QGIS/python/plugins/processing/algs/qgis/PolygonCentroids.py
Nyall Dawson e9423dc4dd [processing] Rework centroid algorithm to handle non-polygon layers
The existing polygoncentroids algorithm has been deprecated
(and hidden from the toolbox), and a new, generic centroids
algorithm added which works with lines and multipoints
2016-08-12 07:50:47 +10:00

97 lines
3.4 KiB
Python

# -*- 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 Qgis, QgsGeometry, QgsFeature, QgsWkbTypes
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from processing.core.parameters import ParameterVector
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector
pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
class PolygonCentroids(GeoAlgorithm):
INPUT_LAYER = 'INPUT_LAYER'
OUTPUT_LAYER = 'OUTPUT_LAYER'
def __init__(self):
GeoAlgorithm.__init__(self)
# this algorithm is deprecated - use Centroids instead
self.showInToolbox = False
def getIcon(self):
return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'centroids.png'))
def defineCharacteristics(self):
self.name, self.i18n_name = self.trAlgorithm('Polygon centroids')
self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')
self.addParameter(ParameterVector(self.INPUT_LAYER,
self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_POLYGON]))
self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Centroids')))
def processAlgorithm(self, progress):
layer = dataobjects.getObjectFromUri(
self.getParameterValue(self.INPUT_LAYER))
writer = self.getOutputFromName(
self.OUTPUT_LAYER).getVectorWriter(
layer.fields(),
QgsWkbTypes.Point,
layer.crs())
outFeat = QgsFeature()
features = vector.features(layer)
total = 100.0 / len(features)
for current, feat in enumerate(features):
inGeom = feat.geometry()
attrs = feat.attributes()
if inGeom.isEmpty():
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)
progress.setPercentage(int(current * total))
del writer