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

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

"""
***************************************************************************
    Clip.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 PyQt4.QtCore import *
from qgis.core import *
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.ProcessingLog import ProcessingLog
from processing.core.parameters import ParameterVector
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector


class Clip(GeoAlgorithm):

    INPUT = 'INPUT'
    OVERLAY = 'OVERLAY'
    OUTPUT = 'OUTPUT'

    def defineCharacteristics(self):
        self.name = 'Clip'
        self.group = 'Vector overlay tools'
        self.addParameter(ParameterVector(Clip.INPUT, 'Input layer',
                          [ParameterVector.VECTOR_TYPE_ANY]))
        self.addParameter(ParameterVector(Clip.OVERLAY, 'Clip layer',
                          [ParameterVector.VECTOR_TYPE_ANY]))
        self.addOutput(OutputVector(Clip.OUTPUT, 'Clipped'))

    def processAlgorithm(self, progress):
        layerA = dataobjects.getObjectFromUri(
                self.getParameterValue(Clip.INPUT))
        layerB = dataobjects.getObjectFromUri(
                self.getParameterValue(Clip.OVERLAY))

        writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(
                layerA.pendingFields(),
                layerA.dataProvider().geometryType(),
                layerA.dataProvider().crs())

        inFeatA = QgsFeature()
        inFeatB = QgsFeature()
        outFeat = QgsFeature()

        index = vector.spatialindex(layerB)

        selectionA = vector.features(layerA)

        current = 0
        total = 100.0 / float(len(selectionA))

        for inFeatA in selectionA:
            geom = QgsGeometry(inFeatA.geometry())
            attrs = inFeatA.attributes()
            intersects = index.intersects(geom.boundingBox())
            first = True
            found = False
            if len(intersects) > 0:
                for i in intersects:
                    layerB.getFeatures(
                            QgsFeatureRequest().setFilterFid(i)).nextFeature(
                                    inFeatB)
                    tmpGeom = QgsGeometry(inFeatB.geometry())
                    if tmpGeom.intersects(geom):
                        found = True
                        if first:
                            outFeat.setGeometry(QgsGeometry(tmpGeom))
                            first = False
                        else:
                            try:
                                cur_geom = QgsGeometry(outFeat.geometry())
                                new_geom = QgsGeometry(
                                        cur_geom.combine(tmpGeom))
                                outFeat.setGeometry(QgsGeometry(new_geom))
                            except:
                                ProcessingLog.addToLog(ProcessingLog.LOG_ERROR,
                                        'GEOS geoprocessing error: One or \
                                        more input features have invalid \
                                        geometry.'
                                        )
                                break
                if found:
                    try:
                        cur_geom = QgsGeometry(outFeat.geometry())
                        new_geom = QgsGeometry(geom.intersection(cur_geom))
                        if new_geom.wkbType() == 0:
                            int_com = QgsGeometry(geom.combine(cur_geom))
                            int_sym = QgsGeometry(geom.symDifference(cur_geom))
                            new_geom = QgsGeometry(int_com.difference(int_sym))
                        try:
                            outFeat.setGeometry(new_geom)
                            outFeat.setAttributes(attrs)
                            writer.addFeature(outFeat)
                        except:
                            ProcessingLog.addToLog(ProcessingLog.LOG_ERROR,
                                    'Feature geometry error: One or more \
                                     output features ignored due to invalid \
                                     geometry.'
                                    )
                            continue
                    except:
                        ProcessingLog.addToLog(ProcessingLog.LOG_ERROR,
                                'GEOS geoprocessing error: One or more input \
                                features have invalid geometry.'
                                )
                        continue

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

        del writer