Nyall Dawson f84d703234 Add method QgsProcessingUtils::mapLayerFromString
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.
2017-05-02 12:33:04 +10:00

84 lines
3.3 KiB
Python

# -*- coding: utf-8 -*-
"""
***************************************************************************
DropGeometry.py
--------------
Date : November 2016
Copyright : (C) 2016 by Nyall Dawson
Email : nyall dot dawson 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__ = 'Nyall Dawson'
__date__ = 'November 2016'
__copyright__ = '(C) 2016, Nyall Dawson'
# This will get replaced with a git SHA1 when you do a git archive323
__revision__ = '$Format:%H$'
from qgis.core import (QgsFeatureRequest,
QgsWkbTypes,
QgsCoordinateReferenceSystem,
QgsApplication,
QgsProcessingUtils)
from processing.core.GeoAlgorithm import GeoAlgorithm
from processing.core.parameters import ParameterVector
from processing.core.outputs import OutputVector
from processing.tools import dataobjects, vector
class DropGeometry(GeoAlgorithm):
INPUT_LAYER = 'INPUT_LAYER'
OUTPUT_TABLE = 'OUTPUT_TABLE'
def icon(self):
return QgsApplication.getThemeIcon("/providerQgis.svg")
def svgIconPath(self):
return QgsApplication.iconPath("providerQgis.svg")
def tags(self):
return self.tr('remove,drop,delete,geometry,objects').split(',')
def group(self):
return self.tr('Vector general tools')
def name(self):
return 'dropgeometries'
def displayName(self):
return self.tr('Drop geometries')
def defineCharacteristics(self):
self.addParameter(ParameterVector(self.INPUT_LAYER,
self.tr('Input layer'), [dataobjects.TYPE_VECTOR_POINT,
dataobjects.TYPE_VECTOR_LINE,
dataobjects.TYPE_VECTOR_POLYGON]))
self.addOutput(OutputVector(self.OUTPUT_TABLE, self.tr('Dropped geometry')))
def processAlgorithm(self, context, feedback):
layer = dataobjects.QgsProcessingUtils.mapLayerFromString(self.getParameterValue(self.INPUT_LAYER), context)
writer = self.getOutputFromName(
self.OUTPUT_TABLE).getVectorWriter(layer.fields(), QgsWkbTypes.NoGeometry, QgsCoordinateReferenceSystem(),
context)
request = QgsFeatureRequest().setFlags(QgsFeatureRequest.NoGeometry)
features = QgsProcessingUtils.getFeatures(layer, context, request)
total = 100.0 / QgsProcessingUtils.featureCount(layer, context)
for current, input_feature in enumerate(features):
writer.addFeature(input_feature)
feedback.setProgress(int(current * total))
del writer