- Qt 5.15
- Qt Widgets
- C++ Classes
- QGraphicsBlurEffect
- Qt 5.15.15 Reference Documentation

# QGraphicsBlurEffect Class

The QGraphicsBlurEffect class provides a blur effect. More...

Header: | #include <QGraphicsBlurEffect>
qmake: | QT += widgets
Since: | Qt 4.6
Inherits: | QGraphicsEffect

This class was introduced in Qt 4.6.

- List of all members, including inherited members

## Public Types

enum | BlurHint { PerformanceHint, QualityHint, AnimationHint }
flags | BlurHints

## Properties

- blurHints : BlurHints
- blurRadius : qreal

## Public Functions

| QGraphicsBlurEffect(QObject *parent = nullptr)
virtual | ~QGraphicsBlurEffect()
BlurHints | blurHints() const
qreal | blurRadius() const

## Reimplemented Public Functions

virtual QRectF | boundingRectFor(const QRectF &rect) const override

## Public Slots

void | setBlurHints(BlurHints hints)
void | setBlurRadius(qreal blurRadius)

## Signals

void | blurHintsChanged(BlurHints hints)
void | blurRadiusChanged(qreal radius)

## Reimplemented Protected Functions

virtual void | draw(QPainter *painter) override

## Detailed Description

A blur effect blurs the source. This effect is useful for reducing details, such as when the source loses focus and you want to draw attention to other elements. The level of detail can be modified using the setBlurRadius() function. Use setBlurHints() to choose the blur hints.

By default, the blur radius is 5 pixels. The blur radius is specified in device coordinates.

See also QGraphicsDropShadowEffect, QGraphicsColorizeEffect, and QGraphicsOpacityEffect.

## Member Type Documentation

### enum QGraphicsBlurEffect::BlurHint
flags QGraphicsBlurEffect::BlurHints

This enum describes the possible hints that can be used to control how blur effects are applied. The hints might not have an effect in all the paint engines.

Constant | Value | Description
--- | --- | ---
`QGraphicsBlurEffect::PerformanceHint` | `0x00` | Indicates that rendering performance is the most important factor, at the potential cost of lower quality.
`QGraphicsBlurEffect::QualityHint` | `0x01` | Indicates that rendering quality is the most important factor, at the potential cost of lower performance.
`QGraphicsBlurEffect::AnimationHint` | `0x02` | Indicates that the blur radius is going to be animated, hinting that the implementation can keep a cache of blurred versions of the source. Do not use this hint if the source is going to be dynamically changing.

This enum was introduced or modified in Qt 4.6.

The BlurHints type is a typedef for QFlags<BlurHint>. It stores an OR combination of BlurHint values.

See also blurHints() and setBlurHints().

## Property Documentation

### blurHints : BlurHints

This property holds the blur hint of the effect.

Use the PerformanceHint hint to say that you want a faster blur, the QualityHint hint to say that you prefer a higher quality blur, or the AnimationHint when you want to animate the blur radius.

By default, the blur hint is PerformanceHint.

Access functions:

BlurHints | blurHints() const
void | setBlurHints(BlurHints hints)

Notifier signal:

void | blurHintsChanged(BlurHints hints)

### blurRadius : qreal

This property holds the blur radius of the effect.

Using a smaller radius results in a sharper appearance, whereas a bigger radius results in a more blurred appearance.

By default, the blur radius is 5 pixels.

The radius is given in device coordinates, meaning it is unaffected by scale.

Access functions:

qreal | blurRadius() const
void | setBlurRadius(qreal blurRadius)

Notifier signal:

void | blurRadiusChanged(qreal radius)

## Member Function Documentation

### QGraphicsBlurEffect::QGraphicsBlurEffect(QObject *parent = nullptr)

Constructs a new QGraphicsBlurEffect instance. The parent parameter is passed to QGraphicsEffect's constructor.

### `[signal]` void QGraphicsBlurEffect::blurHintsChanged(BlurHints hints)

This signal is emitted whenever the effect's blur hints changes. The hints parameter holds the effect's new blur hints.

Note: Notifier signal for property blurHints.

### `[signal]` void QGraphicsBlurEffect::blurRadiusChanged(qreal radius)

This signal is emitted whenever the effect's blur radius changes. The radius parameter holds the effect's new blur radius.

Note: Notifier signal for property blurRadius.

### `[virtual]` QGraphicsBlurEffect::~QGraphicsBlurEffect()

Destroys the effect.

### `[override virtual]` QRectF QGraphicsBlurEffect::boundingRectFor(const QRectF &rect) const

Reimplements: QGraphicsEffect::boundingRectFor(const QRectF &rect) const.

### `[override virtual protected]` void QGraphicsBlurEffect::draw(QPainter *painter)

Reimplements: QGraphicsEffect::draw(QPainter *painter).