Label

class Label(**properties: Any)

Superclasses: Widget, InitiallyUnowned, Object

Implemented Interfaces: Accessible, AccessibleText, Buildable, ConstraintTarget

The GtkLabel widget displays a small amount of text.

As the name implies, most labels are used to label another widget such as a Button.

CSS nodes

label
├── [selection]
├── [link]
┊
╰── [link]

GtkLabel has a single CSS node with the name label. A wide variety of style classes may be applied to labels, such as .title, .subtitle, .dim-label, etc. In the GtkShortcutsWindow, labels are used with the .keycap style class.

If the label has a selection, it gets a subnode with name selection.

If the label has links, there is one subnode per link. These subnodes carry the link or visited state depending on whether they have been visited. In this case, label node also gets a .link style class.

GtkLabel as GtkBuildable

The GtkLabel implementation of the GtkBuildable interface supports a custom <attributes> element, which supports any number of <attribute> elements. The <attribute> element has attributes named “name“, “value“, “start“ and “end“ and allows you to specify Attribute values for this label.

An example of a UI definition fragment specifying Pango attributes:

<object class="GtkLabel">
  <attributes>
    <attribute name="weight" value="PANGO_WEIGHT_BOLD"/>
    <attribute name="background" value="red" start="5" end="10"/>
  </attributes>
</object>

The start and end attributes specify the range of characters to which the Pango attribute applies. If start and end are not specified, the attribute is applied to the whole text. Note that specifying ranges does not make much sense with translatable attributes. Use markup embedded in the translatable content instead.

Accessibility

GtkLabel uses the LABEL role.

Mnemonics

Labels may contain “mnemonics”. Mnemonics are underlined characters in the label, used for keyboard navigation. Mnemonics are created by providing a string with an underscore before the mnemonic character, such as "_File", to the functions new_with_mnemonic or set_text_with_mnemonic.

Mnemonics automatically activate any activatable widget the label is inside, such as a Button; if the label is not inside the mnemonic’s target widget, you have to tell the label about the target using set_mnemonic_widget.

Here’s a simple example where the label is inside a button:

// Pressing Alt+H will activate this button
GtkWidget *button = gtk_button_new ();
GtkWidget *label = gtk_label_new_with_mnemonic ("_Hello");
gtk_button_set_child (GTK_BUTTON (button), label);

There’s a convenience function to create buttons with a mnemonic label already inside:

// Pressing Alt+H will activate this button
GtkWidget *button = gtk_button_new_with_mnemonic ("_Hello");

To create a mnemonic for a widget alongside the label, such as a Entry, you have to point the label at the entry with set_mnemonic_widget:

// Pressing Alt+H will focus the entry
GtkWidget *entry = gtk_entry_new ();
GtkWidget *label = gtk_label_new_with_mnemonic ("_Hello");
gtk_label_set_mnemonic_widget (GTK_LABEL (label), entry);

Markup (styled text)

To make it easy to format text in a label (changing colors, fonts, etc.), label text can be provided in a simple markup format:

Here’s how to create a label with a small font:

GtkWidget *label = gtk_label_new (NULL);
gtk_label_set_markup (GTK_LABEL (label), "<small>Small text</small>");

(See the Pango manual for complete documentation] of available tags, parse_markup)

The markup passed to set_markup must be valid; for example, literal <, > and & characters must be escaped as <, >, and &. If you pass text obtained from the user, file, or a network to set_markup, you’ll want to escape it with markup_escape_text or markup_printf_escaped.

Markup strings are just a convenient way to set the AttrList on a label; set_attributes may be a simpler way to set attributes in some cases. Be careful though; AttrList tends to cause internationalization problems, unless you’re applying attributes to the entire string (i.e. unless you set the range of each attribute to [0, %G_MAXINT)). The reason is that specifying the start_index and end_index for a Attribute requires knowledge of the exact string being displayed, so translations will cause problems.

Selectable labels

Labels can be made selectable with set_selectable. Selectable labels allow the user to copy the label contents to the clipboard. Only labels that contain useful-to-copy information—such as error messages—should be made selectable.

Text layout

A label can contain any number of paragraphs, but will have performance problems if it contains more than a small number. Paragraphs are separated by newlines or other paragraph separators understood by Pango.

Labels can automatically wrap text if you call set_wrap.

set_justify sets how the lines in a label align with one another. If you want to set how the label as a whole aligns in its available space, see the halign and valign properties.

The width_chars and max_width_chars properties can be used to control the size allocation of ellipsized or wrapped labels. For ellipsizing labels, if either is specified (and less than the actual text size), it is used as the minimum width, and the actual text size is used as the natural width of the label. For wrapping labels, width-chars is used as the minimum width, if specified, and max-width-chars is used as the natural width. Even if max-width-chars specified, wrapping labels will be rewrapped to use all of the available width.

Links

GTK supports markup for clickable hyperlinks in addition to regular Pango markup. The markup for links is borrowed from HTML, using the <a> with “href“, “title“ and “class“ attributes. GTK renders links similar to the way they appear in web browsers, with colored, underlined text. The “title“ attribute is displayed as a tooltip on the link. The “class“ attribute is used as style class on the CSS node for the link.

An example of inline links looks like this:

const char *text =
"Go to the "
"<a href=\"https://www.gtk.org\" title=\"&lt;i&gt;Our&lt;/i&gt; website\">"
"GTK website</a> for more...";
GtkWidget *label = gtk_label_new (NULL);
gtk_label_set_markup (GTK_LABEL (label), text);

It is possible to implement custom handling for links and their tooltips with the activate_link signal and the get_current_uri function.

Constructors

class Label

classmethod new(str: str | None = None) → Widget

Creates a new label with the given text inside it.

You can pass None to get an empty label widget.

Parameters:: str – The text of the label

classmethod new_with_mnemonic(str: str | None = None) → Widget

Creates a new GtkLabel, containing the text in str.

If characters in str are preceded by an underscore, they are underlined. If you need a literal underscore character in a label, use ‘__’ (two underscores). The first underlined character represents a keyboard accelerator called a mnemonic. The mnemonic key can be used to activate another widget, chosen automatically, or explicitly using set_mnemonic_widget.

If set_mnemonic_widget is not called, then the first activatable ancestor of the GtkLabel will be chosen as the mnemonic widget. For instance, if the label is inside a button or menu item, the button or menu item will automatically become the mnemonic widget and be activated by the mnemonic.

Parameters:: str – The text of the label, with an underscore in front of the mnemonic character

Methods

class Label

get_attributes() → AttrList | None

Gets the label’s attribute list.

This is the AttrList that was set on the label using set_attributes, if any. This function does not reflect attributes that come from the label’s markup (see set_markup). If you want to get the effective attributes for the label, use pango_layout_get_attributes (gtk_label_get_layout (self)).

get_current_uri() → str | None

Returns the URI for the currently active link in the label.

The active link is the one under the mouse pointer or, in a selectable label, the link in which the text cursor is currently positioned.

This function is intended for use in a activate_link handler or for use in a query_tooltip handler.

get_ellipsize() → EllipsizeMode

Returns the ellipsizing position of the label.

See set_ellipsize.

get_extra_menu() → MenuModel | None

Gets the extra menu model of label.

See set_extra_menu.

get_justify() → Justification

Returns the justification of the label.

See set_justify.

get_label() → str

Fetches the text from a label.

The returned text includes any embedded underlines indicating mnemonics and Pango markup. (See get_text).

get_layout() → Layout

Gets the PangoLayout used to display the label.

The layout is useful to e.g. convert text positions to pixel positions, in combination with get_layout_offsets. The returned layout is owned by the label so need not be freed by the caller. The label is free to recreate its layout at any time, so it should be considered read-only.

get_layout_offsets() → tuple[int, int]

Obtains the coordinates where the label will draw its PangoLayout.

The coordinates are useful to convert mouse events into coordinates inside the Layout, e.g. to take some action if some part of the label is clicked. Remember when using the Layout functions you need to convert to and from pixels using PIXELS() or SCALE.

get_lines() → int

Gets the number of lines to which an ellipsized, wrapping label should be limited.

See set_lines.

get_max_width_chars() → int

Retrieves the desired maximum width of label, in characters.

See set_width_chars.

get_mnemonic_keyval() → int

Return the mnemonic accelerator.

If the label has been set so that it has a mnemonic key this function returns the keyval used for the mnemonic accelerator. If there is no mnemonic set up it returns GDK_KEY_VoidSymbol.

get_mnemonic_widget() → Widget | None

Retrieves the target of the mnemonic (keyboard shortcut) of this label.

See set_mnemonic_widget.

get_natural_wrap_mode() → NaturalWrapMode

Returns line wrap mode used by the label.

See set_natural_wrap_mode.

Added in version 4.6.

get_selectable() → bool: Returns whether the label is selectable.

get_selection_bounds() → tuple[bool, int, int]: Gets the selected range of characters in the label.

get_single_line_mode() → bool: Returns whether the label is in single line mode.

get_tabs() → TabArray | None

Gets the tabs for self.

The returned array will be None if “standard” (8-space) tabs are used. Free the return value with free.

Added in version 4.8.

get_text() → str

Fetches the text from a label.

The returned text is as it appears on screen. This does not include any embedded underlines indicating mnemonics or Pango markup. (See get_label)

get_use_markup() → bool

Returns whether the label’s text is interpreted as Pango markup.

See set_use_markup.

get_use_underline() → bool

Returns whether an embedded underlines in the label indicate mnemonics.

See set_use_underline.

get_width_chars() → int

Retrieves the desired width of label, in characters.

See set_width_chars.

get_wrap() → bool

Returns whether lines in the label are automatically wrapped.

See set_wrap.

get_wrap_mode() → WrapMode

Returns line wrap mode used by the label.

See set_wrap_mode.

get_xalign() → float

Gets the xalign of the label.

See the xalign property.

get_yalign() → float

Gets the yalign of the label.

See the yalign property.

select_region(start_offset: int, end_offset: int) → None

Selects a range of characters in the label, if the label is selectable.

See set_selectable. If the label is not selectable, this function has no effect. If start_offset or end_offset are -1, then the end of the label will be substituted.

Parameters:

start_offset – start offset (in characters not bytes)
end_offset – end offset (in characters not bytes)

set_attributes(attrs: AttrList | None = None) → None

Apply attributes to the label text.

The attributes set with this function will be applied and merged with any other attributes previously effected by way of the use_underline or use_markup properties. While it is not recommended to mix markup strings with manually set attributes, if you must; know that the attributes will be applied to the label after the markup string is parsed.

Parameters:: attrs – a AttrList

set_ellipsize(mode: EllipsizeMode) → None

Sets the mode used to ellipsize the text.

The text will be ellipsized if there is not enough space to render the entire string.

Parameters:: mode – a PangoEllipsizeMode

set_extra_menu(model: MenuModel | None = None) → None

Sets a menu model to add when constructing the context menu for label.

Parameters:: model – a GMenuModel

set_justify(jtype: Justification) → None

Sets the alignment of the lines in the text of the label relative to each other.

LEFT is the default value when the widget is first created with new. If you instead want to set the alignment of the label as a whole, use set_halign instead. set_justify has no effect on labels containing only a single line.

Parameters:: jtype – a GtkJustification

set_label(str: str) → None

Sets the text of the label.

The label is interpreted as including embedded underlines and/or Pango markup depending on the values of the use_underline and use_markup properties.

Parameters:: str – the new text to set for the label

set_lines(lines: int) → None

Sets the number of lines to which an ellipsized, wrapping label should be limited.

This has no effect if the label is not wrapping or ellipsized. Set this to -1 if you don’t want to limit the number of lines.

Parameters:: lines – the desired number of lines, or -1

set_markup(str: str) → None

Sets the labels text and attributes from markup.

The string must be marked up with Pango markup (see parse_markup).

If the str is external data, you may need to escape it with markup_escape_text() or markup_printf_escaped():

GtkWidget *self = gtk_label_new (NULL);
const char *str = "...";
const char *format = "<span style=\"italic\">\``%s``</span>";
char *markup;

markup = g_markup_printf_escaped (format, str);
gtk_label_set_markup (GTK_LABEL (self), markup);
g_free (markup);

This function will set the use_markup property to True as a side effect.

If you set the label contents using the label property you should also ensure that you set the use_markup property accordingly.

Properties

class Label

props.attributes: AttrList: A list of style attributes to apply to the text of the label.

props.ellipsize: EllipsizeMode

The preferred place to ellipsize the string, if the label does not have enough room to display the entire string.

Note that setting this property to a value other than %PANGO_ELLIPSIZE_NONE has the side-effect that the label requests only enough space to display the ellipsis “…”. In particular, this means that ellipsizing labels do not work well in notebook tabs, unless the tab_expand child property is set to True. Other ways to set a label’s width are set_size_request and set_width_chars.

props.extra_menu: MenuModel: A menu model whose contents will be appended to the context menu.

props.justify: Justification

The alignment of the lines in the text of the label, relative to each other.

This does not affect the alignment of the label within its allocation. See xalign for that.

props.label: str

The contents of the label.

If the string contains Pango markup (see parse_markup), you will have to set the use_markup property to True in order for the label to display the markup attributes. See also set_markup for a convenience function that sets both this property and the use_markup property at the same time.

If the string contains underlines acting as mnemonics, you will have to set the use_underline property to True in order for the label to display them.

props.lines: int

The number of lines to which an ellipsized, wrapping label should be limited.

This property has no effect if the label is not wrapping or ellipsized. Set this property to -1 if you don’t want to limit the number of lines.

props.max_width_chars: int

The desired maximum width of the label, in characters.

If this property is set to -1, the width will be calculated automatically.

See the section on text layout for details of how width_chars and max_width_chars determine the width of ellipsized and wrapped labels.

props.mnemonic_keyval: int: The mnemonic accelerator key for the label.

props.mnemonic_widget: Widget: The widget to be activated when the labels mnemonic key is pressed.

props.natural_wrap_mode: NaturalWrapMode

Select the line wrapping for the natural size request.

This only affects the natural size requested. For the actual wrapping used, see the wrap_mode property.

The default is INHERIT, which inherits the behavior of the wrap_mode property.

Added in version 4.6.

props.selectable: bool: Whether the label text can be selected with the mouse.

props.single_line_mode: bool

Whether the label is in single line mode.

In single line mode, the height of the label does not depend on the actual text, it is always set to ascent + descent of the font. This can be an advantage in situations where resizing the label because of text changes would be distracting, e.g. in a statusbar.

props.tabs: TabArray: Custom tabs for this label.

Added in version 4.8.

props.use_markup: bool

True if the text of the label includes Pango markup.

See parse_markup.

props.use_underline: bool: True if the text of the label indicates a mnemonic with an _ before the mnemonic character.

props.width_chars: int

The desired width of the label, in characters.

If this property is set to -1, the width will be calculated automatically.

See the section on text layout for details of how width_chars and max_width_chars determine the width of ellipsized and wrapped labels.

props.wrap: bool: True if the label text will wrap if it gets too wide.

props.wrap_mode: WrapMode

Controls how the line wrapping is done.

This only affects the formatting if line wrapping is on (see the wrap property). The default is %PANGO_WRAP_WORD, which means wrap on word boundaries.

For sizing behavior, also consider the natural_wrap_mode property.

props.xalign: float

The horizontal alignment of the label text inside its size allocation.

Compare this to halign, which determines how the labels size allocation is positioned in the space available for the label.

props.yalign: float

The vertical alignment of the label text inside its size allocation.

Compare this to valign, which determines how the labels size allocation is positioned in the space available for the label.

Signals

class Label.signals

activate_current_link() → None

Gets emitted when the user activates a link in the label.

The ::activate-current-link is a keybinding signal.

Applications may also emit the signal with signal_emit_by_name() if they need to control activation of URIs programmatically.

The default bindings for this signal are all forms of the Enter key.

activate_link(uri: str) → bool

Gets emitted to activate a URI.

Applications may connect to it to override the default behaviour, which is to call launch.

Parameters:: uri – the URI that is activated

copy_clipboard() → None

Gets emitted to copy the selection to the clipboard.

The ::copy-clipboard signal is a keybinding signal.

The default binding for this signal is Ctrl`+:kbd:`c.

move_cursor(step: MovementStep, count: int, extend_selection: bool) → None

Gets emitted when the user initiates a cursor movement.

The ::move-cursor signal is a keybinding signal. If the cursor is not visible in entry, this signal causes the viewport to be moved instead.

Applications should not connect to it, but may emit it with signal_emit_by_name() if they need to control the cursor programmatically.

The default bindings for this signal come in two variants, the variant with the Shift modifier extends the selection, the variant without the Shift modifier does not. There are too many key combinations to list them all here.

←, →, ↑, ↓ move by individual characters/lines
Ctrl`+:kbd:`←, etc. move by words/paragraphs
Home and End move to the ends of the buffer

Parameters:

step – the granularity of the move, as a GtkMovementStep
count – the number of step units to move
extend_selection – True if the move should extend the selection