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6a2625664e
This is a subclass of QgsProcessingParameterNumber, but specifically for numeric parameters which represent distances. It is linked to a parent parameter, from which the distance unit will be determined, and is shown using a dedicated distance widget within the processing parameters panel. This widget shows the distance unit. This avoids the confusion when running algorithms which use distances where the unit depends on a layer or CRS parameter - e.g. the distance parameter in the buffer algorithm gives the distance in layer units... so now we can show those units directly within the dialog. Hopefully this leads to less user confusion and accidental "1000 degree buffers"! Additionally - if the unit is in degrees, a small warning icon is shown next to the parameter. The tooltip for this icon advises users to reproject data into a suitable projected local coordinate system. Initially implemented for the native buffer and single sided buffer algorithm only - but more will be added. Fixes #16290
127 lines
4.8 KiB
Python
127 lines
4.8 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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SingleSidedBuffer.py
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--------------------
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Date : August 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__ = 'August 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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from qgis.core import (QgsGeometry,
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QgsWkbTypes,
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QgsProcessing,
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QgsProcessingParameterDistance,
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QgsProcessingParameterNumber,
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QgsProcessingParameterEnum,
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QgsProcessingException)
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from processing.algs.qgis.QgisAlgorithm import QgisFeatureBasedAlgorithm
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class SingleSidedBuffer(QgisFeatureBasedAlgorithm):
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DISTANCE = 'DISTANCE'
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SIDE = 'SIDE'
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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.side = None
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self.miter_limit = None
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self.sides = [self.tr('Left'),
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'Right']
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self.join_styles = [self.tr('Round'),
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'Miter',
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'Bevel']
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def initParameters(self, config=None):
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self.addParameter(QgsProcessingParameterDistance(self.DISTANCE,
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self.tr('Distance'), parentParameterName='INPUT',
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defaultValue=10.0))
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self.addParameter(QgsProcessingParameterEnum(
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self.SIDE,
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self.tr('Side'),
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options=self.sides))
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self.addParameter(QgsProcessingParameterNumber(self.SEGMENTS,
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self.tr('Segments'), QgsProcessingParameterNumber.Integer,
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minValue=1, defaultValue=8))
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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'), QgsProcessingParameterNumber.Double,
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minValue=1, defaultValue=2))
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def name(self):
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return 'singlesidedbuffer'
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def displayName(self):
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return self.tr('Single sided buffer')
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def outputName(self):
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return self.tr('Buffer')
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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.TypeVectorPolygon
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def outputWkbType(self, input_wkb_type):
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return QgsWkbTypes.Polygon
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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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if self.parameterAsEnum(parameters, self.SIDE, context) == 0:
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self.side = QgsGeometry.SideLeft
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else:
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self.side = QgsGeometry.SideRight
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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.singleSidedBuffer(self.distance, self.segments,
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self.side, 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 single sided buffer'))
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feature.setGeometry(output_geometry)
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return [feature]
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