QgsSizeScaleTransformer Class Reference

QgsPropertyTransformer subclass for scaling a value into a size according to various scaling methods. More...

#include <qgspropertytransformer.h>

Inheritance diagram for QgsSizeScaleTransformer:

Public Types
enum	ScaleType { Linear , Area , Flannery , Exponential }
	Size scaling methods. More...
Public Types inherited from QgsPropertyTransformer
enum	Type { GenericNumericTransformer , SizeScaleTransformer , ColorRampTransformer }
	Transformer types. More...

Public Member Functions
	QgsSizeScaleTransformer (ScaleType type=Linear, double minValue=0.0, double maxValue=1.0, double minSize=0.0, double maxSize=1.0, double nullSize=0.0, double exponent=1.0)
	Constructor for QgsSizeScaleTransformer. More...
QgsSizeScaleTransformer *	clone () const override
	Returns a clone of the transformer. More...
double	exponent () const
	Returns the exponent for an exponential expression. More...
bool	loadVariant (const QVariant &definition) override
	Loads this transformer from a QVariantMap, wrapped in a QVariant. More...
double	maxSize () const
	Returns the maximum calculated size. More...
double	minSize () const
	Returns the minimum calculated size. More...
double	nullSize () const
	Returns the size value when an expression evaluates to NULL. More...
void	setExponent (double exponent)
	Sets the exponent for an exponential expression. More...
void	setMaxSize (double size)
	Sets the maximum calculated size. More...
void	setMinSize (double size)
	Sets the minimum calculated size. More...
void	setNullSize (double size)
	Sets the size value for when an expression evaluates to NULL. More...
void	setType (ScaleType type)
	Sets the size transformer's scaling type (the method used to calculate the size from a value). More...
double	size (double value) const
	Calculates the size corresponding to a specific value. More...
QString	toExpression (const QString &baseExpression) const override
	Converts the transformer to a QGIS expression string. More...
QVariant	toVariant () const override
	Saves this transformer to a QVariantMap, wrapped in a QVariant. More...
QVariant	transform (const QgsExpressionContext &context, const QVariant &value) const override
	Calculates the transform of a value. More...
Type	transformerType () const override
	Returns the transformer type. More...
ScaleType	type () const
	Returns the size transformer's scaling type (the method used to calculate the size from a value). More...
Public Member Functions inherited from QgsPropertyTransformer
	QgsPropertyTransformer (const QgsPropertyTransformer &other)
	Copy constructor. More...
	QgsPropertyTransformer (double minValue=0.0, double maxValue=1.0)
	Constructor for QgsPropertyTransformer. More...
virtual	~QgsPropertyTransformer ()
virtual QgsPropertyTransformer *	clone () const =0
	Returns a clone of the transformer. More...
QgsCurveTransform *	curveTransform () const
	Returns the curve transform applied to input values before they are transformed by the individual transform subclasses. More...
virtual bool	loadVariant (const QVariant &transformer)
	Loads this transformer from a QVariantMap, wrapped in a QVariant. More...
double	maxValue () const
	Returns the maximum value expected by the transformer. More...
double	minValue () const
	Returns the minimum value expected by the transformer. More...
QgsPropertyTransformer &	operator= (const QgsPropertyTransformer &other)
void	setCurveTransform (QgsCurveTransform *transform)
	Sets a curve transform to apply to input values before they are transformed by the individual transform subclasses. More...
void	setMaxValue (double max)
	Sets the maximum value expected by the transformer. More...
void	setMinValue (double min)
	Sets the minimum value expected by the transformer. More...
virtual QString	toExpression (const QString &baseExpression) const =0
	Converts the transformer to a QGIS expression string. More...
virtual QVariant	toVariant () const
	Saves this transformer to a QVariantMap, wrapped in a QVariant. More...
virtual QVariant	transform (const QgsExpressionContext &context, const QVariant &value) const =0
	Calculates the transform of a value. More...
virtual Type	transformerType () const =0
	Returns the transformer type. More...

Static Public Member Functions
static QgsSizeScaleTransformer *	fromExpression (const QString &expression, QString &baseExpression, QString &fieldName)
	Attempts to parse an expression into a corresponding QgsSizeScaleTransformer. More...
Static Public Member Functions inherited from QgsPropertyTransformer
static QgsPropertyTransformer *	create (Type type)
	Factory method for creating a new property transformer of the specified type. More...
static QgsPropertyTransformer *	fromExpression (const QString &expression, QString &baseExpression, QString &fieldName)
	Attempts to parse an expression into a corresponding property transformer. More...

Additional Inherited Members
Protected Member Functions inherited from QgsPropertyTransformer
double	transformNumeric (double input) const
	Applies base class numeric transformations. More...
Protected Attributes inherited from QgsPropertyTransformer
std::unique_ptr< QgsCurveTransform >	mCurveTransform
	Optional curve transform. More...
double	mMaxValue
	Maximum value expected by the transformer. More...
double	mMinValue
	Minimum value expected by the transformer. More...

Detailed Description

QgsPropertyTransformer subclass for scaling a value into a size according to various scaling methods.

Since

QGIS 3.0

Definition at line 461 of file qgspropertytransformer.h.

Member Enumeration Documentation

ScaleType

enum QgsSizeScaleTransformer::ScaleType

Size scaling methods.

Enumerator
Linear	Linear scaling.
Area	Area based scaling.
Flannery	Flannery scaling method.
Exponential	Scale using set exponent.

Definition at line 466 of file qgspropertytransformer.h.

Constructor & Destructor Documentation

QgsSizeScaleTransformer()

QgsSizeScaleTransformer::QgsSizeScaleTransformer	(	ScaleType	type = Linear,
		double	minValue = 0.0,
		double	maxValue = 1.0,
		double	minSize = 0.0,
		double	maxSize = 1.0,
		double	nullSize = 0.0,
		double	exponent = 1.0
	)

Constructor for QgsSizeScaleTransformer.

Parameters

type	scaling type
minValue	minimum expected value
maxValue	maximum expected value
minSize	minimum size to return
maxSize	maximum size to return
nullSize	size to return for null values
exponent	exponent for Exponential scaling method

Definition at line 304 of file qgspropertytransformer.cpp.

Member Function Documentation

clone()

QgsSizeScaleTransformer * QgsSizeScaleTransformer::clone ( ) const

overridevirtual

Returns a clone of the transformer.

Implements QgsPropertyTransformer.

Definition at line 314 of file qgspropertytransformer.cpp.

exponent()

double QgsSizeScaleTransformer::exponent ( ) const

inline

Returns the exponent for an exponential expression.

See also

setExponent()

type()

Definition at line 567 of file qgspropertytransformer.h.

fromExpression()

QgsSizeScaleTransformer * QgsSizeScaleTransformer::fromExpression ( const QString &  expression, QString &  baseExpression, QString &  fieldName  )

static

Attempts to parse an expression into a corresponding QgsSizeScaleTransformer.

Parameters

expression	expression to parse
baseExpression	will be set to the component of the source expression which is used to calculate the input to the property transformer. This will be set to an empty string if a field reference is the transformer input.
fieldName	will be set to a field name which is used to calculate the input to the property transformer. This will be set to an empty string if an expression is the transformer input.

Returns

corresponding QgsSizeScaleTransformer, or nullptr if expression could not be parsed to a size scale transformer.

Definition at line 438 of file qgspropertytransformer.cpp.

loadVariant()

bool QgsSizeScaleTransformer::loadVariant ( const QVariant &  transformer )

overridevirtual

Loads this transformer from a QVariantMap, wrapped in a QVariant.

You can use QgsXmlUtils::readVariant to read it from an XML document.

See also

toVariant()

Reimplemented from QgsPropertyTransformer.

Definition at line 341 of file qgspropertytransformer.cpp.

maxSize()

double QgsSizeScaleTransformer::maxSize ( ) const

inline

Returns the maximum calculated size.

See also

minSize()

Definition at line 539 of file qgspropertytransformer.h.

minSize()

double QgsSizeScaleTransformer::minSize ( ) const

inline

Returns the minimum calculated size.

See also

setMinSize()

maxSize()

Definition at line 525 of file qgspropertytransformer.h.

nullSize()

double QgsSizeScaleTransformer::nullSize ( ) const

inline

Returns the size value when an expression evaluates to NULL.

See also

setNullSize()

Definition at line 553 of file qgspropertytransformer.h.

setExponent()

void QgsSizeScaleTransformer::setExponent ( double  exponent )

inline

Sets the exponent for an exponential expression.

Parameters

exponent

exponent

See also

exponent()

Definition at line 574 of file qgspropertytransformer.h.

setMaxSize()

void QgsSizeScaleTransformer::setMaxSize ( double  size )

inline

Sets the maximum calculated size.

Parameters

size	maximum size

See also

maxSize()

setMinSize()

Definition at line 547 of file qgspropertytransformer.h.

setMinSize()

void QgsSizeScaleTransformer::setMinSize ( double  size )

inline

Sets the minimum calculated size.

Parameters

size	minimum size

See also

minSize()

setMaxSize()

Definition at line 533 of file qgspropertytransformer.h.

setNullSize()

void QgsSizeScaleTransformer::setNullSize ( double  size )

inline

Sets the size value for when an expression evaluates to NULL.

Parameters

size

null size

See also

nullSize()

Definition at line 560 of file qgspropertytransformer.h.

setType()

void QgsSizeScaleTransformer::setType

(

QgsSizeScaleTransformer::ScaleType

type

)

Sets the size transformer's scaling type (the method used to calculate the size from a value).

Parameters

type	scale type

See also

type()

Definition at line 374 of file qgspropertytransformer.cpp.

size()

double QgsSizeScaleTransformer::size

(

double

value

)

const

Calculates the size corresponding to a specific value.

Parameters

value

value to calculate size for

Returns

calculated size using size scale transformer's parameters and type

Definition at line 356 of file qgspropertytransformer.cpp.

toExpression()

QString QgsSizeScaleTransformer::toExpression ( const QString &  baseExpression ) const

overridevirtual

Converts the transformer to a QGIS expression string.

The baseExpression string consists of a sub-expression reflecting the parent property's state.

Implements QgsPropertyTransformer.

Definition at line 415 of file qgspropertytransformer.cpp.

toVariant()

QVariant QgsSizeScaleTransformer::toVariant ( ) const

overridevirtual

Saves this transformer to a QVariantMap, wrapped in a QVariant.

You can use QgsXmlUtils::writeVariant to save it to an XML document.

See also

loadVariant()

Reimplemented from QgsPropertyTransformer.

Definition at line 328 of file qgspropertytransformer.cpp.

transform()

QVariant QgsSizeScaleTransformer::transform ( const QgsExpressionContext &  context, const QVariant &  value  ) const

overridevirtual

Calculates the transform of a value.

Derived classes must implement this to perform their transformations on input values

Parameters

context	expression context
value	input value to transform

Implements QgsPropertyTransformer.

Definition at line 394 of file qgspropertytransformer.cpp.

transformerType()

Type QgsSizeScaleTransformer::transformerType ( ) const

inlineoverridevirtual

Returns the transformer type.

Implements QgsPropertyTransformer.

Definition at line 492 of file qgspropertytransformer.h.

type()

ScaleType QgsSizeScaleTransformer::type ( ) const

inline

Returns the size transformer's scaling type (the method used to calculate the size from a value).

See also

setType()

Definition at line 581 of file qgspropertytransformer.h.

---

The documentation for this class was generated from the following files:

• /build/qgis-3.28.0+99sid/src/core/qgspropertytransformer.h
• /build/qgis-3.28.0+99sid/src/core/qgspropertytransformer.cpp