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[processing] Avoid confusing use of expression parameter type in

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Random Points in Polygon algorithm

Instead, use a standard numeric parameter which accepts data-defined
expression values

Fixes #27640
This commit is contained in:
Nyall Dawson 2019-09-30 11:05:45 +10:00
parent a49edf1f25
commit 196e15a0ff
1 changed files with 51 additions and 18 deletions
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69
python/plugins/processing/algs/qgis/RandomPointsPolygons.py
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@ -36,8 +36,12 @@ from qgis.core import (QgsApplication,
QgsSpatialIndex,
QgsExpression,
QgsDistanceArea,
QgsPropertyDefinition,
QgsProcessing,
QgsProcessingException,
QgsProcessingParameters,
QgsProcessingParameterDefinition,
QgsProcessingParameterNumber,
QgsProcessingParameterDistance,
QgsProcessingParameterFeatureSource,
QgsProcessingParameterFeatureSink,
@ -51,8 +55,8 @@ pluginPath = os.path.split(os.path.split(os.path.dirname(__file__))[0])[0]
class RandomPointsPolygons(QgisAlgorithm):
INPUT = 'INPUT'
VALUE = 'VALUE'
EXPRESSION = 'EXPRESSION'
MIN_DISTANCE = 'MIN_DISTANCE'
STRATEGY = 'STRATEGY'
@ -85,9 +89,24 @@ class RandomPointsPolygons(QgisAlgorithm):
self.strategies,
False,
0))
self.addParameter(QgsProcessingParameterExpression(self.EXPRESSION,
self.tr('Expression'),
parentLayerParameterName=self.INPUT))
value_param = QgsProcessingParameterNumber(self.VALUE,
self.tr('Point count or density'),
QgsProcessingParameterNumber.Double,
1,
minValue=0)
value_param.setIsDynamic(True)
value_param.setDynamicLayerParameterName(self.INPUT)
value_param.setDynamicPropertyDefinition(
QgsPropertyDefinition("Value", self.tr("Point count or density"), QgsPropertyDefinition.Double))
self.addParameter(value_param)
# deprecated expression parameter - overrides value parameter if set
exp_param = QgsProcessingParameterExpression(self.EXPRESSION,
self.tr('Expression'), optional=True,
parentLayerParameterName=self.INPUT)
exp_param.setFlags(exp_param.flags() | QgsProcessingParameterDefinition.FlagHidden)
self.addParameter(exp_param)
self.addParameter(QgsProcessingParameterDistance(self.MIN_DISTANCE,
self.tr('Minimum distance between points'),
None, self.INPUT, True, 0, 1000000000))
@ -112,18 +131,27 @@ class RandomPointsPolygons(QgisAlgorithm):
else:
minDistance = None
expression = QgsExpression(self.parameterAsString(parameters, self.EXPRESSION, context))
if expression.hasParserError():
raise QgsProcessingException(expression.parserErrorString())
expressionContext = self.createExpressionContext(parameters, context, source)
expression.prepare(expressionContext)
dynamic_value = QgsProcessingParameters.isDynamic(parameters, "VALUE")
value_property = None
if self.EXPRESSION in parameters and parameters[self.EXPRESSION] is not None:
expression = QgsExpression(self.parameterAsString(parameters, self.EXPRESSION, context))
value = None
if expression.hasParserError():
raise QgsProcessingException(expression.parserErrorString())
expression.prepare(expressionContext)
else:
expression = None
if dynamic_value:
value_property = parameters["VALUE"]
value = self.parameterAsDouble(parameters, self.VALUE, context)
fields = QgsFields()
fields.append(QgsField('id', QVariant.Int, '', 10, 0))
(sink, dest_id) = self.parameterAsSink(parameters, self.OUTPUT, context,
fields, QgsWkbTypes.Point, source.sourceCrs(), QgsFeatureSink.RegeneratePrimaryKey)
fields, QgsWkbTypes.Point, source.sourceCrs(),
QgsFeatureSink.RegeneratePrimaryKey)
if sink is None:
raise QgsProcessingException(self.invalidSinkError(parameters, self.OUTPUT))
@ -144,12 +172,17 @@ class RandomPointsPolygons(QgisAlgorithm):
current_progress = total * current
feedback.setProgress(current_progress)
expressionContext.setFeature(f)
value = expression.evaluate(expressionContext)
if expression.hasEvalError():
feedback.pushInfo(
self.tr('Evaluation error for feature ID {}: {}').format(f.id(), expression.evalErrorString()))
continue
this_value = value
if value_property is not None or expression is not None:
expressionContext.setFeature(f)
if value_property:
this_value, _ = value_property.valueAsDouble(expressionContext, value)
else:
this_value = expression.evaluate(expressionContext)
if expression.hasEvalError():
feedback.pushInfo(
self.tr('Evaluation error for feature ID {}: {}').format(f.id(), expression.evalErrorString()))
continue
fGeom = f.geometry()
engine = QgsGeometry.createGeometryEngine(fGeom.constGet())
@ -157,9 +190,9 @@ class RandomPointsPolygons(QgisAlgorithm):
bbox = fGeom.boundingBox()
if strategy == 0:
pointCount = int(value)
pointCount = int(this_value)
else:
pointCount = int(round(value * da.measureArea(fGeom)))
pointCount = int(round(this_value * da.measureArea(fGeom)))
if pointCount == 0:
feedback.pushInfo("Skip feature {} as number of points for it is 0.".format(f.id()))