QGIS/python/plugins/sextante/algs/ftools/Dissolve.py

# -*- coding: utf-8 -*-

"""
***************************************************************************
    Dissolve.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.                                   *
*                                                                         *
***************************************************************************
"""
from sextante.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException

__author__ = 'Victor Olaya'
__date__ = 'August 2012'
__copyright__ = '(C) 2012, Victor Olaya'
# This will get replaced with a git SHA1 when you do a git archive
__revision__ = '$Format:%H$'

from sextante.core.GeoAlgorithm import GeoAlgorithm
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from qgis.core import *
from sextante.algs.ftools import FToolsUtils as utils
from sextante.parameters.ParameterVector import ParameterVector
from sextante.core.QGisLayers import QGisLayers
from sextante.outputs.OutputVector import OutputVector
from sextante.parameters.ParameterBoolean import ParameterBoolean
from sextante.parameters.ParameterTableField import ParameterTableField
from sextante.core.SextanteLog import SextanteLog

class Dissolve(GeoAlgorithm):

    INPUT = "INPUT"
    OUTPUT = "OUTPUT"
    FIELD = "FIELD"
    DISSOLVE_ALL = "DISSOLVE_ALL"

    #===========================================================================
    # def getIcon(self):
    #    return QtGui.QIcon(os.path.dirname(__file__) + "/icons/dissolve.png")
    #===========================================================================

    def processAlgorithm(self, progress):
        useField = not self.getParameterValue(Dissolve.DISSOLVE_ALL)
        fieldname = self.getParameterValue(Dissolve.FIELD)
        vlayerA = QGisLayers.getObjectFromUri(self.getParameterValue(Dissolve.INPUT))
        field = vlayerA.fieldNameIndex(fieldname)
        vproviderA = vlayerA.dataProvider()
        fields = vproviderA.fields()
        writer = self.getOutputFromName(Dissolve.OUTPUT).getVectorWriter(fields, vproviderA.geometryType(), vproviderA.crs() )
        outFeat = QgsFeature()
        nElement = 0
        nFeat = vproviderA.featureCount()
        if not useField:
            first = True
            features = QGisLayers.features(vlayerA)
            for inFeat in features:
                nElement += 1
                progress.setPercentage(int(nElement/nFeat * 100))
                if first:
                    attrs = inFeat.attributes()
                    tmpInGeom = QgsGeometry( inFeat.geometry() )
                    outFeat.setGeometry( tmpInGeom )
                    first = False
                else:
                    tmpInGeom = QgsGeometry( inFeat.geometry() )
                    tmpOutGeom = QgsGeometry( outFeat.geometry() )
                    try:
                        tmpOutGeom = QgsGeometry( tmpOutGeom.combine( tmpInGeom ) )
                        outFeat.setGeometry( tmpOutGeom )
                    except:
                        raise GeoAlgorithmExecutionException("Geometry exception while dissolving")                        
                    outFeat.setAttributes( attrs )
                    writer.addFeature( outFeat )
        else:
            unique = utils.getUniqueValues( vlayerA, int( field ) )
            nFeat = nFeat * len( unique )
            for item in unique:
                first = True
                add = True
                features = QGisLayers.features(vlayerA)
                for inFeat in features:
                    nElement += 1
                    progress.setPercentage(int(nElement/nFeat * 100))
                    atMap = inFeat.attributes()
                    tempItem = atMap[ field ]
                    if tempItem.toString().trimmed() == item.toString().trimmed():
                        if first:
                            QgsGeometry( inFeat.geometry() )
                            tmpInGeom = QgsGeometry( inFeat.geometry() )
                            outFeat.setGeometry( tmpInGeom )
                            first = False
                            attrs = inFeat.attributes()
                        else:                        
                            tmpInGeom = QgsGeometry( inFeat.geometry() )
                            tmpOutGeom = QgsGeometry( outFeat.geometry() )  
                            try:                      
                                tmpOutGeom = QgsGeometry( tmpOutGeom.combine( tmpInGeom ) )
                                outFeat.setGeometry( tmpOutGeom )
                            except:
                                raise GeoAlgorithmExecutionException("Geometry exception while dissolving")                                                       
                if add:
                    outFeat.setAttributes( attrs )
                    writer.addFeature( outFeat )
        del writer

    def defineCharacteristics(self):
        self.name = "Dissolve"
        self.group = "Vector geometry tools"
        self.addParameter(ParameterVector(Dissolve.INPUT, "Input layer", ParameterVector.VECTOR_TYPE_POLYGON))
        self.addParameter(ParameterBoolean(Dissolve.DISSOLVE_ALL, "Dissolve all (do not use field)", True))
        self.addParameter(ParameterTableField(Dissolve.FIELD, "Unique ID field",Dissolve.INPUT, optional=True ))
        self.addOutput(OutputVector(Dissolve.OUTPUT, "Dissolved"))

    #=========================================================