mirror of
https://github.com/qgis/QGIS.git
synced 2025-02-27 00:33:48 -05:00
116 lines
4.8 KiB
Python
116 lines
4.8 KiB
Python
# -*- coding: utf-8 -*-
|
|
|
|
"""
|
|
***************************************************************************
|
|
__init__.py
|
|
---------------------
|
|
Date : July 2013
|
|
Copyright : (C) 2013 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__ = 'July 2013'
|
|
__copyright__ = '(C) 2013, Victor Olaya'
|
|
# This will get replaced with a git SHA1 when you do a git archive
|
|
__revision__ = '$Format:%H$'
|
|
|
|
|
|
from PyQt4.QtCore import *
|
|
from PyQt4.QtGui import *
|
|
|
|
from qgis.core import *
|
|
|
|
from processing.core.Processing import Processing
|
|
from processing.core.GeoAlgorithm import GeoAlgorithm
|
|
from processing.core.QGisLayers import QGisLayers
|
|
|
|
from processing.parameters.ParameterVector import ParameterVector
|
|
|
|
from processing.outputs.OutputVector import OutputVector
|
|
|
|
|
|
class ExampleAlgorithm(GeoAlgorithm):
|
|
'''This is an example algorithm that takes a vector layer and creates
|
|
a new one just with just those features of the input layer that are
|
|
selected.
|
|
|
|
It is meant to be used as an example of how to create your own
|
|
algorithms and explain methods and variables used to do it. An algorithm
|
|
like this will be available in all elements, and there is not need
|
|
for additional work.
|
|
|
|
All processing algorithms should extend the GeoAlgorithm class.
|
|
'''
|
|
|
|
# constants used to refer to parameters and outputs.
|
|
# They will be used when calling the algorithm from another algorithm,
|
|
# or when calling from the QGIS console.
|
|
OUTPUT_LAYER = "OUTPUT_LAYER"
|
|
INPUT_LAYER = "INPUT_LAYER"
|
|
|
|
def defineCharacteristics(self):
|
|
'''Here we define the inputs and output of the algorithm, along
|
|
with some other properties
|
|
'''
|
|
|
|
# the name that the user will see in the toolbox
|
|
self.name = "Create copy of layer"
|
|
|
|
# the branch of the toolbox under which the algorithm will appear
|
|
self.group = "Algorithms for vector layers"
|
|
|
|
# we add the input vector layer. It can have any kind of geometry
|
|
# It is a mandatory (not optional) one, hence the False argument
|
|
self.addParameter(ParameterVector(self.INPUT_LAYER, "Input layer", [ParameterVector.VECTOR_TYPE_ANY], False))
|
|
|
|
# we add a vector layer as output
|
|
self.addOutput(OutputVector(self.OUTPUT_LAYER, "Output layer with selected features"))
|
|
|
|
def processAlgorithm(self, progress):
|
|
'''Here is where the processing itself takes place'''
|
|
|
|
# the first thing to do is retrieve the values of the parameters
|
|
# entered by the user
|
|
inputFilename = self.getParameterValue(self.INPUT_LAYER)
|
|
output = self.getOutputValue(self.OUTPUT_LAYER)
|
|
|
|
# input layers vales are always a string with its location.
|
|
# That string can be converted into a QGIS object (a QgsVectorLayer in
|
|
# this case) using the Processing.getObjectFromUri() method.
|
|
vectorLayer = QGisLayers.getObjectFromUri(inputFilename)
|
|
|
|
# And now we can process
|
|
|
|
# First we create the output layer. The output value entered by the user
|
|
# is a string containing a filename, so we can use it directly
|
|
settings = QSettings()
|
|
systemEncoding = settings.value( "/UI/encoding", "System" )
|
|
provider = vectorLayer.dataProvider()
|
|
writer = QgsVectorFileWriter(output,
|
|
systemEncoding,
|
|
provider.fields(),
|
|
provider.geometryType(),
|
|
provider.crs()
|
|
)
|
|
|
|
# Now we take the features from input layer and add them to the output.
|
|
# Method features() returns an iterator, considering the selection that
|
|
# might exist in layer and the configuration that indicates
|
|
# should algorithm use only selected features or all of them
|
|
features = QGisLayers.features(vectorLayer)
|
|
for f in features:
|
|
writer.addFeature(f)
|
|
|
|
# There is nothing more to do here. We do not have to open the layer
|
|
# that we have created. The framework will take care of that, or will handle
|
|
# it if this algorithm is executed within a complex model
|