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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.
99 lines
3.7 KiB
Python
99 lines
3.7 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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SelectByExpression.py
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---------------------
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Date : July 2014
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Copyright : (C) 2014 by Michael Douchin
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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__ = 'Michael Douchin'
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__date__ = 'July 2014'
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__copyright__ = '(C) 2014, Michael Douchin'
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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 (QgsExpression,
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QgsVectorLayer,
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QgsProcessingAlgorithm,
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QgsProcessingException,
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QgsProcessingParameterVectorLayer,
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QgsProcessingParameterExpression,
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QgsProcessingParameterEnum,
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QgsProcessingOutputVectorLayer)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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class SelectByExpression(QgisAlgorithm):
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INPUT = 'INPUT'
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EXPRESSION = 'EXPRESSION'
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OUTPUT = 'OUTPUT'
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METHOD = 'METHOD'
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def group(self):
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return self.tr('Vector selection')
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def groupId(self):
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return 'vectorselection'
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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.methods = [self.tr('creating new selection'),
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self.tr('adding to current selection'),
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self.tr('removing from current selection'),
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self.tr('selecting within current selection')]
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self.addParameter(QgsProcessingParameterVectorLayer(self.INPUT, self.tr('Input layer')))
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self.addParameter(QgsProcessingParameterExpression(self.EXPRESSION,
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self.tr('Expression'), parentLayerParameterName=self.INPUT))
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self.addParameter(QgsProcessingParameterEnum(self.METHOD,
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self.tr('Modify current selection by'), self.methods, 0))
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self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr('Selected (attribute)')))
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def name(self):
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return 'selectbyexpression'
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def displayName(self):
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return self.tr('Select by expression')
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def processAlgorithm(self, parameters, context, feedback):
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layer = self.parameterAsVectorLayer(parameters, self.INPUT, context)
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method = self.parameterAsEnum(parameters, self.METHOD, context)
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if method == 0:
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behavior = QgsVectorLayer.SetSelection
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elif method == 1:
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behavior = QgsVectorLayer.AddToSelection
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elif method == 2:
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behavior = QgsVectorLayer.RemoveFromSelection
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elif method == 3:
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behavior = QgsVectorLayer.IntersectSelection
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expression = self.parameterAsString(parameters, self.EXPRESSION, context)
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qExp = QgsExpression(expression)
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if qExp.hasParserError():
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raise QgsProcessingException(qExp.parserErrorString())
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layer.selectByExpression(expression, behavior)
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return {self.OUTPUT: parameters[self.INPUT]}
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