Class

GtkLayoutManager

Description [src]

abstract class Gtk.LayoutManager : GObject.Object
{
  /* No available fields */
}

Layout managers are delegate classes that handle the preferred size and the allocation 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 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 GtkLayoutChild 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 gtk_layout_manager_get_layout_child() method; a GtkLayoutManager controls the creation of its GtkLayoutChild instances by overriding the GtkLayoutManagerClass.create_layout_child() virtual function. The typical implementation should look like:

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 GtkLayoutChild:layout-manager and GtkLayoutChild: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 gtk_layout_manager_get_layout_child() every time it needs to query the layout properties; each GtkLayoutChild instance should call gtk_layout_manager_layout_changed() every time a property is updated, in order to queue a new size measuring and allocation.

Hierarchy

Ancestors

GObject

Descendants

Instance methods

gtk_layout_manager_allocate

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.

gtk_layout_manager_get_layout_child

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

gtk_layout_manager_get_request_mode

Retrieves the request mode of manager.

gtk_layout_manager_get_widget

Retrieves the GtkWidget using the given GtkLayoutManager.

gtk_layout_manager_layout_changed

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

gtk_layout_manager_measure

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

Methods inherited from GObject (43)

Please see GObject for a full list of methods.

Signals

Signals inherited from GObject (1)

GObject::notify

The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.

Class structure

struct GtkLayoutManagerClass {
  GtkSizeRequestMode (* get_request_mode) (
    GtkLayoutManager* manager,
    GtkWidget* widget
  );
  void (* measure) (
    GtkLayoutManager* manager,
    GtkWidget* widget,
    GtkOrientation orientation,
    int for_size,
    int* minimum,
    int* natural,
    int* minimum_baseline,
    int* natural_baseline
  );
  void (* allocate) (
    GtkLayoutManager* manager,
    GtkWidget* widget,
    int width,
    int height,
    int baseline
  );
  GType layout_child_type;
  GtkLayoutChild* (* create_layout_child) (
    GtkLayoutManager* manager,
    GtkWidget* widget,
    GtkWidget* for_child
  );
  void (* root) (
    GtkLayoutManager* manager
  );
  void (* unroot) (
    GtkLayoutManager* manager
  );
  
}

The GtkLayoutManagerClass structure contains only private data, and should only be accessed through the provided API, or when subclassing GtkLayoutManager.

Class members

get_request_mode: GtkSizeRequestMode (* get_request_mode) ( GtkLayoutManager* manager, GtkWidget* widget ): 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.
measure: void (* measure) ( GtkLayoutManager* manager, GtkWidget* widget, GtkOrientation orientation, int for_size, int* minimum, int* natural, int* minimum_baseline, int* natural_baseline ): A virtual function, used to measure the minimum and preferred sizes of the widget using the layout manager for a given orientation.
allocate: void (* allocate) ( GtkLayoutManager* manager, GtkWidget* widget, int width, int height, int baseline ): A virtual function, used to allocate the size of the widget using the layout manager.
layout_child_type: GType: The type of GtkLayoutChild used by this layout manager.
create_layout_child: GtkLayoutChild* (* create_layout_child) ( GtkLayoutManager* manager, GtkWidget* widget, GtkWidget* for_child ): A virtual function, used to create a GtkLayoutChild meta object for the layout properties.
root: void (* root) ( GtkLayoutManager* manager ): A virtual function, called when the widget using the layout manager is attached to a GtkRoot.
unroot: void (* unroot) ( GtkLayoutManager* manager ): A virtual function, called when the widget using the layout manager is detached from a GtkRoot.