79 lines
2.9 KiB
Python
79 lines
2.9 KiB
Python
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from django.contrib.gis.gdal.base import GDALBase
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from django.contrib.gis.gdal.prototypes import raster as capi
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class GDALRasterBase(GDALBase):
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"""
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Attributes that exist on both GDALRaster and GDALBand.
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"""
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@property
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def metadata(self):
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"""
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Return the metadata for this raster or band. The return value is a
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nested dictionary, where the first-level key is the metadata domain and
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the second-level is the metadata item names and values for that domain.
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"""
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if not capi.get_ds_metadata_domain_list:
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raise ValueError('GDAL ≥ 1.11 is required for using the metadata property.')
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# The initial metadata domain list contains the default domain.
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# The default is returned if domain name is None.
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domain_list = ['DEFAULT']
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# Get additional metadata domains from the raster.
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meta_list = capi.get_ds_metadata_domain_list(self._ptr)
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if meta_list:
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# The number of domains is unknown, so retrieve data until there
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# are no more values in the ctypes array.
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counter = 0
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domain = meta_list[counter]
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while domain:
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domain_list.append(domain.decode())
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counter += 1
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domain = meta_list[counter]
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# Free domain list array.
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capi.free_dsl(meta_list)
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# Retrieve metadata values for each domain.
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result = {}
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for domain in domain_list:
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# Get metadata for this domain.
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data = capi.get_ds_metadata(
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self._ptr,
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(None if domain == 'DEFAULT' else domain.encode()),
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)
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if not data:
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continue
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# The number of metadata items is unknown, so retrieve data until
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# there are no more values in the ctypes array.
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domain_meta = {}
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counter = 0
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item = data[counter]
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while item:
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key, val = item.decode().split('=')
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domain_meta[key] = val
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counter += 1
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item = data[counter]
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# The default domain values are returned if domain is None.
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result[domain if domain else 'DEFAULT'] = domain_meta
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return result
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@metadata.setter
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def metadata(self, value):
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"""
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Set the metadata. Update only the domains that are contained in the
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value dictionary.
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"""
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# Loop through domains.
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for domain, metadata in value.items():
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# Set the domain to None for the default, otherwise encode.
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domain = None if domain == 'DEFAULT' else domain.encode()
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# Set each metadata entry separately.
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for meta_name, meta_value in metadata.items():
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capi.set_ds_metadata_item(
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self._ptr, meta_name.encode(),
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meta_value.encode() if meta_value else None,
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domain,
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)
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