Gtk.Size_Group.Gtk_Size_Group provides a mechanism for grouping a number of widgets together so they all request the same amount of space. This is typically useful when you want a column of widgets to have the same size, but you can't use a Gtk.Grid.Gtk_Grid widget.
In detail, the size requested for each widget in a Gtk.Size_Group.Gtk_Size_Group is the maximum of the sizes that would have been requested for each widget in the size group if they were not in the size group. The mode of the size group (see Gtk.Size_Group.Set_Mode) determines whether this applies to the horizontal size, the vertical size, or both sizes.
Note that size groups only affect the amount of space requested, not the size that the widgets finally receive. If you want the widgets in a Gtk.Size_Group.Gtk_Size_Group to actually be the same size, you need to pack them in such a way that they get the size they request and not more. For example, if you are packing your widgets into a table, you would not include the Gtk.Enums.Fill flag.
Gtk.Size_Group.Gtk_Size_Group objects are referenced by each widget in the size group, so once you have added all widgets to a Gtk.Size_Group.Gtk_Size_Group, you can drop the initial reference to the size group with g_object_unref. If the widgets in the size group are subsequently destroyed, then they will be removed from the size group and drop their references on the size group; when all widgets have been removed, the size group will be freed.
Widgets can be part of multiple size groups; GTK+ will compute the horizontal size of a widget from the horizontal requisition of all widgets that can be reached from the widget by a chain of size groups of type Gtk.Size_Group.Horizontal or Gtk.Size_Group.Both, and the vertical size from the vertical requisition of all widgets that can be reached from the widget by a chain of size groups of type Gtk.Size_Group.Vertical or Gtk.Size_Group.Both.
Note that only non-contextual sizes of every widget are ever consulted by size groups (since size groups have no knowledge of what size a widget will be allocated in one dimension, it cannot derive how much height a widget will receive for a given width). When grouping widgets that trade height for width in mode Gtk.Size_Group.Vertical or Gtk.Size_Group.Both: the height for the minimum width will be the requested height for all widgets in the group. The same is of course true when horizontally grouping width for height widgets.
Widgets that trade height-for-width should set a reasonably large minimum width by way of Gtk.Label.Gtk_Label:width-chars for instance. Widgets with static sizes as well as widgets that grow (such as ellipsizing text) need no such considerations.
# GtkSizeGroup as GtkBuildable
Size groups can be specified in a UI definition by placing an <object> element with class="GtkSizeGroup" somewhere in the UI definition. The widgets that belong to the size group are specified by a <widgets> element that may contain multiple <widget> elements, one for each member of the size group. The "name" attribute gives the id of the widget.
An example of a UI definition fragment with GtkSizeGroup:
<object class="GtkSizeGroup">
<property name="mode">GTK_SIZE_GROUP_HORIZONTAL</property>
<widgets>
<widget name="radio1"/>
<widget name="radio2"/>
</widgets>
</object>
<testgtk>create_size_groups.adb</testgtk>
function "+"
(Widget : access Gtk_Size_Group_Record'Class)
return Gtk.Buildable.Gtk_Buildable
function "-"
(Interf : Gtk.Buildable.Gtk_Buildable)
return Gtk_Size_Group
procedure Add_Widget
(Size_Group : not null access Gtk_Size_Group_Record;
Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class)
Adds a widget to a Gtk.Size_Group.Gtk_Size_Group. In the future, the requisition of the widget will be determined as the maximum of its requisition and the requisition of the other widgets in the size group. Whether this applies horizontally, vertically, or in both directions depends on the mode of the size group. See Gtk.Size_Group.Set_Mode. When the widget is destroyed or no longer referenced elsewhere, it will be removed from the size group.
the Gtk.Widget.Gtk_Widget to add
function Get_Ignore_Hidden
(Size_Group : not null access Gtk_Size_Group_Record) return Boolean
Returns if invisible widgets are ignored when calculating the size. Since: gtk+ 2.8 Deprecated since 3.22, 1
True if invisible widgets are ignored.
function Get_Mode
(Size_Group : not null access Gtk_Size_Group_Record)
return Size_Group_Mode
Gets the current mode of the size group. See Gtk.Size_Group.Set_Mode.
the current mode of the size group.
function Get_Type return Glib.GType
function Get_Widgets
(Size_Group : not null access Gtk_Size_Group_Record)
return Gtk.Widget.Widget_SList.GSlist
Returns the list of widgets associated with Size_Group. Since: gtk+ 2.10
procedure Gtk_New
(Size_Group : out Gtk_Size_Group;
Mode : Size_Group_Mode := Both)
Create a new Gtk.Size_Group.Gtk_Size_Group. Initialize does nothing if the object was already created with another call to Initialize* or G_New.
the mode for the new size group.
type Gtk_Size_Group is access all Gtk_Size_Group_Record'Class;
function Gtk_Size_Group_New
(Mode : Size_Group_Mode := Both) return Gtk_Size_Group
Create a new Gtk.Size_Group.Gtk_Size_Group.
the mode for the new size group.
type Gtk_Size_Group_Record is new GObject_Record with null record;
Ignore_Hidden_Property : constant Glib.Properties.Property_Boolean;
If True, unmapped widgets are ignored when determining the size of the group.
package Implements_Gtk_Buildable is new Glib.Types.Implements
(Gtk.Buildable.Gtk_Buildable, Gtk_Size_Group_Record, Gtk_Size_Group);
procedure Initialize
(Size_Group : not null access Gtk_Size_Group_Record'Class;
Mode : Size_Group_Mode := Both)
Create a new Gtk.Size_Group.Gtk_Size_Group. Initialize does nothing if the object was already created with another call to Initialize* or G_New.
the mode for the new size group.
Mode_Property : constant Gtk.Size_Group.Property_Size_Group_Mode;
Type: Size_Group_Mode
type Property_Size_Group_Mode is new Size_Group_Mode_Properties.Property;
procedure Remove_Widget
(Size_Group : not null access Gtk_Size_Group_Record;
Widget : not null access Gtk.Widget.Gtk_Widget_Record'Class)
Removes a widget from a Gtk.Size_Group.Gtk_Size_Group.
the Gtk.Widget.Gtk_Widget to remove
procedure Set_Ignore_Hidden
(Size_Group : not null access Gtk_Size_Group_Record;
Ignore_Hidden : Boolean)
Sets whether unmapped widgets should be ignored when calculating the size. Since: gtk+ 2.8 Deprecated since 3.22, 1
whether unmapped widgets should be ignored when calculating the size
procedure Set_Mode
(Size_Group : not null access Gtk_Size_Group_Record;
Mode : Size_Group_Mode)
Sets the Gtk.Size_Group.Size_Group_Mode of the size group. The mode of the size group determines whether the widgets in the size group should all have the same horizontal requisition (Gtk.Size_Group.Horizontal) all have the same vertical requisition (Gtk.Size_Group.Vertical), or should all have the same requisition in both directions (Gtk.Size_Group.Both).
the mode to set for the size group.
type Size_Group_Mode is (
None,
Horizontal,
Vertical,
Both);
The mode of the size group determines the directions in which the size group affects the requested sizes of its component widgets.
package Size_Group_Mode_Properties is
new Generic_Internal_Discrete_Property (Size_Group_Mode);