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Algorithms and other processing code should use this method (instead of dataobjects.getLayerFromString) to retrieve layers from a string, as it considers the processing context and allows resolving strings to temporarily stored layers. This permits processing models to function correctly when intermediate results are stored as memory layers. Subsequent model algorithms can then access these temporary layers as inputs. All temporary layers will be removed when the context object is destroyed after the model algorithm is run.
202 lines
7.1 KiB
Python
202 lines
7.1 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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PointsFromLines.py
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---------------------
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Date : August 2013
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Copyright : (C) 2013 by Alexander Bruy
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Email : alexander dot bruy at gmail dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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from builtins import str
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from builtins import range
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__author__ = 'Alexander Bruy'
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__date__ = 'August 2013'
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__copyright__ = '(C) 2013, Alexander Bruy'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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from osgeo import gdal
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from qgis.PyQt.QtCore import QVariant
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from qgis.core import (QgsApplication,
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QgsFeature,
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QgsFields,
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QgsField,
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QgsGeometry,
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QgsPoint,
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QgsWkbTypes,
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QgsProcessingUtils)
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from processing.tools import vector, raster, dataobjects
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.parameters import ParameterRaster
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from processing.core.parameters import ParameterVector
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from processing.core.outputs import OutputVector
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class PointsFromLines(GeoAlgorithm):
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INPUT_RASTER = 'INPUT_RASTER'
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RASTER_BAND = 'RASTER_BAND'
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INPUT_VECTOR = 'INPUT_VECTOR'
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OUTPUT_LAYER = 'OUTPUT_LAYER'
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def icon(self):
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return QgsApplication.getThemeIcon("/providerQgis.svg")
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def svgIconPath(self):
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return QgsApplication.iconPath("providerQgis.svg")
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def group(self):
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return self.tr('Vector analysis tools')
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def name(self):
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return 'generatepointspixelcentroidsalongline'
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def displayName(self):
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return self.tr('Generate points (pixel centroids) along line')
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def defineCharacteristics(self):
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self.addParameter(ParameterRaster(self.INPUT_RASTER,
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self.tr('Raster layer')))
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self.addParameter(ParameterVector(self.INPUT_VECTOR,
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self.tr('Vector layer'), [dataobjects.TYPE_VECTOR_LINE]))
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self.addOutput(OutputVector(self.OUTPUT_LAYER, self.tr('Points along line'), datatype=[dataobjects.TYPE_VECTOR_POINT]))
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def processAlgorithm(self, context, feedback):
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layer = dataobjects.QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_VECTOR), context)
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rasterPath = str(self.getParameterValue(self.INPUT_RASTER))
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rasterDS = gdal.Open(rasterPath, gdal.GA_ReadOnly)
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geoTransform = rasterDS.GetGeoTransform()
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rasterDS = None
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fields = QgsFields()
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fields.append(QgsField('id', QVariant.Int, '', 10, 0))
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fields.append(QgsField('line_id', QVariant.Int, '', 10, 0))
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fields.append(QgsField('point_id', QVariant.Int, '', 10, 0))
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writer = self.getOutputFromName(self.OUTPUT_LAYER).getVectorWriter(fields.toList(), QgsWkbTypes.Point,
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layer.crs(), context)
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outFeature = QgsFeature()
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outFeature.setFields(fields)
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self.fid = 0
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self.lineId = 0
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self.pointId = 0
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features = QgsProcessingUtils.getFeatures(layer, context)
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total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
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for current, f in enumerate(features):
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geom = f.geometry()
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if geom.isMultipart():
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lines = geom.asMultiPolyline()
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for line in lines:
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for i in range(len(line) - 1):
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p1 = line[i]
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p2 = line[i + 1]
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(x1, y1) = raster.mapToPixel(p1.x(), p1.y(),
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geoTransform)
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(x2, y2) = raster.mapToPixel(p2.x(), p2.y(),
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geoTransform)
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self.buildLine(x1, y1, x2, y2, geoTransform,
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writer, outFeature)
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else:
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points = geom.asPolyline()
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for i in range(len(points) - 1):
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p1 = points[i]
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p2 = points[i + 1]
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(x1, y1) = raster.mapToPixel(p1.x(), p1.y(), geoTransform)
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(x2, y2) = raster.mapToPixel(p2.x(), p2.y(), geoTransform)
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self.buildLine(x1, y1, x2, y2, geoTransform, writer,
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outFeature)
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self.pointId = 0
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self.lineId += 1
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feedback.setProgress(int(current * total))
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del writer
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def buildLine(self, startX, startY, endX, endY, geoTransform, writer, feature):
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if startX == endX:
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if startY > endY:
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(startY, endY) = (endY, startY)
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row = startX
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for col in range(startY, endY + 1):
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self.createPoint(row, col, geoTransform, writer, feature)
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elif startY == endY:
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if startX > endX:
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(startX, endX) = (endX, startX)
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col = startY
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for row in range(startX, endX + 1):
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self.createPoint(row, col, geoTransform, writer, feature)
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else:
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width = endX - startX
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height = endY - startY
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if width < 0:
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dx1 = -1
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dx2 = -1
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else:
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dx1 = 1
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dx2 = 1
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if height < 0:
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dy1 = -1
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else:
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dy1 = 1
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dy2 = 0
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longest = abs(width)
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shortest = abs(height)
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if not longest > shortest:
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(longest, shortest) = (shortest, longest)
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if height < 0:
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dy2 = -1
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else:
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dy2 = 1
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dx2 = 0
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err = longest / 2
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for i in range(longest + 1):
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self.createPoint(startX, startY, geoTransform, writer, feature)
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err += shortest
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if not err < longest:
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err = err - longest
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startX += dx1
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startY += dy1
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else:
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startX += dx2
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startY += dy2
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def createPoint(self, pX, pY, geoTransform, writer, feature):
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(x, y) = raster.pixelToMap(pX, pY, geoTransform)
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feature.setGeometry(QgsGeometry.fromPoint(QgsPoint(x, y)))
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feature['id'] = self.fid
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feature['line_id'] = self.lineId
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feature['point_id'] = self.pointId
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self.fid += 1
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self.pointId += 1
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writer.addFeature(feature)
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