Gtk.LayoutManager

g GObject.Object GObject.Object Gtk.LayoutManager Gtk.LayoutManager GObject.Object->Gtk.LayoutManager

Subclasses:

Gtk.BinLayout, Gtk.BoxLayout, Gtk.CenterLayout, Gtk.ConstraintLayout, Gtk.CustomLayout, Gtk.FixedLayout, Gtk.GridLayout, Gtk.OverlayLayout

Methods

Inherited:

GObject.Object (37)

Structs:

GObject.ObjectClass (5)

allocate (widget, width, height, baseline)

get_layout_child (child)

get_request_mode ()

get_widget ()

layout_changed ()

measure (widget, orientation, for_size)

Virtual Methods

Inherited:

GObject.Object (7)

do_allocate (widget, width, height, baseline)

do_create_layout_child (widget, for_child)

do_get_request_mode (widget)

do_measure (widget, orientation, for_size)

do_root ()

do_unroot ()

Properties

None

Signals

Inherited:

GObject.Object (1)

Fields

Inherited:

GObject.Object (1)

Name

Type

Access

Description

parent_instance

GObject.Object

r

Class Details

class Gtk.LayoutManager(**kwargs)
Bases:

GObject.Object

Abstract:

Yes

Structure:

Gtk.LayoutManagerClass

Handles the preferred size and allocation for children of a widget.

You typically subclass GtkLayoutManager if you want to implement a layout policy for the children of a widget, or if you want to determine the size of a widget depending on its contents.

Each GtkWidget can only have a GtkLayoutManager instance associated to it at any given time; it is possible, though, to replace the layout manager instance using [method`Gtk`.Widget.set_layout_manager].

Layout properties

A layout manager can expose properties for controlling the layout of each child, by creating an object type derived from [class`Gtk`.LayoutChild] and installing the properties on it as normal GObject properties.

Each GtkLayoutChild instance storing the layout properties for a specific child is created through the [method`Gtk`.LayoutManager.get_layout_child] method; a GtkLayoutManager controls the creation of its GtkLayoutChild instances by overriding the Gtk.LayoutManager.do_create_layout_child() virtual function. The typical implementation should look like:

``c static GtkLayoutChild * create_layout_child (GtkLayoutManager *manager,

GtkWidget *container, GtkWidget *child)

{
return g_object_new (your_layout_child_get_type (),

“layout-manager”, manager, “child-widget”, child, NULL);

}

The [property`Gtk`.LayoutChild:layout-manager] and [property`Gtk`.LayoutChild:child-widget] properties on the newly created GtkLayoutChild instance are mandatory. The GtkLayoutManager will cache the newly created GtkLayoutChild instance until the widget is removed from its parent, or the parent removes the layout manager.

Each GtkLayoutManager instance creating a GtkLayoutChild should use [method`Gtk`.LayoutManager.get_layout_child] every time it needs to query the layout properties; each GtkLayoutChild instance should call [method`Gtk`.LayoutManager.layout_changed] every time a property is updated, in order to queue a new size measuring and allocation.

allocate(widget, width, height, baseline)[source]
Parameters:

  • widget (Gtk.Widget) – the GtkWidget using self

  • width (int) – the new width of the widget

  • height (int) – the new height of the widget

  • baseline (int) – the baseline position of the widget, or -1

Assigns the given width, height, and baseline to a widget, and computes the position and sizes of the children of the widget using the layout management policy of self.

get_layout_child(child)[source]
Parameters:

child (Gtk.Widget) – a GtkWidget

Returns:

a GtkLayoutChild

Return type:

Gtk.LayoutChild

Retrieves a GtkLayoutChild instance for the GtkLayoutManager, creating one if necessary.

The child widget must be a child of the widget using self.

The GtkLayoutChild instance is owned by the GtkLayoutManager, and is guaranteed to exist as long as child is a child of the GtkWidget using the given GtkLayoutManager.

get_request_mode()[source]
Returns:

a GtkSizeRequestMode

Return type:

Gtk.SizeRequestMode

Retrieves the request mode of self.

get_widget()[source]
Returns:

a GtkWidget

Return type:

Gtk.Widget or None

Retrieves the GtkWidget using the given GtkLayoutManager.

layout_changed()[source]

Queues a resize on the GtkWidget using self, if any.

This function should be called by subclasses of GtkLayoutManager in response to changes to their layout management policies.

measure(widget, orientation, for_size)[source]
Parameters:

  • widget (Gtk.Widget) – the GtkWidget using self

  • orientation (Gtk.Orientation) – the orientation to measure

  • for_size (int) – Size for the opposite of orientation; for instance, if the orientation is Gtk.Orientation.HORIZONTAL, this is the height of the widget; if the orientation is Gtk.Orientation.VERTICAL, this is the width of the widget. This allows to measure the height for the given width, and the width for the given height. Use -1 if the size is not known

Returns:

minimum:

the minimum size for the given size and orientation

natural:

the natural, or preferred size for the given size and orientation

minimum_baseline:

the baseline position for the minimum size

natural_baseline:

the baseline position for the natural size

Return type:

(minimum: int, natural: int, minimum_baseline: int, natural_baseline: int)

Measures the size of the widget using self, for the given orientation and size.

See the [class`Gtk`.Widget] documentation on layout management for more details.

do_allocate(widget, width, height, baseline) virtual
Parameters:

  • widget (Gtk.Widget) – the GtkWidget using manager

  • width (int) – the new width of the widget

  • height (int) – the new height of the widget

  • baseline (int) – the baseline position of the widget, or -1

Assigns the given width, height, and baseline to a widget, and computes the position and sizes of the children of the widget using the layout management policy of manager.

do_create_layout_child(widget, for_child) virtual
Parameters:

  • widget (Gtk.Widget) – the widget using the manager

  • for_child (Gtk.Widget) – the child of widget

Returns:

a GtkLayoutChild

Return type:

Gtk.LayoutChild

Create a GtkLayoutChild instance for the given for_child widget.

do_get_request_mode(widget) virtual
Parameters:

widget (Gtk.Widget) –

Return type:

Gtk.SizeRequestMode

a virtual function, used to return the preferred request mode for the layout manager; for instance, “width for height” or “height for width”; see GtkSizeRequestMode

do_measure(widget, orientation, for_size) virtual
Parameters:

  • widget (Gtk.Widget) – the GtkWidget using manager

  • orientation (Gtk.Orientation) – the orientation to measure

  • for_size (int) – Size for the opposite of orientation; for instance, if the orientation is Gtk.Orientation.HORIZONTAL, this is the height of the widget; if the orientation is Gtk.Orientation.VERTICAL, this is the width of the widget. This allows to measure the height for the given width, and the width for the given height. Use -1 if the size is not known

Returns:

minimum:

the minimum size for the given size and orientation

natural:

the natural, or preferred size for the given size and orientation

minimum_baseline:

the baseline position for the minimum size

natural_baseline:

the baseline position for the natural size

Return type:

(minimum: int, natural: int, minimum_baseline: int, natural_baseline: int)

Measures the size of the widget using manager, for the given orientation and size.

See the [class`Gtk`.Widget] documentation on layout management for more details.

do_root() virtual

a virtual function, called when the widget using the layout manager is attached to a GtkRoot

do_unroot() virtual

a virtual function, called when the widget using the layout manager is detached from a GtkRoot