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.                                   *
*                                                                         *
***************************************************************************
"""

__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 qgis.core import QgsFeature, QgsGeometry
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.GeoAlgorithmExecutionException import GeoAlgorithmExecutionException
from processing.core.parameters import ParameterVector
from processing.core.parameters import ParameterBoolean
from processing.core.parameters import ParameterTableField
from processing.core.outputs import OutputVector
from processing.tools import vector, dataobjects


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 = dataobjects.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 = vlayerA.selectedFeatureCount()

        if nFeat == 0:
            nFeat = vlayerA.featureCount()

        if not useField:
            first = True
            features = vector.features(vlayerA)
            for inFeat in features:
                nElement += 1
                progress.setPercentage(int(nElement * 100/ nFeat))
                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(
                            self.tr('Geometry exception while dissolving'))
            outFeat.setAttributes(attrs)
            writer.addFeature(outFeat)
        else:
            unique = vector.getUniqueValues(vlayerA, int(field))
            nFeat = nFeat * len(unique)
            for item in unique:
                first = True
                add = True
                features = vector.features(vlayerA)
                for inFeat in features:
                    nElement += 1
                    progress.setPercentage(int(nElement * 100/ nFeat))
                    atMap = inFeat.attributes()
                    tempItem = atMap[field]
                    if unicode(tempItem).strip() == unicode(item).strip():
                        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(
                                    self.tr('Geometry exception while dissolving'))
                if add:
                    outFeat.setAttributes(attrs)
                    writer.addFeature(outFeat)
        del writer

    def defineCharacteristics(self):
        self.name, self.i18n_name = self.trAlgorithm('Dissolve')
        self.group, self.i18n_group = self.trAlgorithm('Vector geometry tools')
        self.addParameter(ParameterVector(Dissolve.INPUT,
            self.tr('Input layer'),
            [ParameterVector.VECTOR_TYPE_POLYGON, ParameterVector.VECTOR_TYPE_LINE]))
        self.addParameter(ParameterBoolean(Dissolve.DISSOLVE_ALL,
            self.tr('Dissolve all (do not use field)'), True))
        self.addParameter(ParameterTableField(Dissolve.FIELD,
            self.tr('Unique ID field'), Dissolve.INPUT, optional=True))
        self.addOutput(OutputVector(Dissolve.OUTPUT, self.tr('Dissolved')))