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Algorithms and other processing code should use this method (instead of dataobjects.getLayerFromString) to retrieve layers from a string, as it considers the processing context and allows resolving strings to temporarily stored layers. This permits processing models to function correctly when intermediate results are stored as memory layers. Subsequent model algorithms can then access these temporary layers as inputs. All temporary layers will be removed when the context object is destroyed after the model algorithm is run.
94 lines
3.3 KiB
Python
94 lines
3.3 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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CreateConstantRaster.py
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---------------------
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Date : August 2012
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Copyright : (C) 2012 by Victor Olaya
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Email : volayaf at gmail dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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__author__ = 'Victor Olaya'
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__date__ = 'August 2012'
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__copyright__ = '(C) 2012, Victor Olaya'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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from osgeo import gdal
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from qgis.core import (QgsApplication)
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.parameters import ParameterRaster
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from processing.core.parameters import ParameterNumber
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from processing.core.outputs import OutputRaster
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from processing.tools.raster import RasterWriter
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from processing.tools import dataobjects
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class CreateConstantRaster(GeoAlgorithm):
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INPUT = 'INPUT'
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OUTPUT = 'OUTPUT'
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NUMBER = 'NUMBER'
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def icon(self):
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return QgsApplication.getThemeIcon("/providerQgis.svg")
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def svgIconPath(self):
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return QgsApplication.iconPath("providerQgis.svg")
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def group(self):
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return self.tr('Raster tools')
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def name(self):
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return 'createconstantrasterlayer'
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def displayName(self):
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return self.tr('Create constant raster layer')
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def defineCharacteristics(self):
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self.addParameter(ParameterRaster(self.INPUT,
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self.tr('Reference layer')))
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self.addParameter(ParameterNumber(self.NUMBER,
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self.tr('Constant value'),
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default=1.0))
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self.addOutput(OutputRaster(self.OUTPUT,
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self.tr('Constant')))
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def processAlgorithm(self, context, feedback):
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layer = dataobjects.QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT), context)
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value = self.getParameterValue(self.NUMBER)
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output = self.getOutputFromName(self.OUTPUT)
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raster = gdal.Open(layer.source(), gdal.GA_ReadOnly)
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geoTransform = raster.GetGeoTransform()
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cellsize = (layer.extent().xMaximum() - layer.extent().xMinimum()) \
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/ layer.width()
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w = RasterWriter(output.getCompatibleFileName(self),
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layer.extent().xMinimum(),
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layer.extent().yMinimum(),
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layer.extent().xMaximum(),
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layer.extent().yMaximum(),
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cellsize,
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1,
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layer.crs(),
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geoTransform
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)
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w.matrix.fill(value)
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w.close()
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