Struct gtk4::Expander

#[repr(transparent)]
pub struct Expander { /* private fields */ }

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

This is similar to the triangles used in a TreeView.

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 Expander but do not add a child to it. The expander widget has an property::Expander::expanded[ property which can be used to monitor its expansion state. You should watch this property with a signal connection as follows:

⚠️ The following code is in 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

The Expander implementation of the 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 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
╰── box
    ├── title
    │   ├── arrow
    │   ╰── <label widget>
    ╰── <child>

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

Expander uses the AccessibleRole::Button role.

Implements

WidgetExt, glib::ObjectExt, AccessibleExt, BuildableExt, ConstraintTargetExt, WidgetExtManual, AccessibleExtManual

Implementations

impl Expander

pub fn new(label: Option<&str>) -> Expander

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

label

the text of the label

Returns

a new Expander widget.

pub fn with_mnemonic(label: &str) -> Expander

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.

label

the text of the label with an underscore in front of the mnemonic character

Returns

a new Expander widget.

pub fn builder() -> ExpanderBuilder

Creates a new builder-pattern struct instance to construct Expander objects.

This method returns an instance of ExpanderBuilder which can be used to create Expander objects.

pub fn child(&self) -> Option<Widget>

Gets the child widget of @self.

Returns

the child widget of @self

pub fn is_expanded(&self) -> bool

Queries a Expander and returns its current state.

Returns true if the child widget is revealed.

Returns

the current state of the expander

pub fn label(&self) -> Option<GString>

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 gtk_button_new() to use as a container.

Returns

The text of the label widget. This string is owned by the widget and must not be modified or freed.

pub fn label_widget(&self) -> Option<Widget>

Retrieves the label widget for the frame.

Returns

the label widget

pub fn resizes_toplevel(&self) -> bool

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

Returns

the “resize toplevel” setting.

pub fn uses_markup(&self) -> bool

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

Returns

true if the label’s text will be parsed for markup

pub fn uses_underline(&self) -> bool

Returns whether an underline in the text indicates a mnemonic.

Returns

true if an embedded underline in the expander label indicates the mnemonic accelerator keys

pub fn set_child(&self, child: Option<&impl IsA<Widget>>)

Sets the child widget of @self.

child

the child widget

pub fn set_expanded(&self, expanded: bool)

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.

expanded

whether the child widget is revealed

pub fn set_label(&self, label: Option<&str>)

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

This will also clear any previously set labels.

label

a string

pub fn set_label_widget(&self, label_widget: Option<&impl IsA<Widget>>)

Set the label widget for the expander.

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

label_widget

the new label widget

pub fn set_resize_toplevel(&self, resize_toplevel: bool)

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

resize_toplevel

whether to resize the toplevel

pub fn set_use_markup(&self, use_markup: bool)

Sets whether the text of the label contains Pango markup.

use_markup

true if the label’s text should be parsed for markup

pub fn set_use_underline(&self, use_underline: bool)

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

use_underline

true if underlines in the text indicate mnemonics

pub fn connect_activate<F: Fn(&Self) + 'static>(&self, f: F) -> SignalHandlerId

Activates the Expander.

pub fn emit_activate(&self)

pub fn connect_child_notify<F: Fn(&Self) + 'static>(
    &self,
    f: F
) -> SignalHandlerId

pub fn connect_expanded_notify<F: Fn(&Self) + 'static>(
    &self,
    f: F
) -> SignalHandlerId

pub fn connect_label_notify<F: Fn(&Self) + 'static>(
    &self,
    f: F
) -> SignalHandlerId

pub fn connect_label_widget_notify<F: Fn(&Self) + 'static>(
    &self,
    f: F
) -> SignalHandlerId

pub fn connect_resize_toplevel_notify<F: Fn(&Self) + 'static>(
    &self,
    f: F
) -> SignalHandlerId

pub fn connect_use_markup_notify<F: Fn(&Self) + 'static>(
    &self,
    f: F
) -> SignalHandlerId

pub fn connect_use_underline_notify<F: Fn(&Self) + 'static>(
    &self,
    f: F
) -> SignalHandlerId

Trait Implementations

impl Clone for Expander

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Expander

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Expander

fn default() -> Self

Returns the “default value” for a type.

impl Display for Expander

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for Expander

fn hash<H>(&self, state: &mut H) where
    H: Hasher, 

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl Ord for Expander

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

Restrict a value to a certain interval.

impl ParentClassIs for Expander

type Parent = Widget

impl<OT: ObjectType> PartialEq<OT> for Expander

fn eq(&self, other: &OT) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<OT: ObjectType> PartialOrd<OT> for Expander

fn partial_cmp(&self, other: &OT) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl StaticType for Expander

fn static_type() -> Type

Returns the type identifier of Self.

impl Eq for Expander

impl IsA<Accessible> for Expander

impl IsA<Buildable> for Expander

impl IsA<ConstraintTarget> for Expander

impl IsA<Widget> for Expander