# Django 3.2.12 documentation

# Source code for django.contrib.gis.forms.widgets

    import logging

    from django.conf import settings
    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
    from django.utils import translation

    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.
        """
        geom_type = 'GEOMETRY'
        map_srid = 4326
        map_width = 600
        map_height = 400
        display_raw = False

        supports_3d = False
        template_name = ''  # set on subclasses

        def __init__(self, attrs=None):
            self.attrs = {}
            for key in ('geom_type', 'map_srid', 'map_width', 'map_height', 'display_raw'):
                self.attrs[key] = getattr(self, key)
            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
                        )

            geom_type = gdal.OGRGeomType(self.attrs['geom_type']).name
            context.update(self.build_attrs(self.attrs, {
                'name': name,
                'module': 'geodjango_%s' % name.replace('-', '_'),  # JS-safe
                'serialized': self.serialize(value),
                'geom_type': 'Geometry' if geom_type == 'Unknown' else geom_type,
                'STATIC_URL': settings.STATIC_URL,
                'LANGUAGE_BIDI': translation.get_language_bidi(),
                **(attrs or {}),
            }))
            return context

    class OpenLayersWidget(BaseGeometryWidget):
        template_name = 'gis/openlayers.html'
        map_srid = 3857

        class Media:
            css = {
                'all': (
                    'https://cdnjs.cloudflare.com/ajax/libs/ol3/4.6.5/ol.css',
                    'gis/css/ol3.css',
                )
            }
            js = (
                'https://cdnjs.cloudflare.com/ajax/libs/ol3/4.6.5/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.
        """
        template_name = 'gis/openlayers-osm.html'
        default_lon = 5
        default_lat = 47
        default_zoom = 12

        def __init__(self, attrs=None):
            super().__init__()
            for key in ('default_lon', 'default_lat', 'default_zoom'):
                self.attrs[key] = getattr(self, key)
            if attrs:
                self.attrs.update(attrs)