layer.py

# -*- coding: utf-8 -*-

'''
This translation file adds a __LAYER field to a datasource before translating it

Copyright (c) 2012 Paul Norman
<penorman@mac.com>
Released under the MIT license: http://opensource.org/licenses/mit-license.php

'''

from osgeo import ogr
import ogr2osm

class LayerTranslation(ogr2osm.TranslationBase):
    def filter_layer(self, layer):
        if not layer:
            return
        
        layername = layer.GetName()
        
        # Add a __LAYER field
        field = ogr.FieldDefn('__LAYER', ogr.OFTString)
        field.SetWidth(len(layername))
        layer.CreateField(field)

        # Set the __LAYER field to the name of the current layer
        for j in range(layer.GetFeatureCount()):
            ogrfeature = layer.GetNextFeature()
            ogrfeature.SetField('__LAYER', layername)
            layer.SetFeature(ogrfeature)
        
        # Reset the layer's read position so features are read later on
        layer.ResetReading()
        
        return layer