mirror of
https://github.com/protomaps/PMTiles.git
synced 2026-02-04 19:01:08 +00:00
78 lines
2.5 KiB
Python
78 lines
2.5 KiB
Python
import json
|
|
import mmap
|
|
from contextlib import contextmanager
|
|
|
|
@contextmanager
|
|
def read(fname):
|
|
r = Reader(fname)
|
|
try:
|
|
yield r
|
|
finally:
|
|
r.close()
|
|
|
|
class Reader:
|
|
def __init__(self,fname):
|
|
self.f = open(fname, "r+b")
|
|
self.mmap = mmap.mmap(self.f.fileno(), 0)
|
|
assert int.from_bytes(self.mmap[0:2],byteorder='little') == 0x4D50
|
|
first_entry_idx = 10+self.metadata_len
|
|
self.root_dir, self.leaves = self.load_directory(first_entry_idx,self.root_entries)
|
|
|
|
def load_directory(self,offset,num_entries):
|
|
directory = {}
|
|
leaves = {}
|
|
for i in range(offset,offset+num_entries*17,17):
|
|
z = int.from_bytes(self.mmap[i:i+1],byteorder='little')
|
|
x = int.from_bytes(self.mmap[i+1:i+4],byteorder='little')
|
|
y = int.from_bytes(self.mmap[i+4:i+7],byteorder='little')
|
|
tile_off = int.from_bytes(self.mmap[i+7:i+13],byteorder='little')
|
|
tile_len = int.from_bytes(self.mmap[i+13:i+17],byteorder='little')
|
|
if (z & 0b10000000):
|
|
leaves[(z & 0b01111111,x,y)] = (tile_off,tile_len)
|
|
else:
|
|
directory[(z,x,y)] = (tile_off,tile_len)
|
|
return (directory,leaves)
|
|
|
|
def close(self):
|
|
self.f.close()
|
|
|
|
@property
|
|
def metadata_len(self):
|
|
return int.from_bytes(self.mmap[4:8],byteorder='little')
|
|
|
|
@property
|
|
def metadata(self):
|
|
s = self.mmap[10:10+self.metadata_len]
|
|
return json.loads(s)
|
|
|
|
@property
|
|
def version(self):
|
|
return int.from_bytes(self.mmap[2:4],byteorder='little')
|
|
|
|
@property
|
|
def root_entries(self):
|
|
return int.from_bytes(self.mmap[8:10],byteorder='little')
|
|
|
|
def get(self,z,x,y):
|
|
val = self.root_dir.get((z,x,y))
|
|
if val:
|
|
return self.mmap[val[0]:val[0]+val[1]]
|
|
else:
|
|
z7_tile_diff = z - 7
|
|
z7_tile = (7,x // (1 << z7_tile_diff),y // (1 << z7_tile_diff))
|
|
val = self.leaves.get(z7_tile)
|
|
if val:
|
|
directory, _ = self.load_directory(val[0],val[1]//17)
|
|
val = directory.get((z,x,y))
|
|
if val:
|
|
return self.mmap[val[0]:val[0]+val[1]]
|
|
|
|
def tiles(self):
|
|
for k,v in self.root_dir.items():
|
|
yield (k,self.mmap[v[0]:v[0]+v[1]])
|
|
for val in self.leaves.values():
|
|
leaf_dir, _ = self.load_directory(val[0],val[1]//17)
|
|
for k,v in leaf_dir.items():
|
|
yield (k,self.mmap[v[0]:v[0]+v[1]])
|
|
|