QgsPointDisplacementRenderer class

A renderer that automatically displaces points with the same geographic location.

Reference

Base classes

class QgsPointDistanceRenderer: An abstract base class for distance based point renderers (e.g., clusterer and displacement renderers).

Public types

enum Placement { Ring, ConcentricRings, Grid }: Placement methods for dispersing points.

Public static functions

static auto convertFromRenderer(const QgsFeatureRenderer* renderer) -> QgsPointDisplacementRenderer*: Creates a QgsPointDisplacementRenderer from an existing renderer.
static auto create(QDomElement& symbologyElem, const QgsReadWriteContext& context) -> QgsFeatureRenderer*: Create a renderer from XML element.

Constructors, destructors, conversion operators

QgsPointDisplacementRenderer(const QString& labelAttributeName = QString()): Constructor for QgsPointDisplacementRenderer.

Public functions

auto centerSymbol() -> QgsMarkerSymbol*: Returns the symbol for the center of a displacement group (but not ownership of the symbol).
auto circleColor() const -> QColor: Returns the color used for drawing the displacement group circle.
auto circleRadiusAddition() const -> double: Returns the factor for increasing the ring size of displacement groups.
auto circleWidth() const -> double: Returns the line width for the displacement group circle in mm.
auto clone() const -> QgsPointDisplacementRenderer* override: Create a deep copy of this renderer.
auto placement() const -> Placement: Returns the placement method used for dispersing the points.
auto save(QDomDocument& doc, const QgsReadWriteContext& context) -> QDomElement override: store renderer info to XML element
void setCenterSymbol(QgsMarkerSymbol* symbol): Sets the center symbol for a displacement group.
void setCircleColor(const QColor& color): Sets the color used for drawing the displacement group circle.
void setCircleRadiusAddition(double distance): Sets a factor for increasing the ring size of displacement groups.
void setCircleWidth(double width): Sets the line width for the displacement group circle.
void setPlacement(Placement placement): Sets the placement method used for dispersing the points.
void startRender(QgsRenderContext& context, const QgsFields& fields) override: Must be called when a new render cycle is started.
void stopRender(QgsRenderContext& context) override: Must be called when a render cycle has finished, to allow the renderer to clean up.
auto usedAttributes(const QgsRenderContext& context) const -> QSet<QString> override: Returns a list of attributes required by this renderer.

Enum documentation

enum QgsPointDisplacementRenderer::Placement

Placement methods for dispersing points.

Enumerators
Ring	Place points in a single ring around group.
ConcentricRings	Place points in concentric rings around group.
Grid	Place points in a grid around group.

Function documentation

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

Creates a QgsPointDisplacementRenderer from an existing renderer.

Returns	a new renderer if the conversion was possible, otherwise nullptr.

QgsPointDisplacementRenderer::QgsPointDisplacementRenderer(const QString& labelAttributeName = QString())

Constructor for QgsPointDisplacementRenderer.

Parameters
labelAttributeName	optional attribute name for labeling points

QgsMarkerSymbol* QgsPointDisplacementRenderer::centerSymbol()

Returns the symbol for the center of a displacement group (but not ownership of the symbol).

QColor QgsPointDisplacementRenderer::circleColor() const

Returns the color used for drawing the displacement group circle.

double QgsPointDisplacementRenderer::circleRadiusAddition() const

Returns the factor for increasing the ring size of displacement groups.

double QgsPointDisplacementRenderer::circleWidth() const

Returns the line width for the displacement group circle in mm.

QgsPointDisplacementRenderer* QgsPointDisplacementRenderer::clone() const override

Create a deep copy of this renderer.

Returns	A copy of this renderer

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

Placement QgsPointDisplacementRenderer::placement() const

Returns the placement method used for dispersing the points.

void QgsPointDisplacementRenderer::setCenterSymbol(QgsMarkerSymbol* symbol)

Sets the center symbol for a displacement group.

Parameters
symbol	new center symbol. Ownership is transferred to the renderer.

void QgsPointDisplacementRenderer::setCircleColor(const QColor& color)

Sets the color used for drawing the displacement group circle.

Parameters
color	circle color

void QgsPointDisplacementRenderer::setCircleRadiusAddition(double distance)

Sets a factor for increasing the ring size of displacement groups.

Parameters
distance	addition factor

void QgsPointDisplacementRenderer::setCircleWidth(double width)

Sets the line width for the displacement group circle.

Parameters
width	line width in mm

void QgsPointDisplacementRenderer::setPlacement(Placement placement)

Sets the placement method used for dispersing the points.

Parameters
placement	placement method

void QgsPointDisplacementRenderer::startRender(QgsRenderContext& context, const QgsFields& fields) override

Must be called when a new render cycle is started.

Parameters
context	Additional information passed to the renderer about the job which will be rendered
fields	The fields available for rendering

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

void QgsPointDisplacementRenderer::stopRender(QgsRenderContext& context) override

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().

QSet<QString> QgsPointDisplacementRenderer::usedAttributes(const QgsRenderContext& context) const override

Returns a list of attributes required by this renderer.

Returns	A set of attributes

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