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1e13d733c2
initAlgorithm() method This allows 2 benefits: - algorithms can be subclassed and have subclasses add additional parameters/outputs to the algorithm. With the previous approach of declaring parameters/outputs in the constructor, it's not possible to call virtual methods to add additional parameters/ outputs (since you can't call virtual methods from a constructor). - initAlgorithm takes a variant map argument, allowing the algorithm to dynamically adjust its declared parameters and outputs according to this configuration map. This potentially allows model algorithms which can be configured to have variable numbers of parameters and outputs at run time. E.g. a "router" algorithm which directs features to one of any number of output sinks depending on some user configured criteria.
123 lines
5.1 KiB
Python
123 lines
5.1 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 qgis.PyQt.QtCore import QVariant
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from qgis.core import (QgsApplication,
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QgsFields,
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QgsField,
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QgsFeature,
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QgsFeatureSink,
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QgsGeometry,
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QgsWkbTypes,
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QgsFeatureRequest,
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QgsProcessingUtils)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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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
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class Polygonize(QgisAlgorithm):
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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 tags(self):
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return self.tr('create,lines,polygons,convert').split(',')
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def group(self):
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return self.tr('Vector geometry tools')
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def __init__(self):
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super().__init__()
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def initAlgorithm(self, config=None):
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self.addParameter(ParameterVector(self.INPUT,
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self.tr('Input layer'), [dataobjects.TYPE_VECTOR_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'), datatype=[dataobjects.TYPE_VECTOR_POLYGON]))
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def name(self):
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return 'polygonize'
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def displayName(self):
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return self.tr('Polygonize')
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def processAlgorithm(self, parameters, context, feedback):
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vlayer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT), context)
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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 = QgsProcessingUtils.getFeatures(vlayer, context, QgsFeatureRequest().setSubsetOfAttributes([]))
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feedback.pushInfo(self.tr('Processing lines...'))
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total = 40.0 / QgsProcessingUtils.featureCount(vlayer, context)
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for current, inFeat in enumerate(features):
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if inFeat.geometry():
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allLinesList.append(inFeat.geometry())
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feedback.setProgress(int(current * total))
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feedback.setProgress(40)
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feedback.pushInfo(self.tr('Noding lines...'))
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allLines = QgsGeometry.unaryUnion(allLinesList)
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feedback.setProgress(45)
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feedback.pushInfo(self.tr('Polygonizing...'))
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polygons = QgsGeometry.polygonize([allLines])
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if polygons.isEmpty():
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raise GeoAlgorithmExecutionException(self.tr('No polygons were created!'))
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feedback.setProgress(50)
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feedback.pushInfo('Saving polygons...')
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writer = output.getVectorWriter(fields, QgsWkbTypes.Polygon, vlayer.crs(), context)
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total = 50.0 / polygons.geometry().numGeometries()
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for i in range(polygons.geometry().numGeometries()):
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outFeat = QgsFeature()
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geom = QgsGeometry(polygons.geometry().geometryN(i).clone())
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outFeat.setGeometry(geom)
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if self.getParameterValue(self.GEOMETRY):
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outFeat.setAttributes([None] * fieldsCount + [geom.geometry().area(),
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geom.geometry().perimeter()])
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writer.addFeature(outFeat, QgsFeatureSink.FastInsert)
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feedback.setProgress(50 + int(current * total))
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del writer
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