A Gtk.Expander.Gtk_Expander allows the user to hide or show its child by clicking on an expander triangle similar to the triangles used in a Gtk.Tree_View.Gtk_Tree_View.
Normally you use an expander as you would use any other descendant of Gtk.Bin.Gtk_Bin; you create the child widget and use Gtk.Container.Add to add it to the expander. When the expander is toggled, it will take care of showing and hiding the child automatically.
# Special Usage
There are situations in which you may prefer to show and hide the expanded widget yourself, such as when you want to actually create the widget at expansion time. In this case, create a Gtk.Expander.Gtk_Expander but do not add a child to it. The expander widget has an Gtk.Expander.Gtk_Expander:expanded property which can be used to monitor its expansion state. You should watch this property with a signal connection as follows:
static void
expander_callback (GObject *object,
GParamSpec *param_spec,
gpointer user_data)
{
GtkExpander *expander;
expander = GTK_EXPANDER (object);
if (gtk_expander_get_expanded (expander))
{
// Show or create widgets
}
else
{
// Hide or destroy widgets
}
}
static void
create_expander (void)
{
GtkWidget *expander = gtk_expander_new_with_mnemonic ("_More Options");
g_signal_connect (expander, "notify::expanded",
G_CALLBACK (expander_callback), NULL);
// ...
}
# GtkExpander as GtkBuildable
The GtkExpander implementation of the GtkBuildable interface supports placing a child in the label position by specifying "label" as the "type" attribute of a <child> element. A normal content child can be specified without specifying a <child> type attribute.
An example of a UI definition fragment with GtkExpander:
<object class="GtkExpander">
<child type="label">
<object class="GtkLabel" id="expander-label"/>
</child>
<child>
<object class="GtkEntry" id="expander-content"/>
</child>
</object>
# CSS nodes
expander
âââ title
â âââ arrow
â â°ââ <label widget>
â°ââ <child>
GtkExpander has three CSS nodes, the main node with the name expander, a subnode with name title and node below it with name arrow. The arrow of an expander that is showing its child gets the :checked pseudoclass added to it.
<screenshot>gtk-expanded</screenshot> <group>Layout containers</group>
function "+"
(Widget : access Gtk_Expander_Record'Class)
return Gtk.Buildable.Gtk_Buildable
function "-"
(Interf : Gtk.Buildable.Gtk_Buildable)
return Gtk_Expander
type Cb_GObject_Void is not null access procedure
(Self : access Glib.Object.GObject_Record'Class);
type Cb_Gtk_Expander_Void is not null access procedure (Self : access Gtk_Expander_Record'Class);
Expanded_Property : constant Glib.Properties.Property_Boolean;
function Get_Expanded
(Expander : not null access Gtk_Expander_Record) return Boolean
Queries a Gtk.Expander.Gtk_Expander and returns its current state. Returns True if the child widget is revealed. See Gtk.Expander.Set_Expanded. Since: gtk+ 2.4
the current state of the expander
function Get_Label
(Expander : not null access Gtk_Expander_Record) return UTF8_String
Fetches the text from a label widget including any embedded underlines indicating mnemonics and Pango markup, as set by Gtk.Expander.Set_Label. If the label text has not been set the return value will be null. This will be the case if you create an empty button with gtk_button_new to use as a container. Note that this function behaved differently in versions prior to 2.14 and used to return the label text stripped of embedded underlines indicating mnemonics and Pango markup. This problem can be avoided by fetching the label text directly from the label widget. Since: gtk+ 2.4
The text of the label widget. This string is owned by the widget and must not be modified or freed.
function Get_Label_Fill
(Expander : not null access Gtk_Expander_Record) return Boolean
Returns whether the label widget will fill all available horizontal space allocated to Expander. Since: gtk+ 2.22
True if the label widget will fill all available horizontal space
function Get_Label_Widget
(Expander : not null access Gtk_Expander_Record)
return Gtk.Widget.Gtk_Widget
Retrieves the label widget for the frame. See Gtk.Expander.Set_Label_Widget. Since: gtk+ 2.4
the label widget, or null if there is none
function Get_Resize_Toplevel
(Expander : not null access Gtk_Expander_Record) return Boolean
Returns whether the expander will resize the toplevel widget containing the expander upon resizing and collpasing. Since: gtk+ 3.2
the "resize toplevel" setting.
function Get_Spacing
(Expander : not null access Gtk_Expander_Record) return Glib.Gint
Gets the value set by Gtk.Expander.Set_Spacing. Since: gtk+ 2.4 Deprecated since 3.20, 1
spacing between the expander and child
function Get_Type return Glib.GType
function Get_Use_Markup
(Expander : not null access Gtk_Expander_Record) return Boolean
Returns whether the label's text is interpreted as marked up with the [Pango text markup language][PangoMarkupFormat]. See Gtk.Expander.Set_Use_Markup. Since: gtk+ 2.4
True if the label's text will be parsed for markup
function Get_Use_Underline
(Expander : not null access Gtk_Expander_Record) return Boolean
Returns whether an embedded underline in the expander label indicates a mnemonic. See Gtk.Expander.Set_Use_Underline. Since: gtk+ 2.4
True if an embedded underline in the expander label indicates the mnemonic accelerator keys
type Gtk_Expander is access all Gtk_Expander_Record'Class;
function Gtk_Expander_New (Label : UTF8_String := "") return Gtk_Expander
Creates a new expander using Label as the text of the label. Since: gtk+ 2.4
the text of the label
function Gtk_Expander_New_With_Mnemonic
(Label : UTF8_String := "") return Gtk_Expander
Creates a new expander using Label as the text of the label. If characters in Label are preceded by an underscore, they are underlined. If you need a literal underscore character in a label, use "__" (two underscores). The first underlined character represents a keyboard accelerator called a mnemonic. Pressing Alt and that key activates the button. Since: gtk+ 2.4
the text of the label with an underscore in front of the mnemonic character
type Gtk_Expander_Record is new Gtk_Bin_Record with null record;
procedure Gtk_New
(Expander : out Gtk_Expander;
Label : UTF8_String := "")
Creates a new expander using Label as the text of the label. Since: gtk+ 2.4 Initialize does nothing if the object was already created with another call to Initialize* or G_New.
the text of the label
procedure Gtk_New_With_Mnemonic
(Expander : out Gtk_Expander;
Label : UTF8_String := "")
Creates a new expander using Label as the text of the label. If characters in Label are preceded by an underscore, they are underlined. If you need a literal underscore character in a label, use "__" (two underscores). The first underlined character represents a keyboard accelerator called a mnemonic. Pressing Alt and that key activates the button. Since: gtk+ 2.4 Initialize_With_Mnemonic does nothing if the object was already created with another call to Initialize* or G_New.
the text of the label with an underscore in front of the mnemonic character
package Implements_Gtk_Buildable is new Glib.Types.Implements
(Gtk.Buildable.Gtk_Buildable, Gtk_Expander_Record, Gtk_Expander);
procedure Initialize
(Expander : not null access Gtk_Expander_Record'Class;
Label : UTF8_String := "")
Creates a new expander using Label as the text of the label. Since: gtk+ 2.4 Initialize does nothing if the object was already created with another call to Initialize* or G_New.
the text of the label
procedure Initialize_With_Mnemonic
(Expander : not null access Gtk_Expander_Record'Class;
Label : UTF8_String := "")
Creates a new expander using Label as the text of the label. If characters in Label are preceded by an underscore, they are underlined. If you need a literal underscore character in a label, use "__" (two underscores). The first underlined character represents a keyboard accelerator called a mnemonic. Pressing Alt and that key activates the button. Since: gtk+ 2.4 Initialize_With_Mnemonic does nothing if the object was already created with another call to Initialize* or G_New.
the text of the label with an underscore in front of the mnemonic character
Label_Fill_Property : constant Glib.Properties.Property_Boolean;
Whether the label widget should fill all available horizontal space.
Note that this property is ignored since 3.20.
Label_Property : constant Glib.Properties.Property_String;
Label_Widget_Property : constant Glib.Properties.Property_Object;
Type: Gtk.Widget.Gtk_Widget
procedure On_Activate
(Self : not null access Gtk_Expander_Record;
Call : Cb_GObject_Void;
Slot : not null access Glib.Object.GObject_Record'Class;
After : Boolean := False)
procedure On_Activate
(Self : not null access Gtk_Expander_Record;
Call : Cb_Gtk_Expander_Void;
After : Boolean := False)
Resize_Toplevel_Property : constant Glib.Properties.Property_Boolean;
When this property is True, the expander will resize the toplevel widget containing the expander upon expanding and collapsing.
procedure Set_Expanded
(Expander : not null access Gtk_Expander_Record;
Expanded : Boolean)
Sets the state of the expander. Set to True, if you want the child widget to be revealed, and False if you want the child widget to be hidden. Since: gtk+ 2.4
whether the child widget is revealed
procedure Set_Label
(Expander : not null access Gtk_Expander_Record;
Label : UTF8_String := "")
Sets the text of the label of the expander to Label. This will also clear any previously set labels. Since: gtk+ 2.4
a string
procedure Set_Label_Fill
(Expander : not null access Gtk_Expander_Record;
Label_Fill : Boolean)
Sets whether the label widget should fill all available horizontal space allocated to Expander. Note that this function has no effect since 3.20. Since: gtk+ 2.22
True if the label should should fill all available horizontal space
procedure Set_Label_Widget
(Expander : not null access Gtk_Expander_Record;
Label_Widget : access Gtk.Widget.Gtk_Widget_Record'Class)
Set the label widget for the expander. This is the widget that will appear embedded alongside the expander arrow. Since: gtk+ 2.4
the new label widget
procedure Set_Resize_Toplevel
(Expander : not null access Gtk_Expander_Record;
Resize_Toplevel : Boolean)
Sets whether the expander will resize the toplevel widget containing the expander upon resizing and collpasing. Since: gtk+ 3.2
whether to resize the toplevel
procedure Set_Spacing
(Expander : not null access Gtk_Expander_Record;
Spacing : Glib.Gint)
Sets the spacing field of Expander, which is the number of pixels to place between expander and the child. Since: gtk+ 2.4 Deprecated since 3.20, 1
distance between the expander and child in pixels
procedure Set_Use_Markup
(Expander : not null access Gtk_Expander_Record;
Use_Markup : Boolean)
Sets whether the text of the label contains markup in [Pango's text markup language][PangoMarkupFormat]. See Gtk.Label.Set_Markup. Since: gtk+ 2.4
True if the label's text should be parsed for markup
procedure Set_Use_Underline
(Expander : not null access Gtk_Expander_Record;
Use_Underline : Boolean)
If true, an underline in the text of the expander label indicates the next character should be used for the mnemonic accelerator key. Since: gtk+ 2.4
True if underlines in the text indicate mnemonics
Signal_Activate : constant Glib.Signal_Name := "activate";
Spacing_Property : constant Glib.Properties.Property_Int;
Space to put between the label and the child when the expander is expanded.
Use_Markup_Property : constant Glib.Properties.Property_Boolean;
Use_Underline_Property : constant Glib.Properties.Property_Boolean;