/
Buffer.py
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Buffer.py
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# -*- coding: utf-8 -*-
"""
***************************************************************************
Buffer.py
---------------------
Date : Janaury 2015
Copyright : (C) 2015 by Giovanni Manghi
Email : giovanni dot manghi at naturalgis dot pt
***************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
***************************************************************************
"""
__author__ = 'Giovanni Manghi'
__date__ = 'January 2015'
__copyright__ = '(C) 2015, Giovanni Manghi'
from qgis.core import (QgsProcessing,
QgsProcessingParameterDistance,
QgsProcessingParameterDefinition,
QgsProcessingParameterFeatureSource,
QgsProcessingParameterField,
QgsProcessingParameterString,
QgsProcessingParameterNumber,
QgsProcessingException,
QgsProcessingParameterBoolean,
QgsProcessingParameterVectorDestination)
from processing.algs.gdal.GdalAlgorithm import GdalAlgorithm
from processing.algs.gdal.GdalUtils import GdalUtils
class Buffer(GdalAlgorithm):
INPUT = 'INPUT'
FIELD = 'FIELD'
GEOMETRY = 'GEOMETRY'
DISTANCE = 'DISTANCE'
DISSOLVE = 'DISSOLVE'
EXPLODE_COLLECTIONS = 'EXPLODE_COLLECTIONS'
OPTIONS = 'OPTIONS'
OUTPUT = 'OUTPUT'
def __init__(self):
super().__init__()
def initAlgorithm(self, config=None):
self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT,
self.tr('Input layer')))
self.addParameter(QgsProcessingParameterString(self.GEOMETRY,
self.tr('Geometry column name'),
defaultValue='geometry'))
self.addParameter(QgsProcessingParameterDistance(self.DISTANCE,
self.tr('Buffer distance'),
parentParameterName=self.INPUT,
defaultValue=10.0))
self.addParameter(QgsProcessingParameterField(self.FIELD,
self.tr('Dissolve by attribute'),
None,
self.INPUT,
QgsProcessingParameterField.Any,
optional=True))
self.addParameter(QgsProcessingParameterBoolean(self.DISSOLVE,
self.tr('Dissolve all results'),
defaultValue=False))
self.addParameter(QgsProcessingParameterBoolean(self.EXPLODE_COLLECTIONS,
self.tr('Produce one feature for each geometry in any kind of geometry collection in the source file'),
defaultValue=False))
options_param = QgsProcessingParameterString(self.OPTIONS,
self.tr('Additional creation options'),
defaultValue='',
optional=True)
options_param.setFlags(options_param.flags() | QgsProcessingParameterDefinition.FlagAdvanced)
self.addParameter(options_param)
self.addParameter(QgsProcessingParameterVectorDestination(self.OUTPUT,
self.tr('Buffer'),
QgsProcessing.TypeVectorPolygon))
def name(self):
return 'buffervectors'
def displayName(self):
return self.tr('Buffer vectors')
def group(self):
return self.tr('Vector geoprocessing')
def groupId(self):
return 'vectorgeoprocessing'
def commandName(self):
return 'ogr2ogr'
def getConsoleCommands(self, parameters, context, feedback, executing=True):
source = self.parameterAsSource(parameters, self.INPUT, context)
if source is None:
raise QgsProcessingException(self.invalidSourceError(parameters, self.INPUT))
fields = source.fields()
ogrLayer, layerName = self.getOgrCompatibleSource(self.INPUT, parameters, context, feedback, executing)
geometry = self.parameterAsString(parameters, self.GEOMETRY, context)
distance = self.parameterAsDouble(parameters, self.DISTANCE, context)
fieldName = self.parameterAsString(parameters, self.FIELD, context)
dissolve = self.parameterAsBoolean(parameters, self.DISSOLVE, context)
options = self.parameterAsString(parameters, self.OPTIONS, context)
outFile = self.parameterAsOutputLayer(parameters, self.OUTPUT, context)
self.setOutputValue(self.OUTPUT, outFile)
output, outputFormat = GdalUtils.ogrConnectionStringAndFormat(outFile, context)
other_fields_exist = any(
True for f in fields
if f.name() != geometry
)
other_fields = ',*' if other_fields_exist else ''
arguments = [
output,
ogrLayer,
'-dialect',
'sqlite',
'-sql'
]
if dissolve or fieldName:
sql = 'SELECT ST_Union(ST_Buffer({}, {})) AS {}{} FROM "{}"'.format(geometry, distance, geometry, other_fields, layerName)
else:
sql = 'SELECT ST_Buffer({}, {}) AS {}{} FROM "{}"'.format(geometry, distance, geometry, other_fields, layerName)
if fieldName:
sql = '{} GROUP BY "{}"'.format(sql, fieldName)
arguments.append(sql)
if self.parameterAsBoolean(parameters, self.EXPLODE_COLLECTIONS, context):
arguments.append('-explodecollections')
if options:
arguments.append(options)
if outputFormat:
arguments.append('-f {}'.format(outputFormat))
return [self.commandName(), GdalUtils.escapeAndJoin(arguments)]