QGIS API Documentation  3.6.0-Noosa (5873452)
qgsheatmaprenderer.h
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1 /***************************************************************************
2  qgsheatmaprenderer.h
3  ---------------------
4  begin : November 2014
5  copyright : (C) 2014 Nyall Dawson
6  email : nyall dot dawson 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 #ifndef QGSHEATMAPRENDERER_H
16 #define QGSHEATMAPRENDERER_H
17 
18 #include "qgis_core.h"
19 #include "qgis_sip.h"
20 #include "qgsrenderer.h"
21 #include "qgssymbol.h"
22 #include "qgsexpression.h"
23 #include "qgsgeometry.h"
24 
25 class QgsColorRamp;
26 
33 class CORE_EXPORT QgsHeatmapRenderer : public QgsFeatureRenderer
34 {
35  public:
36 
38  ~QgsHeatmapRenderer() override;
39 
41  QgsHeatmapRenderer( const QgsHeatmapRenderer & ) = delete;
43  QgsHeatmapRenderer &operator=( const QgsHeatmapRenderer & ) = delete;
44 
45  //reimplemented methods
46  QgsHeatmapRenderer *clone() const override SIP_FACTORY;
47  void startRender( QgsRenderContext &context, const QgsFields &fields ) override;
48  bool renderFeature( const QgsFeature &feature, QgsRenderContext &context, int layer = -1, bool selected = false, bool drawVertexMarker = false ) override;
49  void stopRender( QgsRenderContext &context ) override;
51  QgsSymbol *symbolForFeature( const QgsFeature &feature, QgsRenderContext &context ) const override;
53  QgsSymbolList symbols( QgsRenderContext &context ) const override;
54  QString dump() const override;
55  QSet<QString> usedAttributes( const QgsRenderContext &context ) const override;
57  static QgsFeatureRenderer *create( QDomElement &element, const QgsReadWriteContext &context ) SIP_FACTORY;
58  QDomElement save( QDomDocument &doc, const QgsReadWriteContext &context ) override;
59  static QgsHeatmapRenderer *convertFromRenderer( const QgsFeatureRenderer *renderer ) SIP_FACTORY;
60 
61  //reimplemented to extent the request so that points up to heatmap's radius distance outside
62  //visible area are included
63  void modifyRequestExtent( QgsRectangle &extent, QgsRenderContext &context ) override;
64 
65  //heatmap specific methods
66 
72  QgsColorRamp *colorRamp() const { return mGradientRamp; }
73 
79  void setColorRamp( QgsColorRamp *ramp SIP_TRANSFER );
80 
88  double radius() const { return mRadius; }
89 
97  void setRadius( const double radius ) { mRadius = radius; }
98 
106  QgsUnitTypes::RenderUnit radiusUnit() const { return mRadiusUnit; }
107 
115  void setRadiusUnit( const QgsUnitTypes::RenderUnit unit ) { mRadiusUnit = unit; }
116 
124  const QgsMapUnitScale &radiusMapUnitScale() const { return mRadiusMapUnitScale; }
125 
133  void setRadiusMapUnitScale( const QgsMapUnitScale &scale ) { mRadiusMapUnitScale = scale; }
134 
141  double maximumValue() const { return mExplicitMax; }
142 
149  void setMaximumValue( const double value ) { mExplicitMax = value; }
150 
157  double renderQuality() const { return mRenderQuality; }
158 
165  void setRenderQuality( const int quality ) { mRenderQuality = quality; }
166 
172  QString weightExpression() const { return mWeightExpressionString; }
173 
179  void setWeightExpression( const QString &expression ) { mWeightExpressionString = expression; }
180 
181  private:
182 
183  QVector<double> mValues;
184 
185  double mCalculatedMaxValue = 0;
186 
187  double mRadius = 10;
188  int mRadiusPixels = 0;
189  double mRadiusSquared = 0;
191  QgsMapUnitScale mRadiusMapUnitScale;
192 
193  QString mWeightExpressionString;
194  int mWeightAttrNum = -1;
195  std::unique_ptr<QgsExpression> mWeightExpression;
196 
197  QgsColorRamp *mGradientRamp = nullptr;
198 
199  double mExplicitMax = 0.0;
200  int mRenderQuality = 3;
201 
202  int mFeaturesRendered = 0;
203 
204  double uniformKernel( double distance, int bandwidth ) const;
205  double quarticKernel( double distance, int bandwidth ) const;
206  double triweightKernel( double distance, int bandwidth ) const;
207  double epanechnikovKernel( double distance, int bandwidth ) const;
208  double triangularKernel( double distance, int bandwidth ) const;
209 
210  QgsMultiPointXY convertToMultipoint( const QgsGeometry *geom );
211  void initializeValues( QgsRenderContext &context );
212  void renderImage( QgsRenderContext &context );
213 };
214 
215 
216 #endif // QGSHEATMAPRENDERER_H
The class is used as a container of context for various read/write operations on other objects...
A rectangle specified with double values.
Definition: qgsrectangle.h:41
double renderQuality() const
Returns the render quality used for drawing the heatmap.
Abstract base class for all rendered symbols.
Definition: qgssymbol.h:61
virtual QDomElement save(QDomDocument &doc, const QgsReadWriteContext &context)
store renderer info to XML element
Abstract base class for color ramps.
Definition: qgscolorramp.h:31
double maximumValue() const
Returns the maximum value used for shading the heatmap.
Container of fields for a vector layer.
Definition: qgsfields.h:42
A geometry is the spatial representation of a feature.
Definition: qgsgeometry.h:106
void setWeightExpression(const QString &expression)
Sets the expression used for weighting points when generating the heatmap.
QVector< QgsPointXY > QgsMultiPointXY
A collection of QgsPoints that share a common collection of attributes.
Definition: qgsgeometry.h:74
The feature class encapsulates a single feature including its id, geometry and a list of field/values...
Definition: qgsfeature.h:55
virtual QgsSymbol * symbolForFeature(const QgsFeature &feature, QgsRenderContext &context) const =0
To be overridden.
virtual QSet< QString > usedAttributes(const QgsRenderContext &context) const =0
Returns a list of attributes required by this renderer.
QList< QgsSymbol * > QgsSymbolList
Definition: qgsrenderer.h:43
virtual bool renderFeature(const QgsFeature &feature, QgsRenderContext &context, int layer=-1, bool selected=false, bool drawVertexMarker=false)
Render a feature using this renderer in the given context.
A renderer which draws points as a live heatmap.
void setRadiusMapUnitScale(const QgsMapUnitScale &scale)
Sets the map unit scale used for the heatmap&#39;s radius.
virtual void modifyRequestExtent(QgsRectangle &extent, QgsRenderContext &context)
Allows for a renderer to modify the extent of a feature request prior to rendering.
double radius() const
Returns the radius for the heatmap.
const QgsMapUnitScale & radiusMapUnitScale() const
Returns the map unit scale used for the heatmap&#39;s radius.
#define SIP_TRANSFER
Definition: qgis_sip.h:36
QgsColorRamp * colorRamp() const
Returns the color ramp used for shading the heatmap.
#define SIP_FACTORY
Definition: qgis_sip.h:69
void setRenderQuality(const int quality)
Sets the render quality used for drawing the heatmap.
void setRadiusUnit(const QgsUnitTypes::RenderUnit unit)
Sets the units used for the heatmap&#39;s radius.
void setRadius(const double radius)
Sets the radius for the heatmap.
Contains information about the context of a rendering operation.
Struct for storing maximum and minimum scales for measurements in map units.
virtual QgsSymbolList symbols(QgsRenderContext &context) const
Returns list of symbols used by the renderer.
virtual void startRender(QgsRenderContext &context, const QgsFields &fields)
Must be called when a new render cycle is started.
Definition: qgsrenderer.cpp:93
virtual void stopRender(QgsRenderContext &context)
Must be called when a render cycle has finished, to allow the renderer to clean up.
QString weightExpression() const
Returns the expression used for weighting points when generating the heatmap.
void setMaximumValue(const double value)
Sets the maximum value used for shading the heatmap.
QgsUnitTypes::RenderUnit radiusUnit() const
Returns the units used for the heatmap&#39;s radius.
virtual QgsFeatureRenderer * clone() const =0
Create a deep copy of this renderer.
RenderUnit
Rendering size units.
Definition: qgsunittypes.h:111
virtual QString dump() const
Returns debug information about this renderer.