1 /***************************************************************************
2 qgsalgorithmsimplify.cpp
3 ---------------------
4 begin : April 2017
5 copyright : (C) 2017 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
18 #include "qgsalgorithmsimplify.h"
19
20 ///@cond PRIVATE
21
name() const22 QString QgsSimplifyAlgorithm::name() const
23 {
24 return QStringLiteral( "simplifygeometries" );
25 }
26
displayName() const27 QString QgsSimplifyAlgorithm::displayName() const
28 {
29 return QObject::tr( "Simplify" );
30 }
31
tags() const32 QStringList QgsSimplifyAlgorithm::tags() const
33 {
34 return QObject::tr( "simplify,generalize,douglas,peucker,visvalingam" ).split( ',' );
35 }
36
group() const37 QString QgsSimplifyAlgorithm::group() const
38 {
39 return QObject::tr( "Vector geometry" );
40 }
41
groupId() const42 QString QgsSimplifyAlgorithm::groupId() const
43 {
44 return QStringLiteral( "vectorgeometry" );
45 }
46
outputName() const47 QString QgsSimplifyAlgorithm::outputName() const
48 {
49 return QObject::tr( "Simplified" );
50 }
51
shortHelpString() const52 QString QgsSimplifyAlgorithm::shortHelpString() const
53 {
54 return QObject::tr( "This algorithm simplifies the geometries in a line or polygon layer. It creates a new layer "
55 "with the same features as the ones in the input layer, but with geometries containing a lower number of vertices.\n\n"
56 "The algorithm gives a choice of simplification methods, including distance based "
57 "(the \"Douglas-Peucker\" algorithm), area based (\"Visvalingam\" algorithm) and snapping geometries to a grid." );
58 }
59
createInstance() const60 QgsSimplifyAlgorithm *QgsSimplifyAlgorithm::createInstance() const
61 {
62 return new QgsSimplifyAlgorithm();
63 }
64
inputLayerTypes() const65 QList<int> QgsSimplifyAlgorithm::inputLayerTypes() const
66 {
67 return QList<int>() << QgsProcessing::TypeVectorLine << QgsProcessing::TypeVectorPolygon;
68 }
69
initParameters(const QVariantMap &)70 void QgsSimplifyAlgorithm::initParameters( const QVariantMap & )
71 {
72 QStringList methods;
73 methods << QObject::tr( "Distance (Douglas-Peucker)" )
74 << QObject::tr( "Snap to grid" )
75 << QObject::tr( "Area (Visvalingam)" );
76
77 addParameter( new QgsProcessingParameterEnum(
78 QStringLiteral( "METHOD" ),
79 QObject::tr( "Simplification method" ),
80 methods, false, 0 ) );
81 std::unique_ptr< QgsProcessingParameterDistance > tolerance = qgis::make_unique< QgsProcessingParameterDistance >( QStringLiteral( "TOLERANCE" ),
82 QObject::tr( "Tolerance" ), 1.0, QStringLiteral( "INPUT" ), false, 0, 10000000.0 );
83 tolerance->setIsDynamic( true );
84 tolerance->setDynamicPropertyDefinition( QgsPropertyDefinition( QStringLiteral( "Tolerance" ), QObject::tr( "Tolerance distance" ), QgsPropertyDefinition::DoublePositive ) );
85 tolerance->setDynamicLayerParameterName( QStringLiteral( "INPUT" ) );
86 addParameter( tolerance.release() );
87 }
88
prepareAlgorithm(const QVariantMap & parameters,QgsProcessingContext & context,QgsProcessingFeedback *)89 bool QgsSimplifyAlgorithm::prepareAlgorithm( const QVariantMap ¶meters, QgsProcessingContext &context, QgsProcessingFeedback * )
90 {
91 mTolerance = parameterAsDouble( parameters, QStringLiteral( "TOLERANCE" ), context );
92 mDynamicTolerance = QgsProcessingParameters::isDynamic( parameters, QStringLiteral( "TOLERANCE" ) );
93 if ( mDynamicTolerance )
94 mToleranceProperty = parameters.value( QStringLiteral( "TOLERANCE" ) ).value< QgsProperty >();
95
96 mMethod = static_cast< QgsMapToPixelSimplifier::SimplifyAlgorithm >( parameterAsEnum( parameters, QStringLiteral( "METHOD" ), context ) );
97 if ( mMethod != QgsMapToPixelSimplifier::Distance )
98 mSimplifier.reset( new QgsMapToPixelSimplifier( QgsMapToPixelSimplifier::SimplifyGeometry, mTolerance, mMethod ) );
99
100 return true;
101 }
102
processFeature(const QgsFeature & feature,QgsProcessingContext & context,QgsProcessingFeedback *)103 QgsFeatureList QgsSimplifyAlgorithm::processFeature( const QgsFeature &feature, QgsProcessingContext &context, QgsProcessingFeedback * )
104 {
105 QgsFeature f = feature;
106 if ( f.hasGeometry() )
107 {
108 QgsGeometry inputGeometry = f.geometry();
109 QgsGeometry outputGeometry;
110 if ( mMethod == QgsMapToPixelSimplifier::Distance )
111 {
112 double tolerance = mTolerance;
113 if ( mDynamicTolerance )
114 tolerance = mToleranceProperty.valueAsDouble( context.expressionContext(), tolerance );
115 outputGeometry = inputGeometry.simplify( tolerance );
116 }
117 else
118 {
119 if ( !mDynamicTolerance )
120 {
121 outputGeometry = mSimplifier->simplify( inputGeometry );
122 }
123 else
124 {
125 double tolerance = mToleranceProperty.valueAsDouble( context.expressionContext(), mTolerance );
126 QgsMapToPixelSimplifier simplifier( QgsMapToPixelSimplifier::SimplifyGeometry, tolerance, mMethod );
127 outputGeometry = simplifier.simplify( inputGeometry );
128 }
129 }
130 f.setGeometry( outputGeometry );
131 }
132 return QgsFeatureList() << f;
133 }
134
sourceFlags() const135 QgsProcessingFeatureSource::Flag QgsSimplifyAlgorithm::sourceFlags() const
136 {
137 return QgsProcessingFeatureSource::FlagSkipGeometryValidityChecks;
138 }
139
140 ///@endcond
141
142
143