Gtk.Expander – gtk+-2.0 Reference Manual

Expander

Object Hierarchy:

Object hierarchy for Expander

Description:

public class Expander : Bin, Implementor, Buildable

Allows the user to reveal or conceal a child widget.

<picture> <source srcset="expander-dark.png" media="(prefers-color-scheme: dark)"> <img alt="An example GtkExpander" src="expander.png"> </picture>

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 [method@Gtk.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 [ 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:

```c 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

An example of a UI definition fragment with GtkExpander:

```xml <object class="GtkExpander"> <property name="label-widget"> <object class="GtkLabel" id="expander-label"/> </property> <property name="child"> <object class="GtkEntry" id="expander-content"/> </property> </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 `GtkExpander:checked` pseudoclass set on it.

Accessibility

`GtkExpander` uses the [enum@Gtk.AccessibleRole.button] role.

Namespace: Gtk

Package: gtk+-2.0

Content:

Properties:

public bool expanded { get; set construct; }
Whether the expander has been opened to reveal the child.
public string label { get; set construct; }
The text of the expanders label.
public bool label_fill { get; set construct; }
Whether the label widget should fill all available horizontal space.
public Widget label_widget { get; set; }
A widget to display instead of the usual expander label.
public int spacing { get; set; }
Space to put between the label and the child when the expander is expanded.
public bool use_markup { get; set construct; }
Whether the text in the label is Pango markup.
public bool use_underline { get; set construct; }
Whether an underline in the text indicates a mnemonic.

Creation methods:

public Expander (string label)
Creates a new expander using label as the text of the label.
public Expander.with_mnemonic (string label)
Creates a new expander using label as the text of the label.

Methods:

public bool get_expanded ()
Queries a `GtkExpander` and returns its current state.
public unowned string get_label ()
Fetches the text from a label widget.
public bool get_label_fill ()
Returns whether the label widget will fill all available horizontal space allocated to this.
public unowned Widget get_label_widget ()
Retrieves the label widget for the frame.
public int get_spacing ()
Gets the value set by set_spacing.
public bool get_use_markup ()
Returns whether the label’s text is interpreted as Pango markup.
public bool get_use_underline ()
Returns whether an underline in the text indicates a mnemonic.
public void set_expanded (bool expanded)
Sets the state of the expander.
public void set_label (string label)
Sets the text of the label of the expander to label.
public void set_label_fill (bool label_fill)
Sets whether the label widget should fill all available horizontal space allocated to this.
public void set_label_widget (Widget label_widget)
Set the label widget for the expander.
public void set_spacing (int spacing)
Sets the spacing field of this, which is the number of pixels to place between expander and the child.
public void set_use_markup (bool use_markup)
Sets whether the text of the label contains Pango markup.
public void set_use_underline (bool use_underline)
If true, an underline in the text indicates a mnemonic.

Signals:

public virtual signal void activate ()
Activates the `GtkExpander`.

Inherited Members:

All known members inherited from class Gtk.Bin

child

get_child

All known members inherited from class Gtk.Container

All known members inherited from class Gtk.Widget

All known members inherited from class Gtk.Object

user_data

All known members inherited from class GLib.Object

All known members inherited from interface Atk.Implementor

ref_accessible

All known members inherited from interface Gtk.Buildable

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