Expander

class Expander(**properties: Any)

Superclasses: Widget, InitiallyUnowned, Object

Implemented Interfaces: Accessible, Buildable, ConstraintTarget

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

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 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 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:

<object class="GtkExpander">
  <child type="label">
    <object class="GtkLabel" id="expander-label"/>
  </child>
  <child>
    <object class="GtkEntry" id="expander-content"/>
  </child>
</object>

CSS nodes

expander-widget
╰── box
    ├── title
    │   ├── expander
    │   ╰── <label widget>
    ╰── <child>

GtkExpander has a main node expander-widget, and subnode box containing the title and child widget. The box subnode title contains node expander, i.e. the expand/collapse arrow; then the label widget if any. The arrow of an expander that is showing its child gets the :checked pseudoclass set on it.

Accessibility

GtkExpander uses the BUTTON role.

Constructors

class Expander

classmethod new(label: str | None = None) → Widget

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

Parameters:: label – the text of the label

classmethod new_with_mnemonic(label: str | None = None) → Widget

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.

Parameters:: label – the text of the label with an underscore in front of the mnemonic character

Methods

class Expander

get_child() → Widget | None: Gets the child widget of expander.

get_expanded() → bool

Queries a GtkExpander and returns its current state.

Returns True if the child widget is revealed.

get_label() → str | None

Fetches the text from a label widget.

This is including any embedded underlines indicating mnemonics and Pango markup, as set by set_label. If the label text has not been set the return value will be None. This will be the case if you create an empty button with new() to use as a container.

get_label_widget() → Widget | None: Retrieves the label widget for the frame.

get_resize_toplevel() → bool: Returns whether the expander will resize the toplevel widget containing the expander upon resizing and collapsing.

get_use_markup() → bool: Returns whether the label’s text is interpreted as Pango markup.

get_use_underline() → bool: Returns whether an underline in the text indicates a mnemonic.

set_child(child: Widget | None = None) → None

Sets the child widget of expander.

Parameters:: child – the child widget

set_expanded(expanded: bool) → None

Sets the state of the expander.

Set to True, if you want the child widget to be revealed, and False if you want the child widget to be hidden.

Parameters:: expanded – whether the child widget is revealed

set_label(label: str | None = None) → None

Sets the text of the label of the expander to label.

This will also clear any previously set labels.

Parameters:: label – a string

set_label_widget(label_widget: Widget | None = None) → None

Set the label widget for the expander.

This is the widget that will appear embedded alongside the expander arrow.

Parameters:: label_widget – the new label widget

set_resize_toplevel(resize_toplevel: bool) → None

Sets whether the expander will resize the toplevel widget containing the expander upon resizing and collapsing.

Parameters:: resize_toplevel – whether to resize the toplevel

set_use_markup(use_markup: bool) → None

Sets whether the text of the label contains Pango markup.

Parameters:: use_markup – True if the label’s text should be parsed for markup

set_use_underline(use_underline: bool) → None

If true, an underline in the text indicates a mnemonic.

Parameters:: use_underline – True if underlines in the text indicate mnemonics

Properties

class Expander

props.child: Widget: The child widget.

props.expanded: bool: Whether the expander has been opened to reveal the child.

props.label: str: The text of the expanders label.

props.label_widget: Widget: A widget to display instead of the usual expander label.

props.resize_toplevel: bool: When this property is True, the expander will resize the toplevel widget containing the expander upon expanding and collapsing.

props.use_markup: bool: Whether the text in the label is Pango markup.

props.use_underline: bool: Whether an underline in the text indicates a mnemonic.

Signals

class Expander.signals

activate() → None: Activates the GtkExpander.