QgsBlurEffect class

A paint effect which blurs a source picture, using a number of different blur methods.

Reference

Base classes

class QgsPaintEffect: Base class for visual effects which can be applied to QPicture drawings.

Public types

enum BlurMethod { StackBlur, GaussianBlur }: Available blur methods (algorithms)

Public static functions

static auto create(const QgsStringMap& map) -> QgsPaintEffect*: Creates a new QgsBlurEffect effect from a properties string map.

Constructors, destructors, conversion operators

QgsBlurEffect() defaulted: Constructor for QgsBlurEffect.

Public functions

auto blendMode() const -> QPainter::CompositionMode: Returns the blend mode for the effect.
auto blurLevel() const -> int: Returns the blur level (strength)
auto blurMethod() const -> BlurMethod: Returns the blur method (algorithm) used for performing the blur.
auto clone() const -> QgsBlurEffect* override: Duplicates an effect by creating a deep copy of the effect.
auto opacity() const -> double: Returns the opacity for the effect.
auto properties() const -> QgsStringMap override: Returns the properties describing the paint effect encoded in a string format.
void readProperties(const QgsStringMap& props) override: Reads a string map of an effect's properties and restores the effect to the state described by the properties map.
void setBlendMode(const QPainter::CompositionMode mode): Sets the blend mode for the effect.
void setBlurLevel(const int level): Sets blur level (strength)
void setBlurMethod(const BlurMethod method): Sets the blur method (algorithm) to use for performing the blur.
void setOpacity(const double opacity): Sets the opacity for the effect.
auto type() const -> QString override: Returns the effect type.

Protected functions

auto boundingRect(const QRectF& rect, const QgsRenderContext& context) const -> QRectF override: Returns the bounding rect required for drawing the effect.
void draw(QgsRenderContext& context) override: Handles drawing of the effect's result on to the specified render context.

Enum documentation

enum QgsBlurEffect::BlurMethod

Available blur methods (algorithms)

Enumerators
StackBlur	Stack blur, a fast but low quality blur. Valid blur level values are between 0 - 16.
GaussianBlur	Gaussian blur, a slower but high quality blur. Blur level values are the distance in pixels for the blur operation.

Function documentation

static QgsPaintEffect* QgsBlurEffect::create(const QgsStringMap& map)

Creates a new QgsBlurEffect effect from a properties string map.

Parameters
map	encoded properties string map
Returns	new QgsBlurEffect

QPainter::CompositionMode QgsBlurEffect::blendMode() const

Returns the blend mode for the effect.

Returns	blend mode used for drawing the effect on to a destination paint device

int QgsBlurEffect::blurLevel() const

Returns the blur level (strength)

Returns	blur level. Depending on the current blurMethod(), this parameter has different effects

BlurMethod QgsBlurEffect::blurMethod() const

Returns the blur method (algorithm) used for performing the blur.

Returns	blur method

QgsBlurEffect* QgsBlurEffect::clone() const override

Duplicates an effect by creating a deep copy of the effect.

Returns	clone of paint effect

double QgsBlurEffect::opacity() const

Returns the opacity for the effect.

Returns	opacity value between 0 and 1 inclusive, where 0 is fully transparent and 1 is fully opaque

QgsStringMap QgsBlurEffect::properties() const override

Returns the properties describing the paint effect encoded in a string format.

Returns	string map of properties, in the form property key, value

void QgsBlurEffect::readProperties(const QgsStringMap& props) override

Reads a string map of an effect's properties and restores the effect to the state described by the properties map.

Parameters
props	effect properties encoded in a string map

void QgsBlurEffect::setBlendMode(const QPainter::CompositionMode mode)

Sets the blend mode for the effect.

Parameters
mode	blend mode used for drawing the effect on to a destination paint device

void QgsBlurEffect::setBlurLevel(const int level)

Sets blur level (strength)

Parameters
level	blur level. Depending on the current blurMethod(), this parameter has different effects

void QgsBlurEffect::setBlurMethod(const BlurMethod method)

Sets the blur method (algorithm) to use for performing the blur.

Parameters
method	blur method

void QgsBlurEffect::setOpacity(const double opacity)

Sets the opacity for the effect.

Parameters
opacity	double between 0 and 1 inclusive, where 0 is fully transparent and 1 is fully opaque

QString QgsBlurEffect::type() const override

Returns the effect type.

Returns	unique string representation of the effect type

QRectF QgsBlurEffect::boundingRect(const QRectF& rect, const QgsRenderContext& context) const override protected

Returns the bounding rect required for drawing the effect.

Parameters
rect	original source bounding rect
context	destination render context
Returns	modified bounding rect

This method can be used to expand the bounding rect of a source picture to account for offset or blurring effects.

void QgsBlurEffect::draw(QgsRenderContext& context) override protected

Handles drawing of the effect's result on to the specified render context.

Parameters
context	destination render context

Derived classes must reimplement this method to apply any transformations to the source QPicture and draw the result using the context's painter.