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[processing] Add smooth algorithm

Allows for smoothing line or polygon layers
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nyalldawson committed Nov 18, 2015
1 parent 53aa583 commit 9009ef0b2665d1189fbbcf3912017df0e595edba
@@ -131,6 +131,7 @@
from Datasources2Vrt import Datasources2Vrt
from CheckValidity import CheckValidity
from OrientedMinimumBoundingBox import OrientedMinimumBoundingBox
from Smooth import Smooth

pluginPath = os.path.normpath(os.path.join(
os.path.split(os.path.dirname(__file__))[0], os.pardir))
@@ -179,7 +180,7 @@ def __init__(self):
SelectByExpression(), HypsometricCurves(),
SplitLinesWithLines(), CreateConstantRaster(),
FieldsMapper(), SelectByAttributeSum(), Datasources2Vrt(),
CheckValidity(), OrientedMinimumBoundingBox()
CheckValidity(), OrientedMinimumBoundingBox(), Smooth()
]

if hasMatplotlib:
@@ -0,0 +1,89 @@
# -*- coding: utf-8 -*-

"""
***************************************************************************
Smooth.py
---------
Date : November 2015
Copyright : (C) 2015 by Nyall Dawson
Email : nyall dot dawson 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__ = 'Nyall Dawson'
__date__ = 'November 2015'
__copyright__ = '(C) 2015, Nyall Dawson'

# This will get replaced with a git SHA1 when you do a git archive323

__revision__ = '$Format:%H$'

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, ParameterNumber
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector


class Smooth(GeoAlgorithm):

INPUT_LAYER = 'INPUT_LAYER'
OUTPUT_LAYER = 'OUTPUT_LAYER'
ITERATIONS = 'ITERATIONS'
OFFSET = 'OFFSET'

def defineCharacteristics(self):
self.name, self.i18n_name = self.trAlgorithm('Smooth geometry')
self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')

self.addParameter(ParameterVector(self.INPUT_LAYER,
self.tr('Input layer'), [ParameterVector.VECTOR_TYPE_POLYGON, ParameterVector.VECTOR_TYPE_LINE]))
self.addParameter(ParameterNumber(self.ITERATIONS,
self.tr('Iterations'), default=1, minValue=1, maxValue=10))
self.addParameter(ParameterNumber(self.OFFSET,
self.tr('Offset'), default=0.25, minValue=0.0, maxValue=0.5))
self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Smoothed')))

def processAlgorithm(self, progress):
layer = dataobjects.getObjectFromUri(
self.getParameterValue(self.INPUT_LAYER))
provider = layer.dataProvider()
iterations = self.getParameterValue(self.ITERATIONS)
offset = self.getParameterValue(self.OFFSET)

writer = self.getOutputFromName(
self.OUTPUT_LAYER).getVectorWriter(
layer.fields().toList(),
provider.geometryType(),
layer.crs())

outFeat = QgsFeature()

features = vector.features(layer)
total = 100.0 / float(len(features))
current = 0

for inFeat in features:
inGeom = inFeat.constGeometry()
attrs = inFeat.attributes()

outGeom = inGeom.smooth(iterations, offset)
if outGeom is None:
raise GeoAlgorithmExecutionException(
self.tr('Error smoothing geometry'))

outFeat.setGeometry(outGeom)
outFeat.setAttributes(attrs)
writer.addFeature(outFeat)
current += 1
progress.setPercentage(int(current * total))

del writer

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