QGIS API Documentation 3.40.0-Bratislava (b56115d8743)
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qgsalgorithmpixelcentroidsfrompolygons.cpp
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1/***************************************************************************
2 qgsalgorithmpixelcentroidsfrompolygons.cpp
3 ---------------------
4 begin : December 2019
5 copyright : (C) 2019 by Alexander Bruy
6 email : alexander dot bruy 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 "qgsgeos.h"
21
23
24QString QgsPixelCentroidsFromPolygonsAlgorithm::name() const
25{
26 return QStringLiteral( "generatepointspixelcentroidsinsidepolygons" );
27}
28
29QString QgsPixelCentroidsFromPolygonsAlgorithm::displayName() const
30{
31 return QObject::tr( "Generate points (pixel centroids) inside polygons" );
32}
33
34QStringList QgsPixelCentroidsFromPolygonsAlgorithm::tags() const
35{
36 return QObject::tr( "raster,polygon,centroid,pixel,create" ).split( ',' );
37}
38
39QString QgsPixelCentroidsFromPolygonsAlgorithm::group() const
40{
41 return QObject::tr( "Vector creation" );
42}
43
44QString QgsPixelCentroidsFromPolygonsAlgorithm::groupId() const
45{
46 return QStringLiteral( "vectorcreation" );
47}
48
49QString QgsPixelCentroidsFromPolygonsAlgorithm::shortHelpString() const
50{
51 return QObject::tr( "Generates pixel centroids for the raster area falling inside polygons. Used to generate points "
52 "for further raster sampling." );
53}
54
55Qgis::ProcessingAlgorithmDocumentationFlags QgsPixelCentroidsFromPolygonsAlgorithm::documentationFlags() const
56{
58}
59
60QgsPixelCentroidsFromPolygonsAlgorithm *QgsPixelCentroidsFromPolygonsAlgorithm::createInstance() const
61{
62 return new QgsPixelCentroidsFromPolygonsAlgorithm();
63}
64
65void QgsPixelCentroidsFromPolygonsAlgorithm::initAlgorithm( const QVariantMap & )
66{
67 addParameter( new QgsProcessingParameterRasterLayer( QStringLiteral( "INPUT_RASTER" ), QObject::tr( "Raster layer" ) ) );
68 addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT_VECTOR" ), QObject::tr( "Vector layer" ), QList< int >() << static_cast< int >( Qgis::ProcessingSourceType::VectorPolygon ) ) );
69
70 addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Pixel centroids" ), Qgis::ProcessingSourceType::VectorPoint ) );
71}
72
73QVariantMap QgsPixelCentroidsFromPolygonsAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
74{
75 QgsRasterLayer *rasterLayer = parameterAsRasterLayer( parameters, QStringLiteral( "INPUT_RASTER" ), context );
76
77 if ( !rasterLayer )
78 throw QgsProcessingException( invalidRasterError( parameters, QStringLiteral( "INPUT_RASTER" ) ) );
79
80 std::unique_ptr< QgsProcessingFeatureSource > source( parameterAsSource( parameters, QStringLiteral( "INPUT_VECTOR" ), context ) );
81 if ( !source )
82 throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT_VECTOR" ) ) );
83
84 QgsFields fields;
85 fields.append( QgsField( QStringLiteral( "id" ), QMetaType::Type::LongLong ) );
86 fields.append( QgsField( QStringLiteral( "poly_id" ), QMetaType::Type::Int ) );
87 fields.append( QgsField( QStringLiteral( "point_id" ), QMetaType::Type::Int ) );
88
89 QString dest;
90 std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, fields, Qgis::WkbType::Point, rasterLayer->crs(), QgsFeatureSink::RegeneratePrimaryKey ) );
91 if ( !sink )
92 throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );
93
94 const double step = source->featureCount() ? 100.0 / source->featureCount() : 1;
95 QgsFeatureIterator it = source->getFeatures( QgsFeatureRequest().setDestinationCrs( rasterLayer->crs(), context.transformContext() ).setSubsetOfAttributes( QList< int >() ) );
96
97 const double xPixel = rasterLayer->rasterUnitsPerPixelX();
98 const double yPixel = rasterLayer->rasterUnitsPerPixelY();
99 const QgsRectangle extent = rasterLayer->extent();
100
101 QgsFeature feature;
102 feature.setFields( fields );
103
104 int fid = 0;
105 int pointId = 0;
106
107 int i = 0;
108 QgsFeature f;
109 while ( it.nextFeature( f ) )
110 {
111 if ( feedback->isCanceled() )
112 {
113 break;
114 }
115
116 if ( !f.hasGeometry() )
117 {
118 continue;
119 }
120
121 const QgsRectangle bbox = f.geometry().boundingBox();
122 const double xMin = bbox.xMinimum();
123 const double xMax = bbox.xMaximum();
124 const double yMin = bbox.yMinimum();
125 const double yMax = bbox.yMaximum();
126
127 double x, y;
128 int startRow, startColumn;
129 int endRow, endColumn;
130 QgsRasterAnalysisUtils::mapToPixel( xMin, yMax, extent, xPixel, yPixel, startRow, startColumn );
131 QgsRasterAnalysisUtils::mapToPixel( xMax, yMin, extent, xPixel, yPixel, endRow, endColumn );
132
133 std::unique_ptr< QgsGeos > engine = std::make_unique< QgsGeos >( f.geometry().constGet() );
134 engine->prepareGeometry();
135
136 for ( int row = startRow; row <= endRow; row++ )
137 {
138 for ( int col = startColumn; col <= endColumn; col++ )
139 {
140 if ( feedback->isCanceled() )
141 {
142 break;
143 }
144
145 QgsRasterAnalysisUtils::pixelToMap( row, col, extent, xPixel, yPixel, x, y );
146 if ( engine->contains( x, y ) )
147 {
148 feature.setGeometry( std::make_unique< QgsPoint >( x, y ) );
149 feature.setAttributes( QgsAttributes() << fid << i << pointId );
150 if ( !sink->addFeature( feature, QgsFeatureSink::FastInsert ) )
151 throw QgsProcessingException( writeFeatureError( sink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
152
153 fid++;
154 pointId++;
155 }
156 }
157 }
158
159 pointId = 0;
160
161 feedback->setProgress( i * step );
162 i++;
163 }
164
165 QVariantMap outputs;
166 outputs.insert( QStringLiteral( "OUTPUT" ), dest );
167 return outputs;
168}
169
@ VectorPoint
Vector point layers.
@ VectorPolygon
Vector polygon layers.
@ RegeneratesPrimaryKey
Algorithm always drops any existing primary keys or FID values and regenerates them in outputs.
QFlags< ProcessingAlgorithmDocumentationFlag > ProcessingAlgorithmDocumentationFlags
Flags describing algorithm behavior for documentation purposes.
Definition qgis.h:3359
A vector of attributes.
Wrapper for iterator of features from vector data provider or vector layer.
bool nextFeature(QgsFeature &f)
Fetch next feature and stores in f, returns true on success.
This class wraps a request for features to a vector layer (or directly its vector data provider).
QgsFeatureRequest & setSubsetOfAttributes(const QgsAttributeList &attrs)
Set a subset of attributes that will be fetched.
@ FastInsert
Use faster inserts, at the cost of updating the passed features to reflect changes made at the provid...
@ 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
void setAttributes(const QgsAttributes &attrs)
Sets the feature's attributes.
void setFields(const QgsFields &fields, bool initAttributes=false)
Assigns a field map with the feature to allow attribute access by attribute name.
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.
bool isCanceled() const
Tells whether the operation has been canceled already.
Definition qgsfeedback.h:53
void setProgress(double progress)
Sets the current progress for the feedback object.
Definition qgsfeedback.h:61
Encapsulate a field in an attribute table or data source.
Definition qgsfield.h:53
Container of fields for a vector layer.
Definition qgsfields.h:46
bool append(const QgsField &field, Qgis::FieldOrigin origin=Qgis::FieldOrigin::Provider, int originIndex=-1)
Appends a field.
Definition qgsfields.cpp:69
const QgsAbstractGeometry * constGet() const
Returns a non-modifiable (const) reference to the underlying abstract geometry primitive.
QgsRectangle boundingBox() const
Returns the bounding box of the geometry.
virtual QgsRectangle extent() const
Returns the extent of the layer.
QgsCoordinateReferenceSystem crs
Definition qgsmaplayer.h:83
Contains information about the context in which a processing algorithm is executed.
QgsCoordinateTransformContext transformContext() const
Returns the coordinate transform context.
Custom exception class for processing related exceptions.
Base class for providing feedback from a processing algorithm.
A feature sink output for processing algorithms.
An input feature source (such as vector layers) parameter for processing algorithms.
A raster layer parameter for processing algorithms.
Represents a raster layer.
double rasterUnitsPerPixelX() const
Returns the number of raster units per each raster pixel in X axis.
double rasterUnitsPerPixelY() const
Returns the number of raster units per each raster pixel in Y axis.
A rectangle specified with double values.
double xMinimum() const
Returns the x minimum value (left side of rectangle).
double yMinimum() const
Returns the y minimum value (bottom side of rectangle).
double xMaximum() const
Returns the x maximum value (right side of rectangle).
double yMaximum() const
Returns the y maximum value (top side of rectangle).