GtkOverlay — A container which overlays widgets on top of each other
GtkWidget * | gtk_overlay_new () |
void | gtk_overlay_add_overlay () |
void | gtk_overlay_reorder_overlay () |
gboolean | gtk_overlay_get_overlay_pass_through () |
void | gtk_overlay_set_overlay_pass_through () |
int | index | Read / Write |
gboolean | pass-through | Read / Write |
gboolean | get-child-position | Run Last |
struct | GtkOverlay |
struct | GtkOverlayClass |
GObject ╰── GInitiallyUnowned ╰── GtkWidget ╰── GtkContainer ╰── GtkBin ╰── GtkOverlay
GtkOverlay implements AtkImplementorIface and GtkBuildable.
#include <gtk/gtk.h>
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.
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.
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.
GtkWidget *
gtk_overlay_new (void
);
Creates a new GtkOverlay.
a new GtkOverlay object.
Since: 3.2
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.
overlay | ||
widget | a GtkWidget to be added to the container |
Since: 3.2
void gtk_overlay_reorder_overlay (GtkOverlay *overlay
,GtkWidget *child
,int index_
);
Moves child
to a new index
in the list of overlay
children. The list contains overlays in the order that these were added to overlay
by default. See also “index”.
A widget’s index in the overlay
children list determines which order the children are drawn if they overlap. The first child is drawn at the bottom. It also affects the default focus chain order.
overlay | ||
child | the overlaid GtkWidget to move | |
index_ | the new index for |
Since: 3.18
gboolean gtk_overlay_get_overlay_pass_through (GtkOverlay *overlay
,GtkWidget *widget
);
Convenience function to get the value of the “pass-through” child property for widget
.
overlay | ||
widget | an overlay child of GtkOverlay |
whether the widget is a pass through child.
Since: 3.18
void gtk_overlay_set_overlay_pass_through (GtkOverlay *overlay
,GtkWidget *widget
,gboolean pass_through
);
Convenience function to set the value of the “pass-through” child property for widget
.
overlay | ||
widget | an overlay child of GtkOverlay | |
pass_through | whether the child should pass the input through |
Since: 3.18
struct GtkOverlay;
struct GtkOverlayClass { GtkBinClass parent_class; gboolean (*get_child_position) (GtkOverlay *overlay, GtkWidget *widget, GtkAllocation *allocation); };
| Signal emitted to determine the position and size of any overlay child widgets. |
“index”
child property“index” int
The index of the overlay child in the parent (or -1 for the main child). See gtk_overlay_reorder_overlay()
.
Owner: GtkOverlay
Flags: Read / Write
Allowed values: >= -1
Default value: 0
Since: 3.18
“pass-through”
child property“pass-through” gboolean
Whether to pass input through the overlay child to the main child. (Of course, this has no effect when set on the main child itself.)
Owner: GtkOverlay
Flags: Read / Write
Default value: FALSE
Since: 3.18
“get-child-position”
signalgboolean 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.
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. |
TRUE
if the allocation
has been filled
Flags: Run Last
© 2005–2020 The GNOME Project
Licensed under the GNU Lesser General Public License version 2.1 or later.
https://developer.gnome.org/gtk3/3.24/GtkOverlay.html