class Gtk::Expander

• Gtk::Expander
• Gtk::Widget
• GObject::InitiallyUnowned
• GObject::Object
• Reference
• Object

Overview

Gtk::Expander allows the user to reveal its child by clicking on an expander triangle.

This is similar to the triangles used in a Gtk::TreeView.

Normally you use an expander as you would use a frame; you create the child widget and use Gtk::Expander#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 Gtk::Expander but do not add a child to it. The expander widget has an [property@Gtk.Expander:expanded[ property which can be used to monitor its expansion state. You should watch this property with a signal connection as follows:

WARNING ⚠️ The following code is in c ⚠️

static void
expander_callback (GObject    *object,
                   GParamSpec *param_spec,
                   gpointer    user_data)
{
  Gtk::Expander *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)
{
  Gtk::Widget *expander = gtk_expander_new_with_mnemonic ("_More Options");
  g_signal_connect (expander, "notify::expanded",
                    G_CALLBACK (expander_callback), NULL);

  // ...
}

Gtk::Expander as Gtk::Buildable

The Gtk::Expander implementation of the Gtk::Buildable interface supports placing a child in the label position by specifying “label” as the “type” attribute of a element. A normal content child can be specified without specifying a type attribute.

An example of a UI definition fragment with Gtk::Expander:

WARNING ⚠️ The following code is in xml ⚠️

<object class="Gtk::Expander">
  <child type="label">
    <object class="Gtk::Label" id="expander-label"/>
  </child>
  <child>
    <object class="Gtk::Entry" id="expander-content"/>
  </child>
</object>

CSS nodes

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

Gtk::Expander 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

Gtk::Expander uses the %GTK_ACCESSIBLE_ROLE_BUTTON role.

Included Modules

• Gtk::Accessible
• Gtk::Buildable
• Gtk::ConstraintTarget

Defined in:

Constructors

• .new(label : String | Nil) : self

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

• .new

  Initialize a new Expander.

• .new(*, accessible_role : Gtk::AccessibleRole | Nil = nil, can_focus : Bool | Nil = nil, can_target : Bool | Nil = nil, child : Gtk::Widget | Nil = nil, css_classes : Enumerable(String) | Nil = nil, css_name : String | Nil = nil, cursor : Gdk::Cursor | Nil = nil, expanded : Bool | Nil = nil, focus_on_click : Bool | Nil = nil, focusable : Bool | Nil = nil, halign : Gtk::Align | Nil = nil, has_default : Bool | Nil = nil, has_focus : Bool | Nil = nil, has_tooltip : Bool | Nil = nil, height_request : Int32 | Nil = nil, hexpand : Bool | Nil = nil, hexpand_set : Bool | Nil = nil, label : String | Nil = nil, label_widget : Gtk::Widget | Nil = nil, layout_manager : Gtk::LayoutManager | Nil = nil, margin_bottom : Int32 | Nil = nil, margin_end : Int32 | Nil = nil, margin_start : Int32 | Nil = nil, margin_top : Int32 | Nil = nil, name : String | Nil = nil, opacity : Float64 | Nil = nil, overflow : Gtk::Overflow | Nil = nil, parent : Gtk::Widget | Nil = nil, receives_default : Bool | Nil = nil, resize_toplevel : Bool | Nil = nil, root : Gtk::Root | Nil = nil, scale_factor : Int32 | Nil = nil, sensitive : Bool | Nil = nil, tooltip_markup : String | Nil = nil, tooltip_text : String | Nil = nil, use_markup : Bool | Nil = nil, use_underline : Bool | Nil = nil, valign : Gtk::Align | Nil = nil, vexpand : Bool | Nil = nil, vexpand_set : Bool | Nil = nil, visible : Bool | Nil = nil, width_request : Int32 | Nil = nil)
• .new_with_mnemonic(label : String | Nil) : self

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

Class Method Summary

• .g_type : UInt64

  Returns the type id (GType) registered in GLib type system.

Instance Method Summary

• #==(other : self)

  Returns true if this reference is the same as other.

• #activate_signal
• #child : Gtk::Widget | Nil

  Gets the child widget of expander.

• #child=(child : Gtk::Widget | Nil) : Nil

  Sets the child widget of expander.

• #expanded : Bool

  Queries a Gtk::Expander and returns its current state.

• #expanded=(expanded : Bool) : Nil

  Sets the state of the expander.

• #expanded? : Bool
• #hash(hasher)

  See Object#hash(hasher)

• #label : String | Nil

  Fetches the text from a label widget.

• #label=(value : String) : String
• #label=(value : Nil) : Nil

  Set #label property to nil.

• #label=(label : String | Nil) : Nil

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

• #label? : String | Nil

  Same as #label, but can return nil.

• #label_widget : Gtk::Widget | Nil

  Retrieves the label widget for the frame.

• #label_widget=(label_widget : Gtk::Widget | Nil) : Nil

  Set the label widget for the expander.

• #resize_toplevel : Bool

  Returns whether the expander will resize the toplevel widget containing the expander upon resizing and collpasing.

• #resize_toplevel=(resize_toplevel : Bool) : Nil

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

• #resize_toplevel? : Bool
• #use_markup : Bool

  Returns whether the label’s text is interpreted as Pango markup.

• #use_markup=(use_markup : Bool) : Nil

  Sets whether the text of the label contains Pango markup.

• #use_markup? : Bool
• #use_underline : Bool

  Returns whether an underline in the text indicates a mnemonic.

• #use_underline=(use_underline : Bool) : Nil

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

• #use_underline? : Bool

Constructor Detail

Class Method Detail

Instance Method Detail