QGIS API Documentation 3.39.0-Master (67e056379ed)
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qgsalgorithmsplitlinesbylength.cpp
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1/***************************************************************************
2 qgsalgorithmsplitlinesbylength.cpp
3 ---------------------
4 begin : December 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
19#include "qgscurve.h"
20#include "qgslinestring.h"
21#include "qgscircularstring.h"
22#include "qgscompoundcurve.h"
24
26
27QString QgsSplitLinesByLengthAlgorithm::name() const
28{
29 return QStringLiteral( "splitlinesbylength" );
30}
31
32QString QgsSplitLinesByLengthAlgorithm::displayName() const
33{
34 return QObject::tr( "Split lines by maximum length" );
35}
36
37QStringList QgsSplitLinesByLengthAlgorithm::tags() const
38{
39 return QObject::tr( "segments,parts,distance,cut,chop" ).split( ',' );
40}
41
42QString QgsSplitLinesByLengthAlgorithm::group() const
43{
44 return QObject::tr( "Vector geometry" );
45}
46
47QString QgsSplitLinesByLengthAlgorithm::groupId() const
48{
49 return QStringLiteral( "vectorgeometry" );
50}
51
52QString QgsSplitLinesByLengthAlgorithm::shortHelpString() const
53{
54 return QObject::tr( "This algorithm takes a line (or curve) layer and splits each feature into multiple parts, "
55 "where each part is of a specified maximum length.\n\n"
56 "Z and M values at the start and end of the new line substrings are linearly interpolated from existing values." );
57}
58
59QString QgsSplitLinesByLengthAlgorithm::shortDescription() const
60{
61 return QObject::tr( "Splits lines into parts which are no longer than a specified length." );
62}
63
64QList<int> QgsSplitLinesByLengthAlgorithm::inputLayerTypes() const
65{
66 return QList<int>() << static_cast< int >( Qgis::ProcessingSourceType::VectorLine );
67}
68
69Qgis::ProcessingSourceType QgsSplitLinesByLengthAlgorithm::outputLayerType() const
70{
72}
73
74QgsSplitLinesByLengthAlgorithm *QgsSplitLinesByLengthAlgorithm::createInstance() const
75{
76 return new QgsSplitLinesByLengthAlgorithm();
77}
78
79void QgsSplitLinesByLengthAlgorithm::initParameters( const QVariantMap & )
80{
81 std::unique_ptr< QgsProcessingParameterDistance > length = std::make_unique< QgsProcessingParameterDistance >( QStringLiteral( "LENGTH" ),
82 QObject::tr( "Maximum line length" ), 10, QStringLiteral( "INPUT" ), false, 0 );
83 length->setIsDynamic( true );
84 length->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "LENGTH" ), QObject::tr( "Maximum length" ), QgsPropertyDefinition::DoublePositive ) );
85 length->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
86 addParameter( length.release() );
87}
88
89bool QgsSplitLinesByLengthAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
90{
91 mLength = parameterAsDouble( parameters, QStringLiteral( "LENGTH" ), context );
92 mDynamicLength = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "LENGTH" ) );
93 if ( mDynamicLength )
94 mLengthProperty = parameters.value( QStringLiteral( "LENGTH" ) ).value< QgsProperty >();
95
96 return true;
97}
98
99QString QgsSplitLinesByLengthAlgorithm::outputName() const
100{
101 return QObject::tr( "Split" );
102}
103
104Qgis::WkbType QgsSplitLinesByLengthAlgorithm::outputWkbType( Qgis::WkbType inputWkbType ) const
105{
106 return QgsWkbTypes::singleType( inputWkbType );
107}
108
109QgsFeatureList QgsSplitLinesByLengthAlgorithm::processFeature( const QgsFeature &f, QgsProcessingContext &context, QgsProcessingFeedback * )
110{
111 if ( !f.hasGeometry() )
112 {
113 return QgsFeatureList() << f;
114 }
115 else
116 {
117 double distance = mLength;
118 if ( mDynamicLength )
119 distance = mLengthProperty.valueAsDouble( context.expressionContext(), distance );
120
121 QgsFeature outputFeature;
122 outputFeature.setAttributes( f.attributes() );
123 QgsFeatureList features;
124 const QgsGeometry inputGeom = f.geometry();
125 for ( auto it = inputGeom.const_parts_begin(); it != inputGeom.const_parts_end(); ++it )
126 {
127 const QgsCurve *part = qgsgeometry_cast< const QgsCurve * >( *it );
128 if ( !part )
129 continue;
130
131 double start = 0.0;
132 double end = distance;
133 const double length = part->length();
134 while ( start < length )
135 {
136 outputFeature.setGeometry( QgsGeometry( part->curveSubstring( start, end ) ) );
137 start += distance;
138 end += distance;
139 features << outputFeature;
140 }
141
142 }
143 return features;
144 }
145}
146
147Qgis::ProcessingFeatureSourceFlags QgsSplitLinesByLengthAlgorithm::sourceFlags() const
148{
150}
151
152QgsFeatureSink::SinkFlags QgsSplitLinesByLengthAlgorithm::sinkFlags() const
153{
155}
156
157
159
160
161
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...
WkbType
The WKB type describes the number of dimensions a geometry has.
Definition qgis.h:201
QFlags< ProcessingFeatureSourceFlag > ProcessingFeatureSourceFlags
Flags which control how QgsProcessingFeatureSource fetches features.
Definition qgis.h:3153
virtual double length() const
Returns the planar, 2-dimensional length of the geometry.
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.
QFlags< SinkFlag > SinkFlags
@ RegeneratePrimaryKey
This flag indicates, that a primary key field cannot be guaranteed to be unique and the sink should i...
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition qgsfeature.h:58
QgsAttributes attributes
Definition qgsfeature.h:67
void setAttributes(const QgsAttributes &attrs)
Sets the feature's attributes.
QgsGeometry geometry
Definition qgsfeature.h:69
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.
QgsAbstractGeometry::const_part_iterator const_parts_begin() const
Returns STL-style const iterator pointing to the first part of the geometry.
QgsAbstractGeometry::const_part_iterator const_parts_end() const
Returns STL-style iterator pointing to the imaginary part after the last part of the geometry.
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.
static Qgis::WkbType singleType(Qgis::WkbType type)
Returns the single type for a WKB type.
Definition qgswkbtypes.h:53
QList< QgsFeature > QgsFeatureList