat/lon coordinates - # for the bounding box of the tile. - ll = self.pixel_to_lonlat((px[0]-delta, px[1]-delta), zoom) - ur = self.pixel_to_lonlat((px[0]+delta, px[1]+delta), zoom) - - # Constructing the Polygon, representing the tile and returning. - return Polygon(LinearRing(ll, (ll[0], ur[1]), ur, (ur[0], ll[1]), ll), srid=4326) - - def get_zoom(self, geom): - "Returns the optimal Zoom level for the given geometry." - # Checking the input type. - if not isinstance(geom, GEOSGeometry) or geom.srid != 4326: - raise TypeError('get_zoom() expects a GEOS Geometry with an SRID of 4326.') - - # Getting the envelope for the geometry, and its associated width, height - # and centroid. - env = geom.envelope - env_w, env_h = self.get_width_height(env.extent) - center = env.centroid - - for z in xrange(self._nzoom): - # Getting the tile at the zoom level. - tile_w, tile_h = self.get_width_height(self.tile(center, z).extent) - - # When we span more than one tile, this is an approximately good - # zoom level. - if (env_w > tile_w) or (env_h > tile_h): - if z == 0: - raise GoogleMapException('Geometry width and height should not exceed that of the Earth.') - return z-1 - - # Otherwise, we've zoomed in to the max. - return self._nzoom-1 - - def get_width_height(self, extent): - """ - Returns the width and height for the given extent. - """ - # Getting the lower-left, upper-left, and upper-right - # coordinates from the extent. - ll = Point(extent[:2]) - ul = Point(extent[0], extent[3]) - ur = Point(extent[2:]) - # Calculating the width and height. - height = ll.distance(ul) - width = ul.distance(ur) - return width, height |