Package: gtk

Class gtk-label

Superclasses

gtk-misc, gtk-widget, g-initially-unowned, gtk-buildable, g-object, common-lisp:standard-object, common-lisp:t

Documented Subclasses

Direct Slots

angle
The "angle" property of type :double (Read / Write)
The angle that the baseline of the label makes with the horizontal, in degrees, measured counterclockwise. An angle of 90 reads 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
attributes
The "attributes" property of type pango-attr-list (Read / Write)
A list of style attributes to apply to the text of the label.
cursor-position
The "cursor-position" property of type :int (Read)
The current position of the insertion cursor in chars.
Allowed values: >= 0
Default value: 0
ellipsize
The "ellipsize" property of type pango-ellipsize-mode (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 value of the pango-ellipsize-mode enumeration. Note that setting this property to a value other than :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 the functions gtk-widget-size-request and gtk-label-set-width-chars.
Default value: :none
Since 2.6
justify
The "justify" property of type gtk-justification (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 the xalign property of the gtk-misc widget for that.
Default value: :left
label
The "label" property of type :string (Read / Write)
The text of the label.
Default value: ""
lines
The "lines" property of type :int (Read / Write)
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 do not want to limit the number of lines.
Allowed values: >= -1
Default value: -1
Since 3.10
max-width-chars
The "max-width-chars" property of type :int (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 the properties width-chars and "max-width-chars" determine the width of ellipsized and wrapped labels.
Allowed values: >= G_MAXULONG
Default value: -1
Since 2.6
mnemonic-keyval
The "mnemonic-keyval" property of :uint (Read)
The mnemonic accelerator key for this label.
Default value: 16777215
mnemonic-widget
The "mnemonic-widget" property of type gtk-widget (Read / Write)
The widget to be activated when the label's mnemonic key is pressed.
pattern
The "pattern" property of type :string (Write)
A string with "_" characters in positions correspond to characters in the text to underline.
Default value: nil
selectable
The "selectable" property of type :boolean (Read / Write)
Whether the label text can be selected with the mouse.
Default value: nil
selection-bound
The "selection-bound" property of type :int (Read)
The position of the opposite end of the selection from the cursor in chars.
Allowed values: >= 0
Default value: 0
single-line-mode
The "single-line-mode" property of type :boolean (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: nil
Since 2.6
track-visited-links
The "track-visited-links" property of type :boolean (Read / Write)
Set this property to true to make the label track which links have been clicked. It will then apply the color of the style property "visited-link-color" of a gtk-widget object, instead of the color of the style property "link-color".
Default value: true
Since 2.18
use-markup
The "use-markup" property of type :boolean (Read / Write)
The text of the label includes XML markup. See the function pango-parse-markup.
Default value: nil
use-underline
The "use-underline" property of type :boolean (Read / Write)
If set, an underline in the text indicates the next character should be used for the mnemonic accelerator key.
Default value: nil
width-chars
The "width-chars" property of :int (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 the properties "width-chars" and max-width-chars determine the width of ellipsized and wrapped labels.
Allowed values: >= G_MAXULONG
Default value: -1
Since 2.6
wrap
The wrap property of type :boolean (Read / Write)
If set, wrap lines if the text becomes too wide.
Default value: nil
wrap-mode
The wrap-mode property of type pango-wrap-mode (Read / Write)
If line wrapping is on, see the wrap property) this controls how the line wrapping is done. The default is :word, which means wrap on word boundaries.
Default value: :word
Since 2.10

Details

The gtk-label widget displays a small amount of text. As the name implies, most labels are used to label another widget such as a gtk-button, a gtk-menu-item, or a gtk-combo-box.

GtkLabel as GtkBuildable
The gtk-label implementation of the gtk-buildable 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.

Example: 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.

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 gtk-button widget; 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 is 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 is 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 gtk-entry widget, 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 is how to create a label with a small font:
 label = gtk_label_new (NULL);
 gtk_label_set_markup (GTK_LABEL (label),
                       "<span style="color: red">
                          <small>Small text</small></span>");    
(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 pango-attr-list on a label; gtk-label-set-attributes may be a simpler way to set attributes in some cases. Be careful though; pango-attr-list tends to cause internationalization problems, unless you are 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 the function gtk-label-set-line-wrap.

The function gtk-label-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 function 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.

Note
Note that the interpretation of the properties "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:
 gtk_label_set_markup (label,
                       "Go to the <span style="color: red">
                                    <a>GTK+ website</a></span> for more...");    
It is possible to implement custom handling for links and their tooltips with the "activate-link" signal and gtk-label-get-current-uri function.

Signal Details

The "activate-current-link" signal
 lambda (label)   : 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.
label
The label on which the signal was emitted.
Since 2.18

The "activate-link" signal
 lambda (label uri)   : 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 the function gtk-show-uri.
label
The label on which the signal was emitted.
uri
The URI that is activated.
Returns
True if the link has been activated.
Since 2.18

The "copy-clipboard" signal
 lambda (label)   : 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.
label
The object which received the signal.
The "move-cursor" signal
 lambda (entry step count extended-selection)   : 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.
  • Arrow keys move by individual characters/lines.
  • Ctrl-arrow key combinations move by words/paragraphs.
  • Home/End keys move to the ends of the buffer.
entry
The object which received the signal.
step
The granularity of the move, as a value of the gtk-movement-step enumeration.
count
The number of step units to move.
extend-selection
True if the move should extend the selection.
The "populate-popup" signal
 lambda (label menu)   : 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.
label
The label on which the signal is emitted.
menu
The menu that is being populated.
 

Slot Access Functions

Inherited Slot Access Functions

2013-4-12