Description
The GtkLabel widget displays a small amount of text. As the name
implies, most labels are used to label another widget such as a
GtkButton, a GtkMenuItem, or a GtkComboBox.
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 wth 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.
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 PangoAttribute values for
this label.
An example of a UI definition fragment specifying Pango attributes:
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.
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 gtk_label_new_with_mnemonic() or
gtk_label_set_text_with_mnemonic().
Mnemonics automatically activate any activatable widget the label is
inside, such as a GtkButton; if the label is not inside the
mnemonic’s target widget, you have to tell the label about the target
using gtk_label_set_mnemonic_widget(). Here’s a simple example where
the label is inside a button:
There’s a convenience function to create buttons with a mnemonic label
already inside:
To create a mnemonic for a widget alongside the label, such as a
GtkEntry, you have to point the label at the entry with
gtk_label_set_mnemonic_widget():
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:
(See complete documentation of available
tags in the Pango manual.)
The markup passed to gtk_label_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
gtk_label_set_markup(), you’ll want to escape it with
g_markup_escape_text() or g_markup_printf_escaped().
Markup strings are just a convenient way to set the PangoAttrList on
a label; gtk_label_set_attributes() may be a simpler way to set
attributes in some cases. Be careful though; PangoAttrList 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 PangoAttribute requires knowledge of the exact string
being displayed, so translations will cause problems.
Selectable labels
Labels can be made selectable with gtk_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
gtk_label_set_line_wrap().
gtk_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 “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.
Note that the interpretation of “width-chars” and
“max-width-chars” has changed a bit with the introduction of
width-for-height geometry management.
Links
Since 2.18, 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“ and “title“ 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.
An example looks like this:
It is possible to implement custom handling for links and their tooltips with
the “activate-link” signal and the gtk_label_get_current_uri() function.
Functions
gtk_label_new ()
GtkWidget *
gtk_label_new (const gchar *str);
Creates a new label with the given text inside it. You can
pass NULL to get an empty label widget.
gtk_label_set_text ()
void
gtk_label_set_text (GtkLabel *label,
const gchar *str);
Sets the text within the GtkLabel widget. It overwrites any text that
was there before.
This function will clear any previously set mnemonic accelerators, and
set the “use-underline” property to FALSE as a side effect.
This function will set the “use-markup” property to FALSE
as a side effect.
See also: gtk_label_set_markup()
gtk_label_set_attributes ()
void
gtk_label_set_attributes (GtkLabel *label,
PangoAttrList *attrs);
Sets a PangoAttrList; the attributes in the list are applied 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.
gtk_label_set_markup ()
void
gtk_label_set_markup (GtkLabel *label,
const gchar *str);
Parses str
which is marked up with the
Pango text markup language, setting the
label’s text and attribute list based on the parse results.
If the str
is external data, you may need to escape it with
g_markup_escape_text() or g_markup_printf_escaped():
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.
See also: gtk_label_set_text()
gtk_label_set_markup_with_mnemonic ()
void
gtk_label_set_markup_with_mnemonic (GtkLabel *label,
const gchar *str);
Parses str
which is marked up with the
Pango text markup language,
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 gtk_label_set_mnemonic_widget().
gtk_label_set_pattern ()
void
gtk_label_set_pattern (GtkLabel *label,
const gchar *pattern);
The pattern of underlines you want under the existing text within the
GtkLabel widget. For example if the current text of the label says
“FooBarBaz” passing a pattern of “___ ___” will underline
“Foo” and “Baz” but not “Bar”.
gtk_label_set_xalign ()
void
gtk_label_set_xalign (GtkLabel *label,
gfloat xalign);
Sets the “xalign” property for label
.
Since: 3.16
gtk_label_set_yalign ()
void
gtk_label_set_yalign (GtkLabel *label,
gfloat yalign);
Sets the “yalign” property for label
.
Since: 3.16
gtk_label_set_ellipsize ()
void
gtk_label_set_ellipsize (GtkLabel *label,
PangoEllipsizeMode mode);
Sets the mode used to ellipsize (add an ellipsis: "...") to the text
if there is not enough space to render the entire string.
Since: 2.6
gtk_label_set_width_chars ()
void
gtk_label_set_width_chars (GtkLabel *label,
gint n_chars);
Sets the desired width in characters of label
to n_chars
.
Since: 2.6
gtk_label_set_max_width_chars ()
void
gtk_label_set_max_width_chars (GtkLabel *label,
gint n_chars);
Sets the desired maximum width in characters of label
to n_chars
.
Since: 2.6
gtk_label_set_line_wrap ()
void
gtk_label_set_line_wrap (GtkLabel *label,
gboolean wrap);
Toggles line wrapping within the GtkLabel widget. 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 container’s width, because GTK+ widgets
conceptually can’t make their requisition depend on the parent
container’s size. For a label that wraps at a specific position,
set the label’s width using gtk_widget_set_size_request().
gtk_label_set_lines ()
void
gtk_label_set_lines (GtkLabel *label,
gint 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.
Since: 3.10
gtk_label_get_layout_offsets ()
void
gtk_label_get_layout_offsets (GtkLabel *label,
gint *x,
gint *y);
Obtains the coordinates where the label will draw the PangoLayout
representing the text in the label; useful to convert mouse events
into coordinates inside the PangoLayout, e.g. to take some action
if some part of the label is clicked. Of course you will need to
create a GtkEventBox to receive the events, and pack the label
inside it, since labels are windowless (they return FALSE from
gtk_widget_get_has_window()). Remember
when using the PangoLayout functions you need to convert to
and from pixels using PANGO_PIXELS() or PANGO_SCALE.
gtk_label_get_mnemonic_keyval ()
guint
gtk_label_get_mnemonic_keyval (GtkLabel *label);
If the label has been set so that it has an mnemonic key this function
returns the keyval used for the mnemonic accelerator. If there is no
mnemonic set up it returns GDK_KEY_VoidSymbol.
Returns
GDK keyval usable for accelerators, or GDK_KEY_VoidSymbol
gtk_label_get_text ()
const gchar *
gtk_label_get_text (GtkLabel *label);
Fetches the text from a label widget, as displayed on the
screen. This does not include any embedded underlines
indicating mnemonics or Pango markup. (See gtk_label_get_label())
Returns
the text in the label widget. This is the internal
string used by the label, and must not be modified.
gtk_label_new_with_mnemonic ()
GtkWidget *
gtk_label_new_with_mnemonic (const gchar *str);
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
gtk_label_set_mnemonic_widget().
If gtk_label_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.
gtk_label_select_region ()
void
gtk_label_select_region (GtkLabel *label,
gint start_offset,
gint end_offset);
Selects a range of characters in the label, if the label is selectable.
See gtk_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.
gtk_label_set_mnemonic_widget ()
void
gtk_label_set_mnemonic_widget (GtkLabel *label,
GtkWidget *widget);
If the label has been set so that it has an mnemonic key (using
i.e. gtk_label_set_markup_with_mnemonic(),
gtk_label_set_text_with_mnemonic(), gtk_label_new_with_mnemonic()
or the “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 GtkButton or a GtkNotebook tab) it is
automatically associated with the correct widget, but sometimes
(i.e. when the target is a GtkEntry next to the label) you need to
set it explicitly using this function.
The target widget will be accelerated by emitting the
GtkWidget::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.
gtk_label_set_selectable ()
void
gtk_label_set_selectable (GtkLabel *label,
gboolean setting);
Selectable labels allow the user to select text from the label, for
copy-and-paste.
gtk_label_set_text_with_mnemonic ()
void
gtk_label_set_text_with_mnemonic (GtkLabel *label,
const gchar *str);
Sets the label’s text from the string str
.
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 gtk_label_set_mnemonic_widget().
gtk_label_get_attributes ()
PangoAttrList *
gtk_label_get_attributes (GtkLabel *label);
Gets the attribute list that was set on the label using
gtk_label_set_attributes(), if any. This function does
not reflect attributes that come from the labels markup
(see gtk_label_set_markup()). If you want to get the
effective attributes for the label, use
pango_layout_get_attribute (gtk_label_get_layout (label)).
Returns
the attribute list, or NULL
if none was set.
[nullable][transfer none]
gtk_label_get_xalign ()
gfloat
gtk_label_get_xalign (GtkLabel *label);
Gets the “xalign” property for label
.
Returns
the xalign property
Since: 3.16
gtk_label_get_yalign ()
gfloat
gtk_label_get_yalign (GtkLabel *label);
Gets the “yalign” property for label
.
Returns
the yalign property
Since: 3.16
gtk_label_get_width_chars ()
gint
gtk_label_get_width_chars (GtkLabel *label);
Retrieves the desired width of label
, in characters. See
gtk_label_set_width_chars().
Returns
the width of the label in characters.
Since: 2.6
gtk_label_get_max_width_chars ()
gint
gtk_label_get_max_width_chars (GtkLabel *label);
Retrieves the desired maximum width of label
, in characters. See
gtk_label_set_width_chars().
Returns
the maximum width of the label in characters.
Since: 2.6
gtk_label_get_label ()
const gchar *
gtk_label_get_label (GtkLabel *label);
Fetches the text from a label widget including any embedded
underlines indicating mnemonics and Pango markup. (See
gtk_label_get_text()).
Returns
the text of the label widget. This string is
owned by the widget and must not be modified or freed.
gtk_label_get_layout ()
PangoLayout *
gtk_label_get_layout (GtkLabel *label);
Gets the PangoLayout used to display the label.
The layout is useful to e.g. convert text positions to
pixel positions, in combination with gtk_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.
Returns
the PangoLayout for this label.
[transfer none]
gtk_label_get_line_wrap ()
gboolean
gtk_label_get_line_wrap (GtkLabel *label);
Returns whether lines in the label are automatically wrapped.
See gtk_label_set_line_wrap().
Returns
TRUE if the lines of the label are automatically wrapped.
gtk_label_get_lines ()
gint
gtk_label_get_lines (GtkLabel *label);
Gets the number of lines to which an ellipsized, wrapping
label should be limited. See gtk_label_set_lines().
Returns
The number of lines
Since: 3.10
gtk_label_get_mnemonic_widget ()
GtkWidget *
gtk_label_get_mnemonic_widget (GtkLabel *label);
Retrieves the target of the mnemonic (keyboard shortcut) of this
label. See gtk_label_set_mnemonic_widget().
Returns
the target of the label’s mnemonic,
or NULL if none has been set and the default algorithm will be used.
[nullable][transfer none]
gtk_label_get_selection_bounds ()
gboolean
gtk_label_get_selection_bounds (GtkLabel *label,
gint *start,
gint *end);
Gets the selected range of characters in the label, returning TRUE
if there’s a selection.
Returns
TRUE if selection is non-empty
gtk_label_get_use_markup ()
gboolean
gtk_label_get_use_markup (GtkLabel *label);
Returns whether the label’s text is interpreted as marked up with
the Pango text markup language.
See gtk_label_set_use_markup().
Returns
TRUE if the label’s text will be parsed for markup.
gtk_label_get_use_underline ()
gboolean
gtk_label_get_use_underline (GtkLabel *label);
Returns whether an embedded underline in the label indicates a
mnemonic. See gtk_label_set_use_underline().
Returns
TRUE whether an embedded underline in the label indicates
the mnemonic accelerator keys.
gtk_label_get_single_line_mode ()
gboolean
gtk_label_get_single_line_mode (GtkLabel *label);
Returns whether the label is in single line mode.
Returns
TRUE when the label is in single line mode.
Since: 2.6
gtk_label_get_angle ()
gdouble
gtk_label_get_angle (GtkLabel *label);
Gets the angle of rotation for the label. See
gtk_label_set_angle().
Returns
the angle of rotation for the label
Since: 2.6
gtk_label_set_label ()
void
gtk_label_set_label (GtkLabel *label,
const gchar *str);
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.
gtk_label_set_use_markup ()
void
gtk_label_set_use_markup (GtkLabel *label,
gboolean setting);
Sets whether the text of the label contains markup in
Pango’s text markup language.
See gtk_label_set_markup().
gtk_label_set_use_underline ()
void
gtk_label_set_use_underline (GtkLabel *label,
gboolean setting);
If true, an underline in the text indicates the next character should be
used for the mnemonic accelerator key.
gtk_label_set_single_line_mode ()
void
gtk_label_set_single_line_mode (GtkLabel *label,
gboolean single_line_mode);
Sets whether the label is in single line mode.
Since: 2.6
gtk_label_set_angle ()
void
gtk_label_set_angle (GtkLabel *label,
gdouble angle);
Sets the angle of rotation for the label. An angle of 90 reads from
from bottom to top, an angle of 270, from top to bottom. The angle
setting for the label is ignored if the label is selectable,
wrapped, or ellipsized.
Since: 2.6
gtk_label_get_current_uri ()
const gchar *
gtk_label_get_current_uri (GtkLabel *label);
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.
Returns
the currently active URI. The string is owned by GTK+ and must
not be freed or modified.
Since: 2.18
gtk_label_set_track_visited_links ()
void
gtk_label_set_track_visited_links (GtkLabel *label,
gboolean track_links);
Sets whether the label should keep track of clicked
links (and use a different color for them).
Since: 2.18
gtk_label_get_track_visited_links ()
gboolean
gtk_label_get_track_visited_links (GtkLabel *label);
Returns whether the label is currently keeping track
of clicked links.
Returns
TRUE if clicked links are remembered
Since: 2.18
Property Details
The “angle” property
“angle” gdouble
The angle that the baseline of the label makes with the horizontal,
in degrees, measured counterclockwise. An angle of 90 reads from
from bottom to top, an angle of 270, from top to bottom. Ignored
if the label is selectable.
Owner: GtkLabel
Flags: Read / Write
Allowed values: [0,360]
Default value: 0
Since: 2.6
The “attributes” property
“attributes” PangoAttrList *
A list of style attributes to apply to the text of the label.
Owner: GtkLabel
Flags: Read / Write
The “cursor-position” property
“cursor-position” gint
The current position of the insertion cursor in chars.
Owner: GtkLabel
Flags: Read
Allowed values: >= 0
Default value: 0
The “ellipsize” property
“ellipsize” PangoEllipsizeMode
The preferred place to ellipsize the string, if the label does
not have enough room to display the entire string, specified as a
PangoEllipsizeMode.
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 GtkNotebook tab-expand child property is set to TRUE. Other ways
to set a label's width are gtk_widget_set_size_request() and
gtk_label_set_width_chars().
Owner: GtkLabel
Flags: Read / Write
Default value: PANGO_ELLIPSIZE_NONE
Since: 2.6
The “justify” property
“justify” GtkJustification
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 GtkLabel:xalign for that.
Owner: GtkLabel
Flags: Read / Write
Default value: GTK_JUSTIFY_LEFT
The “label” property
“label” gchar *
The contents of the label.
If the string contains Pango XML markup, you will
have to set the “use-markup” property to TRUE in order for the
label to display the markup attributes. See also gtk_label_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.
Owner: GtkLabel
Flags: Read / Write
Default value: ""
The “lines” property
“lines” gint
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.
Owner: GtkLabel
Flags: Read / Write
Allowed values: >= -1
Default value: -1
Since: 3.10
The “max-width-chars” property
“max-width-chars” gint
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.
Owner: GtkLabel
Flags: Read / Write
Allowed values: >= -1
Default value: -1
Since: 2.6
The “mnemonic-keyval” property
“mnemonic-keyval” guint
The mnemonic accelerator key for this label.
Owner: GtkLabel
Flags: Read
Default value: 16777215
The “mnemonic-widget” property
“mnemonic-widget” GtkWidget *
The widget to be activated when the label's mnemonic key is pressed.
Owner: GtkLabel
Flags: Read / Write
The “pattern” property
“pattern” gchar *
A string with _ characters in positions correspond to characters in the text to underline.
Owner: GtkLabel
Flags: Write
Default value: NULL
The “selectable” property
“selectable” gboolean
Whether the label text can be selected with the mouse.
Owner: GtkLabel
Flags: Read / Write
Default value: FALSE
The “selection-bound” property
“selection-bound” gint
The position of the opposite end of the selection from the cursor in chars.
Owner: GtkLabel
Flags: Read
Allowed values: >= 0
Default value: 0
The “single-line-mode” property
“single-line-mode” gboolean
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.
Owner: GtkLabel
Flags: Read / Write
Default value: FALSE
Since: 2.6
The “track-visited-links” property
“track-visited-links” gboolean
Set this property to TRUE to make the label track which links
have been visited. It will then apply the GTK_STATE_FLAG_VISITED
when rendering this link, in addition to GTK_STATE_FLAG_LINK.
Owner: GtkLabel
Flags: Read / Write
Default value: TRUE
Since: 2.18
The “use-markup” property
“use-markup” gboolean
The text of the label includes XML markup. See pango_parse_markup().
Owner: GtkLabel
Flags: Read / Write
Default value: FALSE
The “use-underline” property
“use-underline” gboolean
If set, an underline in the text indicates the next character should be used for the mnemonic accelerator key.
Owner: GtkLabel
Flags: Read / Write
Default value: FALSE
The “width-chars” property
“width-chars” gint
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.
Owner: GtkLabel
Flags: Read / Write
Allowed values: >= -1
Default value: -1
Since: 2.6
The “wrap” property
“wrap” gboolean
If set, wrap lines if the text becomes too wide.
Owner: GtkLabel
Flags: Read / Write
Default value: FALSE
The “wrap-mode” property
“wrap-mode” PangoWrapMode
If line wrapping is on (see the “wrap” property) this controls
how the line wrapping is done. The default is PANGO_WRAP_WORD, which
means wrap on word boundaries.
Owner: GtkLabel
Flags: Read / Write
Default value: PANGO_WRAP_WORD
Since: 2.10
The “xalign” property
“xalign” gfloat
The xalign property determines the horizontal aligment of the label text
inside the labels size allocation. Compare this to “halign”,
which determines how the labels size allocation is positioned in the
space available for the label.
Owner: GtkLabel
Flags: Read / Write
Allowed values: [0,1]
Default value: 0.5
Since: 3.16
The “yalign” property
“yalign” gfloat
The yalign property determines the vertical aligment of the label text
inside the labels size allocation. Compare this to “valign”,
which determines how the labels size allocation is positioned in the
space available for the label.
Owner: GtkLabel
Flags: Read / Write
Allowed values: [0,1]
Default value: 0.5
Since: 3.16