Struct gtk4::Overlay

pub struct Overlay { /* private fields */ }

Overlay is a container which contains a single main child, on top of which it can place “overlay” widgets.

The position of each overlay widget is determined by its halign and valign properties. E.g. a widget with both alignments set to Align::Start will be placed at the top left corner of the Overlay container, whereas an overlay with halign set to Align::Center and valign set to Align::End will be placed a the bottom edge of the Overlay, horizontally centered. The position can be adjusted by setting the margin properties of the child to non-zero values.

More complicated placement of overlays is possible by connecting to the get-child-position signal.

An overlay’s minimum and natural sizes are those of its main child. The sizes of overlay children are not considered when measuring these preferred sizes.

GtkOverlay as GtkBuildable

The Overlay implementation of the Buildable interface supports placing a child as an overlay by specifying “overlay” as the “type” attribute of a <child> element.

CSS nodes

Overlay has a single CSS node with the name “overlay”. Overlay children whose alignments cause them to be positioned at an edge get the style classes “.left”, “.right”, “.top”, and/or “.bottom” according to their position.

Properties

child

The main child widget.

Readable | Writeable

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

get-child-position

Emitted to determine the position and size of any overlay child widgets.

A handler for this signal should fill @allocation with the desired position and size for @widget, relative to the ‘main’ child of @overlay.

The default handler for this signal uses the @widget’s halign and valign properties to determine the position and gives the widget its natural size (except that an alignment of Align::Fill will cause the overlay to be full-width/height). If the main child is a ScrolledWindow, the overlays are placed relative to its contents.

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 Overlay

pub fn new() -> Overlay

Creates a new Overlay.

Returns

a new Overlay object.

pub fn builder() -> OverlayBuilder

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

This method returns an instance of OverlayBuilder which can be used to create Overlay objects.

pub fn add_overlay(&self, widget: &impl IsA<Widget>)

Adds @widget to @self.

The widget will be stacked on top of the main widget added with set_child().

The position at which @widget is placed is determined from its halign and valign properties.

widget

a Widget to be added to the container

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

Gets the child widget of @self.

Returns

the child widget of @self

pub fn is_clip_overlay(&self, widget: &impl IsA<Widget>) -> bool

Gets whether @widget should be clipped within the parent.

widget

an overlay child of Overlay

Returns

whether the widget is clipped within the parent.

pub fn is_measure_overlay(&self, widget: &impl IsA<Widget>) -> bool

Gets whether @widget’s size is included in the measurement of @self.

widget

an overlay child of Overlay

Returns

whether the widget is measured

pub fn remove_overlay(&self, widget: &impl IsA<Widget>)

Removes an overlay that was added with gtk_overlay_add_overlay().

widget

a Widget to be removed

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

Sets the child widget of @self.

child

the child widget

pub fn set_clip_overlay(&self, widget: &impl IsA<Widget>, clip_overlay: bool)

Sets whether @widget should be clipped within the parent.

widget

an overlay child of Overlay

clip_overlay

whether the child should be clipped

pub fn set_measure_overlay(&self, widget: &impl IsA<Widget>, measure: bool)

Sets whether @widget is included in the measured size of @self.

The overlay will request the size of the largest child that has this property set to true. Children who are not included may be drawn outside of @self’s allocation if they are too large.

widget

an overlay child of Overlay

measure

whether the child should be measured

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

impl Overlay

pub fn connect_get_child_position<F>(&self, f: F) -> SignalHandlerId

where F: Fn(&Self, &Widget) -> Option<Rectangle> + 'static,

Emitted to determine the position and size of any overlay child widgets.

A handler for this signal should fill @allocation with the desired position and size for @widget, relative to the ‘main’ child of @overlay.

The default handler for this signal uses the @widget’s halign and valign properties to determine the position and gives the widget its natural size (except that an alignment of Align::Fill will cause the overlay to be full-width/height). If the main child is a ScrolledWindow, the overlays are placed relative to its contents.

widget

the child widget to position

Returns

true if the @allocation has been filled

allocation

return location for the allocation

Trait Implementations

impl Clone for Overlay

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 Overlay

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

Formats the value using the given formatter.

impl Default for Overlay

fn default() -> Self

Returns the “default value” for a type.

impl HasParamSpec for Overlay

type ParamSpec = ParamSpecObject

type SetValue = Overlay

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

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

fn param_spec_builder() -> Self::BuilderFn

impl Hash for Overlay

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 Overlay

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 Overlay

type Parent = Widget

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

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 Overlay

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 Overlay

fn static_type() -> Type

Returns the type identifier of Self.

impl Eq for Overlay

impl IsA<Accessible> for Overlay

impl IsA<Buildable> for Overlay

impl IsA<ConstraintTarget> for Overlay

impl IsA<Widget> for Overlay