QgsColorRampShader class

A ramp shader will color a raster pixel based on a list of values ranges in a ramp.

Reference

Base classes

class QgsRasterShaderFunction: The raster shade function applies a shader to a pixel at render time - typically used to render grayscale images as false color.

Public types

enum ClassificationMode { Continuous = 1, EqualInterval = 2, Quantile = 3 }: Classification modes used to create the color ramp shader.
enum Type { Interpolated, Discrete, Exact }: Supported methods for color interpolation.

Constructors, destructors, conversion operators

QgsColorRampShader(double minimumValue = 0.0, double maximumValue = 255.0, QgsColorRamp* colorRamp = nullptr, Type type = Interpolated, ClassificationMode classificationMode = Continuous): Creates a new color ramp shader.
QgsColorRampShader(const QgsColorRampShader& other): Copy constructor.

Public functions

auto classificationMode() const -> ClassificationMode: Returns the classification mode.
void classifyColorRamp(int classes = 0, int band = -1, const QgsRectangle& extent = QgsRectangle(), QgsRasterInterface* input = nullptr): Classify color ramp shader.
void classifyColorRamp(int band = -1, const QgsRectangle& extent = QgsRectangle(), QgsRasterInterface* input = nullptr): Classify color ramp shader.
auto clip() const -> bool: Returns whether the shader will clip values which are out of range.
auto colorRampItemList() const -> QList<QgsColorRampShader::ColorRampItem>: Returns the custom colormap.
auto colorRampType() const -> Type: Returns the color ramp type.
auto colorRampTypeAsQString() const -> QString: Returns the color ramp type as a string.
auto isEmpty() const -> bool: Whether the color ramp contains any items.
void legendSymbologyItems(QList<QPair<QString, QColor>>& symbolItems) const override: Returns legend symbology items if provided by renderer.
auto operator=(const QgsColorRampShader& other) -> QgsColorRampShader&: Assignment operator.
void readXml(const QDomElement& elem): Reads configuration from the given DOM element.
void setClassificationMode(ClassificationMode classificationMode): Sets classification mode.
void setClip(bool clip): Sets whether the shader should not render values out of range.
void setColorRampItemList(const QList<QgsColorRampShader::ColorRampItem>& list): Sets a custom colormap.
void setColorRampType(QgsColorRampShader::Type colorRampType): Sets the color ramp type.
void setColorRampType(const QString& type): Sets the color ramp type.
void setSourceColorRamp(QgsColorRamp* colorramp): Set the source color ramp.
auto shade(double value, int* returnRedValue, int* returnGreenValue, int* returnBlueValue, int* returnAlphaValue) const -> bool override: Generates and new RGB value based on one input value.
auto shade(double redValue, double greenValue, double blueValue, double alphaValue, int* returnRedValue, int* returnGreenValue, int* returnBlueValue, int* returnAlphaValue) const -> bool override: Generates and new RGB value based on original RGB value.
auto sourceColorRamp() const -> QgsColorRamp*: Gets the source color ramp.
auto writeXml(QDomDocument& doc) const -> QDomElement: Writes configuration to a new DOM element.

Protected variables

std::unique_ptr<QgsColorRamp> mSourceColorRamp: Source color ramp.

Enum documentation

enum QgsColorRampShader::ClassificationMode

Classification modes used to create the color ramp shader.

Enumerators
Continuous	Uses breaks from color palette.
EqualInterval	Uses equal interval.
Quantile	Uses quantile (i.e. equal pixel) count.

enum QgsColorRampShader::Type

Supported methods for color interpolation.

Enumerators
Interpolated	Interpolates the color between two class breaks linearly.
Discrete	Assigns the color of the higher class for every pixel between two class breaks.
Exact	Assigns the color of the exact matching value in the color ramp item list.

Function documentation

QgsColorRampShader::QgsColorRampShader(double minimumValue = 0.0, double maximumValue = 255.0, QgsColorRamp* colorRamp = nullptr, Type type = Interpolated, ClassificationMode classificationMode = Continuous)

Creates a new color ramp shader.

Parameters
minimumValue	minimum value for the raster shader
maximumValue	maximum value for the raster shader
colorRamp	vector color ramp used to classify the color ramp shader. Ownership is transferred to the shader.
type	interpolation type used
classificationMode	method used to classify the color ramp shader
Returns	new QgsColorRampShader

void QgsColorRampShader::classifyColorRamp(int classes = 0, int band = -1, const QgsRectangle& extent = QgsRectangle(), QgsRasterInterface* input = nullptr)

Classify color ramp shader.

Parameters
classes	number of classes
band	raster band used in classification (only used in quantile mode)
extent	extent used in classification (only used in quantile mode)
input	raster input used in classification (only used in quantile mode)

void QgsColorRampShader::classifyColorRamp(int band = -1, const QgsRectangle& extent = QgsRectangle(), QgsRasterInterface* input = nullptr)

Classify color ramp shader.

Parameters
band	raster band used in classification (quantile mode only)
extent	extent used in classification (quantile mode only)
input	raster input used in classification (quantile mode only)

bool QgsColorRampShader::clip() const

Returns whether the shader will clip values which are out of range.

bool QgsColorRampShader::isEmpty() const

Whether the color ramp contains any items.

void QgsColorRampShader::readXml(const QDomElement& elem)

Reads configuration from the given DOM element.

void QgsColorRampShader::setClip(bool clip)

Sets whether the shader should not render values out of range.

Parameters
clip	set to true to clip values which are out of range.

void QgsColorRampShader::setSourceColorRamp(QgsColorRamp* colorramp)

Set the source color ramp.

Ownership is transferred to the shader.

QgsColorRamp* QgsColorRampShader::sourceColorRamp() const

Gets the source color ramp.

QDomElement QgsColorRampShader::writeXml(QDomDocument& doc) const

Writes configuration to a new DOM element.