123 lines
4.8 KiB
Python
123 lines
4.8 KiB
Python
import logging
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from django.contrib.gis.gdal import GDALException
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from django.contrib.gis.geos import GEOSException, GEOSGeometry
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from django.forms.widgets import Textarea
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from django.template import loader
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from django.utils import six, translation
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# Creating a template context that contains Django settings
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# values needed by admin map templates.
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geo_context = {'LANGUAGE_BIDI': translation.get_language_bidi()}
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logger = logging.getLogger('django.contrib.gis')
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class OpenLayersWidget(Textarea):
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"""
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Renders an OpenLayers map using the WKT of the geometry.
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"""
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def render(self, name, value, attrs=None):
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# Update the template parameters with any attributes passed in.
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if attrs:
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self.params.update(attrs)
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self.params['editable'] = self.params['modifiable']
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else:
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self.params['editable'] = True
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# Defaulting the WKT value to a blank string -- this
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# will be tested in the JavaScript and the appropriate
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# interface will be constructed.
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self.params['wkt'] = ''
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# If a string reaches here (via a validation error on another
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# field) then just reconstruct the Geometry.
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if isinstance(value, six.string_types):
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try:
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value = GEOSGeometry(value)
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except (GEOSException, ValueError) as err:
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logger.error(
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"Error creating geometry from value '%s' (%s)" % (
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value, err)
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)
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value = None
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if (value and value.geom_type.upper() != self.geom_type and
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self.geom_type != 'GEOMETRY'):
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value = None
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# Constructing the dictionary of the map options.
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self.params['map_options'] = self.map_options()
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# Constructing the JavaScript module name using the name of
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# the GeometryField (passed in via the `attrs` keyword).
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# Use the 'name' attr for the field name (rather than 'field')
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self.params['name'] = name
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# note: we must switch out dashes for underscores since js
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# functions are created using the module variable
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js_safe_name = self.params['name'].replace('-', '_')
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self.params['module'] = 'geodjango_%s' % js_safe_name
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if value:
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# Transforming the geometry to the projection used on the
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# OpenLayers map.
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srid = self.params['srid']
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if value.srid != srid:
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try:
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ogr = value.ogr
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ogr.transform(srid)
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wkt = ogr.wkt
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except GDALException as err:
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logger.error(
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"Error transforming geometry from srid '%s' to srid '%s' (%s)" % (
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value.srid, srid, err)
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)
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wkt = ''
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else:
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wkt = value.wkt
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# Setting the parameter WKT with that of the transformed
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# geometry.
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self.params['wkt'] = wkt
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self.params.update(geo_context)
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return loader.render_to_string(self.template, self.params)
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def map_options(self):
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"Builds the map options hash for the OpenLayers template."
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# JavaScript construction utilities for the Bounds and Projection.
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def ol_bounds(extent):
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return 'new OpenLayers.Bounds(%s)' % str(extent)
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def ol_projection(srid):
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return 'new OpenLayers.Projection("EPSG:%s")' % srid
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# An array of the parameter name, the name of their OpenLayers
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# counterpart, and the type of variable they are.
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map_types = [('srid', 'projection', 'srid'),
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('display_srid', 'displayProjection', 'srid'),
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('units', 'units', str),
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('max_resolution', 'maxResolution', float),
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('max_extent', 'maxExtent', 'bounds'),
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('num_zoom', 'numZoomLevels', int),
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('max_zoom', 'maxZoomLevels', int),
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('min_zoom', 'minZoomLevel', int),
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]
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# Building the map options hash.
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map_options = {}
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for param_name, js_name, option_type in map_types:
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if self.params.get(param_name, False):
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if option_type == 'srid':
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value = ol_projection(self.params[param_name])
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elif option_type == 'bounds':
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value = ol_bounds(self.params[param_name])
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elif option_type in (float, int):
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value = self.params[param_name]
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elif option_type in (str,):
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value = '"%s"' % self.params[param_name]
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else:
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raise TypeError
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map_options[js_name] = value
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return map_options
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