QGIS API Documentation  3.21.0-Master (909859188c)
qgsvectorlayerlabelprovider.h
Go to the documentation of this file.
1 /***************************************************************************
2  qgsvectorlayerlabelprovider.h
3  --------------------------------------
4  Date : September 2015
5  Copyright : (C) 2015 by Martin Dobias
6  Email : wonder dot sk at gmail dot com
7  ***************************************************************************
8  * *
9  * This program is free software; you can redistribute it and/or modify *
10  * it under the terms of the GNU General Public License as published by *
11  * the Free Software Foundation; either version 2 of the License, or *
12  * (at your option) any later version. *
13  * *
14  ***************************************************************************/
15 
16 #ifndef QGSVECTORLAYERLABELPROVIDER_H
17 #define QGSVECTORLAYERLABELPROVIDER_H
18 
19 #define SIP_NO_FILE
20 
21 #include "qgis_core.h"
22 #include "qgslabelingengine.h"
23 #include "qgsrenderer.h"
24 #include "qgstextrenderer.h"
25 
27 class QgsFeatureRenderer;
28 class QgsSymbol;
29 
41 {
42  public:
43 
46  const QString &providerId,
47  bool withFeatureLoop,
48  const QgsPalLayerSettings *settings,
49  const QString &layerName = QString() );
50 
53  const QgsFields &fields,
55  const QString &providerId,
56  const QgsPalLayerSettings *settings,
57  QgsMapLayer *layer,
58  const QString &layerName = QString() );
59 
60  ~QgsVectorLayerLabelProvider() override;
61 
62  QList<QgsLabelFeature *> labelFeatures( QgsRenderContext &context ) override;
63 
64  void drawLabelBackground( QgsRenderContext &context, pal::LabelPosition *label ) const override;
65  void drawLabel( QgsRenderContext &context, pal::LabelPosition *label ) const override;
66  void drawUnplacedLabel( QgsRenderContext &context, pal::LabelPosition *label ) const override;
67  void startRender( QgsRenderContext &context ) override;
68  void stopRender( QgsRenderContext &context ) override;
69 
70  // new virtual methods
71 
78  virtual bool prepare( QgsRenderContext &context, QSet<QString> &attributeNames );
79 
94  virtual QList< QgsLabelFeature * > registerFeature( const QgsFeature &feature, QgsRenderContext &context, const QgsGeometry &obstacleGeometry = QgsGeometry(), const QgsSymbol *symbol = nullptr );
95 
105  static QgsGeometry getPointObstacleGeometry( QgsFeature &fet, QgsRenderContext &context, const QgsSymbolList &symbols );
106 
111  const QgsPalLayerSettings &settings() const;
112 
119  void setFields( const QgsFields &fields ) { mFields = fields; }
120 
121  protected:
123  void init();
125  void drawLabelPrivate( pal::LabelPosition *label, QgsRenderContext &context, QgsPalLayerSettings &tmpLyr, QgsTextRenderer::TextPart drawType, double dpiRatio = 1.0 ) const;
126 
127  protected:
132 
133  QgsFeatureRenderer *mRenderer = nullptr;
134 
135  // these are needed only if using own renderer loop
136 
142  std::unique_ptr<QgsAbstractFeatureSource> mSource;
143 
145  QList<QgsLabelFeature *> mLabels;
146 
147  private:
148 
149  friend class TestQgsLabelingEngine;
150  void drawCallout( QgsRenderContext &context, pal::LabelPosition *label ) const;
151 };
152 
153 #endif // QGSVECTORLAYERLABELPROVIDER_H
Base class that can be used for any class that is capable of returning features.
The QgsAbstractLabelProvider class is an interface class.
virtual void drawUnplacedLabel(QgsRenderContext &context, pal::LabelPosition *label) const
Draw an unplaced label.
virtual void stopRender(QgsRenderContext &context)
To be called after rendering is complete.
virtual void drawLabel(QgsRenderContext &context, pal::LabelPosition *label) const =0
Draw this label at the position determined by the labeling engine.
virtual QList< QgsLabelFeature * > labelFeatures(QgsRenderContext &context)=0
Returns list of label features (they are owned by the provider and thus deleted on its destruction)
virtual void drawLabelBackground(QgsRenderContext &context, pal::LabelPosition *label) const
Draw the background for the specified label.
virtual void startRender(QgsRenderContext &context)
To be called before rendering of labels begins.
This class represents a coordinate reference system (CRS).
The feature class encapsulates a single feature including its unique ID, geometry and a list of field...
Definition: qgsfeature.h:56
Container of fields for a vector layer.
Definition: qgsfields.h:45
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:124
Base class for all map layer types.
Definition: qgsmaplayer.h:72
Contains settings for how a map layer will be labeled.
Contains information about the context of a rendering operation.
Abstract base class for all rendered symbols.
Definition: qgssymbol.h:38
TextPart
Components of text.
The QgsVectorLayerLabelProvider class implements a label provider for vector layers.
QgsCoordinateReferenceSystem mCrs
Layer's CRS.
QList< QgsLabelFeature * > mLabels
List of generated.
QgsWkbTypes::GeometryType mLayerGeometryType
Geometry type of layer.
QgsPalLayerSettings mSettings
Layer's labeling configuration.
std::unique_ptr< QgsAbstractFeatureSource > mSource
Layer's feature source.
void setFields(const QgsFields &fields)
Sets fields of this label provider.
Represents a vector layer which manages a vector based data sets.
GeometryType
The geometry types are used to group QgsWkbTypes::Type in a coarse way.
Definition: qgswkbtypes.h:141
LabelPosition is a candidate feature label position.
Definition: labelposition.h:56
QList< QgsSymbol * > QgsSymbolList
Definition: qgsrenderer.h:43
const QgsCoordinateReferenceSystem & crs