GtkBuilder UI Definitions

GtkBuilder parses textual descriptions of user interfaces which are specified in an XML format which can be roughly described by the RELAX NG schema below. We refer to these descriptions as “GtkBuilder UI definitions” or just “UI definitions” if the context is clear. Do not confuse GtkBuilder UI Definitions with GtkUIManager UI Definitions, which are more limited in scope. It is common to use .ui as the filename extension for files containing GtkBuilder UI definitions.

RELAX NG Compact Syntax

The toplevel element is <interface>. It optionally takes a “domain” attribute, which will make the builder look for translated strings using dgettext() in the domain specified. This can also be done by calling gtk_builder_set_translation_domain() on the builder. Objects are described by <object> elements, which can contain <property> elements to set properties, <signal> elements which connect signals to handlers, and <child> elements, which describe child objects (most often widgets inside a container, but also e.g. actions in an action group, or columns in a tree model). A <child> element contains an <object> element which describes the child object. The target toolkit version(s) are described by <requires> elements, the “lib” attribute specifies the widget library in question (currently the only supported value is “gtk+”) and the “version” attribute specifies the target version in the form “<major>.<minor>”. The builder will error out if the version requirements are not met.

Typically, the specific kind of object represented by an <object> element is specified by the “class” attribute. If the type has not been loaded yet, GTK+ tries to find the get_type() function from the class name by applying heuristics. This works in most cases, but if necessary, it is possible to specify the name of the get_type() function explictly with the "type-func" attribute. As a special case, GtkBuilder allows to use an object that has been constructed by a GtkUIManager in another part of the UI definition by specifying the id of the GtkUIManager in the “constructor” attribute and the name of the object in the “id” attribute.

Objects may be given a name with the “id” attribute, which allows the application to retrieve them from the builder with gtk_builder_get_object(). An id is also necessary to use the object as property value in other parts of the UI definition. GTK+ reserves ids starting and ending with ___ (3 underscores) for its own purposes.

Setting properties of objects is pretty straightforward with the <property> element: the “name” attribute specifies the name of the property, and the content of the element specifies the value. If the “translatable” attribute is set to a true value, GTK+ uses gettext() (or dgettext() if the builder has a translation domain set) to find a translation for the value. This happens before the value is parsed, so it can be used for properties of any type, but it is probably most useful for string properties. It is also possible to specify a context to disambiguate short strings, and comments which may help the translators.

GtkBuilder can parse textual representations for the most common property types: characters, strings, integers, floating-point numbers, booleans (strings like “TRUE”, “t”, “yes”, “y”, “1” are interpreted as TRUE, strings like “FALSE”, “f”, “no”, “n”, “0” are interpreted as FALSE), enumerations (can be specified by their name, nick or integer value), flags (can be specified by their name, nick, integer value, optionally combined with “|”, e.g. “GTK_VISIBLE|GTK_REALIZED”) and colors (in a format understood by gdk_rgba_parse()).

GVariants can be specified in the format understood by g_variant_parse(), and pixbufs can be specified as a filename of an image file to load.

Objects can be referred to by their name and by default refer to objects declared in the local xml fragment and objects exposed via gtk_builder_expose_object(). In general, GtkBuilder allows forward references to objects — declared in the local xml; an object doesn’t have to be constructed before it can be referred to. The exception to this rule is that an object has to be constructed before it can be used as the value of a construct-only property.

It is also possible to bind a property value to another object's property value using the attributes "bind-source" to specify the source object of the binding, "bind-property" to specify the source property and optionally "bind-flags" to specify the binding flags Internally builder implement this using GBinding objects. For more information see g_object_bind_property()

Signal handlers are set up with the <signal> element. The “name” attribute specifies the name of the signal, and the “handler” attribute specifies the function to connect to the signal. By default, GTK+ tries to find the handler using g_module_symbol(), but this can be changed by passing a custom GtkBuilderConnectFunc to gtk_builder_connect_signals_full(). The remaining attributes, “after”, “swapped” and “object”, have the same meaning as the corresponding parameters of the g_signal_connect_object() or g_signal_connect_data() functions. A “last_modification_time” attribute is also allowed, but it does not have a meaning to the builder.

Sometimes it is necessary to refer to widgets which have implicitly been constructed by GTK+ as part of a composite widget, to set properties on them or to add further children (e.g. the vbox of a GtkDialog). This can be achieved by setting the “internal-child” propery of the <child> element to a true value. Note that GtkBuilder still requires an <object> element for the internal child, even if it has already been constructed.

A number of widgets have different places where a child can be added (e.g. tabs vs. page content in notebooks). This can be reflected in a UI definition by specifying the “type” attribute on a <child> The possible values for the “type” attribute are described in the sections describing the widget-specific portions of UI definitions.

A GtkBuilder UI Definition

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<interface>
  <object class="GtkDialog" id="dialog1">
    <child internal-child="vbox">
      <object class="GtkBox" id="vbox1">
        <property name="border-width">10</property>
        <child internal-child="action_area">
          <object class="GtkButtonBox" id="hbuttonbox1">
            <property name="border-width">20</property>
            <child>
              <object class="GtkButton" id="ok_button">
                <property name="label">gtk-ok</property>
                <property name="use-stock">TRUE</property>
                <signal name="clicked" handler="ok_button_clicked"/>
              </object>
            </child>
          </object>
        </child>
      </object>
    </child>
  </object>
</interface>

Beyond this general structure, several object classes define their own XML DTD fragments for filling in the ANY placeholders in the DTD above. Note that a custom element in a <child> element gets parsed by the custom tag handler of the parent object, while a custom element in an <object> element gets parsed by the custom tag handler of the object.

These XML fragments are explained in the documentation of the respective objects.

Additionally, since 3.10 a special <template> tag has been added to the format allowing one to define a widget class’s components. See the GtkWidget documentation for details.

GtkBuilderConnectFunc ()

void
(*GtkBuilderConnectFunc) (GtkBuilder *builder,
                          GObject *object,
                          const gchar *signal_name,
                          const gchar *handler_name,
                          GObject *connect_object,
                          GConnectFlags flags,
                          gpointer user_data);

This is the signature of a function used to connect signals. It is used by the gtk_builder_connect_signals() and gtk_builder_connect_signals_full() methods. It is mainly intended for interpreted language bindings, but could be useful where the programmer wants more control over the signal connection process. Note that this function can only be called once, subsequent calls will do nothing.

Since: 2.12

gtk_builder_new ()

GtkBuilder *
gtk_builder_new (void);

Creates a new empty builder object.

This function is only useful if you intend to make multiple calls to gtk_builder_add_from_file(), gtk_builder_add_from_resource() or gtk_builder_add_from_string() in order to merge multiple UI descriptions into a single builder.

Most users will probably want to use gtk_builder_new_from_file(), gtk_builder_new_from_resource() or gtk_builder_new_from_string().

Since: 2.12

gtk_builder_new_from_file ()

GtkBuilder *
gtk_builder_new_from_file (const gchar *filename);

Builds the GtkBuilder UI definition in the file filename .

If there is an error opening the file or parsing the description then the program will be aborted. You should only ever attempt to parse user interface descriptions that are shipped as part of your program.

Since: 3.10

gtk_builder_new_from_resource ()

GtkBuilder *
gtk_builder_new_from_resource (const gchar *resource_path);

Builds the GtkBuilder UI definition at resource_path .

If there is an error locating the resource or parsing the description, then the program will be aborted.

Since: 3.10

gtk_builder_new_from_string ()

GtkBuilder *
gtk_builder_new_from_string (const gchar *string,
                             gssize length);

Builds the user interface described by string (in the GtkBuilder UI definition format).

If string is NULL-terminated, then length should be -1. If length is not -1, then it is the length of string .

If there is an error parsing string then the program will be aborted. You should not attempt to parse user interface description from untrusted sources.

Since: 3.10

gtk_builder_add_callback_symbol ()

void
gtk_builder_add_callback_symbol (GtkBuilder *builder,
                                 const gchar *callback_name,
                                 GCallback callback_symbol);

Adds the callback_symbol to the scope of builder under the given callback_name .

Using this function overrides the behavior of gtk_builder_connect_signals() for any callback symbols that are added. Using this method allows for better encapsulation as it does not require that callback symbols be declared in the global namespace.

Since: 3.10

gtk_builder_add_callback_symbols ()

void
gtk_builder_add_callback_symbols (GtkBuilder *builder,
                                  const gchar *first_callback_name,
                                  GCallback first_callback_symbol,
                                  ...);

A convenience function to add many callbacks instead of calling gtk_builder_add_callback_symbol() for each symbol.

Since: 3.10

gtk_builder_lookup_callback_symbol ()

GCallback
gtk_builder_lookup_callback_symbol (GtkBuilder *builder,
                                    const gchar *callback_name);

Fetches a symbol previously added to builder with gtk_builder_add_callback_symbols()

This function is intended for possible use in language bindings or for any case that one might be cusomizing signal connections using gtk_builder_connect_signals_full()

[skip]

Since: 3.10

gtk_builder_add_from_file ()

guint
gtk_builder_add_from_file (GtkBuilder *builder,
                           const gchar *filename,
                           GError **error);

Parses a file containing a GtkBuilder UI definition and merges it with the current contents of builder .

Most users will probably want to use gtk_builder_new_from_file().

If an error occurs, 0 will be returned and error will be assigned a GError from the GTK_BUILDER_ERROR, G_MARKUP_ERROR or type;

the type of the event (

accessible