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

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

"""
***************************************************************************
    PointsFromLines.py
    ---------------------
    Date                 : August 2013
    Copyright            : (C) 2013 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.                                   *
*                                                                         *
***************************************************************************
"""
from builtins import str
from builtins import range

__author__ = 'Alexander Bruy'
__date__ = 'August 2013'
__copyright__ = '(C) 2013, Alexander Bruy'

# This will get replaced with a git SHA1 when you do a git archive

__revision__ = '$Format:%H$'

from osgeo import gdal
from qgis.PyQt.QtCore import QVariant
from qgis.core import (QgsApplication,
                       QgsFeature,
                       QgsFields,
                       QgsField,
                       QgsGeometry,
                       QgsPoint,
                       QgsWkbTypes,
                       QgsProcessingUtils)
from processing.tools import vector, raster, dataobjects
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.parameters import ParameterRaster
from processing.core.parameters import ParameterVector
from processing.core.outputs import OutputVector


class PointsFromLines(GeoAlgorithm):

    INPUT_RASTER = 'INPUT_RASTER'
    RASTER_BAND = 'RASTER_BAND'
    INPUT_VECTOR = 'INPUT_VECTOR'
    OUTPUT_LAYER = 'OUTPUT_LAYER'

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

    def svgIconPath(self):
        return QgsApplication.iconPath("providerQgis.svg")

    def group(self):
        return self.tr('Vector analysis tools')

    def name(self):
        return 'generatepointspixelcentroidsalongline'

    def displayName(self):
        return self.tr('Generate points (pixel centroids) along line')

    def defineCharacteristics(self):
        self.addParameter(ParameterRaster(self.INPUT_RASTER,
                                          self.tr('Raster layer')))
        self.addParameter(ParameterVector(self.INPUT_VECTOR,
                                          self.tr('Vector layer'), [dataobjects.TYPE_VECTOR_LINE]))
        self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Points along line'), datatype=[dataobjects.TYPE_VECTOR_POINT]))

    def processAlgorithm(self, context, feedback):
        layer = QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_VECTOR), context)

        rasterPath = str(self.getParameterValue(self.INPUT_RASTER))

        rasterDS = gdal.Open(rasterPath, gdal.GA_ReadOnly)
        geoTransform = rasterDS.GetGeoTransform()
        rasterDS = None

        fields = QgsFields()
        fields.append(QgsField('id', QVariant.Int, '', 10, 0))
        fields.append(QgsField('line_id', QVariant.Int, '', 10, 0))
        fields.append(QgsField('point_id', QVariant.Int, '', 10, 0))

        writer = self.getOutputFromName(self.OUTPUT_LAYER).getVectorWriter(fields.toList(), QgsWkbTypes.Point,
                                                                           layer.crs(), context)

        outFeature = QgsFeature()
        outFeature.setFields(fields)

        self.fid = 0
        self.lineId = 0
        self.pointId = 0

        features = QgsProcessingUtils.getFeatures(layer, context)
        total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
        for current, f in enumerate(features):
            geom = f.geometry()
            if geom.isMultipart():
                lines = geom.asMultiPolyline()
                for line in lines:
                    for i in range(len(line) - 1):
                        p1 = line[i]
                        p2 = line[i + 1]

                        (x1, y1) = raster.mapToPixel(p1.x(), p1.y(),
                                                     geoTransform)
                        (x2, y2) = raster.mapToPixel(p2.x(), p2.y(),
                                                     geoTransform)

                        self.buildLine(x1, y1, x2, y2, geoTransform,
                                       writer, outFeature)
            else:
                points = geom.asPolyline()
                for i in range(len(points) - 1):
                    p1 = points[i]
                    p2 = points[i + 1]

                    (x1, y1) = raster.mapToPixel(p1.x(), p1.y(), geoTransform)
                    (x2, y2) = raster.mapToPixel(p2.x(), p2.y(), geoTransform)

                    self.buildLine(x1, y1, x2, y2, geoTransform, writer,
                                   outFeature)

            self.pointId = 0
            self.lineId += 1

            feedback.setProgress(int(current * total))

        del writer

    def buildLine(self, startX, startY, endX, endY, geoTransform, writer, feature):
        if startX == endX:
            if startY > endY:
                (startY, endY) = (endY, startY)
            row = startX
            for col in range(startY, endY + 1):
                self.createPoint(row, col, geoTransform, writer, feature)
        elif startY == endY:
            if startX > endX:
                (startX, endX) = (endX, startX)
            col = startY
            for row in range(startX, endX + 1):
                self.createPoint(row, col, geoTransform, writer, feature)
        else:
            width = endX - startX
            height = endY - startY

            if width < 0:
                dx1 = -1
                dx2 = -1
            else:
                dx1 = 1
                dx2 = 1

            if height < 0:
                dy1 = -1
            else:
                dy1 = 1
            dy2 = 0

            longest = abs(width)
            shortest = abs(height)
            if not longest > shortest:
                (longest, shortest) = (shortest, longest)
                if height < 0:
                    dy2 = -1
                else:
                    dy2 = 1
                dx2 = 0

            err = longest / 2
            for i in range(longest + 1):
                self.createPoint(startX, startY, geoTransform, writer, feature)

                err += shortest
                if not err < longest:
                    err = err - longest
                    startX += dx1
                    startY += dy1
                else:
                    startX += dx2
                    startY += dy2

    def createPoint(self, pX, pY, geoTransform, writer, feature):
        (x, y) = raster.pixelToMap(pX, pY, geoTransform)

        feature.setGeometry(QgsGeometry.fromPoint(QgsPoint(x, y)))
        feature['id'] = self.fid
        feature['line_id'] = self.lineId
        feature['point_id'] = self.pointId

        self.fid += 1
        self.pointId += 1

        writer.addFeature(feature)