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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.
127 lines
5.0 KiB
Python
127 lines
5.0 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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SimplifyGeometries.py
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---------------------
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Date : August 2012
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Copyright : (C) 2012 by Victor Olaya
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Email : volayaf at gmail dot com
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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__ = 'Victor Olaya'
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__date__ = 'August 2012'
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__copyright__ = '(C) 2012, Victor Olaya'
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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 (QgsMapToPixelSimplifier,
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QgsMessageLog,
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QgsFeatureSink,
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QgsProcessingUtils,
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QgsProcessingParameterFeatureSource,
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QgsProcessingParameterFeatureSink,
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QgsProcessingParameterEnum,
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QgsProcessingParameterNumber,
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QgsProcessingOutputVectorLayer)
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from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
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from processing.tools import dataobjects
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class SimplifyGeometries(QgisAlgorithm):
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INPUT = 'INPUT'
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TOLERANCE = 'TOLERANCE'
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OUTPUT = 'OUTPUT'
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METHOD = 'METHOD'
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'simplify.png'))
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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,
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self.tr('Input layer'),
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[dataobjects.TYPE_VECTOR_POLYGON, dataobjects.TYPE_VECTOR_LINE]))
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self.methods = [self.tr('Distance (Douglas-Peucker)'),
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'Snap to grid',
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'Area (Visvalingam)']
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self.addParameter(QgsProcessingParameterEnum(
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self.METHOD,
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self.tr('Simplification method'),
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self.methods, defaultValue=0))
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self.addParameter(QgsProcessingParameterNumber(self.TOLERANCE,
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self.tr('Tolerance'), minValue=0.0, maxValue=10000000.0, defaultValue=1.0))
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self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Simplified')))
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self.addOutput(QgsProcessingOutputVectorLayer(self.OUTPUT, self.tr('Simplified')))
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def name(self):
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return 'simplifygeometries'
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def displayName(self):
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return self.tr('Simplify geometries')
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def processAlgorithm(self, parameters, context, feedback):
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source = self.parameterAsSource(parameters, self.INPUT, context)
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tolerance = self.parameterAsDouble(parameters, self.TOLERANCE, context)
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method = self.parameterAsEnum(parameters, self.METHOD, context)
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pointsBefore = 0
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pointsAfter = 0
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(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
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source.fields(), source.wkbType(), source.sourceCrs())
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features = source.getFeatures()
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total = 100.0 / source.featureCount() if source.featureCount() else 0
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if method != 0:
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simplifier = QgsMapToPixelSimplifier(QgsMapToPixelSimplifier.SimplifyGeometry, tolerance, method)
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for current, input_feature in enumerate(features):
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if feedback.isCanceled():
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break
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out_feature = input_feature
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if input_feature.geometry():
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input_geometry = input_feature.geometry()
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pointsBefore += input_geometry.geometry().nCoordinates()
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if method == 0: # distance
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output_geometry = input_geometry.simplify(tolerance)
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else:
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output_geometry = simplifier.simplify(input_geometry)
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pointsAfter += output_geometry.geometry().nCoordinates()
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out_feature.setGeometry(output_geometry)
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sink.addFeature(out_feature, QgsFeatureSink.FastInsert)
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feedback.setProgress(int(current * total))
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QgsMessageLog.logMessage(self.tr('Simplify: Input geometries have been simplified from {0} to {1} points').format(pointsBefore, pointsAfter),
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self.tr('Processing'), QgsMessageLog.INFO)
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return {self.OUTPUT: dest_id}
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