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Fixed #8113. Made `get_width_height` a `GoogleZoom` method that takes the extent instead of an envelope so it may handle Point geometries. Thanks to Santiago Aguiar for the bug report. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8428 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Justin Bronn 2008-08-17 21:09:28 +00:00
parent e3ea9ddef5
commit b25d759bed
1 changed files with 34 additions and 37 deletions
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43
django/contrib/gis/maps/google/zoom.py
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@ -6,17 +6,6 @@ from math import pi, sin, cos, log, exp, atan
DTOR = pi / 180.
RTOD = 180. / pi
def get_width_height(envelope):
# Getting the lower-left, upper-left, and upper-right
# coordinates of the envelope.
ll = Point(envelope[0][0])
ul = Point(envelope[0][1])
ur = Point(envelope[0][2])
height = ll.distance(ul)
width = ul.distance(ur)
return width, height
class GoogleZoom(object):
"""
GoogleZoom is a utility for performing operations related to the zoom
@ -34,21 +23,19 @@ class GoogleZoom(object):
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.
# 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.
# 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
@ -79,9 +66,8 @@ class GoogleZoom(object):
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.
# 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
@ -136,7 +122,6 @@ class GoogleZoom(object):
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.')
@ -144,13 +129,12 @@ class GoogleZoom(object):
# Getting the envelope for the geometry, and its associated width, height
# and centroid.
env = geom.envelope
env_w, env_h = get_width_height(env)
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 = self.tile(center, z)
tile_w, tile_h = get_width_height(tile)
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.
@ -162,3 +146,16 @@ class GoogleZoom(object):
# 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