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

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

"""
***************************************************************************
    Delaunay.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 builtins import next

__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__ = '$Format:%H$'

import os

from qgis.PyQt.QtGui import QIcon
from qgis.PyQt.QtCore import QVariant

from qgis.core import (QgsField,
                       QgsFeatureRequest,
                       QgsFeatureSink,
                       QgsFeature,
                       QgsGeometry,
                       QgsPointXY,
                       QgsWkbTypes,
                       QgsProcessing,
                       QgsFields,
                       QgsProcessingException,
                       QgsProcessingParameterFeatureSource,
                       QgsProcessingParameterFeatureSink)

from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm

from . import voronoi

pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]


class Delaunay(QgisAlgorithm):

    INPUT = 'INPUT'
    OUTPUT = 'OUTPUT'

    def icon(self):
        return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'delaunay.png'))

    def group(self):
        return self.tr('Vector geometry')

    def __init__(self):
        super().__init__()

    def initAlgorithm(self, config=None):
        self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT, self.tr('Input layer'), [QgsProcessing.TypeVectorPoint]))
        self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Delaunay triangulation'), type=QgsProcessing.TypeVectorPolygon))

    def name(self):
        return 'delaunaytriangulation'

    def displayName(self):
        return self.tr('Delaunay triangulation')

    def processAlgorithm(self, parameters, context, feedback):
        source = self.parameterAsSource(parameters, self.INPUT, context)

        fields = QgsFields()
        fields.append(QgsField('POINTA', QVariant.Double, '', 24, 15))
        fields.append(QgsField('POINTB', QVariant.Double, '', 24, 15))
        fields.append(QgsField('POINTC', QVariant.Double, '', 24, 15))

        (sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
                                               fields, QgsWkbTypes.Polygon, source.sourceCrs())

        pts = []
        ptDict = {}
        ptNdx = -1
        c = voronoi.Context()
        features = source.getFeatures()
        total = 100.0 / source.featureCount() if source.featureCount() else 0
        for current, inFeat in enumerate(features):
            if feedback.isCanceled():
                break

            geom = QgsGeometry(inFeat.geometry())
            if geom.isNull():
                continue
            if geom.isMultipart():
                points = geom.asMultiPoint()
            else:
                points = [geom.asPoint()]
            for n, point in enumerate(points):
                x = point.x()
                y = point.y()
                pts.append((x, y))
                ptNdx += 1
                ptDict[ptNdx] = (inFeat.id(), n)
            feedback.setProgress(int(current * total))

        if len(pts) < 3:
            raise QgsProcessingException(
                self.tr('Input file should contain at least 3 points. Choose '
                        'another file and try again.'))

        uniqueSet = set(item for item in pts)
        ids = [pts.index(item) for item in uniqueSet]
        sl = voronoi.SiteList([voronoi.Site(*i) for i in uniqueSet])
        c.triangulate = True
        voronoi.voronoi(sl, c)
        triangles = c.triangles
        feat = QgsFeature()

        total = 100.0 / len(triangles) if triangles else 1
        for current, triangle in enumerate(triangles):
            if feedback.isCanceled():
                break

            indices = list(triangle)
            indices.append(indices[0])
            polygon = []
            attrs = []
            step = 0
            for index in indices:
                fid, n = ptDict[ids[index]]
                request = QgsFeatureRequest().setFilterFid(fid)
                inFeat = next(source.getFeatures(request))
                geom = QgsGeometry(inFeat.geometry())
                if geom.isMultipart():
                    point = QgsPointXY(geom.asMultiPoint()[n])
                else:
                    point = QgsPointXY(geom.asPoint())
                polygon.append(point)
                if step <= 3:
                    attrs.append(ids[index])
                step += 1
            feat.setAttributes(attrs)
            geometry = QgsGeometry().fromPolygon([polygon])
            feat.setGeometry(geometry)
            sink.addFeature(feat, QgsFeatureSink.FastInsert)
            feedback.setProgress(int(current * total))

        return {self.OUTPUT: dest_id}