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import logging
from django.contrib.gis import gdal
from django.contrib.gis.geometry import json_regex
from django.contrib.gis.geos import GEOSException, GEOSGeometry
from django.forms.widgets import Widget
logger = logging.getLogger("django.contrib.gis")
class BaseGeometryWidget(Widget):
"""
The base class for rich geometry widgets.
Render a map using the WKT of the geometry.
"""
base_layer = None
geom_type = "GEOMETRY"
map_srid = 4326
display_raw = False
supports_3d = False
template_name = "" # set on subclasses
def __init__(self, attrs=None):
self.attrs = {
key: getattr(self, key)
for key in ("base_layer", "geom_type", "map_srid", "display_raw")
}
if attrs:
self.attrs.update(attrs)
def serialize(self, value):
return value.wkt if value else ""
def deserialize(self, value):
try:
return GEOSGeometry(value)
except (GEOSException, ValueError, TypeError) as err:
logger.error("Error creating geometry from value '%s' (%s)", value, err)
return None
def get_context(self, name, value, attrs):
context = super().get_context(name, value, attrs)
# If a string reaches here (via a validation error on another
# field) then just reconstruct the Geometry.
if value and isinstance(value, str):
value = self.deserialize(value)
if value:
# Check that srid of value and map match
if value.srid and value.srid != self.map_srid:
try:
ogr = value.ogr
ogr.transform(self.map_srid)
value = ogr
except gdal.GDALException as err:
logger.error(
"Error transforming geometry from srid '%s' to srid '%s' (%s)",
value.srid,
self.map_srid,
err,
)
context["serialized"] = self.serialize(value)
geom_type = gdal.OGRGeomType(self.attrs["geom_type"]).name
context["widget"]["attrs"]["geom_name"] = (
"Geometry" if geom_type == "Unknown" else geom_type
)
return context
class OpenLayersWidget(BaseGeometryWidget):
base_layer = "nasaWorldview"
template_name = "gis/openlayers.html"
map_srid = 3857
class Media:
css = {
"all": (
"https://cdn.jsdelivr.net/npm/ol@v7.2.2/ol.css",
"gis/css/ol3.css",
)
}
js = (
"https://cdn.jsdelivr.net/npm/ol@v7.2.2/dist/ol.js",
"gis/js/OLMapWidget.js",
)
def serialize(self, value):
return value.json if value else ""
def deserialize(self, value):
geom = super().deserialize(value)
# GeoJSON assumes WGS84 (4326). Use the map's SRID instead.
if geom and json_regex.match(value) and self.map_srid != 4326:
geom.srid = self.map_srid
return geom
class OSMWidget(OpenLayersWidget):
"""
An OpenLayers/OpenStreetMap-based widget.
"""
base_layer = "osm"
default_lon = 5
default_lat = 47
default_zoom = 12
def __init__(self, attrs=None):
if attrs is None:
attrs = {}
attrs.setdefault("default_lon", self.default_lon)
attrs.setdefault("default_lat", self.default_lat)
attrs.setdefault("default_zoom", self.default_zoom)
super().__init__(attrs=attrs)
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