QLabel Class

Member Function Documentation

[explicit] QLabel::QLabel(QWidget *parent = nullptr, Qt::WindowFlags f = Qt::WindowFlags())

Constructs an empty label.

The parent and widget flag f, arguments are passed to the QFrame constructor.

See also setAlignment(), setFrameStyle(), and setIndent().

[explicit] QLabel::QLabel(const QString &text, QWidget *parent = nullptr, Qt::WindowFlags f = Qt::WindowFlags())

Constructs a label that displays the text, text.

The parent and widget flag f, arguments are passed to the QFrame constructor.

See also setText(), setAlignment(), setFrameStyle(), and setIndent().

[virtual noexcept] QLabel::~QLabel()

Destroys the label.

QWidget *QLabel::buddy() const

Returns this label's buddy, or nullptr if no buddy is currently set.

See also setBuddy().

[override virtual protected] void QLabel::changeEvent(QEvent *ev)

Reimplements: QFrame::changeEvent(QEvent *ev).

[slot] void QLabel::clear()

Clears any label contents.

[override virtual protected] void QLabel::contextMenuEvent(QContextMenuEvent *ev)

Reimplements: QWidget::contextMenuEvent(QContextMenuEvent *event).

[override virtual protected] bool QLabel::event(QEvent *e)

Reimplements: QFrame::event(QEvent *e).

[override virtual protected] void QLabel::focusInEvent(QFocusEvent *ev)

Reimplements: QWidget::focusInEvent(QFocusEvent *event).

[override virtual protected] bool QLabel::focusNextPrevChild(bool next)

Reimplements: QWidget::focusNextPrevChild(bool next).

[override virtual protected] void QLabel::focusOutEvent(QFocusEvent *ev)

Reimplements: QWidget::focusOutEvent(QFocusEvent *event).

[override virtual] int QLabel::heightForWidth(int w) const

Reimplements: QWidget::heightForWidth(int w) const.

[override virtual protected] void QLabel::keyPressEvent(QKeyEvent *ev)

Reimplements: QWidget::keyPressEvent(QKeyEvent *event).

[signal] void QLabel::linkActivated(const QString &link)

This signal is emitted when the user clicks a link. The URL referred to by the anchor is passed in link.

See also linkHovered().

[signal] void QLabel::linkHovered(const QString &link)

This signal is emitted when the user hovers over a link. The URL referred to by the anchor is passed in link.

See also linkActivated().

[override virtual] QSize QLabel::minimumSizeHint() const

Reimplements an access function for property: QWidget::minimumSizeHint.

[override virtual protected] void QLabel::mouseMoveEvent(QMouseEvent *ev)

Reimplements: QWidget::mouseMoveEvent(QMouseEvent *event).

[override virtual protected] void QLabel::mousePressEvent(QMouseEvent *ev)

Reimplements: QWidget::mousePressEvent(QMouseEvent *event).

[override virtual protected] void QLabel::mouseReleaseEvent(QMouseEvent *ev)

Reimplements: QWidget::mouseReleaseEvent(QMouseEvent *event).

QMovie *QLabel::movie() const

Returns a pointer to the label's movie, or nullptr if no movie has been set.

See also setMovie().

[override virtual protected] void QLabel::paintEvent(QPaintEvent *)

Reimplements: QFrame::paintEvent(QPaintEvent *).

[since 6.0] QPicture QLabel::picture() const

Returns the label's picture.

This function was introduced in Qt 6.0.

See also setPicture().

[since 6.1] QTextDocument::ResourceProvider QLabel::resourceProvider() const

Returns the resource provider for rich text of this label.

This function was introduced in Qt 6.1.

See also setResourceProvider().

int QLabel::selectionStart() const

selectionStart() returns the index of the first selected character in the label or -1 if no text is selected.

Note: The textInteractionFlags set on the label need to include either TextSelectableByMouse or TextSelectableByKeyboard.

See also selectedText().

void QLabel::setBuddy(QWidget *buddy)

Sets this label's buddy to buddy.

When the user presses the shortcut key indicated by this label, the keyboard focus is transferred to the label's buddy widget.

The buddy mechanism is only available for QLabels that contain text in which one character is prefixed with an ampersand, '&'. This character is set as the shortcut key. See the QKeySequence::mnemonic() documentation for details (to display an actual ampersand, use '&&').

In a dialog, you might create two data entry widgets and a label for each, and set up the geometry layout so each label is just to the left of its data entry widget (its "buddy"), for example:

QLineEdit *nameEdit  = new QLineEdit(this);
QLabel    *nameLabel = new QLabel("&Name:", this);
nameLabel->setBuddy(nameEdit);
QLineEdit *phoneEdit  = new QLineEdit(this);
QLabel    *phoneLabel = new QLabel("&Phone:", this);
phoneLabel->setBuddy(phoneEdit);
// (layout setup not shown)

With the code above, the focus jumps to the Name field when the user presses Alt+N, and to the Phone field when the user presses Alt+P.

To unset a previously set buddy, call this function with buddy set to nullptr.

See also buddy(), setText(), QShortcut, and setAlignment().

[slot] void QLabel::setMovie(QMovie *movie)

Sets the label contents to movie. Any previous content is cleared. The label does NOT take ownership of the movie.

The buddy shortcut, if any, is disabled.

See also movie() and setBuddy().

[slot] void QLabel::setNum(int num)

Sets the label contents to plain text containing the textual representation of integer num. Any previous content is cleared. Does nothing if the integer's string representation is the same as the current contents of the label.

The buddy shortcut, if any, is disabled.

See also setText(), QString::setNum(), and setBuddy().

[slot] void QLabel::setNum(double num)

This is an overloaded function.

Sets the label contents to plain text containing the textual representation of double num. Any previous content is cleared. Does nothing if the double's string representation is the same as the current contents of the label.

The buddy shortcut, if any, is disabled.

See also setText(), QString::setNum(), and setBuddy().

[slot] void QLabel::setPicture(const QPicture &picture)

Sets the label contents to picture. Any previous content is cleared.

The buddy shortcut, if any, is disabled.

See also picture() and setBuddy().

[since 6.1] void QLabel::setResourceProvider(const QTextDocument::ResourceProvider &provider)

Sets the provider of resources for rich text of this label.

This function was introduced in Qt 6.1.

See also resourceProvider().

void QLabel::setSelection(int start, int length)

Selects text from position start and for length characters.

Note: The textInteractionFlags set on the label need to include either TextSelectableByMouse or TextSelectableByKeyboard.

See also selectedText().

[override virtual] QSize QLabel::sizeHint() const

Reimplements: QFrame::sizeHint() const.