Class: QgsColorRampTransformer

QgsPropertyTransformer subclass for transforming a numeric value into a color from a color ramp.

Class Hierarchy

Base classes

QgsPropertyTransformer

Abstract base class for objects which transform the calculated value of a property. Possible uses include transformers which map a value into a scaled size or color from a gradient.

Methods

color	Calculates the color corresponding to a specific value.
colorRamp	Returns the color ramp used for calculating property colors.
nullColor	Returns the color corresponding to a null value.
rampName	Returns the color ramp's name.
setColorRamp	Sets the color ramp to use for calculating property colors.
setNullColor	Sets the color corresponding to a null value.
setRampName	Sets the color ramp's name.

class qgis.core.QgsColorRampTransformer

Bases: QgsPropertyTransformer

__init__(minValue: float = 0, maxValue: float = 1, ramp: QgsColorRamp | None = None, nullColor: QColor | Qt.GlobalColor = QColor(0, 0, 0, 0), rampName: str | None = '')

Constructor for QgsColorRampTransformer.

Parameters:

• minValue (float = 0) – minimum expected value

• maxValue (float = 1) – maximum expected value

• ramp (Optional[QgsColorRamp] = None) – source color ramp. Ownership is transferred to the transformer.

• nullColor (Union[QColor, Qt.GlobalColor] = QColor(0, 0, 0, 0)) – color to return for null values

• rampName (Optional[str] = '') – name of the source color ramp (since QGIS 3.36)

__init__(other: QgsColorRampTransformer)

Parameters:

other (QgsColorRampTransformer)

color(self, value: float) → QColor

Calculates the color corresponding to a specific value.

Parameters:

value (float) – value to calculate color for

Return type:

QColor

Returns:

calculated color using transformer’s parameters and type

colorRamp(self) → QgsColorRamp | None

Returns the color ramp used for calculating property colors.

Return type:

Optional[QgsColorRamp]

Returns:

color ramp

See also

setColorRamp()

nullColor(self) → QColor

Returns the color corresponding to a null value.

See also

setNullColor()

Return type:

QColor

rampName(self) → str

Returns the color ramp’s name.

See also

setRampName()

Return type:

str

setColorRamp(self, ramp: QgsColorRamp | None)

Sets the color ramp to use for calculating property colors.

Parameters:

ramp (Optional[QgsColorRamp]) – color ramp, ownership of ramp is transferred to the transformer.

See also

colorRamp()

setNullColor(self, color: QColor | Qt.GlobalColor)

Sets the color corresponding to a null value.

Parameters:

color (Union[QColor, Qt.GlobalColor]) – null color

See also

nullColor()

setRampName(self, name: str | None)

Sets the color ramp’s name. The ramp name must be set to match a color ramp available in the style database for conversion to expression to work correctly.

See also

rampName()

Parameters:

name (Optional[str])