Gtk.Label¶
class — extends Widget, Accessible, AccessibleHypertext, AccessibleText, Buildable, ConstraintTarget
Displays a small amount of text.
Most labels are used to label another widget (such as an Entry).
<picture> <source srcset="label-dark.png" media="(prefers-color-scheme: dark)"> <img alt="An example GtkLabel" src="label.png"> </picture>
Shortcuts and Gestures¶
GtkLabel supports the following keyboard shortcuts, when the cursor is
visible:
- <kbd>Shift</kbd>+<kbd>F10</kbd> or <kbd>Menu</kbd> opens the context menu.
- <kbd>Ctrl</kbd>+<kbd>A</kbd> or <kbd>Ctrl</kbd>+<kbd>/</kbd> selects all.
- <kbd>Ctrl</kbd>+<kbd>Shift</kbd>+<kbd>A</kbd> or <kbd>Ctrl</kbd>+<kbd>\</kbd> unselects all.
Additionally, the following signals have default keybindings:
Actions¶
GtkLabel defines a set of built-in actions:
clipboard.copycopies the text to the clipboard.clipboard.cutdoesn't do anything, since text in labels can't be deleted.clipboard.pastedoesn't do anything, since text in labels can't be edited.link.openopens the link, when activated on a link inside the label.link.copycopies the link to the clipboard, when activated on a link inside the label.menu.popupopens the context menu.selection.deletedoesn't do anything, since text in labels can't be deleted.selection.select-allselects all of the text, if the label allows selection.
CSS nodes¶
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 Pango.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 AccessibleRole.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 Label.new_with_mnemonic or
Label.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 Label.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
Label.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, Pango.parse_markup)
The markup passed to Label.set_markup must be valid XML; for example,
literal <, > and & characters must be escaped as <, >, and &.
If you pass text obtained from the user, file, or a network to
Label.set_markup, you’ll want to escape it with
GLib.markup_escape_text or GLib.markup_printf_escaped.
Markup strings are just a convenient way to set the Pango.AttrList
on a label; Label.set_attributes may be a simpler way to set
attributes in some cases. Be careful though; Pango.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 Pango.Attribute requires knowledge of the exact
string being displayed, so translations will cause problems.
Selectable labels¶
Labels can be made selectable with Label.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 Label.set_wrap.
Label.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 Widget.halign and
Widget.valign properties.
The Label.width-chars and Label.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> tag
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=\"<i>Our</i> 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 Label.activate-link signal and the
Label.get_current_uri function.
Constructors¶
new¶
Creates a new label with the given text inside it.
You can pass NULL to get an empty label widget.
Parameters:
str— the text of the label
new_with_mnemonic¶
Creates a new label with the given text inside it, and a mnemonic.
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
Label.set_mnemonic_widget.
If Label.set_mnemonic_widget is not called, then the first
activatable ancestor of the label 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¶
get_attributes¶
Gets the label's attribute list.
This is the Pango.AttrList that was set on the label using
Label.set_attributes, if any. This function does not
reflect attributes that come from the label's markup (see
Label.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¶
Returns the URI for the 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 Label.activate-link
handler or for use in a Widget.query-tooltip handler.
get_ellipsize¶
Returns the ellipsization mode of the label.
See Label.set_ellipsize.
get_extra_menu¶
Gets the extra menu model of the label.
See Label.set_extra_menu.
get_justify¶
Returns the justification of the label.
See Label.set_justify.
get_label¶
Fetches the text from a label.
The returned text includes any embedded underlines indicating
mnemonics and Pango markup. (See Label.get_text).
get_layout¶
Gets the Pango layout used to display the label.
The layout is useful to e.g. convert text positions to pixel
positions, in combination with Label.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¶
Obtains the coordinates where the label will draw its Pango layout.
The coordinates are useful to convert mouse events into coordinates
inside the Pango.Layout, e.g. to take some action if some part
of the label is clicked. Remember when using the Pango.Layout
functions you need to convert to and from pixels using PANGO_PIXELS()
or Pango.SCALE.
get_lines¶
Gets the number of lines to which an ellipsized, wrapping label should be limited.
See Label.set_lines.
get_max_width_chars¶
Retrieves the maximum width of the label in characters.
get_mnemonic_keyval¶
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¶
Retrieves the mnemonic target of this label.
See Label.set_mnemonic_widget.
get_natural_wrap_mode¶
Returns natural line wrap mode used by the label.
See Label.set_natural_wrap_mode.
get_selectable¶
Returns whether the label is selectable.
get_selection_bounds¶
Gets the selected range of characters in the label.
The returned start and end positions are in characters.
get_single_line_mode¶
Returns whether the label is in single line mode.
get_tabs¶
Gets the tab stops for the label.
The returned array will be NULL if “standard” (8-space) tabs are used.
get_text¶
Gets the text of the label.
The returned text is as it appears on screen. This does not include
any embedded underlines indicating mnemonics or Pango markup. (See
Label.get_label)
get_use_markup¶
Returns whether the label’s text is interpreted as Pango markup.
See Label.set_use_markup.
get_use_underline¶
Returns whether underlines in the label indicate mnemonics.
get_width_chars¶
Retrieves the desired width of the label in characters.
get_wrap¶
Returns whether lines in the label are automatically wrapped.
See Label.set_wrap.
get_wrap_mode¶
Returns line wrap mode used by the label.
See Label.set_wrap_mode.
get_xalign¶
Gets the xalign of the label.
See the Label.xalign property.
get_yalign¶
Gets the yalign of the label.
See the Label.yalign property.
select_region¶
Selects a range of characters in the label, if the label is selectable.
See Label.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 charactersend_offset— end offset, in characters
set_attributes¶
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
Label.use-underline or Label.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 list of style attributes
set_ellipsize¶
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— the ellipsization mode
set_extra_menu¶
Sets a menu model to add to the context menu of the label.
Parameters:
model— a menu model
set_justify¶
Sets the alignment of lines in the label relative to each other.
This function has no effect on labels containing only a single line.
Justification.left is the default value when the widget
is first created with Label.new.
If you instead want to set the alignment of the label as a whole,
use Widget.set_halign instead.
Parameters:
jtype— the new justification
set_label¶
Sets the text of the label.
The label is interpreted as including embedded underlines and/or Pango
markup depending on the values of the Label.use-underline
and Label.use-markup properties.
Parameters:
str— the new text to set for the label
set_lines¶
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¶
Sets the labels text and attributes from markup.
The string must be marked up with Pango markup
(see Pango.parse_markup).
If str is external data, you may need to escape it
with GLib.markup_escape_text or GLib.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 sets the Label.use-markup property
to true.
Also see Label.set_text.
Parameters:
str— the markup string
set_markup_with_mnemonic¶
Sets the labels text, attributes and mnemonic from markup.
Parses str which is marked up with Pango markup (see Pango.parse_markup),
setting the label’s text and attribute list based on the parse results.
If characters in str are preceded by an underscore, they are underlined
indicating that they represent a keyboard accelerator called a mnemonic.
The mnemonic key can be used to activate another widget, chosen
automatically, or explicitly using Label.set_mnemonic_widget.
Parameters:
str— the markup string
set_max_width_chars¶
Sets the maximum width of the label in characters.
Parameters:
n_chars— the new maximum width, in characters.
set_mnemonic_widget¶
Associate the label with its mnemonic target.
If the label has been set so that it has a mnemonic key (using
i.e. Label.set_markup_with_mnemonic,
Label.set_text_with_mnemonic,
Label.new_with_mnemonic
or the Label.use_underline property) the label can
be associated with a widget that is the target of the mnemonic.
When the label is inside a widget (like a Button or a
Notebook tab) it is automatically associated with the
correct widget, but sometimes (i.e. when the target is a Entry
next to the label) you need to set it explicitly using this function.
The target widget will be accelerated by emitting the
Widget.mnemonic-activate signal on it. The default handler
for this signal will activate the widget if there are no mnemonic
collisions and toggle focus between the colliding widgets otherwise.
Parameters:
widget— the target widget
set_natural_wrap_mode¶
Selects the line wrapping for the natural size request.
This only affects the natural size requested, for the actual wrapping used,
see the Label.wrap-mode property.
Parameters:
wrap_mode— the line wrapping mode
set_selectable¶
Makes text in the label selectable.
Selectable labels allow the user to select text from the label, for copy-and-paste.
Parameters:
setting— true to allow selecting text in the label
set_single_line_mode¶
Sets whether the label is in single line mode.
Parameters:
single_line_mode— true to enable single line mode
set_tabs¶
Sets tab stops for the label.
Parameters:
tabs— tab stops
set_text¶
Sets the text for the label.
It overwrites any text that was there before and clears any
previously set mnemonic accelerators, and sets the
Label.use-underline and
Label.use-markup properties to false.
Also see Label.set_markup.
Parameters:
str— the text to show inself
set_text_with_mnemonic¶
Sets the text for the label, with mnemonics.
If characters in str are preceded by an underscore, they are underlined
indicating that they represent a keyboard accelerator called a mnemonic.
The mnemonic key can be used to activate another widget, chosen
automatically, or explicitly using Label.set_mnemonic_widget.
Parameters:
str— the text
set_use_markup¶
Sets whether the text of the label contains markup.
See Label.set_markup.
Parameters:
setting— true if the label’s text should be parsed for markup.
set_use_underline¶
Sets whether underlines in the text indicate mnemonics.
Parameters:
setting— true if underlines in the text indicate mnemonics
set_width_chars¶
Sets the desired width in characters of the label.
Parameters:
n_chars— the new desired width, in characters.
set_wrap¶
Toggles line wrapping within the label.
True makes it break lines if text exceeds the widget’s size. false lets the text get cut off by the edge of the widget if it exceeds the widget size.
Note that setting line wrapping to true does not make the label
wrap at its parent widget’s width, because GTK widgets conceptually
can’t make their requisition depend on the parent widget’s size.
For a label that wraps at a specific position, set the label’s width
using Widget.set_size_request.
Parameters:
wrap— whether to wrap lines
set_wrap_mode¶
Controls how line wrapping is done.
This only affects the label if line wrapping is on. (See
Label.set_wrap)
The default is Pango.WrapMode.word, which means
wrap on word boundaries.
For sizing behavior, also consider the
Label.natural-wrap-mode property.
Parameters:
wrap_mode— the line wrapping mode
set_xalign¶
Sets the xalign of the label.
See the Label.xalign property.
Parameters:
xalign— the new xalign value, between 0 and 1
set_yalign¶
Sets the yalign of the label.
See the Label.yalign property.
Parameters:
yalign— the new yalign value, between 0 and 1
Properties¶
attributes¶
A list of style attributes to apply to the text of the label.
ellipsize¶
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
[enum.Pango.EllipsizeMode.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 NotebookPage.tab-expand child property is set to true.
Other ways to set a label's width are Widget.set_size_request
and Label.set_width_chars.
extra_menu¶
A menu model whose contents will be appended to the context menu.
justify¶
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 Label.xalign for that.
label¶
The contents of the label.
If the string contains Pango markup (see Pango.parse_markup),
you will have to set the Label.use-markup property to
true in order for the label to display the markup attributes. See also
Label.set_markup for a convenience function that sets both
this property and the Label.use-markup property at the
same time.
If the string contains underlines acting as mnemonics, you will have to
set the Label.use-underline property to true in order
for the label to display them.
lines¶
The number of lines to which an ellipsized, wrapping label should display before it gets ellipsized. This both prevents the label from ellipsizing before this many lines are displayed, and limits the height request of the label to this many lines.
::: warning Setting this property has unintuitive and unfortunate consequences for the minimum width of the label. Specifically, if the height of the label is such that it fits a smaller number of lines than the value of this property, the label can not be ellipsized at all, which means it must be wide enough to fit all the text fully.
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.
max_width_chars¶
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 Label.width-chars and Label.max-width-chars
determine the width of ellipsized and wrapped labels.
mnemonic_keyval¶
The mnemonic accelerator key for the label.
mnemonic_widget¶
The widget to be activated when the labels mnemonic key is pressed.
natural_wrap_mode¶
Select the line wrapping for the natural size request.
This only affects the natural size requested. For the actual wrapping
used, see the Label.wrap-mode property.
The default is NaturalWrapMode.inherit, which inherits
the behavior of the Label.wrap-mode property.
selectable¶
Whether the label text can be selected with the mouse.
single_line_mode¶
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.
tabs¶
Custom tabs for this label.
use_markup¶
True if the text of the label includes Pango markup.
See Pango.parse_markup.
use_underline¶
True if the text of the label indicates a mnemonic with an _
before the mnemonic character.
width_chars¶
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 Label.width-chars and Label.max-width-chars
determine the width of ellipsized and wrapped labels.
wrap¶
True if the label text will wrap if it gets too wide.
wrap_mode¶
Controls how the line wrapping is done.
This only affects the formatting if line wrapping is on (see the
Label.wrap property). The default is Pango.WrapMode.word,
which means wrap on word boundaries.
For sizing behavior, also consider the Label.natural-wrap-mode
property.
xalign¶
The horizontal alignment of the label text inside its size allocation.
Compare this to Widget.halign, which determines how the
labels size allocation is positioned in the space available for the label.
yalign¶
The vertical alignment of the label text inside its size allocation.
Compare this to Widget.valign, which determines how the
labels size allocation is positioned in the space available for the label.
Signals¶
activate-current-link¶
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 g_signal_emit_by_name() if they need to control activation of URIs programmatically.
The default bindings for this signal are all forms of the <kbd>Enter</kbd> key.
activate-link¶
Gets emitted to activate a URI.
Applications may connect to it to override the default behaviour,
which is to call FileLauncher.launch.
copy-clipboard¶
Gets emitted to copy the selection to the clipboard.
The ::copy-clipboard signal is a keybinding signal.
The default binding for this signal is <kbd>Ctrl</kbd>+<kbd>c</kbd>.
move-cursor¶
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
GObject.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 <kbd>Shift</kbd> modifier extends the selection, the variant without the <kbd>Shift</kbd> modifier does not. There are too many key combinations to list them all here.
- <kbd>←</kbd>, <kbd>→</kbd>, <kbd>↑</kbd>, <kbd>↓</kbd> move by individual characters/lines
- <kbd>Ctrl</kbd>+<kbd>←</kbd>, etc. move by words/paragraphs
- <kbd>Home</kbd> and <kbd>End</kbd> move to the ends of the buffer