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Viewing changes to django/contrib/gis/geos/io.py

  • Committer: Bazaar Package Importer
  • Author(s): Chris Lamb
  • Date: 2009-07-29 11:26:28 UTC
  • mfrom: (1.1.8 upstream) (4.1.5 sid)
  • Revision ID: james.westby@ubuntu.com-20090729112628-pg09ino8sz0sj21t
Tags: 1.1-1
http://bugs.debian.org/538863
* New upstream release.
* Merge from experimental:
  - Ship FastCGI initscript and /etc/default file in python-django's examples
    directory (Closes: #538863)
  - Drop "05_10539-sphinx06-compatibility.diff"; it has been applied
    upstream.
  - Bump Standards-Version to 3.8.2.

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django/contrib/gis/geos/io.py
 
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"""
 
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Module that holds classes for performing I/O operations on GEOS geometry
 
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objects.  Specifically, this has Python implementations of WKB/WKT
 
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reader and writer classes.
 
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"""
 
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from ctypes import byref, c_size_t
 
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from django.contrib.gis.geos.base import GEOSBase
 
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from django.contrib.gis.geos.error import GEOSException
 
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from django.contrib.gis.geos.geometry import GEOSGeometry
 
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from django.contrib.gis.geos.libgeos import GEOM_PTR
 
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from django.contrib.gis.geos.prototypes import io as capi
 
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class IOBase(GEOSBase):
 
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    "Base class for GEOS I/O objects."
 
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    def __init__(self):
 
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        # Getting the pointer with the constructor.
 
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        self.ptr = self.constructor()
 
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    def __del__(self):
 
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        # Cleaning up with the appropriate destructor.
 
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        if self._ptr: self.destructor(self._ptr)
 
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### WKT Reading and Writing objects ###
 
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# Non-public class for internal use because its `read` method returns
 
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# _pointers_ instead of a GEOSGeometry object.
 
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class _WKTReader(IOBase):
 
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    constructor = capi.wkt_reader_create
 
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    destructor = capi.wkt_reader_destroy
 
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    ptr_type = capi.WKT_READ_PTR
 
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    def read(self, wkt):
 
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        if not isinstance(wkt, basestring): raise TypeError
 
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        return capi.wkt_reader_read(self.ptr, wkt)
 
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class WKTReader(_WKTReader):
 
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    def read(self, wkt):
 
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        "Returns a GEOSGeometry for the given WKT string."
 
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        return GEOSGeometry(super(WKTReader, self).read(wkt))
 
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class WKTWriter(IOBase):
 
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    constructor = capi.wkt_writer_create
 
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    destructor = capi.wkt_writer_destroy
 
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    ptr_type = capi.WKT_WRITE_PTR
 
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    def write(self, geom):
 
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        "Returns the WKT representation of the given geometry."
 
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        return capi.wkt_writer_write(self.ptr, geom.ptr)
 
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### WKB Reading and Writing objects ###
 
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# Non-public class for the same reason as _WKTReader above.
 
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class _WKBReader(IOBase):
 
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    constructor = capi.wkb_reader_create
 
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    destructor = capi.wkb_reader_destroy
 
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    ptr_type = capi.WKB_READ_PTR
 
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    def read(self, wkb):
 
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        "Returns a _pointer_ to C GEOS Geometry object from the given WKB."
 
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        if isinstance(wkb, buffer):
 
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            wkb_s = str(wkb)
 
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            return capi.wkb_reader_read(self.ptr, wkb_s, len(wkb_s))
 
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        elif isinstance(wkb, basestring):
 
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            return capi.wkb_reader_read_hex(self.ptr, wkb, len(wkb))
 
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        else:
 
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            raise TypeError
 
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class WKBReader(_WKBReader):
 
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    def read(self, wkb):
 
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        "Returns a GEOSGeometry for the given WKB buffer."
 
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        return GEOSGeometry(super(WKBReader, self).read(wkb))
 
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class WKBWriter(IOBase):
 
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    constructor = capi.wkb_writer_create
 
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    destructor = capi.wkb_writer_destroy
 
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    ptr_type = capi.WKB_WRITE_PTR
 
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    def write(self, geom):
 
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        "Returns the WKB representation of the given geometry."
 
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        return buffer(capi.wkb_writer_write(self.ptr, geom.ptr, byref(c_size_t())))
 
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    def write_hex(self, geom):
 
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        "Returns the HEXEWKB representation of the given geometry."
 
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        return capi.wkb_writer_write_hex(self.ptr, geom.ptr, byref(c_size_t()))
 
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    ### WKBWriter Properties ###
 
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    # Property for getting/setting the byteorder.
 
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    def _get_byteorder(self):
 
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        return capi.wkb_writer_get_byteorder(self.ptr)
 
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    def _set_byteorder(self, order):
 
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        if not order in (0, 1): raise ValueError('Byte order parameter must be 0 (Big Endian) or 1 (Little Endian).')
 
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        capi.wkb_writer_set_byteorder(self.ptr, order)
 
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    byteorder = property(_get_byteorder, _set_byteorder)
 
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    # Property for getting/setting the output dimension.
 
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    def _get_outdim(self):
 
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        return capi.wkb_writer_get_outdim(self.ptr)
 
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    def _set_outdim(self, new_dim):
 
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        if not new_dim in (2, 3): raise ValueError('WKB output dimension must be 2 or 3')
 
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        capi.wkb_writer_set_outdim(self.ptr, new_dim)
 
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    outdim = property(_get_outdim, _set_outdim)
 
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    # Property for getting/setting the include srid flag.
 
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    def _get_include_srid(self):
 
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        return bool(ord(capi.wkb_writer_get_include_srid(self.ptr)))
 
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    def _set_include_srid(self, include):
 
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        if bool(include): flag = chr(1)
 
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        else: flag = chr(0)
 
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        capi.wkb_writer_set_include_srid(self.ptr, flag)
 
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    srid = property(_get_include_srid, _set_include_srid)
 
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# Instances of the WKT and WKB reader/writer objects.
 
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wkt_r = _WKTReader()
 
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wkt_w = WKTWriter()
 
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wkb_r = _WKBReader()
 
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wkb_w = WKBWriter()