QgsDrawSourceEffect class

A paint effect which draws the source picture with minor or no alterations.

Reference

The draw source effect can be used to draw an unaltered copy of the original source picture. Minor changes like lowering the opacity and applying a blend mode are supported, however these changes will force the resultant output to be rasterized. If no alterations are performed then the original picture will be rendered as a vector.

Base classes

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

Public static functions

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

Constructors, destructors, conversion operators

QgsDrawSourceEffect() defaulted: Constructor for QgsDrawSourceEffect.

Public functions

auto blendMode() const -> QPainter::CompositionMode: Returns the blend mode for the effect.
auto clone() const -> QgsDrawSourceEffect* 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 setOpacity(const double opacity): Sets the opacity for the effect.
auto type() const -> QString override: Returns the effect type.

Protected functions

void draw(QgsRenderContext& context) override: Handles drawing of the effect's result on to the specified render context.

Function documentation

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

Creates a new QgsDrawSource effect from a properties string map.

Parameters
map	encoded properties string map
Returns	new QgsDrawSourceEffect

QPainter::CompositionMode QgsDrawSourceEffect::blendMode() const

Returns the blend mode for the effect.

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

QgsDrawSourceEffect* QgsDrawSourceEffect::clone() const override

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

Returns	clone of paint effect

double QgsDrawSourceEffect::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 QgsDrawSourceEffect::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 QgsDrawSourceEffect::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 QgsDrawSourceEffect::setBlendMode(const QPainter::CompositionMode mode)

Sets the blend mode for the effect.

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

void QgsDrawSourceEffect::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 QgsDrawSourceEffect::type() const override

Returns the effect type.

Returns	unique string representation of the effect type

void QgsDrawSourceEffect::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.