137 lines
3.7 KiB
Markdown
137 lines
3.7 KiB
Markdown
**STRUCT**
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# `Overlay`
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`GtkOverlay` is a container which contains a single main child, on top
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of which it can place “overlay” widgets.
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The position of each overlay widget is determined by its
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[property@Gtk.Widget:halign] and [property@Gtk.Widget:valign]
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properties. E.g. a widget with both alignments set to %GTK_ALIGN_START
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will be placed at the top left corner of the `GtkOverlay` container,
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whereas an overlay with halign set to %GTK_ALIGN_CENTER and valign set
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to %GTK_ALIGN_END will be placed a the bottom edge of the `GtkOverlay`,
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horizontally centered. The position can be adjusted by setting the margin
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properties of the child to non-zero values.
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More complicated placement of overlays is possible by connecting
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to the [signal@Gtk.Overlay::get-child-position] signal.
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An overlay’s minimum and natural sizes are those of its main child.
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The sizes of overlay children are not considered when measuring these
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preferred sizes.
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# GtkOverlay as GtkBuildable
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The `GtkOverlay` implementation of the `GtkBuildable` interface
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supports placing a child as an overlay by specifying “overlay” as
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the “type” attribute of a `<child>` element.
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# CSS nodes
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`GtkOverlay` has a single CSS node with the name “overlay”. Overlay children
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whose alignments cause them to be positioned at an edge get the style classes
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“.left”, “.right”, “.top”, and/or “.bottom” according to their position.
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## Properties
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### `updateFunctions`
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Additional update functions for type extensions.
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### `appearFunctions`
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Additional appear functions for type extensions.
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### `accessibleRole`
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The accessible role of the given `GtkAccessible` implementation.
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The accessible role cannot be changed once set.
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### `child`
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The main child widget.
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### `getChildPosition`
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Emitted to determine the position and size of any overlay
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child widgets.
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A handler for this signal should fill @allocation with
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the desired position and size for @widget, relative to
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the 'main' child of @overlay.
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The default handler for this signal uses the @widget's
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halign and valign properties to determine the position
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and gives the widget its natural size (except that an
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alignment of %GTK_ALIGN_FILL will cause the overlay to
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be full-width/height). If the main child is a
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`GtkScrolledWindow`, the overlays are placed relative
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to its contents.
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### `overlay`
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The body for the widget "overlay".
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### `app`
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The application.
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### `window`
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The window.
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## Methods
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### `init()`
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Initialize `Overlay`.
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### `container(modifiers:)`
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Get the widget's view storage.
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- Parameter modifiers: The view modifiers.
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- Returns: The view storage.
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### `update(_:modifiers:updateProperties:)`
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Update the widget's view storage.
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- Parameters:
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- storage: The view storage.
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- modifiers: The view modifiers.
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- updateProperties: Whether to update the view's properties.
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### `accessibleRole(_:)`
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The accessible role of the given `GtkAccessible` implementation.
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The accessible role cannot be changed once set.
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### `child(_:)`
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The main child widget.
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### `getChildPosition(_:)`
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Emitted to determine the position and size of any overlay
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child widgets.
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A handler for this signal should fill @allocation with
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the desired position and size for @widget, relative to
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the 'main' child of @overlay.
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The default handler for this signal uses the @widget's
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halign and valign properties to determine the position
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and gives the widget its natural size (except that an
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alignment of %GTK_ALIGN_FILL will cause the overlay to
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be full-width/height). If the main child is a
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`GtkScrolledWindow`, the overlays are placed relative
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to its contents.
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### `overlay(_:)`
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Set the body for "overlay".
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- Parameter body: The body.
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- Returns: The widget.
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