--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/contrib/gis/gdal/field.py Tue Oct 14 16:00:59 2008 +0000
@@ -0,0 +1,179 @@
+from ctypes import byref, c_int
+from datetime import date, datetime, time
+from django.contrib.gis.gdal.error import OGRException
+from django.contrib.gis.gdal.prototypes.ds import \
+ get_feat_field_defn, get_field_as_datetime, get_field_as_double, \
+ get_field_as_integer, get_field_as_string, get_field_name, get_field_precision, \
+ get_field_type, get_field_type_name, get_field_width
+
+# For more information, see the OGR C API source code:
+# http://www.gdal.org/ogr/ogr__api_8h.html
+#
+# The OGR_Fld_* routines are relevant here.
+class Field(object):
+ "A class that wraps an OGR Field, needs to be instantiated from a Feature object."
+
+ #### Python 'magic' routines ####
+ def __init__(self, feat, index):
+ """
+ Initializes on the feature pointer and the integer index of
+ the field within the feature.
+ """
+ # Setting the feature pointer and index.
+ self._feat = feat
+ self._index = index
+
+ # Getting the pointer for this field.
+ fld = get_feat_field_defn(feat, index)
+ if not fld:
+ raise OGRException('Cannot create OGR Field, invalid pointer given.')
+ self._ptr = fld
+
+ # Setting the class depending upon the OGR Field Type (OFT)
+ self.__class__ = FIELD_CLASSES[self.type]
+
+ # OFTReal with no precision should be an OFTInteger.
+ if isinstance(self, OFTReal) and self.precision == 0:
+ self.__class__ = OFTInteger
+
+ def __str__(self):
+ "Returns the string representation of the Field."
+ return str(self.value).strip()
+
+ #### Field Methods ####
+ def as_double(self):
+ "Retrieves the Field's value as a double (float)."
+ return get_field_as_double(self._feat, self._index)
+
+ def as_int(self):
+ "Retrieves the Field's value as an integer."
+ return get_field_as_integer(self._feat, self._index)
+
+ def as_string(self):
+ "Retrieves the Field's value as a string."
+ return get_field_as_string(self._feat, self._index)
+
+ def as_datetime(self):
+ "Retrieves the Field's value as a tuple of date & time components."
+ yy, mm, dd, hh, mn, ss, tz = [c_int() for i in range(7)]
+ status = get_field_as_datetime(self._feat, self._index, byref(yy), byref(mm), byref(dd),
+ byref(hh), byref(mn), byref(ss), byref(tz))
+ if status:
+ return (yy, mm, dd, hh, mn, ss, tz)
+ else:
+ raise OGRException('Unable to retrieve date & time information from the field.')
+
+ #### Field Properties ####
+ @property
+ def name(self):
+ "Returns the name of this Field."
+ return get_field_name(self._ptr)
+
+ @property
+ def precision(self):
+ "Returns the precision of this Field."
+ return get_field_precision(self._ptr)
+
+ @property
+ def type(self):
+ "Returns the OGR type of this Field."
+ return get_field_type(self._ptr)
+
+ @property
+ def type_name(self):
+ "Return the OGR field type name for this Field."
+ return get_field_type_name(self.type)
+
+ @property
+ def value(self):
+ "Returns the value of this Field."
+ # Default is to get the field as a string.
+ return self.as_string()
+
+ @property
+ def width(self):
+ "Returns the width of this Field."
+ return get_field_width(self._ptr)
+
+### The Field sub-classes for each OGR Field type. ###
+class OFTInteger(Field):
+ @property
+ def value(self):
+ "Returns an integer contained in this field."
+ return self.as_int()
+
+ @property
+ def type(self):
+ """
+ GDAL uses OFTReals to represent OFTIntegers in created
+ shapefiles -- forcing the type here since the underlying field
+ type may actually be OFTReal.
+ """
+ return 0
+
+class OFTReal(Field):
+ @property
+ def value(self):
+ "Returns a float contained in this field."
+ return self.as_double()
+
+# String & Binary fields, just subclasses
+class OFTString(Field): pass
+class OFTWideString(Field): pass
+class OFTBinary(Field): pass
+
+# OFTDate, OFTTime, OFTDateTime fields.
+class OFTDate(Field):
+ @property
+ def value(self):
+ "Returns a Python `date` object for the OFTDate field."
+ yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
+ try:
+ return date(yy.value, mm.value, dd.value)
+ except ValueError:
+ return None
+
+class OFTDateTime(Field):
+ @property
+ def value(self):
+ "Returns a Python `datetime` object for this OFTDateTime field."
+ yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
+ # TODO: Adapt timezone information.
+ # See http://lists.maptools.org/pipermail/gdal-dev/2006-February/007990.html
+ # The `tz` variable has values of: 0=unknown, 1=localtime (ambiguous),
+ # 100=GMT, 104=GMT+1, 80=GMT-5, etc.
+ try:
+ return datetime(yy.value, mm.value, dd.value, hh.value, mn.value, ss.value)
+ except ValueError:
+ return None
+
+class OFTTime(Field):
+ @property
+ def value(self):
+ "Returns a Python `time` object for this OFTTime field."
+ yy, mm, dd, hh, mn, ss, tz = self.as_datetime()
+ try:
+ return time(hh.value, mn.value, ss.value)
+ except ValueError:
+ return None
+
+# List fields are also just subclasses
+class OFTIntegerList(Field): pass
+class OFTRealList(Field): pass
+class OFTStringList(Field): pass
+class OFTWideStringList(Field): pass
+
+# Class mapping dictionary for OFT Types
+FIELD_CLASSES = { 0 : OFTInteger,
+ 1 : OFTIntegerList,
+ 2 : OFTReal,
+ 3 : OFTRealList,
+ 4 : OFTString,
+ 5 : OFTStringList,
+ 6 : OFTWideString,
+ 7 : OFTWideStringList,
+ 8 : OFTBinary,
+ 9 : OFTDate,
+ 10 : OFTTime,
+ 11 : OFTDateTime,
+ }