Sideband/sbapp/mapview/mbtsource.py

122 lines
3.5 KiB
Python

# coding=utf-8
"""
MBTiles provider for MapView
============================
This provider is based on .mbfiles from MapBox.
See: http://mbtiles.org/
"""
__all__ = ["MBTilesMapSource"]
import io
import sqlite3
import threading
from kivy.core.image import Image as CoreImage
from kivy.core.image import ImageLoader
from mapview.downloader import Downloader
from mapview.source import MapSource
class MBTilesMapSource(MapSource):
def __init__(self, filename, **kwargs):
super().__init__(**kwargs)
self.filename = filename
self.db = sqlite3.connect(filename)
# read metadata
c = self.db.cursor()
metadata = dict(c.execute("SELECT * FROM metadata"))
if metadata["format"] == "pbf":
raise ValueError("Only raster maps are supported, not vector maps.")
self.min_zoom = int(metadata["minzoom"])
self.max_zoom = int(metadata["maxzoom"])
self.attribution = metadata.get("attribution", "")
self.bounds = bounds = None
cx = cy = 0.0
cz = 5
if "bounds" in metadata:
self.bounds = bounds = tuple(map(float, metadata["bounds"].split(",")))
if "center" in metadata:
cx, cy, cz = tuple(map(float, metadata["center"].split(",")))
elif self.bounds:
cx = (bounds[2] + bounds[0]) / 2.0
cy = (bounds[3] + bounds[1]) / 2.0
cz = self.min_zoom
self.default_lon = cx
self.default_lat = cy
self.default_zoom = int(cz)
self.projection = metadata.get("projection", "")
self.is_xy = self.projection == "xy"
def fill_tile(self, tile):
if tile.state == "done":
return
Downloader.instance(self.cache_dir).submit(self._load_tile, tile)
def _load_tile(self, tile):
# global db context cannot be shared across threads.
ctx = threading.local()
if not hasattr(ctx, "db"):
ctx.db = sqlite3.connect(self.filename)
# get the right tile
c = ctx.db.cursor()
c.execute(
(
"SELECT tile_data FROM tiles WHERE "
"zoom_level=? AND tile_column=? AND tile_row=?"
),
(tile.zoom, tile.tile_x, tile.tile_y),
)
row = c.fetchone()
if not row:
tile.state = "done"
return
# no-file loading
try:
data = io.BytesIO(row[0])
except Exception:
# android issue, "buffer" does not have the buffer interface
# ie row[0] buffer is not compatible with BytesIO on Android??
data = io.BytesIO(bytes(row[0]))
im = CoreImage(
data,
ext='png',
filename="{}.{}.{}.png".format(tile.zoom, tile.tile_x, tile.tile_y),
)
if im is None:
tile.state = "done"
return
return self._load_tile_done, (tile, im,)
def _load_tile_done(self, tile, im):
tile.texture = im.texture
tile.state = "need-animation"
def get_x(self, zoom, lon):
if self.is_xy:
return lon
return super().get_x(zoom, lon)
def get_y(self, zoom, lat):
if self.is_xy:
return lat
return super().get_y(zoom, lat)
def get_lon(self, zoom, x):
if self.is_xy:
return x
return super().get_lon(zoom, x)
def get_lat(self, zoom, y):
if self.is_xy:
return y
return super().get_lat(zoom, y)