Class: QgsDiagram¶

Base class for all diagram types.

Note

This is an abstract class, with methods which must be implemented by a subclass.

The following methods must be implemented: clone(), diagramName(), diagramSize(), legendSize(), renderDiagram()

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.

Abstract Methods

`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.
`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)

Methods

`clearCache`
`getExpression`	Returns a prepared expression for the specified context.
`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[source]¶

Bases: object

clearCache(self)[source]¶

abstract clone(self) → QgsDiagram | None[source]¶

Returns an instance that is equivalent to this one

Return type:: Optional[QgsDiagram]

abstract diagramName(self) → str[source]¶

Gets a descriptive name for this diagram type.

Return type:: str

abstract diagramSize(self, attributes: Any, c: QgsRenderContext, s: QgsDiagramSettings) → QSizeF[source]¶

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

Parameters:

attributes (Any)
c (QgsRenderContext)
s (QgsDiagramSettings)

Return type:

QSizeF

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

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[source]¶

Returns a prepared expression for the specified context.

Parameters:

expression (Optional[str]) – expression string
context (QgsExpressionContext) – expression context

Return type:

Optional[QgsExpression]

abstract legendSize(self, value: float, s: QgsDiagramSettings, interpolationSettings: QgsDiagramInterpolationSettings) → float[source]¶

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

abstract renderDiagram(self, feature: QgsFeature, c: QgsRenderContext, s: QgsDiagramSettings, position: QPointF | QPoint)[source]¶

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[source]¶

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)[source]¶

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[source]¶

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[source]¶

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[source]

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