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a05d941e4e
Since the underlying issues with the Python bindings are now fixed, in most cases we can safely default to allowing an algorithm to run in a background thread!! So now we make this the default, and require individual algorithms which are NOT thread safe to declare this. This includes algorithms which directly manipulate the current project or layers (such as setting layer styles), alter the selections in layers, or which rely on 3rd party libraries (for now, SAGA and GRASS algorithms are marked as not thread safe... TODO - someone more familiar with these libraries can investigate and remove the flag if appropriate). Also models are marked as non-thread safe. TODO: only flag an individual model as thread-unsafe if any of its child algorithms report this flag.
234 lines
8.6 KiB
Python
234 lines
8.6 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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EliminateSelection.py
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---------------------
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Date : January 2017
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Copyright : (C) 2017 by Bernhard Ströbl
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Email : bernhard.stroebl@jena.de
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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__ = 'Bernhard Ströbl'
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__date__ = 'January 2017'
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__copyright__ = '(C) 2017, Bernhard Ströbl'
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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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import os
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from qgis.PyQt.QtGui import QIcon
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from qgis.core import (QgsFeatureRequest,
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QgsFeature,
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QgsFeatureSink,
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QgsGeometry,
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QgsProcessingAlgorithm,
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QgsProcessingException,
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QgsProcessingUtils,
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QgsProcessingParameterVectorLayer,
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QgsProcessingParameterEnum,
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QgsProcessing,
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QgsProcessingParameterFeatureSink)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class EliminateSelection(QgisAlgorithm):
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INPUT = 'INPUT'
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OUTPUT = 'OUTPUT'
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MODE = 'MODE'
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MODE_LARGEST_AREA = 0
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MODE_SMALLEST_AREA = 1
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MODE_BOUNDARY = 2
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'eliminate.png'))
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def group(self):
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return self.tr('Vector geometry')
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def groupId(self):
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return 'vectorgeometry'
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def __init__(self):
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super().__init__()
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def flags(self):
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return super().flags() | QgsProcessingAlgorithm.FlagNoThreading
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def initAlgorithm(self, config=None):
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self.modes = [self.tr('Largest Area'),
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self.tr('Smallest Area'),
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self.tr('Largest Common Boundary')]
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self.addParameter(QgsProcessingParameterVectorLayer(self.INPUT,
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self.tr('Input layer'), [QgsProcessing.TypeVectorPolygon]))
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self.addParameter(QgsProcessingParameterEnum(self.MODE,
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self.tr('Merge selection with the neighbouring polygon with the'),
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options=self.modes))
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self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Eliminated'), QgsProcessing.TypeVectorPolygon))
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def name(self):
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return 'eliminateselectedpolygons'
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def displayName(self):
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return self.tr('Eliminate selected polygons')
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def processAlgorithm(self, parameters, context, feedback):
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inLayer = self.parameterAsVectorLayer(parameters, self.INPUT, context)
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boundary = self.parameterAsEnum(parameters, self.MODE, context) == self.MODE_BOUNDARY
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smallestArea = self.parameterAsEnum(parameters, self.MODE, context) == self.MODE_SMALLEST_AREA
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if inLayer.selectedFeatureCount() == 0:
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feedback.reportError(self.tr('{0}: (No selection in input layer "{1}")').format(self.displayName(), parameters[self.INPUT]))
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featToEliminate = []
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selFeatIds = inLayer.selectedFeatureIds()
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(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
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inLayer.fields(), inLayer.wkbType(), inLayer.sourceCrs())
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for aFeat in inLayer.getFeatures():
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if feedback.isCanceled():
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break
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if aFeat.id() in selFeatIds:
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# Keep references to the features to eliminate
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featToEliminate.append(aFeat)
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else:
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# write the others to output
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sink.addFeature(aFeat, QgsFeatureSink.FastInsert)
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# Delete all features to eliminate in processLayer
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processLayer = QgsProcessingUtils.mapLayerFromString(dest_id, context)
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processLayer.startEditing()
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# ANALYZE
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if len(featToEliminate) > 0: # Prevent zero division
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start = 20.00
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add = 80.00 / len(featToEliminate)
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else:
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start = 100
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feedback.setProgress(start)
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madeProgress = True
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# We go through the list and see if we find any polygons we can
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# merge the selected with. If we have no success with some we
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# merge and then restart the whole story.
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while madeProgress: # Check if we made any progress
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madeProgress = False
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featNotEliminated = []
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# Iterate over the polygons to eliminate
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for i in range(len(featToEliminate)):
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if feedback.isCanceled():
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break
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feat = featToEliminate.pop()
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geom2Eliminate = feat.geometry()
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bbox = geom2Eliminate.boundingBox()
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fit = processLayer.getFeatures(
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QgsFeatureRequest().setFilterRect(bbox).setSubsetOfAttributes([]))
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mergeWithFid = None
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mergeWithGeom = None
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max = 0
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min = -1
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selFeat = QgsFeature()
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# use prepared geometries for faster intersection tests
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engine = QgsGeometry.createGeometryEngine(geom2Eliminate.constGet())
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engine.prepareGeometry()
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while fit.nextFeature(selFeat):
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if feedback.isCanceled():
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break
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selGeom = selFeat.geometry()
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if engine.intersects(selGeom.constGet()):
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# We have a candidate
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iGeom = geom2Eliminate.intersection(selGeom)
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if not iGeom:
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continue
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if boundary:
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selValue = iGeom.length()
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else:
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# area. We need a common boundary in
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# order to merge
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if 0 < iGeom.length():
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selValue = selGeom.area()
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else:
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selValue = -1
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if -1 != selValue:
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useThis = True
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if smallestArea:
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if -1 == min:
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min = selValue
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else:
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if selValue < min:
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min = selValue
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else:
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useThis = False
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else:
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if selValue > max:
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max = selValue
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else:
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useThis = False
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if useThis:
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mergeWithFid = selFeat.id()
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mergeWithGeom = QgsGeometry(selGeom)
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# End while fit
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if mergeWithFid is not None:
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# A successful candidate
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newGeom = mergeWithGeom.combine(geom2Eliminate)
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if processLayer.changeGeometry(mergeWithFid, newGeom):
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madeProgress = True
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else:
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raise QgsProcessingException(
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self.tr('Could not replace geometry of feature with id {0}').format(mergeWithFid))
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start = start + add
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feedback.setProgress(start)
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else:
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featNotEliminated.append(feat)
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# End for featToEliminate
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featToEliminate = featNotEliminated
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# End while
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if not processLayer.commitChanges():
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raise QgsProcessingException(self.tr('Could not commit changes'))
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for feature in featNotEliminated:
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if feedback.isCanceled():
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break
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sink.addFeature(feature, QgsFeatureSink.FastInsert)
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return {self.OUTPUT: dest_id}
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