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43cd62b62f
Instead of returning a single QgsFeature from processFeature, we now return a list of features. This allows feature based algorithms which return multiple features per input feature, e.g. "explode" type algorithms which split a single input feature into multiple output features.
117 lines
4.4 KiB
Python
117 lines
4.4 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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OffsetLine.py
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--------------
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Date : July 2016
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Copyright : (C) 2016 by Nyall Dawson
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Email : nyall dot dawson 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__ = 'Nyall Dawson'
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__date__ = 'July 2016'
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__copyright__ = '(C) 2016, Nyall Dawson'
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# This will get replaced with a git SHA1 when you do a git archive323
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__revision__ = '$Format:%H$'
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import os
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from qgis.core import (QgsFeatureSink,
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QgsProcessing,
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QgsProcessingException,
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QgsProcessingParameterFeatureSource,
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QgsProcessingParameterNumber,
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QgsProcessingParameterEnum,
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QgsProcessingParameterFeatureSink)
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from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class OffsetLine(QgisFeatureBasedAlgorithm):
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DISTANCE = 'DISTANCE'
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SEGMENTS = 'SEGMENTS'
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JOIN_STYLE = 'JOIN_STYLE'
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MITER_LIMIT = 'MITER_LIMIT'
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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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self.distance = None
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self.segments = None
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self.join_style = None
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self.miter_limit = None
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def initParameters(self, config=None):
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self.addParameter(QgsProcessingParameterNumber(self.DISTANCE,
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self.tr('Distance'),
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type=QgsProcessingParameterNumber.Double,
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defaultValue=10.0))
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self.addParameter(QgsProcessingParameterNumber(self.SEGMENTS,
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self.tr('Segments'),
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type=QgsProcessingParameterNumber.Integer,
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minValue=1, defaultValue=8))
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self.join_styles = [self.tr('Round'),
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'Miter',
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'Bevel']
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self.addParameter(QgsProcessingParameterEnum(
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self.JOIN_STYLE,
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self.tr('Join style'),
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options=self.join_styles))
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self.addParameter(QgsProcessingParameterNumber(self.MITER_LIMIT,
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self.tr('Miter limit'), type=QgsProcessingParameterNumber.Double,
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minValue=1, defaultValue=2))
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def name(self):
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return 'offsetline'
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def displayName(self):
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return self.tr('Offset line')
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def outputName(self):
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return self.tr('Offset')
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def inputLayerTypes(self):
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return [QgsProcessing.TypeVectorLine]
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def outputType(self):
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return QgsProcessing.TypeVectorLine
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def prepareAlgorithm(self, parameters, context, feedback):
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self.distance = self.parameterAsDouble(parameters, self.DISTANCE, context)
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self.segments = self.parameterAsInt(parameters, self.SEGMENTS, context)
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self.join_style = self.parameterAsEnum(parameters, self.JOIN_STYLE, context) + 1
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self.miter_limit = self.parameterAsDouble(parameters, self.MITER_LIMIT, context)
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return True
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def processFeature(self, feature, context, feedback):
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input_geometry = feature.geometry()
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if input_geometry:
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output_geometry = input_geometry.offsetCurve(self.distance, self.segments, self.join_style, self.miter_limit)
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if not output_geometry:
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raise QgsProcessingException(
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self.tr('Error calculating line offset'))
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feature.setGeometry(output_geometry)
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return [feature]
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