QGIS/python/plugins/processing/algs/qgis/LinesToPolygons.py

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

"""
***************************************************************************
    LinesToPolygons.py
    ---------------------
    Date                 : August 2012
    Copyright            : (C) 2012 by Victor Olaya
    Email                : volayaf at gmail dot com
***************************************************************************
*                                                                         *
*   This program is free software; you can redistribute it and/or modify  *
*   it under the terms of the GNU General Public License as published by  *
*   the Free Software Foundation; either version 2 of the License, or     *
*   (at your option) any later version.                                   *
*                                                                         *
***************************************************************************
"""

__author__ = 'Victor Olaya'
__date__ = 'August 2012'
__copyright__ = '(C) 2012, Victor Olaya'

# This will get replaced with a git SHA1 when you do a git archive

__revision__ = '$Format:%H$'

from qgis.core import QGis, QgsFeature, QgsGeometry

from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.parameters import ParameterVector
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector


class LinesToPolygons(GeoAlgorithm):

    INPUT = 'INPUT'
    OUTPUT = 'OUTPUT'

    def defineCharacteristics(self):
        self.name = 'Lines to polygons'
        self.group = 'Vector geometry tools'

        self.addParameter(ParameterVector(self.INPUT,
            self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_LINE]))
        self.addOutput(OutputVector(self.OUTPUT, self.tr('Polygons from lines')))

    def processAlgorithm(self, progress):
        layer = dataobjects.getObjectFromUri(self.getParameterValue(self.INPUT))

        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(
            layer.pendingFields().toList(), QGis.WKBPolygon, layer.crs()
        )

        outFeat = QgsFeature()

        current = 0
        features = vector.features(layer)
        total = 100.0 / float(len(features))
        for f in features:
            outGeomList = []
            if f.geometry().isMultipart():
                outGeomList = f.geometry().asMultiPolyline()
            else:
                outGeomList.append(f.geometry().asPolyline())

            polyGeom = self.removeBadLines(outGeomList)
            if len(polyGeom) != 0:
                outFeat.setGeometry(QgsGeometry.fromPolygon(polyGeom))
                attrs = f.attributes()
                outFeat.setAttributes(attrs)
                writer.addFeature(outFeat)

            current += 1
            progress.setPercentage(int(current * total))

        del writer

    def removeBadLines(self, lines):
        geom = []
        if len(lines) == 1:
            if len(lines[0]) > 2:
                geom = lines
            else:
                geom = []
        else:
            geom = [elem for elem in lines if len(elem) > 2]
        return geom