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PointsFromLines.py
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PointsFromLines.py
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# -*- 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. *
* *
***************************************************************************
"""
__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 (QgsFeature,
QgsFeatureSink,
QgsFields,
QgsField,
QgsGeometry,
QgsPointXY,
QgsWkbTypes,
QgsProcessing,
QgsFeatureRequest,
QgsProcessingParameterRasterLayer,
QgsProcessingParameterFeatureSource,
QgsProcessingParameterFeatureSink)
from processing.tools import raster
from processing.algs.qgis.QgisAlgorithm import QgisAlgorithm
from processing.tools.dataobjects import exportRasterLayer
class PointsFromLines(QgisAlgorithm):
INPUT_RASTER = 'INPUT_RASTER'
RASTER_BAND = 'RASTER_BAND'
INPUT_VECTOR = 'INPUT_VECTOR'
OUTPUT = 'OUTPUT'
def group(self):
return self.tr('Vector creation')
def __init__(self):
super().__init__()
def initAlgorithm(self, config=None):
self.addParameter(QgsProcessingParameterRasterLayer(self.INPUT_RASTER,
self.tr('Raster layer')))
self.addParameter(QgsProcessingParameterFeatureSource(self.INPUT_VECTOR,
self.tr('Vector layer'), [QgsProcessing.TypeVectorLine]))
self.addParameter(QgsProcessingParameterFeatureSink(self.OUTPUT, self.tr('Points from polygons'), QgsProcessing.TypeVectorPoint))
def name(self):
return 'generatepointspixelcentroidsalongline'
def displayName(self):
return self.tr('Generate points (pixel centroids) along line')
def processAlgorithm(self, parameters, context, feedback):
source = self.parameterAsSource(parameters, self.INPUT_VECTOR, context)
raster_layer = self.parameterAsRasterLayer(parameters, self.INPUT_RASTER, context)
rasterPath = exportRasterLayer(raster_layer)
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))
(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
fields, QgsWkbTypes.Point, raster_layer.crs())
outFeature = QgsFeature()
outFeature.setFields(fields)
self.fid = 0
self.lineId = 0
self.pointId = 0
features = source.getFeatures(QgsFeatureRequest().setDestinationCrs(raster_layer.crs()))
total = 100.0 / source.featureCount() if source.featureCount() else 0
for current, f in enumerate(features):
if feedback.isCanceled():
break
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,
sink, 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, sink,
outFeature)
self.pointId = 0
self.lineId += 1
feedback.setProgress(int(current * total))
return {self.OUTPUT: dest_id}
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.fromPointXY(QgsPointXY(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, QgsFeatureSink.FastInsert)