Expander

open class Expander : Widget, ExpanderProtocol

GtkExpander allows the user to reveal its child by clicking on an expander triangle.

An example GtkExpander

This is similar to the triangles used in a GtkTreeView.

Normally you use an expander as you would use a frame; you create the child widget and use [methodGtk.Expander.set_child] to add it to the expander. When the expander is toggled, it will take care of showing and hiding the child automatically.

Special Usage

There are situations in which you may prefer to show and hide the expanded widget yourself, such as when you want to actually create the widget at expansion time. In this case, create a GtkExpander but do not add a child to it. The expander widget has an [propertyGtk.Expander:expanded[ property which can be used to monitor its expansion state. You should watch this property with a signal connection as follows:

static void
expander_callback (GObject    *object,
                   GParamSpec *param_spec,
                   gpointer    user_data)
{
  GtkExpander *expander;

  expander = GTK_EXPANDER (object);

  if (gtk_expander_get_expanded (expander))
    {
      // Show or create widgets
    }
  else
    {
      // Hide or destroy widgets
    }
}

static void
create_expander (void)
{
  GtkWidget *expander = gtk_expander_new_with_mnemonic ("_More Options");
  g_signal_connect (expander, "notify`expanded`",
                    G_CALLBACK (expander_callback), NULL);

  // ...
}

GtkExpander as GtkBuildable

The GtkExpander implementation of the GtkBuildable interface supports placing a child in the label position by specifying “label” as the “type” attribute of a <child> element. A normal content child can be specified without specifying a <child> type attribute.

An example of a UI definition fragment with GtkExpander:

&lt;object class="GtkExpander"&gt;
  &lt;child type="label"&gt;
    &lt;object class="GtkLabel" id="expander-label"/&gt;
  &lt;/child&gt;
  &lt;child&gt;
    &lt;object class="GtkEntry" id="expander-content"/&gt;
  &lt;/child&gt;
&lt;/object&gt;

CSS nodes

expander
╰── box
    ├── title
    │   ├── arrow
    │   ╰── &lt;label widget&gt;
    ╰── &lt;child&gt;

GtkExpander has three CSS nodes, the main node with the name expander, a subnode with name title and node below it with name arrow. The arrow of an expander that is showing its child gets the :checked pseudoclass added to it.

Accessibility

GtkExpander uses the GTK_ACCESSIBLE_ROLE_BUTTON role.

The Expander type acts as a reference-counted owner of an underlying GtkExpander instance. It provides the methods that can operate on this data type through ExpanderProtocol conformance. Use Expander as a strong reference or owner of a GtkExpander instance.

Show on GitHub 
  • Designated initialiser from the underlying `C` data type.

    This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the Expander instance.

    Declaration

    Swift

    @inlinable
public init(_ op: UnsafeMutablePointer<GtkExpander>)

    Parameters

    op

    pointer to the underlying object
    Show on GitHub

  • Designated initialiser from a constant pointer to the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the Expander instance.

    Declaration

    Swift

    @inlinable
public init(_ op: UnsafePointer<GtkExpander>)

    Parameters

    op

    pointer to the underlying object
    Show on GitHub

  • Optional initialiser from a non-mutating gpointer to the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the Expander instance.

    Declaration

    Swift

    @inlinable
override public init!(gpointer op: gpointer?)

    Parameters

    op

    gpointer to the underlying object
    Show on GitHub

  • Optional initialiser from a non-mutating gconstpointer to the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the Expander instance.

    Declaration

    Swift

    @inlinable
override public init!(gconstpointer op: gconstpointer?)

    Parameters

    op

    pointer to the underlying object
    Show on GitHub

  • Optional initialiser from a constant pointer to the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the Expander instance.

    Declaration

    Swift

    @inlinable
public init!(_ op: UnsafePointer<GtkExpander>?)

    Parameters

    op

    pointer to the underlying object
    Show on GitHub

  • Optional initialiser from the underlying C data type. This creates an instance without performing an unbalanced retain i.e., ownership is transferred to the Expander instance.

    Declaration

    Swift

    @inlinable
public init!(_ op: UnsafeMutablePointer<GtkExpander>?)

    Parameters

    op

    pointer to the underlying object
    Show on GitHub

  • Designated initialiser from the underlying C data type. Will retain GtkExpander. i.e., ownership is transferred to the Expander instance.

    Declaration

    Swift

    @inlinable
public init(retaining op: UnsafeMutablePointer<GtkExpander>)

    Parameters

    op

    pointer to the underlying object
    Show on GitHub

  • Reference intialiser for a related type that implements ExpanderProtocol Will retain GtkExpander.

    Declaration

    Swift

    @inlinable
public init<T>(expander other: T) where T : ExpanderProtocol

    Parameters

    other

    an instance of a related type that implements ExpanderProtocol
    Show on GitHub

  • Unsafe typed initialiser. Do not use unless you know the underlying data type the pointer points to conforms to ExpanderProtocol.

    Declaration

    Swift

    @inlinable
override public init<T>(cPointer p: UnsafeMutablePointer<T>)

    Parameters

    cPointer

    pointer to the underlying object
    Show on GitHub

  • Unsafe typed, retaining initialiser. Do not use unless you know the underlying data type the pointer points to conforms to ExpanderProtocol.

    Declaration

    Swift

    @inlinable
override public init<T>(retainingCPointer cPointer: UnsafeMutablePointer<T>)

    Parameters

    cPointer

    pointer to the underlying object
    Show on GitHub

  • Unsafe untyped initialiser. Do not use unless you know the underlying data type the pointer points to conforms to ExpanderProtocol.

    Declaration

    Swift

    @inlinable
override public init(raw p: UnsafeRawPointer)

    Parameters

    p

    raw pointer to the underlying object
    Show on GitHub

  • Unsafe untyped, retaining initialiser. Do not use unless you know the underlying data type the pointer points to conforms to ExpanderProtocol.

    Declaration

    Swift

    @inlinable
override public init(retainingRaw raw: UnsafeRawPointer)
    Show on GitHub

  • Unsafe untyped initialiser. Do not use unless you know the underlying data type the pointer points to conforms to ExpanderProtocol.

    Declaration

    Swift

    @inlinable
public required init(raw p: UnsafeMutableRawPointer)

    Parameters

    p

    mutable raw pointer to the underlying object
    Show on GitHub

  • Unsafe untyped, retaining initialiser. Do not use unless you know the underlying data type the pointer points to conforms to ExpanderProtocol.

    Declaration

    Swift

    @inlinable
required public init(retainingRaw raw: UnsafeMutableRawPointer)

    Parameters

    raw

    mutable raw pointer to the underlying object
    Show on GitHub

  • Unsafe untyped initialiser. Do not use unless you know the underlying data type the pointer points to conforms to ExpanderProtocol.

    Declaration

    Swift

    @inlinable
override public init(opaquePointer p: OpaquePointer)

    Parameters

    p

    opaque pointer to the underlying object
    Show on GitHub

  • Unsafe untyped, retaining initialiser. Do not use unless you know the underlying data type the pointer points to conforms to ExpanderProtocol.

    Declaration

    Swift

    @inlinable
override public init(retainingOpaquePointer p: OpaquePointer)

    Parameters

    p

    opaque pointer to the underlying object
    Show on GitHub

  • Creates a new expander using label as the text of the label.

    Declaration

    Swift

    @inlinable
public init(label: UnsafePointer<CChar>? = nil)
    Show on GitHub

  • Creates a new expander using label as the text of the label.

    If characters in label 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.

    Pressing Alt and that key activates the button.

    Declaration

    Swift

    @inlinable
public init(mnemonic label: UnsafePointer<CChar>? = nil)
    Show on GitHub

  • Creates a new expander using label as the text of the label.

    If characters in label 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.

    Pressing Alt and that key activates the button.

    Declaration

    Swift

    @inlinable
public static func newWith(mnemonic label: UnsafePointer<CChar>? = nil) -> Widget!
    Show on GitHub