Struct gtk4::Expander

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 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 <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>

Expander 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

Expander uses the AccessibleRole::Button role.

Properties

child

The child widget.

Readable | Writeable

expanded

Whether the expander has been opened to reveal the child.

Readable | Writeable | Construct

label

The text of the expanders label.

Readable | Writeable | Construct

label-widget

A widget to display instead of the usual expander label.

Readable | Writeable

resize-toplevel

When this property is true, the expander will resize the toplevel widget containing the expander upon expanding and collapsing.

Readable | Writeable

use-markup

Whether the text in the label is Pango markup.

Readable | Writeable | Construct

use-underline

Whether an underline in the text indicates a mnemonic.

Readable | Writeable | Construct

Widget

can-focus

Whether the widget or any of its descendents can accept the input focus.

This property is meant to be set by widget implementations, typically in their instance init function.

Readable | Writeable

can-target

Whether the widget can receive pointer events.

Readable | Writeable

css-classes

A list of css classes applied to this widget.

Readable | Writeable

css-name

The name of this widget in the CSS tree.

This property is meant to be set by widget implementations, typically in their instance init function.

Readable | Writeable | Construct Only

cursor

The cursor used by @widget.

Readable | Writeable

focus-on-click

Whether the widget should grab focus when it is clicked with the mouse.

This property is only relevant for widgets that can take focus.

Readable | Writeable

focusable

Whether this widget itself will accept the input focus.

Readable | Writeable

halign

How to distribute horizontal space if widget gets extra space.

Readable | Writeable

has-default

Whether the widget is the default widget.

Readable

has-focus

Whether the widget has the input focus.

Readable

has-tooltip

Enables or disables the emission of the ::query-tooltip signal on @widget.

A value of true indicates that @widget can have a tooltip, in this case the widget will be queried using query-tooltip to determine whether it will provide a tooltip or not.

Readable | Writeable

height-request

Override for height request of the widget.

If this is -1, the natural request will be used.

Readable | Writeable

hexpand

Whether to expand horizontally.

Readable | Writeable

hexpand-set

Whether to use the hexpand property.

Readable | Writeable

layout-manager

The LayoutManager instance to use to compute the preferred size of the widget, and allocate its children.

This property is meant to be set by widget implementations, typically in their instance init function.

Readable | Writeable

margin-bottom

Margin on bottom side of widget.

This property adds margin outside of the widget’s normal size request, the margin will be added in addition to the size from WidgetExt::set_size_request() for example.

Readable | Writeable

margin-end

Margin on end of widget, horizontally.

This property supports left-to-right and right-to-left text directions.

This property adds margin outside of the widget’s normal size request, the margin will be added in addition to the size from WidgetExt::set_size_request() for example.

Readable | Writeable

margin-start

Margin on start of widget, horizontally.

This property supports left-to-right and right-to-left text directions.

This property adds margin outside of the widget’s normal size request, the margin will be added in addition to the size from WidgetExt::set_size_request() for example.

Readable | Writeable

margin-top

Margin on top side of widget.

This property adds margin outside of the widget’s normal size request, the margin will be added in addition to the size from WidgetExt::set_size_request() for example.

Readable | Writeable

name

The name of the widget.

Readable | Writeable

opacity

The requested opacity of the widget.

Readable | Writeable

overflow

How content outside the widget’s content area is treated.

This property is meant to be set by widget implementations, typically in their instance init function.

Readable | Writeable

parent

The parent widget of this widget.

Readable

receives-default

Whether the widget will receive the default action when it is focused.

Readable | Writeable

root

The Root widget of the widget tree containing this widget.

This will be None if the widget is not contained in a root widget.

Readable

scale-factor

The scale factor of the widget.

Readable

sensitive

Whether the widget responds to input.

Readable | Writeable

tooltip-markup

Sets the text of tooltip to be the given string, which is marked up with Pango markup.

Also see Tooltip::set_markup().

This is a convenience property which will take care of getting the tooltip shown if the given string is not None: has-tooltip will automatically be set to true and there will be taken care of query-tooltip in the default signal handler.

Note that if both tooltip-text and tooltip-markup are set, the last one wins.

Readable | Writeable

tooltip-text

Sets the text of tooltip to be the given string.

Also see Tooltip::set_text().

This is a convenience property which will take care of getting the tooltip shown if the given string is not None: has-tooltip will automatically be set to true and there will be taken care of query-tooltip in the default signal handler.

Note that if both tooltip-text and tooltip-markup are set, the last one wins.

Readable | Writeable

valign

How to distribute vertical space if widget gets extra space.

Readable | Writeable

vexpand

Whether to expand vertically.

Readable | Writeable

vexpand-set

Whether to use the vexpand property.

Readable | Writeable

visible

Whether the widget is visible.

Readable | Writeable

width-request

Override for width request of the widget.

If this is -1, the natural request will be used.

Readable | Writeable

Accessible

accessible-role

The accessible role of the given Accessible implementation.

The accessible role cannot be changed once set.

Readable | Writeable

Signals

activate

Activates the Expander.

Action

Widget

destroy

Signals that all holders of a reference to the widget should release the reference that they hold.

May result in finalization of the widget if all references are released.

This signal is not suitable for saving widget state.

direction-changed

Emitted when the text direction of a widget changes.

hide

Emitted when @widget is hidden.

keynav-failed

Emitted if keyboard navigation fails.

See WidgetExt::keynav_failed() for details.

map

Emitted when @widget is going to be mapped.

A widget is mapped when the widget is visible (which is controlled with visible) and all its parents up to the toplevel widget are also visible.

The ::map signal can be used to determine whether a widget will be drawn, for instance it can resume an animation that was stopped during the emission of unmap.

mnemonic-activate

Emitted when a widget is activated via a mnemonic.

The default handler for this signal activates @widget if @group_cycling is false, or just makes @widget grab focus if @group_cycling is true.

move-focus

Emitted when the focus is moved.

The ::move-focus signal is a keybinding signal.

The default bindings for this signal are Tab to move forward, and Shift+Tab to move backward.

Action

query-tooltip

Emitted when the widget’s tooltip is about to be shown.

This happens when the has-tooltip property is true and the hover timeout has expired with the cursor hovering “above” @widget; or emitted when @widget got focus in keyboard mode.

Using the given coordinates, the signal handler should determine whether a tooltip should be shown for @widget. If this is the case true should be returned, false otherwise. Note that if @keyboard_mode is true, the values of @x and @y are undefined and should not be used.

The signal handler is free to manipulate @tooltip with the therefore destined function calls.

realize

Emitted when @widget is associated with a gdk::Surface.

This means that WidgetExt::realize() has been called or the widget has been mapped (that is, it is going to be drawn).

show

Emitted when @widget is shown.

state-flags-changed

Emitted when the widget state changes.

See WidgetExt::state_flags().

unmap

Emitted when @widget is going to be unmapped.

A widget is unmapped when either it or any of its parents up to the toplevel widget have been set as hidden.

As ::unmap indicates that a widget will not be shown any longer, it can be used to, for example, stop an animation on the widget.

unrealize

Emitted when the gdk::Surface associated with @widget is destroyed.

This means that WidgetExt::unrealize() has been called or the widget has been unmapped (that is, it is going to be hidden).

Implements

WidgetExt, [trait@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 collapsing.

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 collapsing.

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 HasParamSpec for Expander

type ParamSpec = ParamSpecObject

type SetValue = Expander

Preferred value to be used as setter for the associated ParamSpec.

type BuilderFn = fn(_: &str) -> ParamSpecObjectBuilder<'_, Expander>

fn param_spec_builder() -> Self::BuilderFn

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, Self: Sized,

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

where Self: Sized,

Compares and returns the maximum of two values.

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

where Self: Sized,

Compares and returns the minimum of two values.

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

where Self: Sized + PartialOrd,

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 !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

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