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Algorithms and other processing code should use this method (instead of dataobjects.getLayerFromString) to retrieve layers from a string, as it considers the processing context and allows resolving strings to temporarily stored layers. This permits processing models to function correctly when intermediate results are stored as memory layers. Subsequent model algorithms can then access these temporary layers as inputs. All temporary layers will be removed when the context object is destroyed after the model algorithm is run.
161 lines
6.6 KiB
Python
161 lines
6.6 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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QgsWkbTypes,
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QgsApplication)
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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 ParameterNumber
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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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import processing
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from math import sqrt
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class ConcaveHull(GeoAlgorithm):
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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 icon(self):
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return QgsApplication.getThemeIcon("/providerQgis.svg")
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def svgIconPath(self):
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return QgsApplication.iconPath("providerQgis.svg")
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def group(self):
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return self.tr('Vector geometry tools')
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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 defineCharacteristics(self):
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self.addParameter(ParameterVector(ConcaveHull.INPUT,
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self.tr('Input point layer'), [dataobjects.TYPE_VECTOR_POINT]))
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self.addParameter(ParameterNumber(self.ALPHA,
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self.tr('Threshold (0-1, where 1 is equivalent with Convex Hull)'),
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0, 1, 0.3))
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self.addParameter(ParameterBoolean(self.HOLES,
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self.tr('Allow holes'), True))
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self.addParameter(ParameterBoolean(self.NO_MULTIGEOMETRY,
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self.tr('Split multipart geometry into singleparts geometries'), False))
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self.addOutput(
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OutputVector(ConcaveHull.OUTPUT, self.tr('Concave hull'), datatype=[dataobjects.TYPE_VECTOR_POLYGON]))
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def processAlgorithm(self, context, feedback):
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layer = dataobjects.QgsProcessingUtils.mapLayerFromString(self.getParameterValue(ConcaveHull.INPUT), context)
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alpha = self.getParameterValue(self.ALPHA)
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holes = self.getParameterValue(self.HOLES)
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no_multigeom = self.getParameterValue(self.NO_MULTIGEOMETRY)
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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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delone_triangles = processing.run("qgis:delaunaytriangulation", layer, None)['OUTPUT']
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delaunay_layer = dataobjects.QgsProcessingUtils.mapLayerFromString(delone_triangles, context)
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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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if len(features) == 0:
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raise GeoAlgorithmExecutionException(self.tr('No Delaunay triangles created.'))
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counter = 50. / len(features)
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lengths = []
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edges = {}
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for feat in features:
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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 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.selectByIds(ids)
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delaunay_layer.startEditing()
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delaunay_layer.deleteSelectedFeatures()
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delaunay_layer.commitChanges()
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# Dissolve all Delaunay triangles
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feedback.setProgressText(self.tr('Dissolving Delaunay triangles...'))
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dissolved = processing.run("qgis:dissolve", delaunay_layer,
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True, None, None)['OUTPUT']
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dissolved_layer = dataobjects.QgsProcessingUtils.mapLayerFromString(dissolved, context)
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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(QgsFeatureRequest().setFilterFid(0)).nextFeature(feat)
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writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(layer.fields().toList(), QgsWkbTypes.Polygon,
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layer.crs(), context)
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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.asMultiPolygon()
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for single_geom_list in geom_list:
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single_feature = QgsFeature()
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single_geom = QgsGeometry.fromPolygon(single_geom_list)
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if not holes:
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# Delete holes
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deleted = True
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while deleted:
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deleted = single_geom.deleteRing(1)
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single_feature.setGeometry(single_geom)
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writer.addFeature(single_feature)
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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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deleted = True
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while deleted:
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deleted = geom.deleteRing(1)
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writer.addFeature(feat)
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del writer
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