mask.py 文件源码

def get_features_as_geojson(layer, bbox=None, union=False):
    """ Get features in this layer and return as GeoJSON """
    if bbox is not None:
        layer.SetSpatialFilterRect(bbox[0], bbox[3], bbox[2], bbox[1])
    poly = ogr.Geometry(ogr.wkbPolygon)
    if union:
        for feature in layer:
            geom = feature.GetGeometryRef()
            #  required for ogr2
            if hasattr(geom, 'GetLinearGeometry'):
                geom = geom.GetLinearGeometry()
            poly = poly.Union(geom)
    if bbox is not None:
        wkt = "POLYGON ((%s %s, %s %s, %s %s, %s %s, %s %s))" % \
              (bbox[0], bbox[1], bbox[2], bbox[1], bbox[2], bbox[3], bbox[0], bbox[3], bbox[0], bbox[1])
        bbox_wkt = ogr.CreateGeometryFromWkt(wkt)
        poly = poly.Intersection(bbox_wkt)
    return json.loads(poly.ExportToJson())