def generateGrid(self, size):
''' generate a grid overlaying the city
:param size: dimension of the cell for the grid
:rtype: an array of cells that forms the grid
'''
file = 'city-{0}_size-{1}m.p'.format(self.name, size)
path = settings.GRIDS_DIR + file
grids = []
try:
grids = pickle.load(open(path, "rb"))
except EnvironmentError:
start = Point(self.box['nw']['lon'], self.box['nw']['lat'])
lat = lon = start
while self.geom.envelope.intersects(lat):
nw = lat
ne = getNextPoint(nw, size, 90)
sw = getNextPoint(nw, size, 180)
se = getNextPoint(ne, size, 180)
lat = ne
linearRing = LinearRing(nw, ne, se, sw, nw)
polygon = Polygon(linearRing)
if polygon.intersects(self.geom):
grids.append(polygon)
if not self.geom.envelope.intersects(lat):
lon = getNextPoint(lon, size, 180)
lat = lon
pickle.dump(grids, open(path, "wb"))
return grids
def getTilesOfBoundery(boundery, zoom):
"""Get all tiles that covers boundery."""
box = list(list(boundery.polygon.envelope)[0])
startPoint = box[1]
endPoint = box[3]
firstTile = deg2num(startPoint[1], startPoint[0], zoom)
lastTile = deg2num(endPoint[1], endPoint[0], zoom)
results = []
startingPoint = [firstTile[0], firstTile[1]]
while startingPoint[0] >= lastTile[0]:
while startingPoint[1] >= lastTile[1]:
tile = (startingPoint[0], startingPoint[1])
tileBoxNW = num2deg(tile[0], tile[1], zoom)
tileBoxSE = num2deg(tile[0] + 1, tile[1] + 1, zoom)
tileWindow = [tileBoxNW, tileBoxSE]
tileBox = [
(tileBoxNW[1], tileBoxNW[0]),
(tileBoxNW[1], tileBoxSE[0]),
(tileBoxSE[1], tileBoxNW[0]),
(tileBoxSE[1], tileBoxSE[0]),
(tileBoxNW[1], tileBoxNW[0])
]
tilePolygon = Polygon(tileBox)
if tilePolygon.intersects(boundery.polygon):
results.append({
'box': tileWindow,
'image': getTileByXYZoom(tile[0], tile[1], zoom)
})
startingPoint[1] -= 1
startingPoint[1] = firstTile[1]
startingPoint[0] -= 1
return results
