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.

<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.

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:

  // Pressing Alt+H will activate this button
  button = gtk_button_new ();
  label = gtk_label_new_with_mnemonic ("_Hello");
  gtk_container_add (GTK_CONTAINER (button), label);

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

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

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():

  // Pressing Alt+H will focus the entry
  entry = gtk_entry_new ();
  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:

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

(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 \<, \gt;, 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

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 gtk_misc_set_alignment().

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

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:

gtk_label_set_markup (label, "Go to the <a>GTK+ website</a> for more...");

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.

struct GtkLabel

struct GtkLabel;

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 will also clear any previously set mnemonic accelerators.

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.

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():

char *markup;

markup = g_markup_printf_escaped ("<span style=\"italic\">%s</span>", str);
gtk_label_set_markup (GTK_LABEL (label), markup);
g_free (markup);

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_justify ()

void                gtk_label_set_justify               (GtkLabel *label,
                                                         GtkJustification jtype);

Sets the alignment of the lines in the text of the label relative to each other. GTK_JUSTIFY_LEFT is the default value when the widget is first created with gtk_label_new(). If you instead want to set the alignment of the label as a whole, use gtk_misc_set_alignment() instead. gtk_label_set_justify() has no effect on labels containing only a single line.

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_line_wrap_mode ()

void                gtk_label_set_line_wrap_mode        (GtkLabel *label,
                                                         PangoWrapMode wrap_mode);

If line wrapping is on (see gtk_label_set_line_wrap()) this controls how the line wrapping is done. The default is PANGO_WRAP_WORD which means wrap on word boundaries.

Since 2.10

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 a GTK_NO_WINDOW widget. 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.

gtk_label_get_selectable ()

gboolean            gtk_label_get_selectable            (GtkLabel *label);

Gets the value set by gtk_label_set_selectable().

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())

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)).

gtk_label_get_justify ()

GtkJustification    gtk_label_get_justify               (GtkLabel *label);

Returns the justification of the label. See gtk_label_set_justify().

gtk_label_get_ellipsize ()

PangoEllipsizeMode  gtk_label_get_ellipsize             (GtkLabel *label);

Returns the ellipsizing position of the label. See gtk_label_set_ellipsize().

Since 2.6

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().

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().

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()).

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.

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().

gtk_label_get_line_wrap_mode ()

PangoWrapMode       gtk_label_get_line_wrap_mode        (GtkLabel *label);

Returns line wrap mode used by the label. See gtk_label_set_line_wrap_mode().

Since 2.10

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().

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.

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().

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().

gtk_label_get_single_line_mode ()

gboolean            gtk_label_get_single_line_mode      (GtkLabel *label);

Returns whether 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().

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.

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.

Since 2.18

The "angle" property

  "angle"                    gdouble               : Read / Write

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, wrapped, or ellipsized.

Allowed values: [0,360]

Default value: 0

Since 2.6

The "attributes" property

  "attributes"               PangoAttrList*        : Read / Write

A list of style attributes to apply to the text of the label.

The "cursor-position" property

  "cursor-position"          gint                  : Read

The current position of the insertion cursor in chars.

Allowed values: >= 0

Default value: 0

The "ellipsize" property

  "ellipsize"                PangoEllipsizeMode    : Read / Write

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 tab's "tab-expand" 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().

Default value: PANGO_ELLIPSIZE_NONE

Since 2.6

The "justify" property

  "justify"                  GtkJustification      : Read / Write

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 GtkMisc::xalign for that.

Default value: GTK_JUSTIFY_LEFT

The "label" property

  "label"                    gchar*                : Read / Write

The text of the label.

Default value: ""

The "max-width-chars" property

  "max-width-chars"          gint                  : Read / Write

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.

Allowed values: >= -1

Default value: -1

Since 2.6

The "mnemonic-keyval" property

  "mnemonic-keyval"          guint                 : Read

The mnemonic accelerator key for this label.

Default value: 16777215

The "mnemonic-widget" property

  "mnemonic-widget"          GtkWidget*            : Read / Write

The widget to be activated when the label's mnemonic key is pressed.

The "pattern" property

  "pattern"                  gchar*                : Write

A string with _ characters in positions correspond to characters in the text to underline.

Default value: NULL

The "selectable" property

  "selectable"               gboolean              : Read / Write

Whether the label text can be selected with the mouse.

Default value: FALSE

The "selection-bound" property

  "selection-bound"          gint                  : Read

The position of the opposite end of the selection from the cursor in chars.

Allowed values: >= 0

Default value: 0

The "single-line-mode" property

  "single-line-mode"         gboolean              : Read / Write

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.

Default value: FALSE

Since 2.6

The "track-visited-links" property

  "track-visited-links"      gboolean              : Read / Write

Set this property to TRUE to make the label track which links have been clicked. It will then apply the ::visited-link-color color, instead of ::link-color.

Default value: TRUE

Since 2.18

The "use-markup" property

  "use-markup"               gboolean              : Read / Write

The text of the label includes XML markup. See pango_parse_markup().

Default value: FALSE

The "use-underline" property

  "use-underline"            gboolean              : Read / Write

If set, an underline in the text indicates the next character should be used for the mnemonic accelerator key.

Default value: FALSE

The "width-chars" property

  "width-chars"              gint                  : Read / Write

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.

Allowed values: >= -1

Default value: -1

Since 2.6

The "wrap" property

  "wrap"                     gboolean              : Read / Write

If set, wrap lines if the text becomes too wide.

Default value: FALSE

The "wrap-mode" property

  "wrap-mode"                PangoWrapMode         : Read / Write

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.

Default value: PANGO_WRAP_WORD

Since 2.10

The "activate-current-link" signal

void                user_function                      (GtkLabel *label,
                                                        gpointer  user_data)      : Action

A keybinding signal which gets emitted when the user activates a link in the label.

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 Enter key.

Since 2.18

The "activate-link" signal

gboolean            user_function                      (GtkLabel *label,
                                                        gchar    *uri,
                                                        gpointer  user_data)      : Run Last

The signal which gets emitted to activate a URI. Applications may connect to it to override the default behaviour, which is to call gtk_show_uri().

Since 2.18

The "copy-clipboard" signal

void                user_function                      (GtkLabel *label,
                                                        gpointer  user_data)      : Action

The ::copy-clipboard signal is a keybinding signal which gets emitted to copy the selection to the clipboard.

The default binding for this signal is Ctrl-c.

The "move-cursor" signal

void                user_function                      (GtkLabel       *entry,
                                                        GtkMovementStep step,
                                                        gint            count,
                                                        gboolean        extend_selection,
                                                        gpointer        user_data)             : Action

The ::move-cursor signal is a keybinding signal which gets emitted when the user initiates a cursor movement. 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 g_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 modifer does not. There are too many key combinations to list them all here.

The "populate-popup" signal

void                user_function                      (GtkLabel *label,
                                                        GtkMenu  *menu,
                                                        gpointer  user_data)      : Run Last

The ::populate-popup signal gets emitted before showing the context menu of the label. Note that only selectable labels have context menus.

If you need to add items to the context menu, connect to this signal and append your menuitems to the menu.