53 lines
1.3 KiB
Python
53 lines
1.3 KiB
Python
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"""Proxy for coordinates stored outside Shapely geometries
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"""
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from shapely.geometry.base import EMPTY
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from shapely.geos import lgeos
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class CachingGeometryProxy(object):
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context = None
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factory = None
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__geom__ = EMPTY
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_gtag = None
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def __init__(self, context):
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self.context = context
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@property
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def _is_empty(self):
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return self.__geom__ in [EMPTY, None]
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def empty(self, val=EMPTY):
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if not self._is_empty and self.__geom__:
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lgeos.GEOSGeom_destroy(self.__geom__)
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self.__geom__ = val
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@property
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def _geom(self):
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"""Keeps the GEOS geometry in synch with the context."""
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gtag = self.gtag()
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if gtag != self._gtag or self._is_empty:
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self.empty()
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if len(self.context) > 0:
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self.__geom__, n = self.factory(self.context)
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self._gtag = gtag
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return self.__geom__
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def gtag(self):
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return hash(repr(self.context))
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class PolygonProxy(CachingGeometryProxy):
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@property
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def _geom(self):
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"""Keeps the GEOS geometry in synch with the context."""
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gtag = self.gtag()
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if gtag != self._gtag or self._is_empty:
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self.empty()
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self.__geom__, n = self.factory(self.context[0], self.context[1])
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self._gtag = gtag
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return self.__geom__
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