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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.
172 lines
7.1 KiB
Python
172 lines
7.1 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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ConcaveHull.py
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---------------------
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Date : May 2014
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Copyright : (C) 2012 by Piotr Pociask
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Email : piotr dot pociask at gis-support 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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from builtins import range
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__author__ = 'Piotr Pociask'
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__date__ = 'May 2014'
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__copyright__ = '(C) 2014, 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.core import (QgsFeatureRequest,
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QgsFeature,
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QgsGeometry,
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QgsFeatureSink,
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QgsWkbTypes,
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QgsApplication,
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QgsProcessing,
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QgsProcessingUtils,
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QgsProcessingParameterFeatureSource,
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QgsProcessingParameterVectorLayer,
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QgsProcessingParameterDefinition,
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QgsProcessingParameterNumber,
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QgsProcessingParameterBoolean,
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QgsProcessingParameterFeatureSink,
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QgsProcessingOutputVectorLayer)
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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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import processing
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from math import sqrt
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class ConcaveHull(QgisAlgorithm):
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INPUT = 'INPUT'
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ALPHA = 'ALPHA'
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HOLES = 'HOLES'
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NO_MULTIGEOMETRY = 'NO_MULTIGEOMETRY'
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OUTPUT = 'OUTPUT'
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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(QgsProcessingParameterFeatureSource(self.INPUT, self.tr('Input point layer'), [QgsProcessing.TypeVectorPoint]))
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self.addParameter(QgsProcessingParameterNumber(self.ALPHA,
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self.tr('Threshold (0-1, where 1 is equivalent with Convex Hull)'),
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minValue=0, maxValue=1, defaultValue=0.3, type=QgsProcessingParameterNumber.Double))
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self.addParameter(QgsProcessingParameterBoolean(self.HOLES,
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self.tr('Allow holes'), defaultValue=True))
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self.addParameter(QgsProcessingParameterBoolean(self.NO_MULTIGEOMETRY,
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self.tr('Split multipart geometry into singleparts geometries'), defaultValue=False))
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self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Concave hull'), type=QgsProcessing.TypeVectorPolygon))
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self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr("Concave hull"), type=QgsProcessing.TypeVectorPolygon))
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def name(self):
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return 'concavehull'
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def displayName(self):
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return self.tr('Concave hull')
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def processAlgorithm(self, parameters, context, feedback):
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layer = self.parameterAsSource(parameters, ConcaveHull.INPUT, context)
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alpha = self.parameterAsDouble(parameters, self.ALPHA, context)
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holes = self.parameterAsBool(parameters, self.HOLES, context)
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no_multigeom = self.parameterAsBool(parameters, self.NO_MULTIGEOMETRY, context)
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# Delaunay triangulation from input point layer
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feedback.setProgressText(self.tr('Creating Delaunay triangles...'))
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delaunay_layer = processing.run("qgis:delaunaytriangulation", {'INPUT': parameters[ConcaveHull.INPUT], 'OUTPUT': 'memory:'}, feedback=feedback, context=context)['OUTPUT']
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# Get max edge length from Delaunay triangles
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feedback.setProgressText(self.tr('Computing edges max length...'))
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features = delaunay_layer.getFeatures()
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count = delaunay_layer.featureCount()
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if count == 0:
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raise GeoAlgorithmExecutionException(self.tr('No Delaunay triangles created.'))
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counter = 50. / count
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lengths = []
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edges = {}
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for feat in features:
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if feedback.isCanceled():
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break
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line = feat.geometry().asPolygon()[0]
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for i in range(len(line) - 1):
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lengths.append(sqrt(line[i].sqrDist(line[i + 1])))
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edges[feat.id()] = max(lengths[-3:])
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feedback.setProgress(feat.id() * counter)
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max_length = max(lengths)
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# Get features with longest edge longer than alpha*max_length
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feedback.setProgressText(self.tr('Removing features...'))
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counter = 50. / len(edges)
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i = 0
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ids = []
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for id, max_len in list(edges.items()):
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if feedback.isCanceled():
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break
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if max_len > alpha * max_length:
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ids.append(id)
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feedback.setProgress(50 + i * counter)
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i += 1
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# Remove features
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delaunay_layer.dataProvider().deleteFeatures(ids)
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# Dissolve all Delaunay triangles
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feedback.setProgressText(self.tr('Dissolving Delaunay triangles...'))
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dissolved_layer = processing.run("native:dissolve", {'INPUT': delaunay_layer, 'OUTPUT': 'memory:'}, feedback=feedback, context=context)['OUTPUT']
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# Save result
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feedback.setProgressText(self.tr('Saving data...'))
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feat = QgsFeature()
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dissolved_layer.getFeatures().nextFeature(feat)
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# Not needed anymore, free up some resources
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del delaunay_layer
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del dissolved_layer
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(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
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layer.fields(), QgsWkbTypes.Polygon, layer.sourceCrs())
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geom = feat.geometry()
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if no_multigeom and geom.isMultipart():
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# Only singlepart geometries are allowed
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geom_list = geom.asGeometryCollection()
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for single_geom in geom_list:
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if feedback.isCanceled():
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break
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single_feature = QgsFeature()
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if not holes:
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# Delete holes
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single_geom = single_geom.removeInteriorRings()
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single_feature.setGeometry(single_geom)
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sink.addFeature(single_feature, QgsFeatureSink.FastInsert)
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else:
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# Multipart geometries are allowed
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if not holes:
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# Delete holes
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geom = geom.removeInteriorRings()
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feat.setGeometry(geom)
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sink.addFeature(feat, QgsFeatureSink.FastInsert)
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return {self.OUTPUT: dest_id}
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