Nyall Dawson 8dab2cd4d7 [FEATURE][processing] New algorithm to extend lines
Allows extending linestrings by a set distance at the start
and end of the line
2016-10-31 07:56:24 +10:00

87 lines
3.4 KiB
Python

# -*- coding: utf-8 -*-
"""
***************************************************************************
ExtendLines.py
--------------------
Date : October 2016
Copyright : (C) 2016 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__ = 'October 2016'
__copyright__ = '(C) 2016, Nyall Dawson'
# This will get replaced with a git SHA1 when you do a git archive323
__revision__ = '$Format:%H$'
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 ExtendLines(GeoAlgorithm):
INPUT_LAYER = 'INPUT_LAYER'
OUTPUT_LAYER = 'OUTPUT_LAYER'
START_DISTANCE = 'START_DISTANCE'
END_DISTANCE = 'END_DISTANCE'
def defineCharacteristics(self):
self.name, self.i18n_name = self.trAlgorithm('Extend lines')
self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')
self.addParameter(ParameterVector(self.INPUT_LAYER,
self.tr('Input layer'), [dataobjects.TYPE_VECTOR_LINE]))
self.addParameter(ParameterNumber(self.START_DISTANCE,
self.tr('Start distance'), default=0.0))
self.addParameter(ParameterNumber(self.END_DISTANCE,
self.tr('End distance'), default=0.0))
self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Extended lines')))
def processAlgorithm(self, progress):
layer = dataobjects.getObjectFromUri(
self.getParameterValue(self.INPUT_LAYER))
writer = self.getOutputFromName(
self.OUTPUT_LAYER).getVectorWriter(
layer.fields(),
layer.wkbType(),
layer.crs())
start_distance = self.getParameterValue(self.START_DISTANCE)
end_distance = self.getParameterValue(self.END_DISTANCE)
features = vector.features(layer)
total = 100.0 / len(features)
for current, input_feature in enumerate(features):
output_feature = input_feature
input_geometry = input_feature.geometry()
if input_geometry:
output_geometry = input_geometry.extendLine(start_distance, end_distance)
if not output_geometry:
raise GeoAlgorithmExecutionException(
self.tr('Error calculating extended line'))
output_feature.setGeometry(output_geometry)
writer.addFeature(output_feature)
progress.setPercentage(int(current * total))
del writer