Class

GtkBuilder

Description [src]

class Gtk.Builder : GObject.Object {
  parent_instance: GObject,
  priv: GtkBuilderPrivate*
}

A GtkBuilder is an auxiliary object that reads textual descriptions of a user interface and instantiates the described objects. To create a GtkBuilder from a user interface description, call gtk_builder_new_from_file(), gtk_builder_new_from_resource() or gtk_builder_new_from_string().

In the (unusual) case that you want to add user interface descriptions from multiple sources to the same GtkBuilder you can call gtk_builder_new() to get an empty builder and populate it by (multiple) calls to gtk_builder_add_from_file(), gtk_builder_add_from_resource() or gtk_builder_add_from_string().

A GtkBuilder holds a reference to all objects that it has constructed and drops these references when it is finalized. This finalization can cause the destruction of non-widget objects or widgets which are not contained in a toplevel window. For toplevel windows constructed by a builder, it is the responsibility of the user to call gtk_widget_destroy() to get rid of them and all the widgets they contain.

The functions gtk_builder_get_object() and gtk_builder_get_objects() can be used to access the widgets in the interface by the names assigned to them inside the UI description. Toplevel windows returned by these functions will stay around until the user explicitly destroys them with gtk_widget_destroy(). Other widgets will either be part of a larger hierarchy constructed by the builder (in which case you should not have to worry about their lifecycle), or without a parent, in which case they have to be added to some container to make use of them. Non-widget objects need to be reffed with g_object_ref() to keep them beyond the lifespan of the builder.

The function gtk_builder_connect_signals() and variants thereof can be used to connect handlers to the named signals in the description.

GtkBuilder UI Definitions # {BUILDER-UI}

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][XML-UI], 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 implements 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” property 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

<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][composite-templates] for details.

Hierarchy

hierarchy this GtkBuilder ancestor_0 GObject ancestor_0--this

Ancestors

Constructors

gtk_builder_new

Creates a new empty builder object.

Available since: 2.12

gtk_builder_new_from_file

Builds the [GtkBuilder UI definition][BUILDER-UI] in the file filename.

Available since: 3.10

gtk_builder_new_from_resource

Builds the [GtkBuilder UI definition][BUILDER-UI] at resource_path.

Available since: 3.10

gtk_builder_new_from_string

Builds the user interface described by string (in the [GtkBuilder UI definition][BUILDER-UI] format).

Available since: 3.10

Instance methods

gtk_builder_add_callback_symbol

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

Available since: 3.10

gtk_builder_add_callback_symbols

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

Available since: 3.10

gtk_builder_add_from_file

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

Available since: 2.12

gtk_builder_add_from_resource

Parses a resource file containing a [GtkBuilder UI definition][BUILDER-UI] and merges it with the current contents of builder.

Available since: 3.4

gtk_builder_add_from_string

Parses a string containing a [GtkBuilder UI definition][BUILDER-UI] and merges it with the current contents of builder.

Available since: 2.12

gtk_builder_add_objects_from_file

Parses a file containing a [GtkBuilder UI definition][BUILDER-UI] building only the requested objects and merges them with the current contents of builder.

Available since: 2.14

gtk_builder_add_objects_from_resource

Parses a resource file containing a [GtkBuilder UI definition][BUILDER-UI] building only the requested objects and merges them with the current contents of builder.

Available since: 3.4

gtk_builder_add_objects_from_string

Parses a string containing a [GtkBuilder UI definition][BUILDER-UI] building only the requested objects and merges them with the current contents of builder.

Available since: 2.14

gtk_builder_connect_signals

This method is a simpler variation of gtk_builder_connect_signals_full(). It uses symbols explicitly added to builder with prior calls to gtk_builder_add_callback_symbol(). In the case that symbols are not explicitly added; it uses GModule’s introspective features (by opening the module NULL) to look at the application’s symbol table. From here it tries to match the signal handler names given in the interface description with symbols in the application and connects the signals. Note that this function can only be called once, subsequent calls will do nothing.

Available since: 2.12

gtk_builder_connect_signals_full

This function can be thought of the interpreted language binding version of gtk_builder_connect_signals(), except that it does not require GModule to function correctly.

Available since: 2.12

gtk_builder_expose_object

Add object to the builder object pool so it can be referenced just like any other object built by builder.

Available since: 3.8

gtk_builder_extend_with_template

Main private entry point for building composite container components from template XML.

gtk_builder_get_application

Gets the GtkApplication associated with the builder.

Available since: 3.10

gtk_builder_get_object

Gets the object named name. Note that this function does not increment the reference count of the returned object.

Available since: 2.12

gtk_builder_get_objects

Gets all objects that have been constructed by builder. Note that this function does not increment the reference counts of the returned objects.

Available since: 2.12

gtk_builder_get_translation_domain

Gets the translation domain of builder.

Available since: 2.12

gtk_builder_get_type_from_name

Looks up a type by name, using the virtual function that GtkBuilder has for that purpose. This is mainly used when implementing the GtkBuildable interface on a type.

Available since: 2.12

gtk_builder_lookup_callback_symbol

Fetches a symbol previously added to builder with gtk_builder_add_callback_symbols()

Available since: 3.10

gtk_builder_set_application

Sets the application associated with builder.

Available since: 3.10

gtk_builder_set_translation_domain

Sets the translation domain of builder. See GtkBuilder:translation-domain.

Available since: 2.12

gtk_builder_value_from_string

This function demarshals a value from a string. This function calls g_value_init() on the value argument, so it need not be initialised beforehand.

Available since: 2.12

gtk_builder_value_from_string_type

Like gtk_builder_value_from_string(), this function demarshals a value from a string, but takes a GType instead of GParamSpec. This function calls g_value_init() on the value argument, so it need not be initialised beforehand.

Available since: 2.12

Methods inherited from GObject (42)

Properties

Gtk.Builder:translation-domain

The translation domain used when translating property values that have been marked as translatable in interface descriptions. If the translation domain is NULL, GtkBuilder uses gettext(), otherwise g_dgettext().

Available since: 2.12

Signals

Signals inherited from GObject (1)

Class structure

struct GtkBuilderClass {
  GObjectClass parent_class;
  GType (* get_type_from_name) (
    GtkBuilder* builder,
    const char* type_name
  );
  void (* _gtk_reserved1) (
void
  );
  void (* _gtk_reserved2) (
void
  );
  void (* _gtk_reserved3) (
void
  );
  void (* _gtk_reserved4) (
void
  );
  void (* _gtk_reserved5) (
void
  );
  void (* _gtk_reserved6) (
void
  );
  void (* _gtk_reserved7) (
void
  );
  void (* _gtk_reserved8) (
void
  );
  
}
Class members
parent_class
GObjectClass
  No description available.
get_type_from_name
GType (* get_type_from_name) (
    GtkBuilder* builder,
    const char* type_name
  )
  No description available.
_gtk_reserved1
void (* _gtk_reserved1) (
void
  )
  No description available.
_gtk_reserved2
void (* _gtk_reserved2) (
void
  )
  No description available.
_gtk_reserved3
void (* _gtk_reserved3) (
void
  )
  No description available.
_gtk_reserved4
void (* _gtk_reserved4) (
void
  )
  No description available.
_gtk_reserved5
void (* _gtk_reserved5) (
void
  )
  No description available.
_gtk_reserved6
void (* _gtk_reserved6) (
void
  )
  No description available.
_gtk_reserved7
void (* _gtk_reserved7) (
void
  )
  No description available.
_gtk_reserved8
void (* _gtk_reserved8) (
void
  )
  No description available.

Virtual methods

Gtk.BuilderClass.get_type_from_name

Looks up a type by name, using the virtual function that GtkBuilder has for that purpose. This is mainly used when implementing the GtkBuildable interface on a type.

Available since: 2.12