QgsDiagramRenderer class

Evaluates and returns the diagram settings relating to a diagram for a specific feature.

Reference

Derived classes

class QgsSingleCategoryDiagramRenderer: Renders the diagrams for all features with the same settings.

Constructors, destructors, conversion operators

QgsDiagramRenderer() defaulted: Constructor for QgsDiagramRenderer.

Public functions

auto attributeLegend() const -> bool: Returns true if renderer will show legend items for diagram attributes.
auto clone() const -> QgsDiagramRenderer* pure virtual: Returns new instance that is equivalent to this one.
auto diagramAttributes() const -> QList<QString> pure virtual: Returns attribute indices needed for diagram rendering.
auto diagramSettings() const -> QList<QgsDiagramSettings> pure virtual: Returns list with all diagram settings in the renderer.
auto legendItems(QgsLayerTreeLayer* nodeLayer) const -> QList<QgsLayerTreeModelLegendNode*> virtual: Returns list of legend nodes for the diagram.
void readXml(const QDomElement& elem, const QgsReadWriteContext& context) pure virtual: Reads diagram state from a DOM element.
auto referencedFields(const QgsExpressionContext& context = QgsExpressionContext()) const -> QSet<QString> virtual: Returns the set of any fields required for diagram rendering.
void renderDiagram(const QgsFeature& feature, QgsRenderContext& c, QPointF pos, const QgsPropertyCollection& properties = QgsPropertyCollection()) const: Renders the diagram for a specified feature at a specific position in the passed render context.
void setAttributeLegend(bool enabled): Sets whether the renderer will show legend items for diagram attributes.
auto sizeMapUnits(const QgsFeature& feature, const QgsRenderContext& c) const -> QSizeF virtual: Returns size of the diagram for a feature in map units. Returns an invalid QSizeF in case of error.
void writeXml(QDomElement& layerElem, QDomDocument& doc, const QgsReadWriteContext& context) const pure virtual: Writes diagram state to a DOM element.

Protected static functions

static auto dpiPaintDevice(const QPainter*) -> int: Returns the paint device dpi (or -1 in case of error.

Protected functions

void _readXml(const QDomElement& elem, const QgsReadWriteContext& context): Reads internal QgsDiagramRenderer state from a DOM element.
void _writeXml(QDomElement& rendererElem, QDomDocument& doc, const QgsReadWriteContext& context) const: Writes internal QgsDiagramRenderer diagram state to a DOM element.
void convertSizeToMapUnits(QSizeF& size, const QgsRenderContext& context) const: Converts size from mm to map units.
auto diagramSettings(const QgsFeature& feature, const QgsRenderContext& c, QgsDiagramSettings& s) const -> bool pure virtual: Returns diagram settings for a feature (or false if the diagram for the feature is not to be rendered).
auto diagramSize(const QgsFeature& features, const QgsRenderContext& c) const -> QSizeF pure virtual: Returns size of the diagram (in painter units) or an invalid size in case of error.

Protected variables

std::unique_ptr<QgsDiagram> mDiagram: Reference to the object that does the real diagram rendering.
bool mShowAttributeLegend: Whether to show an attribute legend for the diagrams.

Function documentation

bool QgsDiagramRenderer::attributeLegend() const

Returns true if renderer will show legend items for diagram attributes.

QgsDiagramRenderer* QgsDiagramRenderer::clone() const pure virtual

Returns new instance that is equivalent to this one.

QList<QgsLayerTreeModelLegendNode> QgsDiagramRenderer::legendItems(QgsLayerTreeLayer nodeLayer) const virtual

Returns list of legend nodes for the diagram.

void QgsDiagramRenderer::readXml(const QDomElement& elem, const QgsReadWriteContext& context) pure virtual

Reads diagram state from a DOM element.

Subclasses should ensure that _readXml() is called by their readXml implementation to restore the general QgsDiagramRenderer settings.

QSet<QString> QgsDiagramRenderer::referencedFields(const QgsExpressionContext& context = QgsExpressionContext()) const virtual

Returns the set of any fields required for diagram rendering.

Parameters
context	expression context the diagrams will be drawn using

void QgsDiagramRenderer::setAttributeLegend(bool enabled)

Sets whether the renderer will show legend items for diagram attributes.

Parameters
enabled	set to true to show diagram attribute legend

void QgsDiagramRenderer::writeXml(QDomElement& layerElem, QDomDocument& doc, const QgsReadWriteContext& context) const pure virtual

Writes diagram state to a DOM element.

Subclasses should ensure that _writeXml() is called by their writeXml implementation to save the general QgsDiagramRenderer settings.

void QgsDiagramRenderer::_readXml(const QDomElement& elem, const QgsReadWriteContext& context) protected

Reads internal QgsDiagramRenderer state from a DOM element.

void QgsDiagramRenderer::_writeXml(QDomElement& rendererElem, QDomDocument& doc, const QgsReadWriteContext& context) const protected

Writes internal QgsDiagramRenderer diagram state to a DOM element.

bool QgsDiagramRenderer::diagramSettings(const QgsFeature& feature, const QgsRenderContext& c, QgsDiagramSettings& s) const pure virtual protected

Returns diagram settings for a feature (or false if the diagram for the feature is not to be rendered).

Parameters
feature	the feature
c	render context
s	out: diagram settings for the feature

Used internally within renderDiagram()