QGIS API Documentation 3.39.0-Master (67e056379ed)
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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
55QgsPixelCentroidsFromPolygonsAlgorithm *QgsPixelCentroidsFromPolygonsAlgorithm::createInstance() const
56{
57 return new QgsPixelCentroidsFromPolygonsAlgorithm();
58}
59
60void QgsPixelCentroidsFromPolygonsAlgorithm::initAlgorithm( const QVariantMap & )
61{
62 addParameter( new QgsProcessingParameterRasterLayer( QStringLiteral( "INPUT_RASTER" ), QObject::tr( "Raster layer" ) ) );
63 addParameter( new QgsProcessingParameterFeatureSource( QStringLiteral( "INPUT_VECTOR" ), QObject::tr( "Vector layer" ), QList< int >() << static_cast< int >( Qgis::ProcessingSourceType::VectorPolygon ) ) );
64
65 addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Pixel centroids" ), Qgis::ProcessingSourceType::VectorPoint ) );
66}
67
68QVariantMap QgsPixelCentroidsFromPolygonsAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback *feedback )
69{
70 QgsRasterLayer *rasterLayer = parameterAsRasterLayer( parameters, QStringLiteral( "INPUT_RASTER" ), context );
71
72 if ( !rasterLayer )
73 throw QgsProcessingException( invalidRasterError( parameters, QStringLiteral( "INPUT_RASTER" ) ) );
74
75 std::unique_ptr< QgsProcessingFeatureSource > source( parameterAsSource( parameters, QStringLiteral( "INPUT_VECTOR" ), context ) );
76 if ( !source )
77 throw QgsProcessingException( invalidSourceError( parameters, QStringLiteral( "INPUT_VECTOR" ) ) );
78
79 QgsFields fields;
80 fields.append( QgsField( QStringLiteral( "id" ), QMetaType::Type::LongLong ) );
81 fields.append( QgsField( QStringLiteral( "poly_id" ), QMetaType::Type::Int ) );
82 fields.append( QgsField( QStringLiteral( "point_id" ), QMetaType::Type::Int ) );
83
84 QString dest;
85 std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, fields, Qgis::WkbType::Point, rasterLayer->crs(), QgsFeatureSink::RegeneratePrimaryKey ) );
86 if ( !sink )
87 throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );
88
89 const double step = source->featureCount() ? 100.0 / source->featureCount() : 1;
90 QgsFeatureIterator it = source->getFeatures( QgsFeatureRequest().setDestinationCrs( rasterLayer->crs(), context.transformContext() ).setSubsetOfAttributes( QList< int >() ) );
91
92 const double xPixel = rasterLayer->rasterUnitsPerPixelX();
93 const double yPixel = rasterLayer->rasterUnitsPerPixelY();
94 const QgsRectangle extent = rasterLayer->extent();
95
96 QgsFeature feature;
97 feature.setFields( fields );
98
99 int fid = 0;
100 int pointId = 0;
101
102 int i = 0;
103 QgsFeature f;
104 while ( it.nextFeature( f ) )
105 {
106 if ( feedback->isCanceled() )
107 {
108 break;
109 }
110
111 if ( !f.hasGeometry() )
112 {
113 continue;
114 }
115
116 const QgsRectangle bbox = f.geometry().boundingBox();
117 const double xMin = bbox.xMinimum();
118 const double xMax = bbox.xMaximum();
119 const double yMin = bbox.yMinimum();
120 const double yMax = bbox.yMaximum();
121
122 double x, y;
123 int startRow, startColumn;
124 int endRow, endColumn;
125 QgsRasterAnalysisUtils::mapToPixel( xMin, yMax, extent, xPixel, yPixel, startRow, startColumn );
126 QgsRasterAnalysisUtils::mapToPixel( xMax, yMin, extent, xPixel, yPixel, endRow, endColumn );
127
128 std::unique_ptr< QgsGeos > engine = std::make_unique< QgsGeos >( f.geometry().constGet() );
129 engine->prepareGeometry();
130
131 for ( int row = startRow; row <= endRow; row++ )
132 {
133 for ( int col = startColumn; col <= endColumn; col++ )
134 {
135 if ( feedback->isCanceled() )
136 {
137 break;
138 }
139
140 QgsRasterAnalysisUtils::pixelToMap( row, col, extent, xPixel, yPixel, x, y );
141 if ( engine->contains( x, y ) )
142 {
143 feature.setGeometry( std::make_unique< QgsPoint >( x, y ) );
144 feature.setAttributes( QgsAttributes() << fid << i << pointId );
145 if ( !sink->addFeature( feature, QgsFeatureSink::FastInsert ) )
146 throw QgsProcessingException( writeFeatureError( sink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
147
148 fid++;
149 pointId++;
150 }
151 }
152 }
153
154 pointId = 0;
155
156 feedback->setProgress( i * step );
157 i++;
158 }
159
160 QVariantMap outputs;
161 outputs.insert( QStringLiteral( "OUTPUT" ), dest );
162 return outputs;
163}
164
@ VectorPoint
Vector point layers.
@ VectorPolygon
Vector polygon layers.
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:82
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).