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06c4b07222
Since the layer has more complete knowledge of the crs (ie, when provider could not determine crs and user has selected it from the list), and also better knowledge of layer fields (virtual fields, joined fields) we should use these rather than the provider methods.
109 lines
4.6 KiB
Python
109 lines
4.6 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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Polygonize.py
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---------------------
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Date : March 2013
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Copyright : (C) 2013 by Piotr Pociask
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Email : ppociask at o2 dot pl
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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__author__ = 'Piotr Pociask'
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__date__ = 'March 2013'
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__copyright__ = '(C) 2013, Piotr Pociask'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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from shapely.ops import polygonize
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from shapely.ops import unary_union
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from shapely.geometry import MultiLineString
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from qgis.PyQt.QtCore import QVariant
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from qgis.core import Qgis, QgsFields, QgsField, QgsFeature, QgsGeometry, QgsWkbTypes
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
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from processing.core.parameters import ParameterVector
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from processing.core.parameters import ParameterBoolean
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from processing.core.outputs import OutputVector
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from processing.tools import dataobjects, vector
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class Polygonize(GeoAlgorithm):
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INPUT = 'INPUT'
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OUTPUT = 'OUTPUT'
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FIELDS = 'FIELDS'
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GEOMETRY = 'GEOMETRY'
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def defineCharacteristics(self):
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self.name, self.i18n_name = self.trAlgorithm('Polygonize')
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self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')
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self.addParameter(ParameterVector(self.INPUT,
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self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_LINE]))
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self.addParameter(ParameterBoolean(self.FIELDS,
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self.tr('Keep table structure of line layer'), False))
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self.addParameter(ParameterBoolean(self.GEOMETRY,
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self.tr('Create geometry columns'), True))
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self.addOutput(OutputVector(self.OUTPUT, self.tr('Polygons from lines')))
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def processAlgorithm(self, progress):
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vlayer = dataobjects.getObjectFromUri(self.getParameterValue(self.INPUT))
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output = self.getOutputFromName(self.OUTPUT)
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if self.getParameterValue(self.FIELDS):
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fields = vlayer.fields()
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else:
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fields = QgsFields()
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if self.getParameterValue(self.GEOMETRY):
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fieldsCount = fields.count()
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fields.append(QgsField('area', QVariant.Double, 'double', 16, 2))
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fields.append(QgsField('perimeter', QVariant.Double,
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'double', 16, 2))
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allLinesList = []
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features = vector.features(vlayer)
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progress.setInfo(self.tr('Processing lines...'))
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total = 40.0 / len(features)
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for current, inFeat in enumerate(features):
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inGeom = inFeat.geometry()
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if inGeom.isMultipart():
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allLinesList.extend(inGeom.asMultiPolyline())
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else:
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allLinesList.append(inGeom.asPolyline())
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progress.setPercentage(int(current * total))
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progress.setPercentage(40)
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allLines = MultiLineString(allLinesList)
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progress.setInfo(self.tr('Noding lines...'))
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allLines = unary_union(allLines)
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progress.setPercentage(45)
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progress.setInfo(self.tr('Polygonizing...'))
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polygons = list(polygonize([allLines]))
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if not polygons:
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raise GeoAlgorithmExecutionException(self.tr('No polygons were created!'))
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progress.setPercentage(50)
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progress.setInfo('Saving polygons...')
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writer = output.getVectorWriter(fields, QgsWkbTypes.Polygon, vlayer.crs())
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outFeat = QgsFeature()
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total = 50.0 / len(polygons)
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for current, polygon in enumerate(polygons):
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outFeat.setGeometry(QgsGeometry.fromWkt(polygon.wkt))
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if self.getParameterValue(self.GEOMETRY):
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outFeat.setAttributes([None] * fieldsCount + [polygon.area,
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polygon.length])
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writer.addFeature(outFeat)
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progress.setPercentage(50 + int(current * total))
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del writer
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