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

"""
***************************************************************************
    RandomPointsLayer.py
    ---------------------
    Date                 : April 2014
    Copyright            : (C) 2014 by Alexander Bruy
    Email                : alexander dot bruy 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__ = "Alexander Bruy"
__date__ = "April 2014"
__copyright__ = "(C) 2014, Alexander Bruy"

import os
import random

from qgis.PyQt.QtGui import QIcon
from qgis.PyQt.QtCore import QMetaType
from qgis.core import (
    Qgis,
    QgsApplication,
    QgsField,
    QgsFeatureSink,
    QgsFeature,
    QgsFields,
    QgsGeometry,
    QgsPointXY,
    QgsWkbTypes,
    QgsSpatialIndex,
    QgsFeatureRequest,
    QgsProcessing,
    QgsProcessingException,
    QgsProcessingParameterNumber,
    QgsProcessingParameterDistance,
    QgsProcessingParameterFeatureSource,
    QgsProcessingParameterFeatureSink,
    QgsProcessingParameterDefinition,
)

from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
from processing.tools import vector

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


class RandomPointsLayer(QgisAlgorithm):
    INPUT = "INPUT"
    POINTS_NUMBER = "POINTS_NUMBER"
    MIN_DISTANCE = "MIN_DISTANCE"
    OUTPUT = "OUTPUT"

    def icon(self):
        return QgsApplication.getThemeIcon(
            "/algorithms/mAlgorithmRandomPointsWithinExtent.svg"
        )

    def svgIconPath(self):
        return QgsApplication.iconPath(
            "/algorithms/mAlgorithmRandomPointsWithinExtent.svg"
        )

    def group(self):
        return self.tr("Vector creation")

    def groupId(self):
        return "vectorcreation"

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

    def initAlgorithm(self, config=None):
        self.addParameter(
            QgsProcessingParameterFeatureSource(
                self.INPUT,
                self.tr("Input layer"),
                [QgsProcessing.SourceType.TypeVectorPolygon],
            )
        )
        self.addParameter(
            QgsProcessingParameterNumber(
                self.POINTS_NUMBER,
                self.tr("Number of points"),
                QgsProcessingParameterNumber.Type.Integer,
                1,
                False,
                1,
                1000000000,
            )
        )
        self.addParameter(
            QgsProcessingParameterDistance(
                self.MIN_DISTANCE,
                self.tr("Minimum distance between points"),
                0,
                self.INPUT,
                False,
                0,
                1000000000,
            )
        )
        self.addParameter(
            QgsProcessingParameterFeatureSink(
                self.OUTPUT,
                self.tr("Random points"),
                type=QgsProcessing.SourceType.TypeVectorPoint,
            )
        )

    def name(self):
        return "randompointsinlayerbounds"

    def displayName(self):
        return self.tr("Random points in layer bounds")

    def documentationFlags(self):
        return Qgis.ProcessingAlgorithmDocumentationFlag.RegeneratesPrimaryKey

    def processAlgorithm(self, parameters, context, feedback):
        source = self.parameterAsSource(parameters, self.INPUT, context)
        if source is None:
            raise QgsProcessingException(
                self.invalidSourceError(parameters, self.INPUT)
            )

        pointCount = self.parameterAsDouble(parameters, self.POINTS_NUMBER, context)
        minDistance = self.parameterAsDouble(parameters, self.MIN_DISTANCE, context)

        bbox = source.sourceExtent()
        sourceIndex = QgsSpatialIndex(source, feedback)

        fields = QgsFields()
        fields.append(QgsField("id", QMetaType.Type.Int, "", 10, 0))

        (sink, dest_id) = self.parameterAsSink(
            parameters,
            self.OUTPUT,
            context,
            fields,
            QgsWkbTypes.Type.Point,
            source.sourceCrs(),
            QgsFeatureSink.SinkFlag.RegeneratePrimaryKey,
        )
        if sink is None:
            raise QgsProcessingException(self.invalidSinkError(parameters, self.OUTPUT))

        nPoints = 0
        nIterations = 0
        maxIterations = pointCount * 200
        total = 100.0 / pointCount if pointCount else 1

        index = QgsSpatialIndex()
        points = {}

        random.seed()

        while nIterations < maxIterations and nPoints < pointCount:
            if feedback.isCanceled():
                break

            rx = bbox.xMinimum() + bbox.width() * random.random()
            ry = bbox.yMinimum() + bbox.height() * random.random()

            p = QgsPointXY(rx, ry)
            geom = QgsGeometry.fromPointXY(p)
            ids = sourceIndex.intersects(geom.buffer(5, 5).boundingBox())
            if len(ids) > 0 and vector.checkMinDistance(p, index, minDistance, points):
                request = (
                    QgsFeatureRequest().setFilterFids(ids).setSubsetOfAttributes([])
                )
                for f in source.getFeatures(request):
                    if feedback.isCanceled():
                        break

                    tmpGeom = f.geometry()
                    if geom.within(tmpGeom):
                        f = QgsFeature(nPoints)
                        f.initAttributes(1)
                        f.setFields(fields)
                        f.setAttribute("id", nPoints)
                        f.setGeometry(geom)
                        sink.addFeature(f, QgsFeatureSink.Flag.FastInsert)
                        index.addFeature(f)
                        points[nPoints] = p
                        nPoints += 1
                        feedback.setProgress(int(nPoints * total))
            nIterations += 1

        if nPoints < pointCount:
            feedback.pushInfo(
                self.tr(
                    "Could not generate requested number of random points. "
                    "Maximum number of attempts exceeded."
                )
            )

        sink.finalize()
        return {self.OUTPUT: dest_id}