QGIS/python/plugins/processing/algs/qgis/SplitLinesWithLines.py

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

"""
***************************************************************************
    SplitLines.py
    ---------------------
    Date                 : November 2014
    Copyright            : (C) 2014 by Bernhard Ströbl
    Email                : bernhard dot stroebl at jena dot de
***************************************************************************
*                                                                         *
*   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__ = 'Bernhard Ströbl'
__date__ = 'November 2014'
__copyright__ = '(C) 2014, Bernhard Ströbl'

# 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.GeoAlgorithm import GeoAlgorithm
from processing.core.parameters import ParameterVector
from processing.core.outputs import OutputVector
from processing.core.ProcessingLog import ProcessingLog
from processing.tools import dataobjects
from processing.tools import vector


class SplitLinesWithLines(GeoAlgorithm):

    INPUT_A = 'INPUT_A'
    INPUT_B = 'INPUT_B'

    OUTPUT = 'OUTPUT'

    def defineCharacteristics(self):
        self.name = 'Split lines with lines'
        self.group = 'Vector overlay tools'
        self.addParameter(ParameterVector(self.INPUT_A, 'Input layer',
                          [ParameterVector.VECTOR_TYPE_LINE]))
        self.addParameter(ParameterVector(self.INPUT_B, 'Split layer',
                          [ParameterVector.VECTOR_TYPE_LINE]))

        self.addOutput(OutputVector(self.OUTPUT, 'Split lines'))

    def processAlgorithm(self, progress):
        layerA = dataobjects.getObjectFromUri(
                self.getParameterValue(self.INPUT_A))
        layerB = dataobjects.getObjectFromUri(
                self.getParameterValue(self.INPUT_B))

        fieldList = layerA.pendingFields()

        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(fieldList,
                QGis.WKBLineString, layerA.dataProvider().crs())

        spatialIndex = vector.spatialindex(layerB)

        inFeatA = QgsFeature()
        inFeatB = QgsFeature()
        outFeat = QgsFeature()
        inGeom = QgsGeometry()
        splitGeom = QgsGeometry()

        features = vector.features(layerA)
        current = 0
        total = 100.0 / float(len(features))

        for inFeatA in features:
            inGeom = inFeatA.geometry()
            attrsA = inFeatA.attributes()
            outFeat.setAttributes(attrsA)
            inLines = [inGeom]
            lines = spatialIndex.intersects(inGeom.boundingBox())

            if len(lines) > 0: #hasIntersections
                splittingLines = []

                for i in lines:
                    request = QgsFeatureRequest().setFilterFid(i)
                    inFeatB = layerB.getFeatures(request).next()
                    splitGeom = QgsGeometry(inFeatB.geometry())

                    if inGeom.intersects(splitGeom):
                        splittingLines.append(splitGeom)

                if len(splittingLines) > 0:
                    for splitGeom in splittingLines:
                        splitterPList = vector.extractPoints(splitGeom)
                        outLines = []

                        while len(inLines) > 0:
                            inGeom = inLines.pop()
                            inPoints = vector.extractPoints(inGeom)

                            if inGeom.intersects(splitGeom):
                                try:
                                    result, newGeometries, topoTestPoints = inGeom.splitGeometry(splitterPList, False)
                                except:
                                    ProcessingLog.addToLog(ProcessingLog.LOG_WARNING,
                                        'Geometry exception while splitting')
                                    result = 1

                                # splitGeometry: If there are several intersections
                                # between geometry and splitLine, only the first one is considered.
                                if result == 0: #split occured

                                    if inPoints == vector.extractPoints(inGeom):
                                        # bug in splitGeometry: sometimes it returns 0 but
                                        # the geometry is unchanged
                                        outLines.append(inGeom)
                                    else:
                                        inLines.append(inGeom)

                                        for aNewGeom in newGeometries:
                                           inLines.append(aNewGeom)
                                else:
                                    outLines.append(inGeom)
                            else:
                                outLines.append(inGeom)

                        inLines = outLines


            for aLine in inLines:
                outFeat.setGeometry(aLine)
                writer.addFeature(outFeat)

            current += 1
            progress.setPercentage(int(current * total))

        del writer