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

Inheritance diagram of qgis.core.QgsDiagram

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.
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.

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:
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:
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:
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:
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

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 – The length to convert

  • s – The settings that specify the size type

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

Return type:

QSizeF

Returns:

The converted length for rendering