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python supports recursive directories

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This commit is contained in:
Brandon Liu
2021-02-18 20:08:01 +08:00
parent 01602c6846
commit 9279619cd1
1 changed files with 21 additions and 6 deletions
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27
python/pmtiles/reader.py
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@@ -15,17 +15,23 @@ class Reader:
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
self.root_dir = {}
first_entry_idx = 10+self.metadata_len
last_entry_idx = first_entry_idx + self.root_entries * 17
for i in range(first_entry_idx,last_entry_idx,17):
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')
self.root_dir[(z,x,y)] = (tile_off,tile_len)
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()
@@ -47,8 +53,17 @@ class Reader:
def root_entries(self):
return int.from_bytes(self.mmap[8:10],byteorder='little')
# TODO support recursive directories
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]]