QGIS API Documentation  3.26.3-Buenos Aires (65e4edfdad)
qgsalgorithmtransform.cpp
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1 /***************************************************************************
2  qgsalgorithmtransform.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 "qgsalgorithmtransform.h"
19 
21 
22 
23 void QgsTransformAlgorithm::initParameters( const QVariantMap & )
24 {
25  addParameter( new QgsProcessingParameterCrs( QStringLiteral( "TARGET_CRS" ), QObject::tr( "Target CRS" ), QStringLiteral( "EPSG:4326" ) ) );
26 
27  std::unique_ptr< QgsProcessingParameterCoordinateOperation > crsOpParam = std::make_unique< QgsProcessingParameterCoordinateOperation >( QStringLiteral( "OPERATION" ), QObject::tr( "Coordinate operation" ),
28  QVariant(), QStringLiteral( "INPUT" ), QStringLiteral( "TARGET_CRS" ), QVariant(), QVariant(), true );
29  crsOpParam->setFlags( crsOpParam->flags() | QgsProcessingParameterDefinition::FlagAdvanced );
30  addParameter( crsOpParam.release() );
31 }
32 
34 {
35  return mDestCrs;
36 }
37 
38 QString QgsTransformAlgorithm::outputName() const
39 {
40  return QObject::tr( "Reprojected" );
41 }
42 
43 QgsProcessingFeatureSource::Flag QgsTransformAlgorithm::sourceFlags() const
44 {
46 }
47 
48 QString QgsTransformAlgorithm::name() const
49 {
50  return QStringLiteral( "reprojectlayer" );
51 }
52 
53 QString QgsTransformAlgorithm::displayName() const
54 {
55  return QObject::tr( "Reproject layer" );
56 }
57 
58 QStringList QgsTransformAlgorithm::tags() const
59 {
60  return QObject::tr( "transform,reprojection,crs,srs,warp" ).split( ',' );
61 }
62 
63 QString QgsTransformAlgorithm::group() const
64 {
65  return QObject::tr( "Vector general" );
66 }
67 
68 QString QgsTransformAlgorithm::groupId() const
69 {
70  return QStringLiteral( "vectorgeneral" );
71 }
72 
73 QString QgsTransformAlgorithm::shortHelpString() const
74 {
75  return QObject::tr( "This algorithm reprojects a vector layer. It creates a new layer with the same features "
76  "as the input one, but with geometries reprojected to a new CRS.\n\n"
77  "Attributes are not modified by this algorithm." );
78 }
79 
80 QgsTransformAlgorithm *QgsTransformAlgorithm::createInstance() const
81 {
82  return new QgsTransformAlgorithm();
83 }
84 
85 bool QgsTransformAlgorithm::prepareAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
86 {
87  prepareSource( parameters, context );
88  mDestCrs = parameterAsCrs( parameters, QStringLiteral( "TARGET_CRS" ), context );
89  mTransformContext = context.transformContext();
90  mCoordOp = parameterAsString( parameters, QStringLiteral( "OPERATION" ), context );
91  return true;
92 }
93 
94 QgsFeatureList QgsTransformAlgorithm::processFeature( const QgsFeature &f, QgsProcessingContext &, QgsProcessingFeedback *feedback )
95 {
96  QgsFeature feature = f;
97  if ( !mCreatedTransform )
98  {
99  mCreatedTransform = true;
100  if ( !mCoordOp.isEmpty() )
101  mTransformContext.addCoordinateOperation( sourceCrs(), mDestCrs, mCoordOp, false );
102  mTransform = QgsCoordinateTransform( sourceCrs(), mDestCrs, mTransformContext );
103 
104  mTransform.disableFallbackOperationHandler( true );
105  }
106 
107  if ( feature.hasGeometry() )
108  {
109  QgsGeometry g = feature.geometry();
110  try
111  {
112  if ( g.transform( mTransform ) == Qgis::GeometryOperationResult::Success )
113  {
114  feature.setGeometry( g );
115  }
116  else
117  {
118  feature.clearGeometry();
119  }
120 
121  if ( !mWarnedAboutFallbackTransform && mTransform.fallbackOperationOccurred() )
122  {
123  feedback->reportError( QObject::tr( "An alternative, ballpark-only transform was used when transforming coordinates for one or more features. "
124  "(Possibly an incorrect choice of operation was made for transformations between these reference systems - check "
125  "that the selected operation is valid for the full extent of the input layer.)" ) );
126  mWarnedAboutFallbackTransform = true; // only warn once to avoid flooding the log
127  }
128  }
129  catch ( QgsCsException & )
130  {
131  if ( feedback )
132  feedback->reportError( QObject::tr( "Encountered a transform error when reprojecting feature with id %1." ).arg( f.id() ) );
133  feature.clearGeometry();
134  }
135  }
136  return QgsFeatureList() << feature;
137 }
138 
140 
141 
142 
outputCrs
const QgsCoordinateReferenceSystem & outputCrs
Definition: qgswfsgetfeature.cpp:115
QgsProcessingFeedback
Base class for providing feedback from a processing algorithm.
Definition: qgsprocessingfeedback.h:37
QgsGeometry::transform
Qgis::GeometryOperationResult transform(const QgsCoordinateTransform &ct, Qgis::TransformDirection direction=Qgis::TransformDirection::Forward, bool transformZ=false) SIP_THROW(QgsCsException)
Transforms this geometry as described by the coordinate transform ct.
Definition: qgsgeometry.cpp:3128
QgsProcessingFeedback::reportError
virtual void reportError(const QString &error, bool fatalError=false)
Reports that the algorithm encountered an error while executing.
Definition: qgsprocessingfeedback.cpp:59
QgsFeature::geometry
QgsGeometry geometry
Definition: qgsfeature.h:71
QgsProcessingParameterDefinition::FlagAdvanced
@ FlagAdvanced
Parameter is an advanced parameter which should be hidden from users by default.
Definition: qgsprocessingparameters.h:451
QgsProcessingFeatureSource::FlagSkipGeometryValidityChecks
@ FlagSkipGeometryValidityChecks
Invalid geometry checks should always be skipped. This flag can be useful for algorithms which always...
Definition: qgsprocessingutils.h:584
QgsFeature::clearGeometry
void clearGeometry()
Removes any geometry associated with the feature.
Definition: qgsfeature.cpp:184
QgsFeature::id
QgsFeatureId id
Definition: qgsfeature.h:68
QgsCsException
Custom exception class for Coordinate Reference System related exceptions.
Definition: qgsexception.h:65
QgsFeature::setGeometry
void setGeometry(const QgsGeometry &geometry)
Set the feature's geometry.
Definition: qgsfeature.cpp:170
QgsProcessingParameterCrs
A coordinate reference system parameter for processing algorithms.
Definition: qgsprocessingparameters.h:1740
QgsProcessingContext
Contains information about the context in which a processing algorithm is executed.
Definition: qgsprocessingcontext.h:46
QgsFeatureList
QList< QgsFeature > QgsFeatureList
Definition: qgsfeature.h:882
QgsProcessingContext::transformContext
QgsCoordinateTransformContext transformContext() const
Returns the coordinate transform context.
Definition: qgsprocessingcontext.h:165
QgsCoordinateReferenceSystem
This class represents a coordinate reference system (CRS).
Definition: qgscoordinatereferencesystem.h:211
QgsProcessingFeatureSource::Flag
Flag
Flags controlling how QgsProcessingFeatureSource fetches features.
Definition: qgsprocessingutils.h:582
QgsGeometry
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:124
QgsFeature::hasGeometry
bool hasGeometry() const
Returns true if the feature has an associated geometry.
Definition: qgsfeature.cpp:230
Qgis::GeometryOperationResult::Success
@ Success
Operation succeeded.
QgsFeature
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition: qgsfeature.h:55
qgsalgorithmtransform.h
QgsCoordinateTransform
Class for doing transforms between two map coordinate systems.
Definition: qgscoordinatetransform.h:57