125 lines
3.4 KiB
Markdown
125 lines
3.4 KiB
Markdown
**STRUCT**
|
||
|
||
# `Overlay`
|
||
|
||
`GtkOverlay` 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
|
||
[property@Gtk.Widget:halign] and [property@Gtk.Widget:valign]
|
||
properties. E.g. a widget with both alignments set to %GTK_ALIGN_START
|
||
will be placed at the top left corner of the `GtkOverlay` container,
|
||
whereas an overlay with halign set to %GTK_ALIGN_CENTER and valign set
|
||
to %GTK_ALIGN_END will be placed a the bottom edge of the `GtkOverlay`,
|
||
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 [signal@Gtk.Overlay::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 `GtkOverlay` implementation of the `GtkBuildable` interface
|
||
supports placing a child as an overlay by specifying “overlay” as
|
||
the “type” attribute of a `<child>` element.
|
||
|
||
# CSS nodes
|
||
|
||
`GtkOverlay` 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
|
||
### `updateFunctions`
|
||
|
||
Additional update functions for type extensions.
|
||
|
||
### `appearFunctions`
|
||
|
||
Additional appear functions for type extensions.
|
||
|
||
### `child`
|
||
|
||
The main child widget.
|
||
|
||
### `getChildPosition`
|
||
|
||
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 %GTK_ALIGN_FILL will cause the overlay to
|
||
be full-width/height). If the main child is a
|
||
`GtkScrolledWindow`, the overlays are placed relative
|
||
to its contents.
|
||
|
||
### `overlay`
|
||
|
||
The body for the widget "overlay".
|
||
|
||
### `app`
|
||
|
||
The application.
|
||
|
||
### `window`
|
||
|
||
The window.
|
||
|
||
## Methods
|
||
### `init()`
|
||
|
||
Initialize `Overlay`.
|
||
|
||
### `container(modifiers:)`
|
||
|
||
Get the widget's view storage.
|
||
- Parameter modifiers: The view modifiers.
|
||
- Returns: The view storage.
|
||
|
||
### `update(_:modifiers:updateProperties:)`
|
||
|
||
Update the widget's view storage.
|
||
- Parameters:
|
||
- storage: The view storage.
|
||
- modifiers: The view modifiers.
|
||
- updateProperties: Whether to update the view's properties.
|
||
|
||
### `child(_:)`
|
||
|
||
The main child widget.
|
||
|
||
### `getChildPosition(_:)`
|
||
|
||
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 %GTK_ALIGN_FILL will cause the overlay to
|
||
be full-width/height). If the main child is a
|
||
`GtkScrolledWindow`, the overlays are placed relative
|
||
to its contents.
|
||
|
||
### `overlay(_:)`
|
||
|
||
Set the body for "overlay".
|
||
- Parameter body: The body.
|
||
- Returns: The widget.
|