buffer_on_selection

buffer_on_selection.py

# -*- coding: utf-8 -*-

"""
***************************************************************************
*                                                                         *
*   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.                                   *
*                                                                         *
***************************************************************************
"""

import os

from qgis.PyQt.QtCore import QCoreApplication
from qgis.PyQt.QtGui import QIcon
from qgis.core import (QgsProcessing,
                       QgsProcessingAlgorithm,
                       QgsProcessingParameterFeatureSource,
                       QgsProcessingParameterDistance,
                       QgsProcessingParameterBoolean,
                       QgsWkbTypes,
                       QgsProcessingParameterFeatureSink)

from qgis import processing

class EtraBufferAlgorithm(QgsProcessingAlgorithm):

    INPUT = 'INPUT'
    DISSOLVE = 'DISSOLVE'
    DISTANCE = 'DISTANCE'

    OUTPUT = 'OUTPUT'

    def tr(self, string):
        return QCoreApplication.translate('', string)

    def createInstance(self):
        return EtraBufferAlgorithm()

    def name(self):
        return 'etra_buffer'

    def displayName(self):
        return self.tr('Buffer')

    def group(self):
        return self.tr('Strumenti')

    def groupId(self):
        return 'strumenti'

    def icon(self):
        icon_path = QIcon(os.path.join(os.path.dirname(__file__), '..', 'icons', 'mAlgorithmBuffer.svg'))
        return icon_path

    def initAlgorithm(self, config=None):

        self.addParameter(
            QgsProcessingParameterFeatureSource(
                name=self.INPUT,
                description=self.tr('Layer in Input'),
                types=[QgsProcessing.TypeVectorAnyGeometry],
            )
        )

        self.addParameter(
            QgsProcessingParameterDistance(
                self.DISTANCE,
                self.tr('Distanza del buffer'),
                parentParameterName=self.INPUT,
                defaultValue=10
            )
        )

        self.addParameter(
            QgsProcessingParameterBoolean(
                self.DISSOLVE,
                self.tr('Dissolvi il risultato'),
                defaultValue=False
            )
        )

        self.addParameter(
            QgsProcessingParameterFeatureSink(
                self.OUTPUT,
                self.tr('Buffer')
            )
        )

    def processAlgorithm(self, parameters, context, feedback):

        source = self.parameterAsSource(
            parameters,
            self.INPUT,
            context
        )

        distance = self.parameterAsDouble(
            parameters,
            self.DISTANCE,
            context
        )

        dissolve = self.parameterAsBoolean(
            parameters,
            self.DISSOLVE,
            context
        )

        (sink, dest_id) = self.parameterAsSink(
            parameters,
            self.OUTPUT,
            context,
            source.fields(),
            QgsWkbTypes.MultiPolygon,
            source.sourceCrs()
        )

        param = {
            'INPUT': source.sourceName(),
            'DISTANCE': distance,
            'DISSOLVE': dissolve,
            'OUTPUT': QgsProcessing.TEMPORARY_OUTPUT
        }


        buffered = processing.run('native:buffer', param, feedback=feedback, context=context)['OUTPUT']

        for f in buffered.getFeatures():
            sink.addFeature(f)

        return {self.OUTPUT: dest_id}