QSvgRenderer Class | Qt SVG | Qt 6.12.0
Description: The QSvgRenderer class is used to draw the contents of SVG files onto paint devices.
Keywords: class

- Qt 6.12
- Qt SVG
- C++ Classes
- QSvgRenderer
- Qt 6.12.0 Reference Documentation

# QSvgRenderer Class

The QSvgRenderer class is used to draw the contents of SVG files onto paint devices. More...

Header: | `#include <QSvgRenderer>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Svg)` `target_link_libraries(mytarget PRIVATE Qt6::Svg)`
qmake: | `QT += svg`
Inherits: | QObject

- List of all members, including inherited members
- QSvgRenderer is part of Painting Classes.

Note: All functions in this class are reentrant.

## Properties

`(since 6.7)` animationEnabled : bool aspectRatioMode : Qt::AspectRatioMode framesPerSecond : int | `(since 6.7)` options : QtSvg::Options viewBox : QRectF

## Public Functions

| QSvgRenderer(QObject *parent = nullptr)
| QSvgRenderer(QXmlStreamReader *contents, QObject *parent = nullptr)
| QSvgRenderer(const QByteArray &contents, QObject *parent = nullptr)
| QSvgRenderer(const QString &filename, QObject *parent = nullptr)
virtual | ~QSvgRenderer()
bool | animated() const
Qt::AspectRatioMode | aspectRatioMode() const
QRectF | boundsOnElement(const QString &id) const
QSize | defaultSize() const
bool | elementExists(const QString &id) const
int | framesPerSecond() const
bool | isAnimationEnabled() const
bool | isValid() const
QtSvg::Options | options() const
void | setAnimationEnabled(bool enable)
void | setAspectRatioMode(Qt::AspectRatioMode mode)
void | setFramesPerSecond(int num)
void | setOptions(QtSvg::Options flags)
void | setViewBox(const QRect &viewbox)
void | setViewBox(const QRectF &viewbox)
QTransform | transformForElement(const QString &id) const
QRect | viewBox() const
QRectF | viewBoxF() const

## Public Slots

bool | load(QXmlStreamReader *contents)
bool | load(const QByteArray &contents)
bool | load(const QString &filename)
void | render(QPainter *painter)
void | render(QPainter *painter, const QRectF &bounds)
void | render(QPainter *painter, const QString &elementId, const QRectF &bounds = QRectF())

## Signals

void | repaintNeeded()

## Static Public Members

`(since 6.8)` void | setDefaultOptions(QtSvg::Options flags)

## Detailed Description

Using QSvgRenderer, Scalable Vector Graphics (SVG) can be rendered onto any QPaintDevice subclass, including QWidget, QImage, and QGLWidget.

QSvgRenderer provides an API that supports basic features of SVG rendering, such as loading and rendering of static drawings, and more interactive features like animation. Since the rendering is performed using QPainter, SVG drawings can be rendered on any subclass of QPaintDevice.

SVG drawings are either loaded when an QSvgRenderer is constructed, or loaded later using the load() functions. Data is either supplied directly as serialized XML, or indirectly using a file name. If a valid file has been loaded, either when the renderer is constructed or at some later time, isValid() returns true; otherwise it returns false. QSvgRenderer provides the render() slot to render the current document, or the current frame of an animated document, using a given painter.

The defaultSize() function provides information about the amount of space that is required to render the currently loaded SVG file. This is useful for paint devices, such as QWidget, that often need to supply a size hint to their parent layout. The default size of a drawing may differ from its visible area, found using the viewBox property.

Animated SVG drawings are supported, and can be controlled with a simple collection of functions and properties:

- The animated() function indicates whether a drawing contains animation information.
- The framesPerSecond property contains the rate at which the animation plays.

Finally, the QSvgRenderer class provides the repaintNeeded() signal which is emitted whenever the rendering of the document needs to be updated.

See also QSvgWidget, Qt SVG C++ Classes, and QPicture.

## Property Documentation

### `[since 6.7]` animationEnabled : bool

This property holds whether the animation should run, if the SVG is animated

Setting the property to false stops the animation timer. Setting the property to true starts the animation timer, provided that the SVG contains animated elements.

If the SVG is not animated, the property will have no effect. Otherwise, the property defaults to true.

This enumeration was introduced in Qt 6.7.

Access functions:

bool | isAnimationEnabled() const
void | setAnimationEnabled(bool enable)

See also animated().

### aspectRatioMode : Qt::AspectRatioMode

how rendering adheres to the SVG view box aspect ratio

The accepted modes are:

- Qt::IgnoreAspectRatio (the default): the aspect ratio is ignored and the rendering is stretched to the target bounds.
- Qt::KeepAspectRatio: rendering is centered and scaled as large as possible within the target bounds while preserving aspect ratio.

Access functions:

Qt::AspectRatioMode | aspectRatioMode() const
void | setAspectRatioMode(Qt::AspectRatioMode mode)

### framesPerSecond : int

This property holds the number of frames per second to be shown

The number of frames per second is 0 if the current document is not animated.

Access functions:

int | framesPerSecond() const
void | setFramesPerSecond(int num)

See also animated().

### `[since 6.7]` options : QtSvg::Options

This property holds a set of QtSvg::Option flags that can be used to enable or disable various features of the parsing and rendering of SVG files.

In order to take effect, this property must be set `before` load() is executed. Note that the constructors taking an SVG source parameter will perform loading during construction.

This enumeration was introduced in Qt 6.7.

Access functions:

QtSvg::Options | options() const
void | setOptions(QtSvg::Options flags)

See also setDefaultOptions.

### viewBox : QRectF

This property holds the rectangle specifying the visible area of the document in logical coordinates

Access functions:

QRectF | viewBoxF() const
void | setViewBox(const QRect &viewbox)
void | setViewBox(const QRectF &viewbox)

## Member Function Documentation

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

Constructs a new renderer with the given parent.

### QSvgRenderer::QSvgRenderer(QXmlStreamReader *contents, QObject *parent = nullptr)

Constructs a new renderer with the given parent and loads the SVG data using the stream reader specified by contents.

### QSvgRenderer::QSvgRenderer(const QByteArray &contents, QObject *parent = nullptr)

Constructs a new renderer with the given parent and loads the SVG data from the byte array specified by contents.

### QSvgRenderer::QSvgRenderer(const QString &filename, QObject *parent = nullptr)

Constructs a new renderer with the given parent and loads the contents of the SVG file with the specified filename.

### `[virtual noexcept]` QSvgRenderer::~QSvgRenderer()

Destroys the renderer.

### bool QSvgRenderer::animated() const

Returns true if the current document contains animated elements; otherwise returns false.

See also framesPerSecond().

### QRectF QSvgRenderer::boundsOnElement(const QString &id) const

Returns bounding rectangle of the item with the given id. The transformation matrix of parent elements is not affecting the bounds of the element.

See also transformForElement().

### QSize QSvgRenderer::defaultSize() const

Returns the default size of the document contents.

### bool QSvgRenderer::elementExists(const QString &id) const

Returns true if the element with the given id exists in the currently parsed SVG file and is a renderable element.

Note: this method returns true only for elements that can be rendered. Which implies that elements that are considered part of the fill/stroke style properties, e.g. radialGradients even tough marked with "id" attributes will not be found by this method.

### bool QSvgRenderer::isValid() const

Returns true if there is a valid current document; otherwise returns false.

### `[slot]` bool QSvgRenderer::load(QXmlStreamReader *contents)

Loads the specified SVG in contents, returning true if the content was successfully parsed; otherwise returns false.

The reader will be used from where it currently is positioned. If contents is `null`, behavior is undefined.

Note: This slot is overloaded. To connect to this slot:

     // Connect using qOverload:
     connect(sender, &SenderClass::signal,
             svgRenderer, qOverload(&QSvgRenderer::load));

     // Or using a lambda as wrapper:
     connect(sender, &SenderClass::signal,
             svgRenderer, [receiver = svgRenderer](QXmlStreamReader *contents) { receiver->load(contents); });

For more examples and approaches, see connecting to overloaded slots.

### `[slot]` bool QSvgRenderer::load(const QByteArray &contents)

Loads the specified SVG format contents, returning true if the content was successfully parsed; otherwise returns false.

Note: This slot is overloaded. To connect to this slot:

     // Connect using qOverload:
     connect(sender, &SenderClass::signal,
             svgRenderer, qOverload(&QSvgRenderer::load));

     // Or using a lambda as wrapper:
     connect(sender, &SenderClass::signal,
             svgRenderer, [receiver = svgRenderer](const QByteArray &contents) { receiver->load(contents); });

For more examples and approaches, see connecting to overloaded slots.

### `[slot]` bool QSvgRenderer::load(const QString &filename)

Loads the SVG file specified by filename, returning true if the content was successfully parsed; otherwise returns false.

Note: This slot is overloaded. To connect to this slot:

     // Connect using qOverload:
     connect(sender, &SenderClass::signal,
             svgRenderer, qOverload(&QSvgRenderer::load));

     // Or using a lambda as wrapper:
     connect(sender, &SenderClass::signal,
             svgRenderer, [receiver = svgRenderer](const QString &filename) { receiver->load(filename); });

For more examples and approaches, see connecting to overloaded slots.

### `[slot]` void QSvgRenderer::render(QPainter *painter)

Renders the current document, or the current frame of an animated document, using the given painter.

Note: This slot is overloaded. To connect to this slot:

     // Connect using qOverload:
     connect(sender, &SenderClass::signal,
             svgRenderer, qOverload(&QSvgRenderer::render));

     // Or using a lambda as wrapper:
     connect(sender, &SenderClass::signal,
             svgRenderer, [receiver = svgRenderer](QPainter *painter) { receiver->render(painter); });

For more examples and approaches, see connecting to overloaded slots.

### `[slot]` void QSvgRenderer::render(QPainter *painter, const QRectF &bounds)

Renders the current document, or the current frame of an animated document, using the given painter on the specified bounds within the painter. If bounds is not empty, the output will be scaled to fill it, ignoring any aspect ratio implied by the SVG.

Note: This slot is overloaded. To connect to this slot:

     // Connect using qOverload:
     connect(sender, &SenderClass::signal,
             svgRenderer, qOverload(&QSvgRenderer::render));

     // Or using a lambda as wrapper:
     connect(sender, &SenderClass::signal,
             svgRenderer, [receiver = svgRenderer](QPainter *painter, const QRectF &bounds) { receiver->render(painter, bounds); });

For more examples and approaches, see connecting to overloaded slots.

### `[slot]` void QSvgRenderer::render(QPainter *painter, const QString &elementId, const QRectF &bounds = QRectF())

Renders the given element with elementId using the given painter on the specified bounds. If the bounding rectangle is not specified the SVG element is mapped to the whole paint device.

Note: This slot is overloaded. To connect to this slot:

     // Connect using qOverload:
     connect(sender, &SenderClass::signal,
             svgRenderer, qOverload(&QSvgRenderer::render));

     // Or using a lambda as wrapper:
     connect(sender, &SenderClass::signal,
             svgRenderer, [receiver = svgRenderer](QPainter *painter, const QString &elementId, const QRectF &bounds) { receiver->render(painter, elementId, bounds); });

For more examples and approaches, see connecting to overloaded slots.

### `[signal]` void QSvgRenderer::repaintNeeded()

This signal is emitted whenever the rendering of the document needs to be updated, usually for the purposes of animation.

### `[static, since 6.8]` void QSvgRenderer::setDefaultOptions(QtSvg::Options flags)

Sets the option flags that renderers will be created with to flags. By default, no flags are set.

At runtime, this can be overridden by the QT_SVG_DEFAULT_OPTIONS environment variable.

This function was introduced in Qt 6.8.

### QTransform QSvgRenderer::transformForElement(const QString &id) const

Returns the transformation matrix for the element with the given id. The matrix is a product of the transformation of the element's parents. The transformation of the element itself is not included.

To find the bounding rectangle of the element in logical coordinates, you can apply the matrix on the rectangle returned from boundsOnElement().

See also boundsOnElement().

### QRect QSvgRenderer::viewBox() const

Returns viewBoxF().toRect().

See also setViewBox() and viewBoxF().