93 lines
3.6 KiB
Python
93 lines
3.6 KiB
Python
from django.contrib.gis.gdal import OGRException
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from django.contrib.gis.geos import GEOSGeometry, GEOSException
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from django.forms.widgets import Textarea
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from django.template.loader import render_to_string
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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: self.params.update(attrs)
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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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# interfaace 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, basestring):
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try:
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value = GEOSGeometry(value)
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except (GEOSException, ValueError):
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value = None
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if value and value.geom_type.upper() != self.geom_type:
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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 ID of
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# the GeometryField (passed in via the `attrs` keyword).
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self.params['module'] = 'geodjango_%s' % self.params['field_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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value.transform(srid)
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wkt = value.wkt
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except OGRException:
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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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return 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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