# encoding: utf-8
from __future__ import absolute_import, unicode_literals, division
import math
[文档]class Tile(object):
EARTH_RADIUS = 6378137
MIN_LATITUDE = -85.05112878
MAX_LATITUDE = 85.05112878
MIN_LONGITUDE = -180
MAX_LONGITUDE = 180
[文档] @classmethod
def clip(cls, n, min_value, max_value):
"""
将数字剪辑到指定的最小值和最大值
:param n: 要裁剪的数字
:param min_value: 最小值
:param max_value: 最大值
:return: 裁剪后结果
"""
return min(max(n, min_value), max_value)
[文档] @classmethod
def map_size(cls, level_of_detail):
"""
确定指定级别上的地图宽度和高度（以像素为单位）
:param level_of_detail: 地图级别
:return: 地图边长（像素）
"""
return 256 << level_of_detail
[文档] @classmethod
def ground_resolution(cls, latitude, level_of_detail):
"""
获取指定位置的地面分辨率（米/像素）
:param latitude: 纬度
:param level_of_detail: 地图级别
:return: 地面分辨率，单位为米/像素
"""
latitude = cls.clip(latitude, cls.MIN_LATITUDE, cls.MAX_LATITUDE)
return math.cos(latitude * math.pi / 180) * 2 * math.pi * cls.EARTH_RADIUS / cls.map_size(level_of_detail)
[文档] @classmethod
def map_scale(cls, latitude, level_of_detail, screen_dpi):
"""
获取指定位置的地图比例
:param latitude: 纬度
:param level_of_detail: 地图级别
:param screen_dpi: 屏幕分辨率，单位为像素每英寸
:return: 地图比例，表示为比率1:N的分母N
"""
return cls.ground_resolution(latitude, level_of_detail) * screen_dpi / 0.0254
[文档] @classmethod
def lat_long_to_pixel_xy(cls, latitude, longitude, level_of_detail):
"""
经纬度转换为像素坐标
:param latitude: 纬度
:param longitude: 经度
:param level_of_detail: 地图级别
:return: 像素坐标x, 像素坐标y
"""
latitude = cls.clip(latitude, cls.MIN_LATITUDE, cls.MAX_LATITUDE)
longitude = cls.clip(longitude, cls.MIN_LONGITUDE, cls.MAX_LONGITUDE)
x = (longitude + 180) / 360
sin_latitude = math.sin(latitude * math.pi / 180)
y = 0.5 - math.log((1 + sin_latitude) / (1 - sin_latitude)) / (4 * math.pi)
map_size = cls.map_size(level_of_detail)
pixel_x = int(cls.clip(x * map_size + 0.5, 0, map_size - 1))
pixel_y = int(cls.clip(y * map_size + 0.5, 0, map_size - 1))
return pixel_x, pixel_y
[文档] @classmethod
def pixel_xy_to_lat_long(cls, pixel_x, pixel_y, level_of_detail):
"""
像素坐标转换为经纬度
:param pixel_x: 像素坐标x
:param pixel_y: 像素坐标y
:param level_of_detail: 地图级别
:return: 纬度, 经度
"""
map_size = cls.map_size(level_of_detail)
x = (cls.clip(pixel_x, 0, map_size - 1) / map_size) - 0.5
y = 0.5 - (cls.clip(pixel_y, 0, map_size - 1) / map_size)
latitude = 90 - 360 * math.atan(math.exp(-y * 2 * math.pi)) / math.pi
longitude = 360 * x
return latitude, longitude
[文档] @classmethod
def pixel_xy_to_tile_xy(cls, pixel_x, pixel_y):
"""
像素坐标转换为图块序号
:param pixel_x: 像素坐标x
:param pixel_y: 像素坐标y
:return: 图块序号x, 图块序号y
"""
tile_x = pixel_x // 256
tile_y = pixel_y // 256
return tile_x, tile_y
[文档] @classmethod
def tile_xy_to_pixel_xy(cls, tile_x, tile_y):
"""
图块序号转换为像素坐标
:param tile_x: 图块序号x
:param tile_y: 图块序号y
:return: 像素坐标x, 像素坐标y
"""
pixel_x = tile_x * 256
pixel_y = tile_y * 256
return pixel_x, pixel_y
[文档] @classmethod
def tile_xy_to_quad_key(cls, tile_x, tile_y, level_of_detail):
"""
图块序号转换为四叉树键值
:param tile_x: 图块序号x
:param tile_y: 图块序号y
:param level_of_detail: 地图级别
:return: 四叉树键值
"""
quad_key = []
i = level_of_detail
while i > 0:
digit = 0
mask = 1 << (i - 1)
if tile_x & mask:
digit += 1
if tile_y & mask:
digit += 2
quad_key.append(str(digit))
i -= 1
return "".join(quad_key)
[文档] @classmethod
def quad_key_to_tile_xy(cls, quad_key):
"""
四叉树键值转换为图块序号
:param quad_key: 四叉树键值
:return: 图块序号x, 图块序号y, 地图级别
"""
tile_x = 0
tile_y = 0
i, level_of_detail = len(quad_key)
while i > 0:
mask = 1 << (i - 1)
if quad_key[level_of_detail - i] == '0':
pass
elif quad_key[level_of_detail - i] == '1':
tile_x |= mask
elif quad_key[level_of_detail - i] == '2':
tile_y |= mask
elif quad_key[level_of_detail - i] == '3':
tile_x |= mask
tile_y |= mask
else:
raise ValueError('Invalid QuadKey digit sequence')
return tile_x, tile_y, level_of_detail