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https://github.com/protomaps/PMTiles.git
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104 lines
1.9 KiB
Python
104 lines
1.9 KiB
Python
from collections import namedtuple
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Entry = namedtuple("Entry", ["tile_id", "offset", "length", "run_length"])
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Header = namedtuple("Header", [])
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def rotate(n, xy, rx, ry):
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if ry == 0:
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if rx == 1:
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xy[0] = n - 1 - xy[0]
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xy[1] = n - 1 - xy[1]
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xy[0], xy[1] = xy[1], xy[0]
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def t_on_level(z, pos):
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n = 1 << z
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rx, ry, t = pos, pos, pos
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xy = [0, 0]
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s = 1
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while s < n:
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rx = 1 & (t // 2)
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ry = 1 & (t ^ rx)
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rotate(s, xy, rx, ry)
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xy[0] += s * rx
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xy[1] += s * ry
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t //= 4
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s *= 2
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return z, xy[0], xy[1]
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def zxy_to_tileid(z, x, y):
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acc = 0
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tz = 0
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while tz < z:
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acc += (0x1 << tz) * (0x1 << tz)
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tz += 1
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n = 1 << z
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rx = 0
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ry = 0
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d = 0
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xy = [x, y]
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s = n // 2
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while s > 0:
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if (xy[0] & s) > 0:
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rx = 1
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else:
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rx = 0
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if (xy[1] & s) > 0:
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ry = 1
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else:
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ry = 0
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d += s * s * ((3 * rx) ^ ry)
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rotate(s, xy, rx, ry)
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s //= 2
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return acc + d
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def tileid_to_zxy(tile_id):
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num_tiles = 0
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acc = 0
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z = 0
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while True:
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num_tiles = (1 << z) * (1 << z)
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if acc + num_tiles > tile_id:
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return t_on_level(z, tile_id - acc)
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acc += num_tiles
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z += 1
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def find_tile(entries, tile_id):
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m = 0
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n = len(entries) - 1
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while m < n:
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k = (n + m) >> 1
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c = tile_id - entries[k].tile_id
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if c > 0:
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m = k + 1
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elif c < 0:
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n = k - 1
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else:
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return entries[k]
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if n >= 0:
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if entries[n].run_length == 0:
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return entries[n]
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if tile_id - entries[n].tile_id < entries[n].run_length:
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return entries[n]
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def deserialize_directory(bytes):
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pass
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def serialize_directory(bytes):
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pass
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def deserialize_header(bytes):
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pass
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def serialize_header(bytes):
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pass
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