#
# AUTHOR(S): Caitlin Haedrich <caitlin DOT haedrich AT gmail>
#
# PURPOSE: ReprojectionRenderer writes PNGs and geoJSONs that are importable by
# folium. Reprojects rasters to Pseudo-Mercator and vectors to WGS84.
# Exports reprojected rasters and vectors to PNGs and geoJSONs, respectively.
#
# COPYRIGHT: (C) 2022 Caitlin Haedrich, and by the GRASS Development Team
#
# This program is free software under the GNU General Public
# License (>=v2). Read the file COPYING that comes with GRASS
# for details.
"""Reprojects rasters to Pseudo-Mercator and vectors to WGS84. Exports reprojected
rasters and vectors to PNGs and geoJSONs, respectively."""
import os
import tempfile
import weakref
from pathlib import Path
import grass.script as gs
from .map import Map
from .utils import (
get_location_proj_string,
get_region,
reproject_region,
setup_location,
)
from .region import RegionManagerForInteractiveMap
[docs]class ReprojectionRenderer:
"""This class reprojects rasters and vectors to folium-compatible temporary location
and projection.
In preparation to displaying with folium, it saves vectors to geoJSON and rasters to
PNG images.
"""
def __init__(self, use_region=False, saved_region=None, work_dir=None):
"""Creates Pseudo-Mercator and WGS84 locations. If no work_dir provided, also
creates temporary working directory to contain locations.
param bool use_region: use computational region of current mapset
param str saved_region: name of saved computation region to use
param work_dir: path to directory where locations, files should be written
"""
# Temporary folder for all our files
if not work_dir:
# Resource managed by weakref.finalize.
self._tmp_dir = (
# pylint: disable=consider-using-with
tempfile.TemporaryDirectory()
)
def cleanup(tmpdir):
tmpdir.cleanup()
weakref.finalize(self, cleanup, self._tmp_dir)
else:
self._tmp_dir = work_dir
# Remember original environment; all environments used
# in this class are derived from this one
self._src_env = os.environ.copy()
# Set up temporary locations in WGS84 and Pseudo-Mercator
# We need two because folium uses WGS84 for vectors and coordinates
# and Pseudo-Mercator for raster overlays
self._rcfile_psmerc, self._psmerc_env = setup_location(
"psmerc", self._tmp_dir.name, "3857", self._src_env
)
self._rcfile_wgs84, self._wgs84_env = setup_location(
"wgs84", self._tmp_dir.name, "4326", self._src_env
)
# region handling
self._region_manager = RegionManagerForInteractiveMap(
use_region, saved_region, self._src_env, self._psmerc_env
)
[docs] def get_bbox(self):
"""Return bounding box of computation region in WGS84"""
return self._region_manager.bbox
[docs] def render_raster(self, name):
"""Reprojects raster to Pseudo-Mercator and saves PNG in working directory.
Return PNG filename and bounding box of WGS84.
param str name: name of raster
"""
# Find full name of raster
file_info = gs.find_file(name, element="cell", env=self._src_env)
full_name = file_info["fullname"]
name = file_info["name"]
mapset = file_info["mapset"]
self._region_manager.set_region_from_raster(full_name)
# Reproject raster into WGS84/epsg3857 location
env_info = gs.gisenv(env=self._src_env)
tgt_name = full_name.replace("@", "_")
gs.run_command(
"r.proj",
input=full_name,
output=tgt_name,
mapset=mapset,
location=env_info["LOCATION_NAME"],
dbase=env_info["GISDBASE"],
resolution=self._region_manager.resolution,
env=self._psmerc_env,
)
# Write raster to png file with Map
raster_info = gs.raster_info(tgt_name, env=self._psmerc_env)
filename = os.path.join(self._tmp_dir.name, f"{tgt_name}.png")
img = Map(
width=int(raster_info["cols"]),
height=int(raster_info["rows"]),
env=self._psmerc_env,
filename=filename,
use_region=True,
)
img.run("d.rast", map=tgt_name)
# Reproject bounds of raster for overlaying png
# Bounds need to be in WGS84
old_bounds = get_region(self._src_env)
from_proj = get_location_proj_string(env=self._src_env)
to_proj = get_location_proj_string(env=self._wgs84_env)
bounds = reproject_region(old_bounds, from_proj, to_proj)
new_bounds = [
[bounds["north"], bounds["west"]],
[bounds["south"], bounds["east"]],
]
return filename, new_bounds
[docs] def render_vector(self, name):
"""Reproject vector to WGS84 and save geoJSON in working directory. Return
geoJSON filename.
param str name: name of vector"""
# Find full name of vector
file_info = gs.find_file(name, element="vector")
full_name = file_info["fullname"]
name = file_info["name"]
mapset = file_info["mapset"]
new_name = full_name.replace("@", "_")
# set bbox
self._region_manager.set_bbox_vector(full_name)
# Reproject vector into WGS84 Location
env_info = gs.gisenv(env=self._src_env)
gs.run_command(
"v.proj",
input=name,
output=new_name,
mapset=mapset,
location=env_info["LOCATION_NAME"],
dbase=env_info["GISDBASE"],
env=self._wgs84_env,
)
# Convert to GeoJSON
json_file = Path(self._tmp_dir.name) / f"{new_name}.json"
gs.run_command(
"v.out.ogr",
input=new_name,
output=json_file,
format="GeoJSON",
env=self._wgs84_env,
)
return json_file
