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# -*- coding:Latin-1 -*-
import osgeo.ogr, os, sys, string

# function to copy fields (not the data) from one layer to another
# parameters:
#   fromLayer: layer object that contains the fields to copy
#   toLayer: layer object to copy the fields into
def copyFields(fromLayer, toLayer):
    featureDefn = fromLayer.GetLayerDefn()
    for i in range(featureDefn.GetFieldCount()):
        toLayer.CreateField(featureDefn.GetFieldDefn(i))

# function to copy attributes from one feature to another
# (this assumes the features have the same attribute fields!)
# parameters:
#   fromFeature: feature object that contains the data to copy
#   toFeature: feature object that the data is to be copied into
def copyAttributes(fromFeature, toFeature):
    for i in range(fromFeature.GetFieldCount()):
        fieldName = fromFeature.GetFieldDefnRef(i).GetName()
        toFeature.SetField(fieldName, fromFeature.GetField(fieldName))

def doBuffers(inShp, outShp, filtre, taille, proj):
    # get the shapefile driver
    driver = osgeo.ogr.GetDriverByName('ESRI Shapefile')
    # open.shp and get the layer
    shp = driver.Open(inShp, 0)
    if shp is None: return 0
    inLayer = shp.GetLayer()
    # create a new data source and layer
    if os.path.exists(outShp):
        driver.DeleteDataSource(outShp)
    outDS = driver.CreateDataSource(outShp)
    outLayer = outDS.CreateLayer(outShp, geom_type=osgeo.ogr.wkbPolygon, srs=proj)
    # copy the fields from the input layer to the output layer
    copyFields(inLayer, outLayer)
    # get the FeatureDefn for the output shapefile
    featureDefn = outLayer.GetLayerDefn()
    # use an attribute filter
    inLayer.SetAttributeFilter(filtre)
    # get features
    inFeature = inLayer.GetNextFeature()
    while inFeature:
        # get the geometry and buffer it
        inGeom = inFeature.GetGeometryRef()
        bufferGeom = inGeom.Buffer(taille)
        # create a new feature
        outFeature = osgeo.ogr.Feature(featureDefn)
         # set the geometry and attribute
        outFeature.SetGeometry(bufferGeom)
        # copy the attributes
        copyAttributes(inFeature, outFeature)
        # add the feature to the shapefile
        outLayer.CreateFeature(outFeature)
        # destroy the features and get the next input feature
        outFeature.Destroy()
        inFeature.Destroy()
        #Destroy test
        #inGeom.Destroy() #Do not destroy geometries that come from an existing feature Python will crash
        bufferGeom.Destroy() #Do destroy geometries that are created during script execution (even if they are during script execution (even if they are used to create new features)
        # get next feature
        inFeature = inLayer.GetNextFeature()
    # close the shapefiles
    outDS.Destroy()
    shp.Destroy()
    return 1