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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.
154 lines
6.2 KiB
Python
154 lines
6.2 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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Clip.py
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---------------------
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Date : August 2012
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Copyright : (C) 2012 by Victor Olaya
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Email : volayaf 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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__author__ = 'Victor Olaya'
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__date__ = 'August 2012'
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__copyright__ = '(C) 2012, Victor Olaya'
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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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import os
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from qgis.PyQt.QtGui import QIcon
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from qgis.core import (QgsFeature,
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QgsGeometry,
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QgsFeatureRequest,
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QgsWkbTypes,
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QgsMessageLog,
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QgsProcessingUtils)
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from processing.core.GeoAlgorithm import GeoAlgorithm
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from processing.core.parameters import ParameterVector
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from processing.core.outputs import OutputVector
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from processing.tools import dataobjects, vector
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pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
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class Clip(GeoAlgorithm):
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INPUT = 'INPUT'
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OVERLAY = 'OVERLAY'
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OUTPUT = 'OUTPUT'
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def icon(self):
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return QIcon(os.path.join(pluginPath, 'images', 'ftools', 'clip.png'))
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def group(self):
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return self.tr('Vector overlay tools')
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def name(self):
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return 'clip'
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def displayName(self):
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return self.tr('Clip')
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def defineCharacteristics(self):
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self.addParameter(ParameterVector(Clip.INPUT,
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self.tr('Input layer')))
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self.addParameter(ParameterVector(Clip.OVERLAY,
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self.tr('Clip layer'), [dataobjects.TYPE_VECTOR_POLYGON]))
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self.addOutput(OutputVector(Clip.OUTPUT, self.tr('Clipped')))
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def processAlgorithm(self, context, feedback):
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source_layer = dataobjects.QgsProcessingUtils.mapLayerFromString(self.getParameterValue(Clip.INPUT), context)
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mask_layer = dataobjects.QgsProcessingUtils.mapLayerFromString(self.getParameterValue(Clip.OVERLAY), context)
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writer = self.getOutputFromName(self.OUTPUT).getVectorWriter(source_layer.fields(),
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QgsWkbTypes.multiType(source_layer.wkbType()),
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source_layer.crs(), context)
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# first build up a list of clip geometries
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clip_geoms = []
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for maskFeat in QgsProcessingUtils.getFeatures(mask_layer, context, QgsFeatureRequest().setSubsetOfAttributes([])):
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clip_geoms.append(maskFeat.geometry())
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# are we clipping against a single feature? if so, we can show finer progress reports
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if len(clip_geoms) > 1:
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combined_clip_geom = QgsGeometry.unaryUnion(clip_geoms)
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single_clip_feature = False
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else:
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combined_clip_geom = clip_geoms[0]
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single_clip_feature = True
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# use prepared geometries for faster intersection tests
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engine = QgsGeometry.createGeometryEngine(combined_clip_geom.geometry())
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engine.prepareGeometry()
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tested_feature_ids = set()
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for i, clip_geom in enumerate(clip_geoms):
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input_features = [f for f in QgsProcessingUtils.getFeatures(source_layer, context,
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QgsFeatureRequest().setFilterRect(clip_geom.boundingBox()))]
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if not input_features:
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continue
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if single_clip_feature:
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total = 100.0 / len(input_features)
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else:
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total = 0
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for current, in_feat in enumerate(input_features):
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if not in_feat.geometry():
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continue
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if in_feat.id() in tested_feature_ids:
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# don't retest a feature we have already checked
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continue
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tested_feature_ids.add(in_feat.id())
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if not engine.intersects(in_feat.geometry().geometry()):
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continue
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if not engine.contains(in_feat.geometry().geometry()):
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cur_geom = in_feat.geometry()
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new_geom = combined_clip_geom.intersection(cur_geom)
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if new_geom.wkbType() == QgsWkbTypes.Unknown or QgsWkbTypes.flatType(new_geom.geometry().wkbType()) == QgsWkbTypes.GeometryCollection:
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int_com = in_feat.geometry().combine(new_geom)
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int_sym = in_feat.geometry().symDifference(new_geom)
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new_geom = int_com.difference(int_sym)
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else:
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# clip geometry totally contains feature geometry, so no need to perform intersection
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new_geom = in_feat.geometry()
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try:
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out_feat = QgsFeature()
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out_feat.setGeometry(new_geom)
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out_feat.setAttributes(in_feat.attributes())
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writer.addFeature(out_feat)
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except:
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QgsMessageLog.logMessage(self.tr('Feature geometry error: One or more '
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'output features ignored due to '
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'invalid geometry.'), self.tr('Processing'), QgsMessageLog.CRITICAL)
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continue
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if single_clip_feature:
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feedback.setProgress(int(current * total))
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if not single_clip_feature:
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# coarse progress report for multiple clip geometries
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feedback.setProgress(100.0 * i / len(clip_geoms))
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del writer
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