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Object Hierarchy
GObject ╰── GInitiallyUnowned ╰── GtkWidget ╰── GtkContainer ╰── GtkBin ╰── GtkOverlay
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.
Functions
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.
Since: 3.2
gtk_overlay_reorder_overlay ()
void gtk_overlay_reorder_overlay (GtkOverlay *overlay,GtkWidget *child,gint position);
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
.
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.
Parameters
overlay |
||
child |
the overlaid GtkWidget to move |
|
position |
the new index for |
gtk_overlay_get_overlay_pass_through ()
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
.
Since: 3.18
gtk_overlay_set_overlay_pass_through ()
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
.
Parameters
overlay |
||
widget |
an overlay child of GtkOverlay |
|
pass_through |
whether the child should pass the input through |
Since: 3.18
Child Property Details
The “index” child property
“index” gint
The index of the overlay in the parent, -1 for the main child.
Flags: Read / Write
Allowed values: >= -1
Default value: 0
The “pass-through” child property
“pass-through” gboolean
Pass through input, does not affect main child.
Flags: Read / Write
Default value: FALSE
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. |
Flags: Run Last