QIcon Class

 QToolButton *button = new QToolButton;
 button->setIcon(QIcon("open.png"));

 QIcon openIcon("open.png");
 openIcon.addFile("open-disabled.png", QIcon::Disabled);

 button->setIcon(QIcon());

 QIcon undoicon = QIcon::fromTheme(QIcon::ThemeIcon::EditUndo);

 void MyWidget::drawIcon(QPainter *painter, const QRect &rect)
 {
     icon.paint(painter, rect, Qt::AlignCenter, isEnabled() ? QIcon::Normal
                                                            : QIcon::Disabled,
                                                isChecked() ? QIcon::On
                                                            : QIcon::Off);
 }

 [Icon Theme]
 Name=Test
 Comment=Test Theme

 Directories=32x32/actions,32x32@2/actions

 [32x32/actions]
 Size=32
 Context=Actions
 Type=Fixed

 # High DPI version of the entry above.
 [32x32@2/actions]
 Size=32
 Scale=2
 Type=Fixed

 ├── 32x32
 │   └── actions
 │       └── appointment-new.png
 ├── 32x32@2
 │   └── actions
 │       └── appointment-new.png
 └── index.theme

Member Function Documentation

This is an overloaded function.

Returns the QIcon corresponding to icon in the current icon theme.

If the current theme does not provide an icon for icon, the fallback icon theme is consulted, before falling back to looking up standalone icon files in the fallback icon search path. Finally, the platform's native icon library is consulted.

If no icon is found and a fallback is provided, fallback is returned. This is useful to provide a guaranteed fallback, regardless of whether the current set of icon themes and fallbacks paths support the requested icon.

If no icon is found and no fallback is provided, a default constructed, empty QIcon is returned.

This function was introduced in Qt 6.7.

[noexcept] QIcon::QIcon()

Constructs a null icon.

[explicit] QIcon::QIcon(QIconEngine *engine)

Creates an icon with a specific icon engine. The icon takes ownership of the engine.

QIcon::QIcon(const QPixmap &pixmap)

Constructs an icon from a pixmap.

[explicit] QIcon::QIcon(const QString &fileName)

Constructs an icon from the file with the given fileName. The file will be loaded on demand.

If fileName contains a relative path (e.g. the filename only) the relevant file must be found relative to the runtime working directory.

The file name can refer to an actual file on disk or to one of the application's embedded resources. See the Resource System overview for details on how to embed images and other resource files in the application's executable.

Use the QImageReader::supportedImageFormats() and QImageWriter::supportedImageFormats() functions to retrieve a complete list of the supported file formats.

QIcon::QIcon(const QIcon &other)

Constructs a copy of other. This is very fast.

[noexcept] QIcon::QIcon(QIcon &&other)

Move-constructs a QIcon instance, making it point to the same object that other was pointing to.

[noexcept] QIcon::~QIcon()

Destroys the icon.

QSize QIcon::actualSize(const QSize &size, QIcon::Mode mode = Normal, QIcon::State state = Off) const

Returns the actual size of the icon for the requested size, mode, and state. The result might be smaller than requested, but never larger. The returned size is in device-independent pixels (This is relevant for high-dpi pixmaps.)

See also pixmap() and paint().

void QIcon::addFile(const QString &fileName, const QSize &size = QSize(), QIcon::Mode mode = Normal, QIcon::State state = Off)

Adds an image from the file with the given fileName to the icon, as a specialization for size, mode and state. The file will be loaded on demand. Note: custom icon engines are free to ignore additionally added pixmaps.

If fileName contains a relative path (e.g. the filename only) the relevant file must be found relative to the runtime working directory.

The file name can refer to an actual file on disk or to one of the application's embedded resources. See the Resource System overview for details on how to embed images and other resource files in the application's executable.

Use the QImageReader::supportedImageFormats() and QImageWriter::supportedImageFormats() functions to retrieve a complete list of the supported file formats.

If a high resolution version of the image exists (identified by the suffix @2x on the base name), it is automatically loaded and added with the device pixel ratio set to a value of 2. This can be disabled by setting the environment variable QT_HIGHDPI_DISABLE_2X_IMAGE_LOADING (see QImageReader).

See also addPixmap() and QPixmap::devicePixelRatio().

void QIcon::addPixmap(const QPixmap &pixmap, QIcon::Mode mode = Normal, QIcon::State state = Off)

Adds pixmap to the icon, as a specialization for mode and state.

Custom icon engines are free to ignore additionally added pixmaps.

See also addFile().

QList<QSize> QIcon::availableSizes(QIcon::Mode mode = Normal, QIcon::State state = Off) const

Returns a list of available icon sizes for the specified mode and state.

qint64 QIcon::cacheKey() const

Returns a number that identifies the contents of this QIcon object. Distinct QIcon objects can have the same key if they refer to the same contents.

The cacheKey() will change when the icon is altered via addPixmap() or addFile().

Cache keys are mostly useful in conjunction with caching.

See also QPixmap::cacheKey().

[static] QStringList QIcon::fallbackSearchPaths()

Returns the fallback search paths for icons.

The fallback search paths are consulted for standalone icon files if the current icon theme or fallback icon theme do not provide results for an icon lookup.

If not set, the fallback search paths will be defined by the platform.

See also setFallbackSearchPaths() and themeSearchPaths().

[static] QString QIcon::fallbackThemeName()

Returns the name of the fallback icon theme.

If not set, the fallback icon theme will be defined by the platform.

See also setFallbackThemeName() and themeName().

[static] QIcon QIcon::fromTheme(const QString &name)

Returns the QIcon corresponding to name in the current icon theme.

If the current theme does not provide an icon for name, the fallback icon theme is consulted, before falling back to looking up standalone icon files in the fallback icon search path. Finally, the platform's native icon library is consulted.

To fetch an icon from the current icon theme:

 QIcon undoicon = QIcon::fromTheme(QIcon::ThemeIcon::EditUndo);

If an icon theme has not been explicitly set via setThemeName() a platform defined icon theme will be used.

See also themeName(), fallbackThemeName(), setThemeName(), themeSearchPaths(), fallbackSearchPaths(), and Freedesktop Icon Naming Specification.

[static] QIcon QIcon::fromTheme(const QString &name, const QIcon &fallback)

This is an overloaded function.

Returns the QIcon corresponding to name in the current icon theme.

If the current theme does not provide an icon for name, the fallback icon theme is consulted, before falling back to looking up standalone icon files in the fallback icon search path. Finally, the platform's native icon library is consulted.

If no icon is found fallback is returned.

This is useful to provide a guaranteed fallback, regardless of whether the current set of icon themes and fallbacks paths support the requested icon.

For example:

 QIcon undoicon = QIcon::fromTheme(QIcon::ThemeIcon::EditUndo, QIcon(":/undo.png"));

See also fallbackThemeName() and fallbackSearchPaths().

[static] bool QIcon::hasThemeIcon(const QString &name)

Returns true if there is an icon available for name in the current icon theme or any of the fallbacks, as described by fromTheme(), otherwise returns false.

See also themeSearchPaths(), fromTheme(), and setThemeName().

[static, since 6.7] bool QIcon::hasThemeIcon(QIcon::ThemeIcon icon)

This is an overloaded function.

Returns true if there is an icon available for icon in the current icon theme or any of the fallbacks, as described by fromTheme(), otherwise returns false.

This function was introduced in Qt 6.7.

See also fromTheme().

bool QIcon::isMask() const

Returns true if this icon has been marked as a mask image. Certain platforms render mask icons differently (for example, menu icons on macOS).

See also setIsMask().

bool QIcon::isNull() const

Returns true if the icon is empty; otherwise returns false.

An icon is empty if it has neither a pixmap nor a filename.

Note: Even a non-null icon might not be able to create valid pixmaps, eg. if the file does not exist or cannot be read.

QString QIcon::name() const

Returns the name used to create the icon, if available.

Depending on the way the icon was created, it may have an associated name. This is the case for icons created with fromTheme().

See also fromTheme() and QIconEngine::iconName().

void QIcon::paint(QPainter *painter, const QRect &rect, Qt::Alignment alignment = Qt::AlignCenter, QIcon::Mode mode = Normal, QIcon::State state = Off) const

Uses the painter to paint the icon with specified alignment, required mode, and state into the rectangle rect.

See also actualSize() and pixmap().

void QIcon::paint(QPainter *painter, int x, int y, int w, int h, Qt::Alignment alignment = Qt::AlignCenter, QIcon::Mode mode = Normal, QIcon::State state = Off) const

This is an overloaded function.

Paints the icon into the rectangle QRect(x, y, w, h).

QPixmap QIcon::pixmap(const QSize &size, QIcon::Mode mode = Normal, QIcon::State state = Off) const

Returns a pixmap with the requested size, mode, and state, generating one if necessary. The pixmap might be smaller than requested, but never larger, unless the device-pixel ratio of the returned pixmap is larger than 1.

See also actualSize() and paint().

QPixmap QIcon::pixmap(int extent, QIcon::Mode mode = Normal, QIcon::State state = Off) const

This is an overloaded function.

Returns a pixmap of size QSize(extent, extent). The pixmap might be smaller than requested, but never larger, unless the device-pixel ratio of the returned pixmap is larger than 1.

[since 6.0] QPixmap QIcon::pixmap(const QSize &size, qreal devicePixelRatio, QIcon::Mode mode = Normal, QIcon::State state = Off) const

This is an overloaded function.

Returns a pixmap with the requested size, devicePixelRatio, mode, and state, generating one with the given mode and state if necessary. The pixmap might be smaller than requested, but never larger, unless the device-pixel ratio of the returned pixmap is larger than 1.

This function was introduced in Qt 6.0.

See also actualSize() and paint().

QPixmap QIcon::pixmap(int w, int h, QIcon::Mode mode = Normal, QIcon::State state = Off) const

This is an overloaded function.

Returns a pixmap of size QSize(w, h). The pixmap might be smaller than requested, but never larger, unless the device-pixel ratio of the returned pixmap is larger than 1.

[static] void QIcon::setFallbackSearchPaths(const QStringList &paths)

Sets the fallback search paths for icons to paths.

The fallback search paths are consulted for standalone icon files if the current icon theme or fallback icon theme do not provide results for an icon lookup.

For example:

 QIcon::setFallbackSearchPaths(QIcon::fallbackSearchPaths() << "my/search/path");

See also fallbackSearchPaths() and setThemeSearchPaths().

[static] void QIcon::setFallbackThemeName(const QString &name)

Sets the fallback icon theme to name.

The fallback icon theme is consulted for icons not provided by the current icon theme, or if the current icon theme does not exist.

The name should correspond to theme in the same format as documented by setThemeName(), and will be looked up in themeSearchPaths().

See also fallbackThemeName(), themeSearchPaths(), and themeName().

void QIcon::setIsMask(bool isMask)

Indicate that this icon is a mask image(boolean isMask), and hence can potentially be modified based on where it's displayed.

See also isMask().

[static] void QIcon::setThemeName(const QString &name)

Sets the current icon theme to name.

The theme will be will be looked up in themeSearchPaths().

At the moment the only supported icon theme format is the Freedesktop Icon Theme Specification. The name should correspond to a directory name in the themeSearchPath() containing an index.theme file describing its contents.

See also themeSearchPaths(), themeName(), and Freedesktop Icon Theme Specification.

[static] void QIcon::setThemeSearchPaths(const QStringList &paths)

Sets the search paths for icon themes to paths.

The content of paths should follow the theme format documented by setThemeName().

See also themeSearchPaths(), fromTheme(), and setThemeName().

[noexcept] void QIcon::swap(QIcon &other)

Swaps icon other with this icon. This operation is very fast and never fails.

[static] QString QIcon::themeName()

Returns the name of the current icon theme.

If not set, the current icon theme will be defined by the platform.

See also setThemeName(), themeSearchPaths(), fromTheme(), and hasThemeIcon().

[static] QStringList QIcon::themeSearchPaths()

Returns the search paths for icon themes.

The default search paths will be defined by the platform. All platforms will also have the resource directory :\icons as a fallback.

See also setThemeSearchPaths(), fromTheme(), and setThemeName().

QVariant QIcon::operator QVariant() const

Returns the icon as a QVariant.

[noexcept] QIcon &QIcon::operator=(QIcon &&other)

Move-assigns other to this QIcon instance.

QIcon &QIcon::operator=(const QIcon &other)

Assigns the other icon to this icon and returns a reference to this icon.