Nyall Dawson bd7d913379 Refine QgsFeature geometry getters/setters
All pointer based methods have been removed.

Now we have only:

  void setGeometry( const QgsGeometry& geom )

and

  QgsGeometry geometry() const

Benefits include avoiding a whole lot of tricky pointer lifetime
issues, potential memory leaks, and finally closing #777, which
has survived for over 9 years!...

Impacts on PyQGIS code:
- no more need for the messy
  g = QgsGeometry( feature.geometry() )
  workaround, just use g = feature.geometry() instead
- IMPORTANT: you can no longer test whether a feature has geometry
 using `if f.geometry():`, since QgsFeature::geometry() will
 *always* return an object. Instead, use
 `if not f.geometry().isEmpty():`, or preferably the new method
 `if not f.hasGeometry():`

Fix #777
2016-08-01 16:25:46 +10:00

92 lines
3.2 KiB
Python

# -*- coding: utf-8 -*-
"""
***************************************************************************
Centroids.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
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 Centroids(GeoAlgorithm):
INPUT_LAYER = 'INPUT_LAYER'
OUTPUT_LAYER = 'OUTPUT_LAYER'
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.pendingFields().toList(),
Qgis.WKBPoint,
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