QGIS/python/plugins/processing/algs/qgis/VariableDistanceBuffer.py

"""
***************************************************************************
    VariableDistanceBuffer.py
    ---------------------
    Date                 : August 2012
    Copyright            : (C) 2012 by Victor Olaya
    Email                : volayaf at gmail dot com
***************************************************************************
*                                                                         *
*   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__ = "Victor Olaya"
__date__ = "August 2012"
__copyright__ = "(C) 2012, Victor Olaya"

import os

from qgis.PyQt.QtGui import QIcon

from qgis.core import (
    QgsApplication,
    QgsWkbTypes,
    QgsProcessing,
    QgsProcessingException,
    QgsProcessingAlgorithm,
    QgsProcessingParameterFeatureSource,
    QgsProcessingParameterField,
    QgsProcessingParameterNumber,
    QgsProcessingParameterBoolean,
    QgsProcessingParameterEnum,
    QgsProcessingParameterFeatureSink,
)

from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
from . import Buffer as buff

pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]


class VariableDistanceBuffer(QgisAlgorithm):
    INPUT = "INPUT"
    OUTPUT = "OUTPUT"
    FIELD = "FIELD"
    SEGMENTS = "SEGMENTS"
    DISSOLVE = "DISSOLVE"
    END_CAP_STYLE = "END_CAP_STYLE"
    JOIN_STYLE = "JOIN_STYLE"
    MITER_LIMIT = "MITER_LIMIT"

    def icon(self):
        return QgsApplication.getThemeIcon("/algorithms/mAlgorithmBuffer.svg")

    def svgIconPath(self):
        return QgsApplication.iconPath("/algorithms/mAlgorithmBuffer.svg")

    def group(self):
        return self.tr("Vector geometry")

    def groupId(self):
        return "vectorgeometry"

    def __init__(self):
        super().__init__()

    def flags(self):
        return (
            QgsProcessingAlgorithm.Flag.FlagSupportsBatch
            | QgsProcessingAlgorithm.Flag.FlagCanCancel
            | QgsProcessingAlgorithm.Flag.FlagDeprecated
        )

    def initAlgorithm(self, config=None):
        self.addParameter(
            QgsProcessingParameterFeatureSource(self.INPUT, self.tr("Input layer"))
        )

        self.addParameter(
            QgsProcessingParameterField(
                self.FIELD,
                self.tr("Distance field"),
                parentLayerParameterName=self.INPUT,
            )
        )
        self.addParameter(
            QgsProcessingParameterNumber(
                self.SEGMENTS,
                self.tr("Segments"),
                type=QgsProcessingParameterNumber.Type.Integer,
                minValue=1,
                defaultValue=5,
            )
        )
        self.addParameter(
            QgsProcessingParameterBoolean(
                self.DISSOLVE, self.tr("Dissolve result"), defaultValue=False
            )
        )
        self.end_cap_styles = [self.tr("Round"), "Flat", "Square"]
        self.addParameter(
            QgsProcessingParameterEnum(
                self.END_CAP_STYLE,
                self.tr("End cap style"),
                options=self.end_cap_styles,
                defaultValue=0,
            )
        )
        self.join_styles = [self.tr("Round"), "Miter", "Bevel"]
        self.addParameter(
            QgsProcessingParameterEnum(
                self.JOIN_STYLE,
                self.tr("Join style"),
                options=self.join_styles,
                defaultValue=0,
            )
        )
        self.addParameter(
            QgsProcessingParameterNumber(
                self.MITER_LIMIT,
                self.tr("Miter limit"),
                type=QgsProcessingParameterNumber.Type.Double,
                minValue=0,
                defaultValue=2,
            )
        )

        self.addParameter(
            QgsProcessingParameterFeatureSink(
                self.OUTPUT,
                self.tr("Buffer"),
                QgsProcessing.SourceType.TypeVectorPolygon,
            )
        )

    def name(self):
        return "variabledistancebuffer"

    def displayName(self):
        return self.tr("Variable distance buffer")

    def processAlgorithm(self, parameters, context, feedback):
        source = self.parameterAsSource(parameters, self.INPUT, context)
        if source is None:
            raise QgsProcessingException(
                self.invalidSourceError(parameters, self.INPUT)
            )

        dissolve = self.parameterAsBoolean(parameters, self.DISSOLVE, context)
        segments = self.parameterAsInt(parameters, self.SEGMENTS, context)
        end_cap_style = (
            self.parameterAsEnum(parameters, self.END_CAP_STYLE, context) + 1
        )
        join_style = self.parameterAsEnum(parameters, self.JOIN_STYLE, context) + 1
        miter_limit = self.parameterAsDouble(parameters, self.MITER_LIMIT, context)

        field = self.parameterAsString(parameters, self.FIELD, context)

        (sink, dest_id) = self.parameterAsSink(
            parameters,
            self.OUTPUT,
            context,
            source.fields(),
            QgsWkbTypes.Type.Polygon,
            source.sourceCrs(),
        )
        if sink is None:
            raise QgsProcessingException(self.invalidSinkError(parameters, self.OUTPUT))

        buff.buffering(
            feedback,
            context,
            sink,
            0,
            field,
            True,
            source,
            dissolve,
            segments,
            end_cap_style,
            join_style,
            miter_limit,
        )

        sink.finalize()
        return {self.OUTPUT: dest_id}