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from django.contrib.gis.gdal.base import GDALBase
from django.contrib.gis.gdal.prototypes import raster as capi
class GDALRasterBase(GDALBase):
"""
Attributes that exist on both GDALRaster and GDALBand.
"""
@property
def metadata(self):
"""
Return the metadata for this raster or band. The return value is a
nested dictionary, where the first-level key is the metadata domain and
the second-level is the metadata item names and values for that domain.
"""
# The initial metadata domain list contains the default domain.
# The default is returned if domain name is None.
domain_list = ["DEFAULT"]
# Get additional metadata domains from the raster.
meta_list = capi.get_ds_metadata_domain_list(self._ptr)
if meta_list:
# The number of domains is unknown, so retrieve data until there
# are no more values in the ctypes array.
counter = 0
domain = meta_list[counter]
while domain:
domain_list.append(domain.decode())
counter += 1
domain = meta_list[counter]
# Free domain list array.
capi.free_dsl(meta_list)
# Retrieve metadata values for each domain.
result = {}
for domain in domain_list:
# Get metadata for this domain.
data = capi.get_ds_metadata(
self._ptr,
(None if domain == "DEFAULT" else domain.encode()),
)
if not data:
continue
# The number of metadata items is unknown, so retrieve data until
# there are no more values in the ctypes array.
domain_meta = {}
counter = 0
item = data[counter]
while item:
key, val = item.decode().split("=")
domain_meta[key] = val
counter += 1
item = data[counter]
# The default domain values are returned if domain is None.
result[domain or "DEFAULT"] = domain_meta
return result
@metadata.setter
def metadata(self, value):
"""
Set the metadata. Update only the domains that are contained in the
value dictionary.
"""
# Loop through domains.
for domain, metadata in value.items():
# Set the domain to None for the default, otherwise encode.
domain = None if domain == "DEFAULT" else domain.encode()
# Set each metadata entry separately.
for meta_name, meta_value in metadata.items():
capi.set_ds_metadata_item(
self._ptr,
meta_name.encode(),
meta_value.encode() if meta_value else None,
domain,
)
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