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

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

"""
***************************************************************************
    PolygonCentroids.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 archive323

__revision__ = '$Format:%H$'

import os

from qgis.PyQt.QtGui import QIcon

from qgis.core import (QgsProcessingAlgorithm,
                       QgsGeometry,
                       QgsFeature,
                       QgsWkbTypes,
                       QgsProcessingUtils)

from processing.algs.qgis import QgisAlgorithm
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from processing.core.parameters import ParameterVector
from processing.core.outputs import OutputVector
from processing.tools import dataobjects

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


class PolygonCentroids(QgisAlgorithm):

    INPUT_LAYER = 'INPUT_LAYER'
    OUTPUT_LAYER = 'OUTPUT_LAYER'

    def flags(self):
        # this algorithm is deprecated - use Centroids instead
        return QgsProcessingAlgorithm.FlagDeprecated

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

    def group(self):
        return self.tr('Vector geometry tools')

    def name(self):
        return 'polygoncentroids'

    def displayName(self):
        return self.tr('Polygon centroids')

    def defineCharacteristics(self):
        self.addParameter(ParameterVector(self.INPUT_LAYER,
                                          self.tr('Input layer'), [dataobjects.TYPE_VECTOR_POLYGON]))

        self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Centroids')))

    def processAlgorithm(self, context, feedback):
        layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_LAYER), context)

        writer = self.getOutputFromName(
            self.OUTPUT_LAYER).getVectorWriter(layer.fields(), QgsWkbTypes.Point, layer.crs(), context)

        outFeat = QgsFeature()

        features = QgsProcessingUtils.getFeatures(layer, context)
        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
        for current, feat in enumerate(features):
            inGeom = feat.geometry()
            attrs = feat.attributes()

            if inGeom.isNull():
                outGeom = QgsGeometry(None)
            else:
                outGeom = QgsGeometry(inGeom.centroid())
                if not outGeom:
                    raise GeoAlgorithmExecutionException(
                        self.tr('Error calculating centroid'))

            outFeat.setGeometry(outGeom)
            outFeat.setAttributes(attrs)
            writer.addFeature(outFeat)
            feedback.setProgress(int(current * total))

        del writer