forked from openstreetmap/mapnik-stylesheets
/
generate_tiles_multiprocess.py
executable file
·173 lines (143 loc) · 5.88 KB
/
generate_tiles_multiprocess.py
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#!/usr/bin/env python
from math import pi, cos, sin, log, exp, atan
from subprocess import call
import sys
import os
import re
import shutil
import tempfile
import urllib.request
import uuid
import multiprocessing
import spherical_mercator
try:
import mapnik2 as mapnik
except:
import mapnik
# Default number of rendering threads to spawn, should be roughly equal to number of CPU cores available
NUM_THREADS = 4
class RenderThread:
def __init__(self, tile_dir, mapfile, q, printLock, maxZoom):
self.tile_dir = tile_dir
self.q = q
self.mapfile = mapfile
self.maxZoom = maxZoom
self.printLock = printLock
def render_tile(self, tile_uri, x, y, z):
# Calculate pixel positions of bottom-left & top-right
p0 = (x * 256, (y + 1) * 256)
p1 = ((x + 1) * 256, y * 256)
# Convert to LatLong (EPSG:4326)
l0 = self.tileproj.lonlat_for_pixel(p0, z)
l1 = self.tileproj.lonlat_for_pixel(p1, z)
# Convert to map projection (e.g. mercator co-ords EPSG:900913)
c0 = self.prj.forward(mapnik.Coord(l0[0], l0[1]))
c1 = self.prj.forward(mapnik.Coord(l1[0], l1[1]))
# Bounding box for the tile
if hasattr(mapnik, 'mapnik_version') and mapnik.mapnik_version() >= 800:
bbox = mapnik.Box2d(c0.x, c0.y, c1.x, c1.y)
else:
bbox = mapnik.Envelope(c0.x, c0.y, c1.x, c1.y)
render_size = 256
self.m.resize(render_size, render_size)
self.m.zoom_to_box(bbox)
if(self.m.buffer_size < 128):
self.m.buffer_size = 128
# Render image with default Agg renderer
im = mapnik.Image(render_size, render_size)
mapnik.render(self.m, im)
im.save(tile_uri, 'png256')
def loop(self):
self.m = mapnik.Map(256, 256)
# Load style XML
mapnik.load_map(self.m, self.mapfile, True)
# Obtain <Map> projection
self.prj = mapnik.Projection(self.m.srs)
# Projects between tile pixel co-ordinates and LatLong (EPSG:4326)
self.tileproj = spherical_mercator.SphericalMercator(self.maxZoom + 1)
while True:
# Fetch a tile from the queue and render it
r = self.q.get()
if (r == None):
self.q.task_done()
break
else:
(name, tile_uri, x, y, z) = r
exists = ""
if os.path.isfile(tile_uri):
exists = "exists"
else:
self.render_tile(tile_uri, x, y, z)
bytes = os.stat(tile_uri)[6]
empty = ''
if bytes == 103:
empty = " Empty Tile "
self.printLock.acquire()
print(name, ":", z, x, y, exists, empty)
self.printLock.release()
self.q.task_done()
def render_tiles(bbox, mapfile, tile_dir, minZoom=1, maxZoom=18, name="unknown", num_threads=NUM_THREADS):
print("render_tiles(", bbox, mapfile, tile_dir, minZoom, maxZoom, name, ")")
# Launch rendering threads
queue = multiprocessing.JoinableQueue(32)
printLock = multiprocessing.Lock()
renderers = {}
for i in range(num_threads):
renderer = RenderThread(tile_dir, mapfile, queue, printLock, maxZoom)
render_thread = multiprocessing.Process(target=renderer.loop)
render_thread.start()
# print("Started render thread %s" % render_thread.getName())
renderers[i] = render_thread
if not os.path.isdir(tile_dir):
os.mkdir(tile_dir)
gprj = spherical_mercator.SphericalMercator(maxZoom + 1)
ll0 = (bbox[0], bbox[3])
ll1 = (bbox[2], bbox[1])
for z in range(minZoom, maxZoom + 1):
px0 = gprj.pixel_for_lonlat(ll0, z)
px1 = gprj.pixel_for_lonlat(ll1, z)
# check if we have directories in place
zoom = "%s" % z
if not os.path.isdir(tile_dir + zoom):
os.mkdir(tile_dir + zoom)
for x in range(int(px0[0] / 256.0), int(px1[0] / 256.0) + 1):
# Validate x co-ordinate
if (x < 0) or (x >= 2**z):
continue
# check if we have directories in place
str_x = "%s" % x
if not os.path.isdir(tile_dir + zoom + '/' + str_x):
os.mkdir(tile_dir + zoom + '/' + str_x)
for y in range(int(px0[1]/256.0), int(px1[1]/256.0)+1):
# Validate x co-ordinate
if (y < 0) or (y >= 2**z):
continue
str_y = "%s" % y
tile_uri = tile_dir + zoom + '/' + str_x + '/' + str_y + '.png'
# Submit tile to be rendered into the queue
t = (name, tile_uri, x, y, z)
queue.put(t)
# Signal render threads to exit by sending empty request to queue
for i in range(num_threads):
queue.put(None)
# wait for pending rendering jobs to complete
queue.join()
for i in range(num_threads):
renderers[i].join()
if __name__ == "__main__":
tiles_name = os.environ["TILES_NAME"]
tiles_bbox = os.environ["TILES_BBOX"]
tiles_style_url = os.environ["TILES_MAPNIK_STYLE"]
tiles_min_zoom = int(os.environ.get("TILES_MIN_ZOOM", "0"))
tiles_max_zoom = int(os.environ.get("TILES_MAX_ZOOM", "18"))
tiles_dir = "/tiles/%(tiles_name)s" % locals()
bbox_parts = re.findall(r"-?\d+(\.\d+", tiles_bbox)
if bbox_parts.count != 4:
raise Exception("invalid bbox: %s(bbox)" % tiles_bbox)
bbox = [(float(bbox_parts[0]), float(bbox_parts[1])), (float(bbox_parts[2]), float(bbox_parts[3]))]
style_path = "/tmp/tiles-%(name)s-%(suffix)s" % {"name": tiles_name, "suffix": uuid.uuid4()}
style_file = open(style_path, "w", encoding="utf-8")
with urllib.request.urlopen(tiles_style_url) as response:
shutil.copyfileobj(response, style_file)
style_file.close()
render_tiles(bbox, style_path, tiles_dir, tiles_min_zoom, tiles_max_zoom)