QGIS API Documentation 3.39.0-Master (67e056379ed)
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qgsalgorithmlinesubstring.cpp
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1/***************************************************************************
2 qgsalgorithmlinesubstring.cpp
3 ---------------------
4 begin : August 2018
5 copyright : (C) 2018 by Nyall Dawson
6 email : nyall dot dawson at gmail dot com
7 ***************************************************************************/
8
9/***************************************************************************
10 * *
11 * This program is free software; you can redistribute it and/or modify *
12 * it under the terms of the GNU General Public License as published by *
13 * the Free Software Foundation; either version 2 of the License, or *
14 * (at your option) any later version. *
15 * *
16 ***************************************************************************/
17
20#include "qgscurve.h"
21
23
24QString QgsLineSubstringAlgorithm::name() const
25{
26 return QStringLiteral( "linesubstring" );
27}
28
29QString QgsLineSubstringAlgorithm::displayName() const
30{
31 return QObject::tr( "Line substring" );
32}
33
34QStringList QgsLineSubstringAlgorithm::tags() const
35{
36 return QObject::tr( "linestring,curve,split,shorten,shrink,portion,part,reference,referencing,distance,interpolate" ).split( ',' );
37}
38
39QString QgsLineSubstringAlgorithm::group() const
40{
41 return QObject::tr( "Vector geometry" );
42}
43
44QString QgsLineSubstringAlgorithm::groupId() const
45{
46 return QStringLiteral( "vectorgeometry" );
47}
48
49QString QgsLineSubstringAlgorithm::outputName() const
50{
51 return QObject::tr( "Substring" );
52}
53
54QString QgsLineSubstringAlgorithm::shortHelpString() const
55{
56 return QObject::tr( "This algorithm returns the portion of a line (or curve) which falls "
57 "between the specified start and end distances (measured from the "
58 "beginning of the line).\n\n"
59 "Z and M values are linearly interpolated from existing values.\n\n"
60 "If a multipart geometry is encountered, only the first part is considered when "
61 "calculating the substring." );
62}
63
64QString QgsLineSubstringAlgorithm::shortDescription() const
65{
66 return QObject::tr( "Returns the substring of lines which fall between start and end distances." );
67}
68
69QList<int> QgsLineSubstringAlgorithm::inputLayerTypes() const
70{
71 return QList<int>() << static_cast< int >( Qgis::ProcessingSourceType::VectorLine );
72}
73
74Qgis::ProcessingSourceType QgsLineSubstringAlgorithm::outputLayerType() const
75{
77}
78
79QgsLineSubstringAlgorithm *QgsLineSubstringAlgorithm::createInstance() const
80{
81 return new QgsLineSubstringAlgorithm();
82}
83
84void QgsLineSubstringAlgorithm::initParameters( const QVariantMap & )
85{
86 std::unique_ptr< QgsProcessingParameterDistance> startDistance = std::make_unique< QgsProcessingParameterDistance >( QStringLiteral( "START_DISTANCE" ),
87 QObject::tr( "Start distance" ), 0.0, QStringLiteral( "INPUT" ), false, 0 );
88 startDistance->setIsDynamic( true );
89 startDistance->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "Start Distance" ), QObject::tr( "Start distance" ), QgsPropertyDefinition::DoublePositive ) );
90 startDistance->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
91 addParameter( startDistance.release() );
92
93 std::unique_ptr< QgsProcessingParameterDistance> endDistance = std::make_unique< QgsProcessingParameterDistance >( QStringLiteral( "END_DISTANCE" ),
94 QObject::tr( "End distance" ), 1.0, QStringLiteral( "INPUT" ), false, 0 );
95 endDistance->setIsDynamic( true );
96 endDistance->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "End Distance" ), QObject::tr( "End distance" ), QgsPropertyDefinition::DoublePositive ) );
97 endDistance->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
98 addParameter( endDistance.release() );
99}
100
101Qgis::ProcessingFeatureSourceFlags QgsLineSubstringAlgorithm::sourceFlags() const
102{
103 // skip geometry checks - this algorithm doesn't care about invalid geometries
105}
106
107bool QgsLineSubstringAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
108{
109 mStartDistance = parameterAsDouble( parameters, QStringLiteral( "START_DISTANCE" ), context );
110 mDynamicStartDistance = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "START_DISTANCE" ) );
111 if ( mDynamicStartDistance )
112 mStartDistanceProperty = parameters.value( QStringLiteral( "START_DISTANCE" ) ).value< QgsProperty >();
113
114 mEndDistance = parameterAsDouble( parameters, QStringLiteral( "END_DISTANCE" ), context );
115 mDynamicEndDistance = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "END_DISTANCE" ) );
116 if ( mDynamicEndDistance )
117 mEndDistanceProperty = parameters.value( QStringLiteral( "END_DISTANCE" ) ).value< QgsProperty >();
118
119 return true;
120}
121
122QgsFeatureList QgsLineSubstringAlgorithm::processFeature( const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback * )
123{
124 QgsFeature f = feature;
125 if ( f.hasGeometry() )
126 {
127 const QgsGeometry geometry = f.geometry();
128 double startDistance = mStartDistance;
129 if ( mDynamicStartDistance )
130 startDistance = mStartDistanceProperty.valueAsDouble( context.expressionContext(), startDistance );
131
132 double endDistance = mEndDistance;
133 if ( mDynamicEndDistance )
134 endDistance = mEndDistanceProperty.valueAsDouble( context.expressionContext(), endDistance );
135
136 const QgsCurve *curve = nullptr;
137 if ( !geometry.isMultipart() )
138 curve = qgsgeometry_cast< const QgsCurve * >( geometry.constGet() );
139 else
140 {
141 if ( const QgsGeometryCollection *collection = qgsgeometry_cast< const QgsGeometryCollection * >( geometry.constGet() ) )
142 {
143 if ( collection->numGeometries() > 0 )
144 {
145 curve = qgsgeometry_cast< const QgsCurve * >( collection->geometryN( 0 ) );
146 }
147 }
148 }
149 if ( curve )
150 {
151 std::unique_ptr< QgsCurve > substring( curve->curveSubstring( startDistance, endDistance ) );
152 const QgsGeometry result( std::move( substring ) );
153 f.setGeometry( result );
154 }
155 else
156 {
157 f.clearGeometry();
158 }
159 }
160 return QgsFeatureList() << f;
161}
162
164
165
ProcessingSourceType
Processing data source types.
Definition qgis.h:3000
@ VectorLine
Vector line layers.
@ SkipGeometryValidityChecks
Invalid geometry checks should always be skipped. This flag can be useful for algorithms which always...
QFlags< ProcessingFeatureSourceFlag > ProcessingFeatureSourceFlags
Flags which control how QgsProcessingFeatureSource fetches features.
Definition qgis.h:3153
Abstract base class for curved geometry type.
Definition qgscurve.h:35
virtual QgsCurve * curveSubstring(double startDistance, double endDistance) const =0
Returns a new curve representing a substring of this curve.
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:58
QgsGeometry geometry
Definition qgsfeature.h:69
void clearGeometry()
Removes any geometry associated with the feature.
bool hasGeometry() const
Returns true if the feature has an associated geometry.
void setGeometry(const QgsGeometry &geometry)
Set the feature's geometry.
A geometry is the spatial representation of a feature.
const QgsAbstractGeometry * constGet() const
Returns a non-modifiable (const) reference to the underlying abstract geometry primitive.
bool isMultipart() const
Returns true if WKB of the geometry is of WKBMulti* type.
Contains information about the context in which a processing algorithm is executed.
QgsExpressionContext & expressionContext()
Returns the expression context.
Base class for providing feedback from a processing algorithm.
static bool isDynamic(const QVariantMap &parameters, const QString &name)
Returns true if the parameter with matching name is a dynamic parameter, and must be evaluated once f...
Definition for a property.
Definition qgsproperty.h:45
@ DoublePositive
Positive double value (including 0)
Definition qgsproperty.h:56
A store for object properties.
double valueAsDouble(const QgsExpressionContext &context, double defaultValue=0.0, bool *ok=nullptr) const
Calculates the current value of the property and interprets it as a double.
QList< QgsFeature > QgsFeatureList