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Enso-Bot/venv/Lib/site-packages/django/contrib/gis/gdal/feature.py

116 lines
3.8 KiB
Python

from django.contrib.gis.gdal.base import GDALBase
from django.contrib.gis.gdal.error import GDALException
from django.contrib.gis.gdal.field import Field
from django.contrib.gis.gdal.geometries import OGRGeometry, OGRGeomType
from django.contrib.gis.gdal.prototypes import ds as capi, geom as geom_api
from django.utils.encoding import force_bytes, force_str
# For more information, see the OGR C API source code:
# https://www.gdal.org/ogr__api_8h.html
#
# The OGR_F_* routines are relevant here.
class Feature(GDALBase):
"""
This class that wraps an OGR Feature, needs to be instantiated
from a Layer object.
"""
destructor = capi.destroy_feature
def __init__(self, feat, layer):
"""
Initialize Feature from a pointer and its Layer object.
"""
if not feat:
raise GDALException('Cannot create OGR Feature, invalid pointer given.')
self.ptr = feat
self._layer = layer
def __getitem__(self, index):
"""
Get the Field object at the specified index, which may be either
an integer or the Field's string label. Note that the Field object
is not the field's _value_ -- use the `get` method instead to
retrieve the value (e.g. an integer) instead of a Field instance.
"""
if isinstance(index, str):
i = self.index(index)
elif 0 <= index < self.num_fields:
i = index
else:
raise IndexError('Index out of range when accessing field in a feature: %s.' % index)
return Field(self, i)
def __len__(self):
"Return the count of fields in this feature."
return self.num_fields
def __str__(self):
"The string name of the feature."
return 'Feature FID %d in Layer<%s>' % (self.fid, self.layer_name)
def __eq__(self, other):
"Do equivalence testing on the features."
return bool(capi.feature_equal(self.ptr, other._ptr))
# #### Feature Properties ####
@property
def encoding(self):
return self._layer._ds.encoding
@property
def fid(self):
"Return the feature identifier."
return capi.get_fid(self.ptr)
@property
def layer_name(self):
"Return the name of the layer for the feature."
name = capi.get_feat_name(self._layer._ldefn)
return force_str(name, self.encoding, strings_only=True)
@property
def num_fields(self):
"Return the number of fields in the Feature."
return capi.get_feat_field_count(self.ptr)
@property
def fields(self):
"Return a list of fields in the Feature."
return [
force_str(
capi.get_field_name(capi.get_field_defn(self._layer._ldefn, i)),
self.encoding,
strings_only=True
) for i in range(self.num_fields)
]
@property
def geom(self):
"Return the OGR Geometry for this Feature."
# Retrieving the geometry pointer for the feature.
geom_ptr = capi.get_feat_geom_ref(self.ptr)
return OGRGeometry(geom_api.clone_geom(geom_ptr))
@property
def geom_type(self):
"Return the OGR Geometry Type for this Feature."
return OGRGeomType(capi.get_fd_geom_type(self._layer._ldefn))
# #### Feature Methods ####
def get(self, field):
"""
Return the value of the field, instead of an instance of the Field
object. May take a string of the field name or a Field object as
parameters.
"""
field_name = getattr(field, 'name', field)
return self[field_name].value
def index(self, field_name):
"Return the index of the given field name."
i = capi.get_field_index(self.ptr, force_bytes(field_name))
if i < 0:
raise IndexError('Invalid OFT field name given: %s.' % field_name)
return i