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

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

"""
***************************************************************************
    SumLines.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'

# This will get replaced with a git SHA1 when you do a git archive

__revision__ = '$Format:%H$'

import os

from qgis.PyQt.QtGui import QIcon
from qgis.PyQt.QtCore import QVariant
from qgis.core import (QgsFeature,
                       QgsFeatureSink,
                       QgsField,
                       QgsGeometry,
                       QgsFeatureRequest,
                       QgsDistanceArea,
                       QgsProject,
                       QgsProcessing,
                       QgsProcessingParameterString,
                       QgsProcessingParameterFeatureSource,
                       QgsProcessingParameterFeatureSink,
                       QgsSpatialIndex)

from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm

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


class SumLines(QgisAlgorithm):

    LINES = 'LINES'
    POLYGONS = 'POLYGONS'
    LEN_FIELD = 'LEN_FIELD'
    COUNT_FIELD = 'COUNT_FIELD'
    OUTPUT = 'OUTPUT'

    def icon(self):
        return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'sum_lines.png'))

    def group(self):
        return self.tr('Vector analysis')

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

    def initAlgorithm(self, config=None):
        self.addParameter(QgsProcessingParameterFeatureSource(self.LINES,
                                                              self.tr('Lines'), [QgsProcessing.TypeVectorLine]))
        self.addParameter(QgsProcessingParameterFeatureSource(self.POLYGONS,
                                                              self.tr('Polygons'), [QgsProcessing.TypeVectorPolygon]))
        self.addParameter(QgsProcessingParameterString(self.LEN_FIELD,
                                                       self.tr('Lines length field name'), defaultValue='LENGTH'))
        self.addParameter(QgsProcessingParameterString(self.COUNT_FIELD,
                                                       self.tr('Lines count field name'), defaultValue='COUNT'))

        self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Line length'), QgsProcessing.TypeVectorPolygon))

    def name(self):
        return 'sumlinelengths'

    def displayName(self):
        return self.tr('Sum line lengths')

    def processAlgorithm(self, parameters, context, feedback):
        line_source = self.parameterAsSource(parameters, self.LINES, context)
        poly_source = self.parameterAsSource(parameters, self.POLYGONS, context)

        length_field_name = self.parameterAsString(parameters, self.LEN_FIELD, context)
        count_field_name = self.parameterAsString(parameters, self.COUNT_FIELD, context)

        fields = poly_source.fields()
        if fields.lookupField(length_field_name) < 0:
            fields.append(QgsField(length_field_name, QVariant.Double))
        length_field_index = fields.lookupField(length_field_name)
        if fields.lookupField(count_field_name) < 0:
            fields.append(QgsField(count_field_name, QVariant.Int))
        count_field_index = fields.lookupField(count_field_name)

        (sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
                                               fields, poly_source.wkbType(), poly_source.sourceCrs())

        spatialIndex = QgsSpatialIndex(line_source.getFeatures(
            QgsFeatureRequest().setSubsetOfAttributes([]).setDestinationCrs(poly_source.sourceCrs())), feedback)

        distArea = QgsDistanceArea()
        distArea.setSourceCrs(poly_source.sourceCrs())
        distArea.setEllipsoid(context.project().ellipsoid())

        features = poly_source.getFeatures()
        total = 100.0 / poly_source.featureCount() if poly_source.featureCount() else 0
        for current, poly_feature in enumerate(features):
            if feedback.isCanceled():
                break

            output_feature = QgsFeature()
            count = 0
            length = 0
            if poly_feature.hasGeometry():
                poly_geom = poly_feature.geometry()
                has_intersections = False
                lines = spatialIndex.intersects(poly_geom.boundingBox())
                engine = None
                if len(lines) > 0:
                    has_intersections = True
                    # use prepared geometries for faster intersection tests
                    engine = QgsGeometry.createGeometryEngine(poly_geom.geometry())
                    engine.prepareGeometry()

                if has_intersections:
                    request = QgsFeatureRequest().setFilterFids(lines).setSubsetOfAttributes([]).setDestinationCrs(poly_source.sourceCrs())
                    for line_feature in line_source.getFeatures(request):
                        if feedback.isCanceled():
                            break

                        if engine.intersects(line_feature.geometry().geometry()):
                            outGeom = poly_geom.intersection(line_feature.geometry())
                            length += distArea.measureLength(outGeom)
                            count += 1

                output_feature.setGeometry(poly_geom)

            attrs = poly_feature.attributes()
            if length_field_index == len(attrs):
                attrs.append(length)
            else:
                attrs[length_field_index] = length
            if count_field_index == len(attrs):
                attrs.append(count)
            else:
                attrs[count_field_index] = count
            output_feature.setAttributes(attrs)
            sink.addFeature(output_feature, QgsFeatureSink.FastInsert)

            feedback.setProgress(int(current * total))

        return {self.OUTPUT: dest_id}