QGIS API Documentation  3.11.0-Master (68611307d7)
Public Member Functions | Static Public Member Functions | List of all members
QgsHeatmapRenderer Class Reference

A renderer which draws points as a live heatmap. More...

#include <qgsheatmaprenderer.h>

Inheritance diagram for QgsHeatmapRenderer:
Inheritance graph
[legend]

Public Member Functions

 QgsHeatmapRenderer ()
 
 QgsHeatmapRenderer (const QgsHeatmapRenderer &)=delete
 Direct copies are forbidden. Use clone() instead. More...
 
 ~QgsHeatmapRenderer () override
 
bool accept (QgsStyleEntityVisitorInterface *visitor) const override
 Accepts the specified symbology visitor, causing it to visit all symbols associated with the renderer. More...
 
QgsHeatmapRendererclone () const override
 Create a deep copy of this renderer. More...
 
QgsColorRampcolorRamp () const
 Returns the color ramp used for shading the heatmap. More...
 
QString dump () const override
 Returns debug information about this renderer. More...
 
double maximumValue () const
 Returns the maximum value used for shading the heatmap. More...
 
void modifyRequestExtent (QgsRectangle &extent, QgsRenderContext &context) override
 Allows for a renderer to modify the extent of a feature request prior to rendering. More...
 
QgsHeatmapRendereroperator= (const QgsHeatmapRenderer &)=delete
 Direct copies are forbidden. Use clone() instead. More...
 
double radius () const
 Returns the radius for the heatmap. More...
 
const QgsMapUnitScaleradiusMapUnitScale () const
 Returns the map unit scale used for the heatmap's radius. More...
 
QgsUnitTypes::RenderUnit radiusUnit () const
 Returns the units used for the heatmap's radius. More...
 
bool renderFeature (const QgsFeature &feature, QgsRenderContext &context, int layer=-1, bool selected=false, bool drawVertexMarker=false) override SIP_THROW(QgsCsException)
 Render a feature using this renderer in the given context. More...
 
double renderQuality () const
 Returns the render quality used for drawing the heatmap. More...
 
QDomElement save (QDomDocument &doc, const QgsReadWriteContext &context) override
 store renderer info to XML element More...
 
void setColorRamp (QgsColorRamp *ramp)
 Sets the color ramp to use for shading the heatmap. More...
 
void setMaximumValue (const double value)
 Sets the maximum value used for shading the heatmap. More...
 
void setRadius (const double radius)
 Sets the radius for the heatmap. More...
 
void setRadiusMapUnitScale (const QgsMapUnitScale &scale)
 Sets the map unit scale used for the heatmap's radius. More...
 
void setRadiusUnit (const QgsUnitTypes::RenderUnit unit)
 Sets the units used for the heatmap's radius. More...
 
void setRenderQuality (const int quality)
 Sets the render quality used for drawing the heatmap. More...
 
void setWeightExpression (const QString &expression)
 Sets the expression used for weighting points when generating the heatmap. More...
 
void startRender (QgsRenderContext &context, const QgsFields &fields) override
 Must be called when a new render cycle is started. More...
 
void stopRender (QgsRenderContext &context) override
 Must be called when a render cycle has finished, to allow the renderer to clean up. More...
 
QgsSymbolsymbolForFeature (const QgsFeature &feature, QgsRenderContext &context) const override
 
QgsSymbolList symbols (QgsRenderContext &context) const override
 
QSet< QString > usedAttributes (const QgsRenderContext &context) const override
 Returns a list of attributes required by this renderer. More...
 
QString weightExpression () const
 Returns the expression used for weighting points when generating the heatmap. More...
 
- Public Member Functions inherited from QgsFeatureRenderer
virtual ~QgsFeatureRenderer ()
 
virtual QgsFeatureRenderer::Capabilities capabilities ()
 Returns details about internals of this renderer. More...
 
virtual void checkLegendSymbolItem (const QString &key, bool state=true)
 item in symbology was checked More...
 
virtual const QgsFeatureRendererembeddedRenderer () const
 Returns the current embedded renderer (subrenderer) for this feature renderer. More...
 
virtual QString filter (const QgsFields &fields=QgsFields())
 If a renderer does not require all the features this method may be overridden and return an expression used as where clause. More...
 
virtual bool filterNeedsGeometry () const
 Returns true if this renderer requires the geometry to apply the filter. More...
 
bool forceRasterRender () const
 Returns whether the renderer must render as a raster. More...
 
virtual QString legendClassificationAttribute () const
 If supported by the renderer, return classification attribute for the use in legend. More...
 
virtual QSet< QString > legendKeysForFeature (const QgsFeature &feature, QgsRenderContext &context) const
 Returns legend keys matching a specified feature. More...
 
virtual bool legendSymbolItemChecked (const QString &key)
 items of symbology items in legend is checked More...
 
virtual QgsLegendSymbolList legendSymbolItems () const
 Returns a list of symbology items for the legend. More...
 
virtual bool legendSymbolItemsCheckable () const
 items of symbology items in legend should be checkable More...
 
QgsFeatureRequest::OrderBy orderBy () const
 Gets the order in which features shall be processed by this renderer. More...
 
bool orderByEnabled () const
 Returns whether custom ordering will be applied before features are processed by this renderer. More...
 
virtual QgsSymboloriginalSymbolForFeature (const QgsFeature &feature, QgsRenderContext &context) const
 Returns symbol for feature. More...
 
virtual QgsSymbolList originalSymbolsForFeature (const QgsFeature &feature, QgsRenderContext &context) const
 Equivalent of originalSymbolsForFeature() call extended to support renderers that may use more symbols per feature - similar to symbolsForFeature() More...
 
QgsPaintEffectpaintEffect () const
 Returns the current paint effect for the renderer. More...
 
virtual void setEmbeddedRenderer (QgsFeatureRenderer *subRenderer)
 Sets an embedded renderer (subrenderer) for this feature renderer. More...
 
void setForceRasterRender (bool forceRaster)
 Sets whether the renderer should be rendered to a raster destination. More...
 
virtual void setLegendSymbolItem (const QString &key, QgsSymbol *symbol)
 Sets the symbol to be used for a legend symbol item. More...
 
void setOrderBy (const QgsFeatureRequest::OrderBy &orderBy)
 Define the order in which features shall be processed by this renderer. More...
 
void setOrderByEnabled (bool enabled)
 Sets whether custom ordering should be applied before features are processed by this renderer. More...
 
void setPaintEffect (QgsPaintEffect *effect)
 Sets the current paint effect for the renderer. More...
 
void setUsingSymbolLevels (bool usingSymbolLevels)
 
void setVertexMarkerAppearance (int type, double size)
 Sets type and size of editing vertex markers for subsequent rendering. More...
 
virtual QgsSymbolList symbolsForFeature (const QgsFeature &feature, QgsRenderContext &context) const
 Returns list of symbols used for rendering the feature. More...
 
virtual void toSld (QDomDocument &doc, QDomElement &element, const QgsStringMap &props=QgsStringMap()) const
 used from subclasses to create SLD Rule elements following SLD v1.1 specs More...
 
QString type () const
 
bool usingSymbolLevels () const
 
virtual bool willRenderFeature (const QgsFeature &feature, QgsRenderContext &context) const
 Returns whether the renderer will render a feature or not. More...
 
virtual QDomElement writeSld (QDomDocument &doc, const QString &styleName, const QgsStringMap &props=QgsStringMap()) const
 create the SLD UserStyle element following the SLD v1.1 specs with the given name More...
 

Static Public Member Functions

static QgsHeatmapRendererconvertFromRenderer (const QgsFeatureRenderer *renderer)
 
static QgsFeatureRenderercreate (QDomElement &element, const QgsReadWriteContext &context)
 Creates a new heatmap renderer instance from XML. More...
 
- Static Public Member Functions inherited from QgsFeatureRenderer
static QgsFeatureRendererdefaultRenderer (QgsWkbTypes::GeometryType geomType)
 Returns a new renderer - used by default in vector layers. More...
 
static QgsFeatureRendererload (QDomElement &symbologyElem, const QgsReadWriteContext &context)
 create a renderer from XML element More...
 
static QgsFeatureRendererloadSld (const QDomNode &node, QgsWkbTypes::GeometryType geomType, QString &errorMessage)
 Create a new renderer according to the information contained in the UserStyle element of a SLD style document. More...
 

Additional Inherited Members

- Public Types inherited from QgsFeatureRenderer
enum  Capability { SymbolLevels = 1, MoreSymbolsPerFeature = 1 << 2, Filter = 1 << 3, ScaleDependent = 1 << 4 }
 Used to specify details about a renderer. More...
 
- Protected Member Functions inherited from QgsFeatureRenderer
 QgsFeatureRenderer (const QString &type)
 
void copyRendererData (QgsFeatureRenderer *destRenderer) const
 Clones generic renderer data to another renderer. More...
 
void renderFeatureWithSymbol (const QgsFeature &feature, QgsSymbol *symbol, QgsRenderContext &context, int layer, bool selected, bool drawVertexMarker) SIP_THROW(QgsCsException)
 Render the feature with the symbol using context. More...
 
void renderVertexMarker (QPointF pt, QgsRenderContext &context)
 render editing vertex marker at specified point More...
 
void renderVertexMarkerPolygon (QPolygonF &pts, QList< QPolygonF > *rings, QgsRenderContext &context)
 render editing vertex marker for a polygon More...
 
void renderVertexMarkerPolyline (QPolygonF &pts, QgsRenderContext &context)
 render editing vertex marker for a polyline More...
 
- Static Protected Member Functions inherited from QgsFeatureRenderer
static QPointF _getPoint (QgsRenderContext &context, const QgsPoint &point)
 Creates a point in screen coordinates from a wkb string in map coordinates. More...
 
static void convertSymbolRotation (QgsSymbol *symbol, const QString &field)
 
static void convertSymbolSizeScale (QgsSymbol *symbol, QgsSymbol::ScaleMethod method, const QString &field)
 
- Protected Attributes inherited from QgsFeatureRenderer
double mCurrentVertexMarkerSize
 The current size of editing marker. More...
 
int mCurrentVertexMarkerType
 The current type of editing marker. More...
 
bool mForceRaster
 
QgsFeatureRequest::OrderBy mOrderBy
 
bool mOrderByEnabled
 
QgsPaintEffectmPaintEffect = nullptr
 
QString mType
 
bool mUsingSymbolLevels
 

Detailed Description

A renderer which draws points as a live heatmap.

Since
QGIS 2.7

Definition at line 33 of file qgsheatmaprenderer.h.

Constructor & Destructor Documentation

◆ QgsHeatmapRenderer() [1/2]

QgsHeatmapRenderer::QgsHeatmapRenderer ( )

Definition at line 35 of file qgsheatmaprenderer.cpp.

◆ ~QgsHeatmapRenderer()

QgsHeatmapRenderer::~QgsHeatmapRenderer ( )
override

Definition at line 41 of file qgsheatmaprenderer.cpp.

◆ QgsHeatmapRenderer() [2/2]

QgsHeatmapRenderer::QgsHeatmapRenderer ( const QgsHeatmapRenderer )
delete

Direct copies are forbidden. Use clone() instead.

Member Function Documentation

◆ accept()

bool QgsHeatmapRenderer::accept ( QgsStyleEntityVisitorInterface visitor) const
overridevirtual

Accepts the specified symbology visitor, causing it to visit all symbols associated with the renderer.

Returns true if the visitor should continue visiting other objects, or false if visiting should be canceled.

Since
QGIS 3.10

Reimplemented from QgsFeatureRenderer.

Definition at line 399 of file qgsheatmaprenderer.cpp.

◆ clone()

QgsHeatmapRenderer * QgsHeatmapRenderer::clone ( ) const
overridevirtual

Create a deep copy of this renderer.

Should be implemented by all subclasses and generate a proper subclass.

Returns
A copy of this renderer

Implements QgsFeatureRenderer.

Definition at line 279 of file qgsheatmaprenderer.cpp.

◆ colorRamp()

QgsColorRamp* QgsHeatmapRenderer::colorRamp ( ) const
inline

Returns the color ramp used for shading the heatmap.

Returns
color ramp for heatmap
See also
setColorRamp

Definition at line 73 of file qgsheatmaprenderer.h.

◆ convertFromRenderer()

QgsHeatmapRenderer * QgsHeatmapRenderer::convertFromRenderer ( const QgsFeatureRenderer renderer)
static

Definition at line 387 of file qgsheatmaprenderer.cpp.

◆ create()

QgsFeatureRenderer * QgsHeatmapRenderer::create ( QDomElement &  element,
const QgsReadWriteContext context 
)
static

Creates a new heatmap renderer instance from XML.

Definition at line 308 of file qgsheatmaprenderer.cpp.

◆ dump()

QString QgsHeatmapRenderer::dump ( ) const
overridevirtual

Returns debug information about this renderer.

Reimplemented from QgsFeatureRenderer.

Definition at line 274 of file qgsheatmaprenderer.cpp.

◆ maximumValue()

double QgsHeatmapRenderer::maximumValue ( ) const
inline

Returns the maximum value used for shading the heatmap.

Returns
maximum value for heatmap shading. If 0, then maximum value will be automatically calculated.
See also
setMaximumValue

Definition at line 142 of file qgsheatmaprenderer.h.

◆ modifyRequestExtent()

void QgsHeatmapRenderer::modifyRequestExtent ( QgsRectangle extent,
QgsRenderContext context 
)
overridevirtual

Allows for a renderer to modify the extent of a feature request prior to rendering.

Parameters
extentreference to request's filter extent. Modify extent to change the extent of feature request
contextrender context
Since
QGIS 2.7

Reimplemented from QgsFeatureRenderer.

Definition at line 297 of file qgsheatmaprenderer.cpp.

◆ operator=()

QgsHeatmapRenderer& QgsHeatmapRenderer::operator= ( const QgsHeatmapRenderer )
delete

Direct copies are forbidden. Use clone() instead.

◆ radius()

double QgsHeatmapRenderer::radius ( ) const
inline

Returns the radius for the heatmap.

Returns
heatmap radius
See also
setRadius
radiusUnit
radiusMapUnitScale

Definition at line 89 of file qgsheatmaprenderer.h.

◆ radiusMapUnitScale()

const QgsMapUnitScale& QgsHeatmapRenderer::radiusMapUnitScale ( ) const
inline

Returns the map unit scale used for the heatmap's radius.

Returns
map unit scale for heatmap's radius
See also
radius
radiusUnit
setRadiusMapUnitScale

Definition at line 125 of file qgsheatmaprenderer.h.

◆ radiusUnit()

QgsUnitTypes::RenderUnit QgsHeatmapRenderer::radiusUnit ( ) const
inline

Returns the units used for the heatmap's radius.

Returns
units for heatmap radius
See also
radius
setRadiusUnit
radiusMapUnitScale

Definition at line 107 of file qgsheatmaprenderer.h.

◆ renderFeature()

bool QgsHeatmapRenderer::renderFeature ( const QgsFeature feature,
QgsRenderContext context,
int  layer = -1,
bool  selected = false,
bool  drawVertexMarker = false 
)
overridevirtual

Render a feature using this renderer in the given context.

Must be called between startRender() and stopRender() calls. Default implementation renders a symbol as determined by symbolForFeature() call. Returns true if the feature has been returned (this is used for example to determine whether the feature may be labelled).

If layer is not -1, the renderer should draw only a particula layer from symbols (in order to support symbol level rendering).

See also
startRender()
stopRender()

Reimplemented from QgsFeatureRenderer.

Definition at line 91 of file qgsheatmaprenderer.cpp.

◆ renderQuality()

double QgsHeatmapRenderer::renderQuality ( ) const
inline

Returns the render quality used for drawing the heatmap.

Returns
render quality. A value of 1 indicates maximum quality, and increasing the value will result in faster drawing but lower quality rendering.
See also
setRenderQuality

Definition at line 158 of file qgsheatmaprenderer.h.

◆ save()

QDomElement QgsHeatmapRenderer::save ( QDomDocument &  doc,
const QgsReadWriteContext context 
)
overridevirtual

store renderer info to XML element

Reimplemented from QgsFeatureRenderer.

Definition at line 327 of file qgsheatmaprenderer.cpp.

◆ setColorRamp()

void QgsHeatmapRenderer::setColorRamp ( QgsColorRamp ramp)

Sets the color ramp to use for shading the heatmap.

Parameters
rampcolor ramp for heatmap. Ownership of ramp is transferred to the renderer.
See also
colorRamp

Definition at line 410 of file qgsheatmaprenderer.cpp.

◆ setMaximumValue()

void QgsHeatmapRenderer::setMaximumValue ( const double  value)
inline

Sets the maximum value used for shading the heatmap.

Parameters
valuemaximum value for heatmap shading. Set to 0 for automatic calculation of maximum value.
See also
maximumValue

Definition at line 150 of file qgsheatmaprenderer.h.

◆ setRadius()

void QgsHeatmapRenderer::setRadius ( const double  radius)
inline

Sets the radius for the heatmap.

Parameters
radiusheatmap radius
See also
radius
setRadiusUnit
setRadiusMapUnitScale

Definition at line 98 of file qgsheatmaprenderer.h.

◆ setRadiusMapUnitScale()

void QgsHeatmapRenderer::setRadiusMapUnitScale ( const QgsMapUnitScale scale)
inline

Sets the map unit scale used for the heatmap's radius.

Parameters
scalemap unit scale for heatmap's radius
See also
setRadius
setRadiusUnit
radiusMapUnitScale

Definition at line 134 of file qgsheatmaprenderer.h.

◆ setRadiusUnit()

void QgsHeatmapRenderer::setRadiusUnit ( const QgsUnitTypes::RenderUnit  unit)
inline

Sets the units used for the heatmap's radius.

Parameters
unitunits for heatmap radius
See also
radiusUnit
setRadius
radiusMapUnitScale

Definition at line 116 of file qgsheatmaprenderer.h.

◆ setRenderQuality()

void QgsHeatmapRenderer::setRenderQuality ( const int  quality)
inline

Sets the render quality used for drawing the heatmap.

Parameters
qualityrender quality. A value of 1 indicates maximum quality, and increasing the value will result in faster drawing but lower quality rendering.
See also
renderQuality

Definition at line 166 of file qgsheatmaprenderer.h.

◆ setWeightExpression()

void QgsHeatmapRenderer::setWeightExpression ( const QString &  expression)
inline

Sets the expression used for weighting points when generating the heatmap.

Parameters
expressionpoint weight expression. If set to empty, all points are equally weighted.
See also
weightExpression

Definition at line 180 of file qgsheatmaprenderer.h.

◆ startRender()

void QgsHeatmapRenderer::startRender ( QgsRenderContext context,
const QgsFields fields 
)
overridevirtual

Must be called when a new render cycle is started.

A call to startRender() must always be followed by a corresponding call to stopRender() after all features have been rendered.

Parameters
contextAdditional information passed to the renderer about the job which will be rendered
fieldsThe fields available for rendering
See also
stopRender()
Warning
This method is not thread safe. Before calling startRender() in a non-main thread, the renderer should instead be cloned and startRender()/stopRender() called on the clone.

Reimplemented from QgsFeatureRenderer.

Definition at line 56 of file qgsheatmaprenderer.cpp.

◆ stopRender()

void QgsHeatmapRenderer::stopRender ( QgsRenderContext context)
overridevirtual

Must be called when a render cycle has finished, to allow the renderer to clean up.

Calls to stopRender() must always be preceded by a call to startRender().

Warning
This method is not thread safe. Before calling startRender() in a non-main thread, the renderer should instead be cloned and startRender()/stopRender() called on the clone.
See also
startRender()

Reimplemented from QgsFeatureRenderer.

Definition at line 218 of file qgsheatmaprenderer.cpp.

◆ symbolForFeature()

QgsSymbol * QgsHeatmapRenderer::symbolForFeature ( const QgsFeature feature,
QgsRenderContext context 
) const
overridevirtual
Note
symbolForFeature2 in Python bindings

Implements QgsFeatureRenderer.

Definition at line 359 of file qgsheatmaprenderer.cpp.

◆ symbols()

QgsSymbolList QgsHeatmapRenderer::symbols ( QgsRenderContext context) const
overridevirtual
Note
symbol2 in Python bindings

Reimplemented from QgsFeatureRenderer.

Definition at line 365 of file qgsheatmaprenderer.cpp.

◆ usedAttributes()

QSet< QString > QgsHeatmapRenderer::usedAttributes ( const QgsRenderContext context) const
overridevirtual

Returns a list of attributes required by this renderer.

Attributes not listed in here may not have been requested from the provider at rendering time.

Returns
A set of attributes

Implements QgsFeatureRenderer.

Definition at line 370 of file qgsheatmaprenderer.cpp.

◆ weightExpression()

QString QgsHeatmapRenderer::weightExpression ( ) const
inline

Returns the expression used for weighting points when generating the heatmap.

Returns
point weight expression. If empty, all points are equally weighted.
See also
setWeightExpression

Definition at line 173 of file qgsheatmaprenderer.h.


The documentation for this class was generated from the following files: