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# Package Gtk.Container

Base class for widgets that have children.

When writing your own container widgets, you need to fully handle the size_allocate event, by also resizing all the children (based on their size requisition). The size_allocate event will always be sent to the parent when a child calls Gtk.Widget.Queue_Resize.

- Gtk.Container Widget Hierarchy
- Gtk.Container Signals
- Gtk.Container Types
- Gtk.Container Subprograms

## Widget Hierarchy

    GObject                       (see section Package Glib.Object)
    Gtk_Object                    (see section Package Gtk.Object)
       \___ Gtk_Widget            (see section Package Gtk.Widget)
          \___ Gtk_Container      (see section Package Gtk.Container)

## Signals

- "add" procedure Handler (Container : access Gtk_Container_Record'Class;
  Widget : access Gtk_Widget_Record'Class);
  A new widget is added to the container
- "check_resize" procedure Handler (Container : access Gtk_Container_Record'Class);
  Called every time the Container needs resizing. Upon receiving this signal, Container should check whether it needs to be resized, and if it does should queue a resize request.
- "focus" procedure Handler (Container : access Gtk_Container_Record'Class;
  Direction : Gtk_Direction_Type);
  Moves the current selection to a new widget.
- "remove" procedure Handler (Container : access Gtk_Container_Record'Class;
  Widget : access Gtk_Widget_Record'Class);
  A widget is removed from the container
- "set-focus-child" procedure Handler (Container : access Gtk_Container_Record'Class;
  Widget : access Gtk_Widget_Record'Class);
  Emitted when a new widget gains the focus.

## Types

    type Forall_Function is access procedure
        (Item : access Gtk.Widget.Gtk_Widget_Record'Class);

| Function that can be call for each child of a container. This is called automatically by the Forall subprogram below.

## Subprograms

    function Get_Type              return Glib.GType;

| Return the internal value associated with a Gtk_Container.

    procedure Set_Border_Width
      (Container          : access Gtk_Container_Record;
       Border_Width       :        Guint);

| Modify the size of the frame that surrounds the widget. The exact visual impact depends on the specific widget class.

    function Get_Border_Width
      (Container          : access Gtk_Container_Record)
       return Guint;

| Return the size of the frame that surrounds the widget.

    procedure Add
      (Container          : access Gtk_Container_Record;
       Widget             : access Gtk.Widget.Gtk_Widget_Record'Class);

| Add a new child to the container. Note that some containers can have only one child. Nothing is done if there is already a child. This basically sends the "add" signal (see below)

    procedure Remove
      (Container          : access Gtk_Container_Record;
       Widget             : access Gtk.Widget.Gtk_Widget_Record'Class);

Removes Widget from Container. Widget must be inside Container.
Note that Container will own a reference to Widget, and that this may be the last reference held; so removing a widget from its container can destroy that widget. If you want to use Widget again, you need to add a reference to it while it's not inside a container, using Glib.Object.Ref. If you don't want to use Widget again it's usually more efficient to simply destroy it directly using Gtk.Widget.Destroy since this will remove it from the container and help break any circular reference count cycles.

    procedure Set_Resize_Mode
      (Container          : access Gtk_Container_Record;
       Resize_Mode        :        Gtk.Enums.Gtk_Resize_Mode);

| Change the resizing behavior for the Container. The default value is Resize_Parent.

    function Get_Resize_Mode
      (Container          : access Gtk_Container_Record)
       return Gtk.Enums.Gtk_Resize_Mode;

| Return the resizing behavior for the Container.

    function Get_Children
      (Container          : access Gtk_Container_Record)
       return Gtk.Widget.Widget_List.Glist;

| Return a list of all the children of the container. The caller must free the returned list.

    function Children
      (Container          : access Gtk_Container_Record)
       return Gtk.Widget.Widget_List.Glist;

| This function is deprecated.

    procedure Propagate_Expose
      (Container          : access Gtk_Container_Record;
       Child              : access Gtk.Widget.Gtk_Widget_Record'Class;
       Event              :        Gdk.Event.Gdk_Event_Expose);

When a container receives an expose event, it must send synthetic
expose events to all children that don't have their own Gdk_Window. This function provides a convenient way of doing this. A container, when it receives an expose event, Propagate_Expose once for each child, passing in the event the container received.

Propagate_Expose takes care of deciding whether an expose event needs to be sent to the child, intersecting the event's area with the child area, and sending the event.

In most cases, a container can simply either simply inherit the expose implementation from Gtk_Container, or, do some drawing and then chain to the expose implementation from Gtk_Container.

    procedure Set_Focus_Chain
      (Container          : access Gtk_Container_Record;
       Focusable_Widgets  :        Gtk.Widget.Widget_List.Glist);

| Set the chain of widgets that can take the focus for a given Container. The list should be freed by the user

    procedure Unset_Focus_Chain
      (Container          : access Gtk_Container_Record);

| Unset the focus chain.

### Foreach functions

    procedure Forall
      (Container          : access Gtk_Container_Record;
       Func               :        Forall_Function);

| Execute Func for each of the children of Container. See also the generic package Forall_Pkg if you want to pass some extra data to Func.

### Widget-level methods

    procedure Set_Reallocate_Redraws
      (Container          : access Gtk_Container_Record;
       Needs_Redraws      :        Boolean := False);

| Set the "needs_redraws" field. If Needs_Redraws is True, then a "draw" signal is emitted for the Container whenever one is emitted for a child.

    procedure Set_Focus_Vadjustment
      (Container          : access Gtk_Container_Record;
       Adjustment         :        Gtk.Adjustment.Gtk_Adjustment);

| Set the focus to the vertical adjustment. Adjustment should have been created and displayed at some other place in your application. Container will make sure that Adjustment always matches the range for the focus widget's position (y .. y + height).

    procedure Set_Focus_Hadjustment
      (Container          : access Gtk_Container_Record;
       Adjustment         :        Gtk.Adjustment.Gtk_Adjustment);

| Set the focus to the horizontal adjustment. Adjustment should have been created and displayed at some other place in your application. Container will make sure that Adjustment always matches the range for the focus widget's position (x .. x + width).

    function Child_Type
      (Container          : access Gtk_Container_Record)
       return Gtk.Gtk_Type;

| Return the type of the children in Container. If Container can contain any type of widget, Gtk_Type_None is returned.

    procedure Resize_Children
      (Container          : access Gtk_Container_Record);

| The container hasn't changed size but one of its children queued a resize request. Which means that the allocation is not sufficient for the requisition of some child. Run through the list of widgets and reallocate their size appropriately.

### Signals emission

    procedure Check_Resize
      (Container          : access Gtk_Container_Record);

| Emit the "check_resize" signal

    procedure Set_Focus_Child
      (Container          : access Gtk_Container_Record;
       Child              : access Gtk.Widget.Gtk_Widget_Record'Class);

| Emit a "set_focus_child" signal.

    function Get_Focus_Child
      (Container          : access Gtk_Container_Record)
       return Gtk.Widget.Gtk_Widget;

| Return the child that currently has the keyboard focus. Note that null can be returned.

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