QGIS API Documentation 3.39.0-Master (67e056379ed)
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qgsalgorithmextentfromlayer.cpp
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1/***************************************************************************
2 qgsalgorithmextentfromlayer.cpp
3 ---------------------
4 begin : November 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 "qgsapplication.h"
20#include "qgsvectorlayer.h"
21
23
24QString QgsExtentFromLayerAlgorithm::name() const
25{
26 return QStringLiteral( "polygonfromlayerextent" );
27}
28
29QString QgsExtentFromLayerAlgorithm::displayName() const
30{
31 return QObject::tr( "Extract layer extent" );
32}
33
34QStringList QgsExtentFromLayerAlgorithm::tags() const
35{
36 return QObject::tr( "polygon,vector,raster,extent,envelope,bounds,bounding,boundary,layer,round,rounded" ).split( ',' );
37}
38
39QString QgsExtentFromLayerAlgorithm::group() const
40{
41 return QObject::tr( "Layer tools" );
42}
43
44QString QgsExtentFromLayerAlgorithm::groupId() const
45{
46 return QStringLiteral( "layertools" );
47}
48
49QString QgsExtentFromLayerAlgorithm::shortHelpString() const
50{
51 return QObject::tr( "This algorithm takes a map layer and generates a new vector "
52 "layer with the minimum bounding box (rectangle polygon with "
53 "N-S orientation) that covers the input layer. Optionally, the "
54 "extent can be enlarged to a rounded value." );
55}
56
57QString QgsExtentFromLayerAlgorithm::svgIconPath() const
58{
59 return QgsApplication::iconPath( QStringLiteral( "/algorithms/mAlgorithmExtractLayerExtent.svg" ) );
60}
61
62QIcon QgsExtentFromLayerAlgorithm::icon() const
63{
64 return QgsApplication::getThemeIcon( QStringLiteral( "/algorithms/mAlgorithmExtractLayerExtent.svg" ) );
65}
66
67QgsExtentFromLayerAlgorithm *QgsExtentFromLayerAlgorithm::createInstance() const
68{
69 return new QgsExtentFromLayerAlgorithm();
70}
71
72void QgsExtentFromLayerAlgorithm::initAlgorithm( const QVariantMap & )
73{
74 addParameter( new QgsProcessingParameterMapLayer( QStringLiteral( "INPUT" ), QObject::tr( "Input layer" ) ) );
75
76 auto roundParam = std::make_unique < QgsProcessingParameterDistance >( QStringLiteral( "ROUND_TO" ), QObject::tr( "Round values to" ), 0, QStringLiteral( "INPUT" ), 0 );
77 roundParam->setFlags( Qgis::ProcessingParameterFlag::Advanced );
78 addParameter( roundParam.release() );
79
80 addParameter( new QgsProcessingParameterFeatureSink( QStringLiteral( "OUTPUT" ), QObject::tr( "Extent" ), Qgis::ProcessingSourceType::VectorPolygon ) );
81}
82
83QVariantMap QgsExtentFromLayerAlgorithm::processAlgorithm( const QVariantMap &parameters, QgsProcessingContext &context, QgsProcessingFeedback * )
84{
85 QgsMapLayer *layer = parameterAsLayer( parameters, QStringLiteral( "INPUT" ), context );
86
87 if ( !layer )
88 throw QgsProcessingException( QObject::tr( "Invalid input layer" ) );
89
90 const double roundTo = parameterAsDouble( parameters, QStringLiteral( "ROUND_TO" ), context );
91
92 QgsFields fields;
93 fields.append( QgsField( QStringLiteral( "MINX" ), QMetaType::Type::Double ) );
94 fields.append( QgsField( QStringLiteral( "MINY" ), QMetaType::Type::Double ) );
95 fields.append( QgsField( QStringLiteral( "MAXX" ), QMetaType::Type::Double ) );
96 fields.append( QgsField( QStringLiteral( "MAXY" ), QMetaType::Type::Double ) );
97 fields.append( QgsField( QStringLiteral( "CNTX" ), QMetaType::Type::Double ) );
98 fields.append( QgsField( QStringLiteral( "CNTY" ), QMetaType::Type::Double ) );
99 fields.append( QgsField( QStringLiteral( "AREA" ), QMetaType::Type::Double ) );
100 fields.append( QgsField( QStringLiteral( "PERIM" ), QMetaType::Type::Double ) );
101 fields.append( QgsField( QStringLiteral( "HEIGHT" ), QMetaType::Type::Double ) );
102 fields.append( QgsField( QStringLiteral( "WIDTH" ), QMetaType::Type::Double ) );
103
104 QString dest;
105 std::unique_ptr< QgsFeatureSink > sink( parameterAsSink( parameters, QStringLiteral( "OUTPUT" ), context, dest, fields, Qgis::WkbType::Polygon, layer->crs() ) );
106 if ( !sink )
107 throw QgsProcessingException( invalidSinkError( parameters, QStringLiteral( "OUTPUT" ) ) );
108
109 if ( QgsVectorLayer *vl = qobject_cast< QgsVectorLayer * >( layer ) )
110 {
111 vl->updateExtents();
112 }
113
114 QgsRectangle rect = layer->extent();
115
116 if ( roundTo > 0 )
117 {
118 rect.setXMinimum( std::floor( rect.xMinimum() / roundTo ) * roundTo );
119 rect.setYMinimum( std::floor( rect.yMinimum() / roundTo ) * roundTo );
120 rect.setXMaximum( std::ceil( rect.xMaximum() / roundTo ) * roundTo );
121 rect.setYMaximum( std::ceil( rect.yMaximum() / roundTo ) * roundTo );
122 }
123
124 const QgsGeometry geom = QgsGeometry::fromRect( rect );
125
126 const double minX = rect.xMinimum();
127 const double maxX = rect.xMaximum();
128 const double minY = rect.yMinimum();
129 const double maxY = rect.yMaximum();
130 const double height = rect.height();
131 const double width = rect.width();
132 const double cntX = minX + width / 2.0;
133 const double cntY = minY + height / 2.0;
134 const double area = width * height;
135 const double perim = 2 * width + 2 * height;
136
137 QgsFeature feat;
138 feat.setGeometry( geom );
139 feat.setAttributes( QgsAttributes() << minX << minY << maxX << maxY << cntX << cntY << area << perim << height << width );
140 if ( !sink->addFeature( feat, QgsFeatureSink::FastInsert ) )
141 throw QgsProcessingException( writeFeatureError( sink.get(), parameters, QStringLiteral( "OUTPUT" ) ) );
142
143 QVariantMap outputs;
144 outputs.insert( QStringLiteral( "OUTPUT" ), dest );
145 return outputs;
146}
147
@ VectorPolygon
Vector polygon layers.
@ Polygon
Polygon.
@ Advanced
Parameter is an advanced parameter which should be hidden from users by default.
static QIcon getThemeIcon(const QString &name, const QColor &fillColor=QColor(), const QColor &strokeColor=QColor())
Helper to get a theme icon.
static QString iconPath(const QString &iconFile)
Returns path to the desired icon file.
A vector of attributes.
@ FastInsert
Use faster inserts, at the cost of updating the passed features to reflect changes made at the provid...
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 setGeometry(const QgsGeometry &geometry)
Set the feature's geometry.
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
A geometry is the spatial representation of a feature.
static QgsGeometry fromRect(const QgsRectangle &rect)
Creates a new geometry from a QgsRectangle.
Base class for all map layer types.
Definition qgsmaplayer.h:75
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.
Custom exception class for processing related exceptions.
Base class for providing feedback from a processing algorithm.
A feature sink output for processing algorithms.
A map layer parameter for processing algorithms.
A rectangle specified with double values.
double xMinimum() const
Returns the x minimum value (left side of rectangle).
void setYMinimum(double y)
Set the minimum y value.
double yMinimum() const
Returns the y minimum value (bottom side of rectangle).
void setXMinimum(double x)
Set the minimum x value.
double width() const
Returns the width of the 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).
void setYMaximum(double y)
Set the maximum y value.
void setXMaximum(double x)
Set the maximum x value.
double height() const
Returns the height of the rectangle.
Represents a vector layer which manages a vector based data sets.