Class: QgsDiagram

Base class for all diagram types.

Class Hierarchy

Subclasses

QgsHistogramDiagram	A histogram style diagram.
QgsPieDiagram	A pie chart diagram.
QgsStackedBarDiagram	A stacked bar chart diagram.
QgsStackedDiagram	A diagram composed of several subdiagrams, located side by side.
QgsTextDiagram	A text based diagram.

Methods

clearCache
clone	Returns an instance that is equivalent to this one
diagramName	Gets a descriptive name for this diagram type.
diagramSize	Returns the size in map units the diagram will use to render.
getExpression	Returns a prepared expression for the specified context.
legendSize	Returns the size of the legend item for the diagram corresponding to a specified value.
renderDiagram	Draws the diagram at the given position (in pixel coordinates)
scaledFont	Calculates a size to match the current settings and rendering context
setPenWidth	Changes the pen width to match the current settings and rendering context
sizeForValue	Returns the scaled size of a diagram for a value, respecting the specified diagram interpolation settings.
sizePainterUnits	Calculates a size to match the current settings and rendering context

class qgis.core.QgsDiagram

Bases: object

clearCache(self)

clone(self) → QgsDiagram | None

Returns an instance that is equivalent to this one

Return type:

Optional[QgsDiagram]

diagramName(self) → str

Gets a descriptive name for this diagram type.

Return type:

str

diagramSize(self, attributes: Any, c: QgsRenderContext, s: QgsDiagramSettings) → QSizeF

Returns the size in map units the diagram will use to render.

Parameters:

• attributes (Any)

• c (QgsRenderContext)

• s (QgsDiagramSettings)

Return type:

QSizeF

diagramSize(self, feature: QgsFeature, c: QgsRenderContext, s: QgsDiagramSettings, interpolationSettings: QgsDiagramInterpolationSettings) → QSizeF

Returns the size in map units the diagram will use to render. Interpolate size

Parameters:

• feature (QgsFeature)

• c (QgsRenderContext)

• s (QgsDiagramSettings)

• interpolationSettings (QgsDiagramInterpolationSettings)

Return type:

QSizeF

getExpression(self, expression: str | None, context: QgsExpressionContext) → QgsExpression | None

Returns a prepared expression for the specified context.

Parameters:

• expression (Optional[str]) – expression string

• context (QgsExpressionContext) – expression context

Return type:

Optional[QgsExpression]

legendSize(self, value: float, s: QgsDiagramSettings, interpolationSettings: QgsDiagramInterpolationSettings) → float

Returns the size of the legend item for the diagram corresponding to a specified value.

Parameters:

• value (float) – value to return legend item size for

• s (QgsDiagramSettings) – diagram settings

• interpolationSettings (QgsDiagramInterpolationSettings) – interpolation settings

Return type:

float

renderDiagram(self, feature: QgsFeature, c: QgsRenderContext, s: QgsDiagramSettings, position: QPointF | QPoint)

Draws the diagram at the given position (in pixel coordinates)

Parameters:

• feature (QgsFeature)

• c (QgsRenderContext)

• s (QgsDiagramSettings)

• position (Union[QPointF, QPoint])

scaledFont(self, s: QgsDiagramSettings, c: QgsRenderContext) → QFont

Calculates a size to match the current settings and rendering context

Parameters:

• s (QgsDiagramSettings) – The settings that contain the font size and size type

• c (QgsRenderContext) – The rendering specifying the proper scale units for pixel conversion

Return type:

QFont

Returns:

The properly scaled font for rendering

setPenWidth(self, pen: QPen | QColor | Qt.GlobalColor, s: QgsDiagramSettings, c: QgsRenderContext)

Changes the pen width to match the current settings and rendering context

Parameters:

• pen (Union[QPen, Union[QColor, Qt.GlobalColor]]) – The pen to modify

• s (QgsDiagramSettings) – The settings that specify the pen width

• c (QgsRenderContext) – The rendering specifying the proper scale units for pixel conversion

sizeForValue(self, value: float, s: QgsDiagramSettings, interpolationSettings: QgsDiagramInterpolationSettings) → QSizeF

Returns the scaled size of a diagram for a value, respecting the specified diagram interpolation settings.

Parameters:

• value (float) – value to calculate corresponding circular size for

• s (QgsDiagramSettings) – diagram settings

• interpolationSettings (QgsDiagramInterpolationSettings) – interpolation settings

Return type:

QSizeF

sizePainterUnits(self, size: QSizeF, s: QgsDiagramSettings, c: QgsRenderContext) → QSizeF

Calculates a size to match the current settings and rendering context

Parameters:

• size (QSizeF) – The size to convert

• s (QgsDiagramSettings) – The settings that specify the size type

• c (QgsRenderContext) – The rendering specifying the proper scale units for pixel conversion

Return type:

QSizeF

Returns:

The converted size for rendering

sizePainterUnits(self, l: float, s: QgsDiagramSettings, c: QgsRenderContext) → float

Calculates a length to match the current settings and rendering context

Parameters:

• l (float) – The length to convert

• s (QgsDiagramSettings) – The settings that specify the size type

• c (QgsRenderContext) – The rendering specifying the proper scale units for pixel conversion

Return type:

float

Returns:

The converted length for rendering