GtkOverlay

GtkOverlay — A container which overlays widgets on top of each other

Properties

GtkWidget * child Read / Write

Signals

gboolean get-child-position Run Last

Types and Values

Object Hierarchy

    GObject
    ╰── GInitiallyUnowned
        ╰── GtkWidget
            ╰── GtkOverlay

Implemented Interfaces

GtkOverlay implements AtkImplementorIface, GtkBuildable and GtkConstraintTarget.

Includes

#include <gtk/gtk.h>

Description

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 “halign” and “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 “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.

Functions

gtk_overlay_new ()

GtkWidget *
gtk_overlay_new (void);

Creates a new GtkOverlay.

Returns

a new GtkOverlay object.


gtk_overlay_set_child ()

void
gtk_overlay_set_child (GtkOverlay *overlay,
                       GtkWidget *child);

Sets the child widget of overlay .

Parameters

overlay

a GtkOverlay

 

child

the child widget.

[allow-none]

gtk_overlay_get_child ()

GtkWidget *
gtk_overlay_get_child (GtkOverlay *overlay);

Gets the child widget of overlay .

Parameters

overlay

a GtkOverlay

 

Returns

the child widget of overlay .

[nullable][transfer none]


gtk_overlay_add_overlay ()

void
gtk_overlay_add_overlay (GtkOverlay *overlay,
                         GtkWidget *widget);

Adds widget to overlay .

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

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

Parameters

overlay

a GtkOverlay

 

widget

a GtkWidget to be added to the container

 

gtk_overlay_remove_overlay ()

void
gtk_overlay_remove_overlay (GtkOverlay *overlay,
                            GtkWidget *widget);

Removes an overlay that was added with gtk_overlay_add_overlay().

Parameters

overlay

a GtkOverlay

 

widget

a GtkWidget to be removed

 

gtk_overlay_get_measure_overlay ()

gboolean
gtk_overlay_get_measure_overlay (GtkOverlay *overlay,
                                 GtkWidget *widget);

Gets whether widget 's size is included in the measurement of overlay .

Parameters

overlay

a GtkOverlay

 

widget

an overlay child of GtkOverlay

 

Returns

whether the widget is measured


gtk_overlay_set_measure_overlay ()

void
gtk_overlay_set_measure_overlay (GtkOverlay *overlay,
                                 GtkWidget *widget,
                                 gboolean measure);

Sets whether widget is included in the measured size of overlay .

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 overlay 's allocation if they are too large.

Parameters

overlay

a GtkOverlay

 

widget

an overlay child of GtkOverlay

 

measure

whether the child should be measured

 

gtk_overlay_get_clip_overlay ()

gboolean
gtk_overlay_get_clip_overlay (GtkOverlay *overlay,
                              GtkWidget *widget);

Gets whether widget should be clipped within the parent.

Parameters

overlay

a GtkOverlay

 

widget

an overlay child of GtkOverlay

 

Returns

whether the widget is clipped within the parent.


gtk_overlay_set_clip_overlay ()

void
gtk_overlay_set_clip_overlay (GtkOverlay *overlay,
                              GtkWidget *widget,
                              gboolean clip_overlay);

Sets whether widget should be clipped within the parent.

Parameters

overlay

a GtkOverlay

 

widget

an overlay child of GtkOverlay

 

clip_overlay

whether the child should be clipped

 

Types and Values

GtkOverlay

typedef struct _GtkOverlay GtkOverlay;

Property Details

The “child” property

  “child”                    GtkWidget *

The child widget.

Owner: GtkOverlay

Flags: Read / Write

Signal Details

The “get-child-position” signal

gboolean
user_function (GtkOverlay   *overlay,
               GtkWidget    *widget,
               GdkRectangle *allocation,
               gpointer      user_data)

The ::get-child-position signal is 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.

Parameters

overlay

the GtkOverlay

 

widget

the child widget to position

 

allocation

return location for the allocation.

[type Gdk.Rectangle][out caller-allocates]

user_data

user data set when the signal handler was connected.

 

Returns

TRUE if the allocation has been filled

Flags: Run Last