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722fdefe43
The order of the elements is irrelevant and duplicate elements are unwanted. It is therefore a perfect candidate for a set instead of a list. This prevents filtering for duplicates manually be replacing some filer codes with (more performant) builtin methods of QSet.
126 lines
5.6 KiB
C++
126 lines
5.6 KiB
C++
/***************************************************************************
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qgsvectorlayerlabelprovider.h
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--------------------------------------
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Date : September 2015
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Copyright : (C) 2015 by Martin Dobias
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Email : wonder dot sk at gmail dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************/
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#ifndef QGSVECTORLAYERLABELPROVIDER_H
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#define QGSVECTORLAYERLABELPROVIDER_H
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#include "qgslabelingengine.h"
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#include "qgsrenderer.h"
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class QgsAbstractFeatureSource;
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class QgsFeatureRenderer;
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class QgsSymbol;
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/** \ingroup core
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* @brief The QgsVectorLayerLabelProvider class implements a label provider
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* for vector layers. Parameters for the labeling are taken from the layer's
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* custom properties or from the given settings.
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*
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* @note added in QGIS 2.12
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* @note this class is not a part of public API yet. See notes in QgsLabelingEngine
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* @note not available in Python bindings
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*/
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class CORE_EXPORT QgsVectorLayerLabelProvider : public QgsAbstractLabelProvider
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{
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public:
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//! Convenience constructor to initialize the provider from given vector layer
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explicit QgsVectorLayerLabelProvider( QgsVectorLayer* layer,
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const QString& providerId,
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bool withFeatureLoop = true,
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const QgsPalLayerSettings* settings = nullptr,
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const QString& layerName = QString() );
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//! Construct diagram provider with all the necessary configuration parameters
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QgsVectorLayerLabelProvider( const QgsPalLayerSettings& settings,
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const QString& layerId,
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const QgsFields& fields,
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const QgsCoordinateReferenceSystem& crs,
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QgsAbstractFeatureSource* source,
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bool ownsSource,
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QgsFeatureRenderer* renderer = nullptr );
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~QgsVectorLayerLabelProvider();
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virtual QList<QgsLabelFeature*> labelFeatures( QgsRenderContext& context ) override;
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virtual void drawLabel( QgsRenderContext& context, pal::LabelPosition* label ) const override;
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// new virtual methods
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/**
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* Prepare for registration of features. Must be called after provider has been added to engine (uses its map settings)
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* @param context render context.
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* @param attributeNames list of attribute names to which additional required attributes shall be added
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* @return Whether the preparation was successful - if not, the provider shall not be used
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*/
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virtual bool prepare( const QgsRenderContext& context, QSet<QString>& attributeNames );
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/**
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* Register a feature for labeling as one or more QgsLabelFeature objects stored into mLabels
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*
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* @param feature feature to label
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* @param context render context. The QgsExpressionContext contained within the render context
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* must have already had the feature and fields sets prior to calling this method.
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* @param obstacleGeometry optional obstacle geometry, if a different geometry to the feature's geometry
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* should be used as an obstacle for labels (eg, if the feature has been rendered with an offset point
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* symbol, the obstacle geometry should represent the bounds of the offset symbol). If not set,
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* the feature's original geometry will be used as an obstacle for labels.
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*/
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virtual void registerFeature( QgsFeature& feature, QgsRenderContext &context, QgsGeometry* obstacleGeometry = nullptr );
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/** Returns the geometry for a point feature which should be used as an obstacle for labels. This
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* obstacle geometry will respect the dimensions and offsets of the symbol used to render the
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* point, and ensures that labels will not overlap large or offset points.
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* @param fet point feature
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* @param context render context
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* @param symbols symbols rendered for point feature
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* @note added in QGIS 2.14
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*/
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static QgsGeometry* getPointObstacleGeometry( QgsFeature& fet, QgsRenderContext& context, const QgsSymbolList& symbols );
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protected:
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//! initialization method - called from constructors
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void init();
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//! Internal label drawing method
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void drawLabelPrivate( pal::LabelPosition* label, QgsRenderContext& context, QgsPalLayerSettings& tmpLyr, QgsPalLabeling::DrawLabelType drawType, double dpiRatio = 1.0 ) const;
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protected:
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//! Layer's labeling configuration
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QgsPalLayerSettings mSettings;
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//! Geometry type of layer
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QgsWkbTypes::GeometryType mLayerGeometryType;
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QgsFeatureRenderer* mRenderer;
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// these are needed only if using own renderer loop
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//! Layer's fields
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QgsFields mFields;
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//! Layer's CRS
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QgsCoordinateReferenceSystem mCrs;
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//! Layer's feature source
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QgsAbstractFeatureSource* mSource;
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//! Whether layer's feature source is owned
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bool mOwnsSource;
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//! List of generated
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QList<QgsLabelFeature*> mLabels;
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friend class TestQgsLabelingEngine;
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};
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#endif // QGSVECTORLAYERLABELPROVIDER_H
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