class Gtk::Widget

Overview

The base class for all widgets.

It manages the widget lifecycle, layout, states and style.

Height-for-width Geometry Management

GTK uses a height-for-width (and width-for-height) geometry management system. Height-for-width means that a widget can change how much vertical space it needs, depending on the amount of horizontal space that it is given (and similar for width-for-height). The most common example is a label that reflows to fill up the available width, wraps to fewer lines, and therefore needs less height.

Height-for-width geometry management is implemented in GTK by way of two virtual methods:

There are some important things to keep in mind when implementing height-for-width and when using it in widget implementations.

If you implement a direct Gtk::Widget subclass that supports height-for-width or width-for-height geometry management for itself or its child widgets, the Gtk::Widget#request_mode virtual function must be implemented as well and return the widget's preferred request mode. The default implementation of this virtual function returns %GTK_SIZE_REQUEST_CONSTANT_SIZE, which means that the widget will only ever get -1 passed as the for_size value to its Gtk::Widget#measure implementation.

The geometry management system will query a widget hierarchy in only one orientation at a time. When widgets are initially queried for their minimum sizes it is generally done in two initial passes in the Gtk::SizeRequestMode chosen by the toplevel.

For example, when queried in the normal %GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH mode:

First, the default minimum and natural width for each widget in the interface will be computed using Gtk::Widget#measure with an orientation of %GTK_ORIENTATION_HORIZONTAL and a for_size of -1. Because the preferred widths for each widget depend on the preferred widths of their children, this information propagates up the hierarchy, and finally a minimum and natural width is determined for the entire toplevel. Next, the toplevel will use the minimum width to query for the minimum height contextual to that width using Gtk::Widget#measure with an orientation of %GTK_ORIENTATION_VERTICAL and a for_size of the just computed width. This will also be a highly recursive operation. The minimum height for the minimum width is normally used to set the minimum size constraint on the toplevel.

After the toplevel window has initially requested its size in both dimensions it can go on to allocate itself a reasonable size (or a size previously specified with Gtk::Window#default_size=). During the recursive allocation process it’s important to note that request cycles will be recursively executed while widgets allocate their children. Each widget, once allocated a size, will go on to first share the space in one orientation among its children and then request each child's height for its target allocated width or its width for allocated height, depending. In this way a widget will typically be requested its size a number of times before actually being allocated a size. The size a widget is finally allocated can of course differ from the size it has requested. For this reason, Gtk::Widget caches a small number of results to avoid re-querying for the same sizes in one allocation cycle.

If a widget does move content around to intelligently use up the allocated size then it must support the request in both Gtk::SizeRequestModes even if the widget in question only trades sizes in a single orientation.

For instance, a Gtk::Label that does height-for-width word wrapping will not expect to have Gtk::Widget#measure with an orientation of %GTK_ORIENTATION_VERTICAL called because that call is specific to a width-for-height request. In this case the label must return the height required for its own minimum possible width. By following this rule any widget that handles height-for-width or width-for-height requests will always be allocated at least enough space to fit its own content.

Here are some examples of how a %GTK_SIZE_REQUEST_HEIGHT_FOR_WIDTH widget generally deals with width-for-height requests:

WARNING ⚠️ The following code is in c ⚠️

static void
foo_widget_measure (Gtk::Widget      *widget,
                    Gtk::Orientation  orientation,
                    int             for_size,
                    int            *minimum_size,
                    int            *natural_size,
                    int            *minimum_baseline,
                    int            *natural_baseline)
{
  if (orientation == GTK_ORIENTATION_HORIZONTAL)
    {
      // Calculate minimum and natural width
    }
  else // VERTICAL
    {
      if (i_am_in_height_for_width_mode)
        {
          int min_width, dummy;

          // First, get the minimum width of our widget
          GTK_WIDGET_GET_CLASS (widget)->measure (widget, GTK_ORIENTATION_HORIZONTAL, -1,
                                                  &min_width, &dummy, &dummy, &dummy);

          // Now use the minimum width to retrieve the minimum and natural height to display
          // that width.
          GTK_WIDGET_GET_CLASS (widget)->measure (widget, GTK_ORIENTATION_VERTICAL, min_width,
                                                  minimum_size, natural_size, &dummy, &dummy);
        }
      else
        {
          // ... some widgets do both.
        }
    }
}

Often a widget needs to get its own request during size request or allocation. For example, when computing height it may need to also compute width. Or when deciding how to use an allocation, the widget may need to know its natural size. In these cases, the widget should be careful to call its virtual methods directly, like in the code example above.

It will not work to use the wrapper function Gtk::Widget#measure inside your own Gtk::Widget#size_allocate implementation. These return a request adjusted by Gtk::SizeGroup, the widget's align and expand flags, as well as its CSS style.

If a widget used the wrappers inside its virtual method implementations, then the adjustments (such as widget margins) would be applied twice. GTK therefore does not allow this and will warn if you try to do it.

Of course if you are getting the size request for another widget, such as a child widget, you must use Gtk::Widget#measure; otherwise, you would not properly consider widget margins, Gtk::SizeGroup, and so forth.

GTK also supports baseline vertical alignment of widgets. This means that widgets are positioned such that the typographical baseline of widgets in the same row are aligned. This happens if a widget supports baselines, has a vertical alignment using baselines, and is inside a widget that supports baselines and has a natural “row” that it aligns to the baseline, or a baseline assigned to it by the grandparent.

Baseline alignment support for a widget is also done by the Gtk::Widget#measure virtual function. It allows you to report both a minimum and natural size.

If a widget ends up baseline aligned it will be allocated all the space in the parent as if it was %GTK_ALIGN_FILL, but the selected baseline can be found via Gtk::Widget#baseline. If the baseline has a value other than -1 you need to align the widget such that the baseline appears at the position.

Gtk::Widget as Gtk::Buildable

The Gtk::Widget implementation of the Gtk::Buildable interface supports various custom elements to specify additional aspects of widgets that are not directly expressed as properties.

If the widget uses a Gtk::LayoutManager, Gtk::Widget supports a custom <layout> element, used to define layout properties:

WARNING ⚠️ The following code is in xml ⚠️

<object class="Gtk::Grid" id="my_grid">
  <child>
    <object class="Gtk::Label" id="label1">
      <property name="label">Description</property>
      <layout>
        <property name="column">0</property>
        <property name="row">0</property>
        <property name="row-span">1</property>
        <property name="column-span">1</property>
      </layout>
    </object>
  </child>
  <child>
    <object class="Gtk::Entry" id="description_entry">
      <layout>
        <property name="column">1</property>
        <property name="row">0</property>
        <property name="row-span">1</property>
        <property name="column-span">1</property>
      </layout>
    </object>
  </child>
</object>

Gtk::Widget allows style information such as style classes to be associated with widgets, using the custom <style> element:

WARNING ⚠️ The following code is in xml ⚠️

<object class="Gtk::Button" id="button1">
  <style>
    <class name="my-special-button-class"/>
    <class name="dark-button"/>
  </style>
</object>

Gtk::Widget allows defining accessibility information, such as properties, relations, and states, using the custom <accessibility> element:

WARNING ⚠️ The following code is in xml ⚠️

<object class="Gtk::Button" id="button1">
  <accessibility>
    <property name="label">Download</property>
    <relation name="labelled-by">label1</relation>
  </accessibility>
</object>

Building composite widgets from template XML

Gtk::Widget exposes some facilities to automate the procedure of creating composite widgets using "templates".

To create composite widgets with Gtk::Builder XML, one must associate the interface description with the widget class at class initialization time using Gtk::WidgetClass#template=.

The interface description semantics expected in composite template descriptions is slightly different from regular Gtk::Builder XML.

Unlike regular interface descriptions, Gtk::WidgetClass#template= will expect a <template> tag as a direct child of the toplevel <interface> tag. The <template> tag must specify the “class” attribute which must be the type name of the widget. Optionally, the “parent” attribute may be specified to specify the direct parent type of the widget type; this is ignored by Gtk::Builder but can be used by UI design tools to introspect what kind of properties and internal children exist for a given type when the actual type does not exist.

The XML which is contained inside the <template> tag behaves as if it were added to the <object> tag defining the widget itself. You may set properties on a widget by inserting <property> tags into the <template> tag, and also add <child> tags to add children and extend a widget in the normal way you would with <object> tags.

Additionally, <object> tags can also be added before and after the initial <template> tag in the normal way, allowing one to define auxiliary objects which might be referenced by other widgets declared as children of the <template> tag.

Since, unlike the <object> tag, the <template> tag does not contain an “id” attribute, if you need to refer to the instance of the object itself that the template will create, simply refer to the template class name in an applicable element content.

Here is an example of a template definition, which includes an example of this in the <signal> tag:

WARNING ⚠️ The following code is in xml ⚠️

<interface>
  <template class="FooWidget" parent="Gtk::Box">
    <property name="orientation">horizontal</property>
    <property name="spacing">4</property>
    <child>
      <object class="Gtk::Button" id="hello_button">
        <property name="label">Hello World</property>
        <signal name="clicked" handler="hello_button_clicked" object="FooWidget" swapped="yes"/>
      </object>
    </child>
    <child>
      <object class="Gtk::Button" id="goodbye_button">
        <property name="label">Goodbye World</property>
      </object>
    </child>
  </template>
</interface>

Typically, you'll place the template fragment into a file that is bundled with your project, using GResource. In order to load the template, you need to call Gtk::WidgetClass#template_from_resource= from the class initialization of your Gtk::Widget type:

WARNING ⚠️ The following code is in c ⚠️

static void
foo_widget_class_init (FooWidgetClass *klass)
{
  // ...

  gtk_widget_class_set_template_from_resource (GTK_WIDGET_CLASS (klass),
                                               "/com/example/ui/foowidget.ui");
}

You will also need to call Gtk::Widget#init_template from the instance initialization function:

WARNING ⚠️ The following code is in c ⚠️

static void
foo_widget_init (FooWidget *self)
{
  gtk_widget_init_template (GTK_WIDGET (self));

  // Initialize the rest of the widget...
}

as well as calling Gtk::Widget#dispose_template from the dispose function:

WARNING ⚠️ The following code is in c ⚠️

static void
foo_widget_dispose (GObject *gobject)
{
  FooWidget *self = FOO_WIDGET (gobject);

  // Dispose objects for which you have a reference...

  // Clear the template children for this widget type
  gtk_widget_dispose_template (GTK_WIDGET (self), FOO_TYPE_WIDGET);

  G_OBJECT_CLASS (foo_widget_parent_class)->dispose (gobject);
}

You can access widgets defined in the template using the Gtk::Widget#template_child function, but you will typically declare a pointer in the instance private data structure of your type using the same name as the widget in the template definition, and call Gtk::WidgetClass#bind_template_child_full (or one of its wrapper macros Gtk::widget_class_bind_template_child and Gtk::widget_class_bind_template_child_private) with that name, e.g.

WARNING ⚠️ The following code is in c ⚠️

typedef struct {
  Gtk::Widget *hello_button;
  Gtk::Widget *goodbye_button;
} FooWidgetPrivate;

G_DEFINE_TYPE_WITH_PRIVATE (FooWidget, foo_widget, GTK_TYPE_BOX)

static void
foo_widget_dispose (GObject *gobject)
{
  gtk_widget_dispose_template (GTK_WIDGET (gobject), FOO_TYPE_WIDGET);

  G_OBJECT_CLASS (foo_widget_parent_class)->dispose (gobject);
}

static void
foo_widget_class_init (FooWidgetClass *klass)
{
  // ...
  G_OBJECT_CLASS (klass)->dispose = foo_widget_dispose;

  gtk_widget_class_set_template_from_resource (GTK_WIDGET_CLASS (klass),
                                               "/com/example/ui/foowidget.ui");
  gtk_widget_class_bind_template_child_private (GTK_WIDGET_CLASS (klass),
                                                FooWidget, hello_button);
  gtk_widget_class_bind_template_child_private (GTK_WIDGET_CLASS (klass),
                                                FooWidget, goodbye_button);
}

static void
foo_widget_init (FooWidget *widget)
{
  gtk_widget_init_template (GTK_WIDGET (widget));
}

You can also use Gtk::WidgetClass#bind_template_callback_full (or is wrapper macro Gtk::widget_class_bind_template_callback) to connect a signal callback defined in the template with a function visible in the scope of the class, e.g.

WARNING ⚠️ The following code is in c ⚠️

// the signal handler has the instance and user data swapped
// because of the swapped="yes" attribute in the template XML
static void
hello_button_clicked (FooWidget *self,
                      Gtk::Button *button)
{
  g_print ("Hello, world!\n");
}

static void
foo_widget_class_init (FooWidgetClass *klass)
{
  // ...
  gtk_widget_class_set_template_from_resource (GTK_WIDGET_CLASS (klass),
                                               "/com/example/ui/foowidget.ui");
  gtk_widget_class_bind_template_callback (GTK_WIDGET_CLASS (klass), hello_button_clicked);
}

Included Modules

Direct Known Subclasses

Defined in:

lib/gi-crystal/src/auto/gtk-4.0/widget.cr
lib/gtk4/src/bindings/gtk/widget.cr

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from module Gtk::ConstraintTarget

to_unsafe to_unsafe

Constructor methods inherited from module Gtk::ConstraintTarget

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::ConstraintTarget

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from module Gtk::Buildable

buildable_id : String | Nil buildable_id, to_unsafe to_unsafe

Constructor methods inherited from module Gtk::Buildable

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::Buildable

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from module Gtk::Accessible

accessible_parent : Gtk::Accessible | Nil accessible_parent, accessible_role : Gtk::AccessibleRole accessible_role, accessible_role=(value : Gtk::AccessibleRole) : Gtk::AccessibleRole accessible_role=, announce(message : String, priority : Gtk::AccessibleAnnouncementPriority) : Nil announce, at_context : Gtk::ATContext at_context, bounds(x : Int32, y : Int32, width : Int32, height : Int32) : Bool bounds, first_accessible_child : Gtk::Accessible | Nil first_accessible_child, next_accessible_sibling : Gtk::Accessible | Nil next_accessible_sibling, platform_state(state : Gtk::AccessiblePlatformState) : Bool platform_state, reset_property(property : Gtk::AccessibleProperty) : Nil reset_property, reset_relation(relation : Gtk::AccessibleRelation) : Nil reset_relation, reset_state(state : Gtk::AccessibleState) : Nil reset_state, set_accessible_parent(parent : Gtk::Accessible | Nil, next_sibling : Gtk::Accessible | Nil) : Nil set_accessible_parent, to_unsafe to_unsafe, update_next_accessible_sibling(new_sibling : Gtk::Accessible | Nil) : Nil update_next_accessible_sibling, update_platform_state(state : Gtk::AccessiblePlatformState) : Nil update_platform_state, update_property(properties : Enumerable(Gtk::AccessibleProperty), values : Enumerable(_)) : Nil update_property, update_relation(relations : Enumerable(Gtk::AccessibleRelation), values : Enumerable(_)) : Nil update_relation, update_state(states : Enumerable(Gtk::AccessibleState), values : Enumerable(_)) : Nil update_state

Constructor methods inherited from module Gtk::Accessible

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::Accessible

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from class GObject::InitiallyUnowned

==(other : self) ==, hash(hasher) hash

Constructor methods inherited from class GObject::InitiallyUnowned

new new

Class methods inherited from class GObject::InitiallyUnowned

g_type : UInt64 g_type

Instance methods inherited from class GObject::Object

==(other : self) ==, bind_property(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags) : GObject::Binding bind_property, bind_property_full(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags, transform_to : GObject::Closure, transform_from : GObject::Closure) : GObject::Binding bind_property_full, data(key : String) : Pointer(Void) | Nil data, finalize finalize, freeze_notify : Nil freeze_notify, getv(names : Enumerable(String), values : Enumerable(_)) : Nil getv, hash(hasher) hash, notify(property_name : String) : Nil notify, notify_by_pspec(pspec : GObject::ParamSpec) : Nil notify_by_pspec, notify_signal notify_signal, property(property_name : String, value : _) : Nil property, qdata(quark : UInt32) : Pointer(Void) | Nil qdata, ref_count : UInt32 ref_count, run_dispose : Nil run_dispose, set_data(key : String, data : Pointer(Void) | Nil) : Nil set_data, set_property(property_name : String, value : _) : Nil set_property, steal_data(key : String) : Pointer(Void) | Nil steal_data, steal_qdata(quark : UInt32) : Pointer(Void) | Nil steal_qdata, thaw_notify : Nil thaw_notify, to_unsafe : Pointer(Void) to_unsafe, watch_closure(closure : GObject::Closure) : Nil watch_closure

Constructor methods inherited from class GObject::Object

cast(obj : GObject::Object) : self cast, new(pointer : Pointer(Void), transfer : GICrystal::Transfer)
new new, newv(object_type : UInt64, parameters : Enumerable(GObject::Parameter)) : self newv

Class methods inherited from class GObject::Object

cast?(obj : GObject::Object) : self | Nil cast?, compat_control(what : UInt64, data : Pointer(Void) | Nil) : UInt64 compat_control, g_type : UInt64 g_type, interface_find_property(g_iface : GObject::TypeInterface, property_name : String) : GObject::ParamSpec interface_find_property, interface_list_properties(g_iface : GObject::TypeInterface) : Enumerable(GObject::ParamSpec) interface_list_properties

Macros inherited from class GObject::Object

previous_vfunc(*args) previous_vfunc, previous_vfunc!(*args) previous_vfunc!, signal(signature) signal

Constructor Detail

def self.new #

Initialize a new Widget.


def self.new(*, accessible_role : Gtk::AccessibleRole | Nil = nil, can_focus : Bool | Nil = nil, can_target : Bool | Nil = nil, css_classes : Enumerable(String) | Nil = nil, css_name : String | Nil = nil, cursor : Gdk::Cursor | Nil = nil, focus_on_click : Bool | Nil = nil, focusable : Bool | Nil = nil, halign : Gtk::Align | Nil = nil, has_default : Bool | Nil = nil, has_focus : Bool | Nil = nil, has_tooltip : Bool | Nil = nil, height_request : Int32 | Nil = nil, hexpand : Bool | Nil = nil, hexpand_set : Bool | Nil = nil, layout_manager : Gtk::LayoutManager | Nil = nil, limit_events : Bool | Nil = nil, margin_bottom : Int32 | Nil = nil, margin_end : Int32 | Nil = nil, margin_start : Int32 | Nil = nil, margin_top : Int32 | Nil = nil, name : String | Nil = nil, opacity : Float64 | Nil = nil, overflow : Gtk::Overflow | Nil = nil, parent : Gtk::Widget | Nil = nil, receives_default : Bool | Nil = nil, root : Gtk::Root | Nil = nil, scale_factor : Int32 | Nil = nil, sensitive : Bool | Nil = nil, tooltip_markup : String | Nil = nil, tooltip_text : String | Nil = nil, valign : Gtk::Align | Nil = nil, vexpand : Bool | Nil = nil, vexpand_set : Bool | Nil = nil, visible : Bool | Nil = nil, width_request : Int32 | Nil = nil) #

Class Method Detail

def self.default_direction : Gtk::TextDirection #

Obtains the default reading direction.

See Gtk::Widget#default_direction=.


def self.default_direction=(dir : Gtk::TextDirection) : Nil #

Sets the default reading direction for widgets.

See Gtk::Widget#direction=.


def self.g_type : UInt64 #

Returns the type id (GType) registered in GLib type system.


Instance Method Detail

def ==(other : self) #
Description copied from class Reference

Returns true if this reference is the same as other. Invokes same?.


def action_set_enabled(action_name : String, enabled : Bool) : Nil #

Enables or disables an action installed with Gtk::WidgetClass#install_action.


def activate : Bool #

Activates the widget.

The activation will emit the signal set using Gtk::WidgetClass#activate_signal= during class initialization.

Activation is what happens when you press Enter on a widget.

If you wish to handle the activation keybinding yourself, it is recommended to use Gtk::WidgetClass#add_shortcut with an action created with Gtk::SignalAction.new.

If widget is not activatable, the function returns false.


def activate_action(name : String, args : _ | Nil) : Bool #

Activates an action for the widget.

The action is looked up in the action groups associated with widget and its ancestors.

This is a wrapper around Gtk::Widget#activate_action_variant that constructs the args variant according to format_string.


def activate_default : Nil #

Activates the default.activate action for the widget.

The action is looked up in the same was as for Gtk::Widget#activate_action.


def add_controller(controller : Gtk::EventController) : Nil #

Adds an event controller to the widget.

The event controllers of a widget handle the events that are propagated to the widget.

You will usually want to call this function right after creating any kind of Gtk::EventController.


def add_css_class(css_class : String) : Nil #

Adds a style class to the widget.

After calling this function, the widget’s style will match for css_class, according to CSS matching rules.

Use Gtk::Widget#remove_css_class to remove the style again.


def add_mnemonic_label(label : Gtk::Widget) : Nil #

Adds a widget to the list of mnemonic labels for this widget.

See Gtk::Widget#list_mnemonic_labels.

Note that the list of mnemonic labels for the widget is cleared when the widget is destroyed, so the caller must make sure to update its internal state at this point as well.


def add_tick_callback(callback : Gtk::TickCallback) : UInt32 #

Queues an animation frame update and adds a callback to be called before each frame.

Until the tick callback is removed, it will be called frequently (usually at the frame rate of the output device or as quickly as the application can be repainted, whichever is slower). For this reason, is most suitable for handling graphics that change every frame or every few frames.

The tick callback does not automatically imply a relayout or repaint. If you want a repaint or relayout, and aren’t changing widget properties that would trigger that (for example, changing the text of a label), then you will have to call Gtk::Widget#queue_resize or Gtk::Widget#queue_draw yourself.

Gdk::FrameClock#frame_time should generally be used for timing continuous animations and Gdk::FrameTimings#predicted_presentation_time should be used if you are trying to display isolated frames at particular times.

This is a more convenient alternative to connecting directly to the Gdk::FrameClock::#update signal of the frame clock, since you don't have to worry about when a frame clock is assigned to a widget.

To remove a tick callback, pass the ID that is returned by this function to Gtk::Widget#remove_tick_callback.


def allocate(width : Int32, height : Int32, baseline : Int32, transform : Gsk::Transform | Nil) : Nil #

Assigns size, position, (optionally) a baseline and transform to a child widget.

In this function, the allocation and baseline may be adjusted. The given allocation will be forced to be bigger than the widget's minimum size, as well as at least 0×0 in size.

This function is only used by widget implementations.

For a version that does not take a transform, see Gtk::Widget#size_allocate.


def allocated_baseline : Int32 #

Returns the baseline that has currently been allocated to the widget.

This function is intended to be used when implementing handlers for the Gtk::WidgetClass.snapshot() function, and when allocating child widgets in Gtk::WidgetClass.size_allocate().

DEPRECATED


def allocated_height : Int32 #

Returns the height that has currently been allocated to the widget.

To learn more about widget sizes, see the coordinate system overview.

DEPRECATED


def allocated_width : Int32 #

Returns the width that has currently been allocated to the widget.

To learn more about widget sizes, see the coordinate system overview.

DEPRECATED


def allocation : Gdk::Rectangle #

Retrieves the widget’s allocation.

Note, when implementing a layout widget: a widget’s allocation will be its “adjusted” allocation, that is, the widget’s parent typically calls Gtk::Widget#size_allocate with an allocation, and that allocation is then adjusted (to handle margin and alignment for example) before assignment to the widget. Gtk::Widget#allocation returns the adjusted allocation that was actually assigned to the widget. The adjusted allocation is guaranteed to be completely contained within the Gtk::Widget#size_allocate allocation, however.

So a layout widget is guaranteed that its children stay inside the assigned bounds, but not that they have exactly the bounds the widget assigned.

DEPRECATED


def ancestor(widget_type : UInt64) : Gtk::Widget | Nil #

Gets the first ancestor of the widget with type widget_type.

For example, gtk_widget_get_ancestor (widget, GTK_TYPE_BOX) gets the first Gtk::Box that’s an ancestor of widget. No reference will be added to the returned widget; it should not be unreferenced.

Note that unlike Gtk::Widget#is_ancestor?, this function considers widget to be an ancestor of itself.


def baseline : Int32 #

Returns the baseline that has currently been allocated to the widget.

This function is intended to be used when implementing handlers for the Gtk::WidgetClass.snapshot() function, and when allocating child widgets in Gtk::WidgetClass.size_allocate().


def can_focus : Bool #

Determines whether the input focus can enter the widget or any of its children.

See Gtk::Widget#can_focus=.


def can_focus=(can_focus : Bool) : Nil #

Sets whether the input focus can enter the widget or any of its children.

Applications should set can_focus to false to mark a widget as for pointer/touch use only.

Note that having can_focus be true is only one of the necessary conditions for being focusable. A widget must also be sensitive and focusable and not have an ancestor that is marked as not can-focus in order to receive input focus.

See Gtk::Widget#grab_focus for actually setting the input focus on a widget.


def can_focus? : Bool #

def can_target : Bool #

Queries whether the widget can be the target of pointer events.


def can_target=(can_target : Bool) : Nil #

Sets whether the widget can be the target of pointer events.


def can_target? : Bool #

def child_focus(direction : Gtk::DirectionType) : Bool #

Called by widgets as the user moves around the window using keyboard shortcuts.

The direction argument indicates what kind of motion is taking place (up, down, left, right, tab forward, tab backward).

This function calls the Gtk::Widget#focus virtual function; widgets can override the virtual function in order to implement appropriate focus behavior.

The default focus() virtual function for a widget should return true if moving in direction left the focus on a focusable location inside that widget, and false if moving in direction moved the focus outside the widget. When returning true, widgets normally call Gtk::Widget#grab_focus to place the focus accordingly; when returning false, they don’t modify the current focus location.

This function is used by custom widget implementations; if you're writing an app, you’d use Gtk::Widget#grab_focus to move the focus to a particular widget.


def child_visible : Bool #

Gets the value set with Gtk::Widget#child_visible=.

If you feel a need to use this function, your code probably needs reorganization.

This function is only useful for widget implementations and should never be called by an application.


def child_visible=(child_visible : Bool) : Nil #

Sets whether the widget should be mapped along with its parent.

The child visibility can be set for widget before it is added to a container with Gtk::Widget#parent=, to avoid mapping children unnecessary before immediately unmapping them. However it will be reset to its default state of true when the widget is removed from a container.

Note that changing the child visibility of a widget does not queue a resize on the widget. Most of the time, the size of a widget is computed from all visible children, whether or not they are mapped. If this is not the case, the container can queue a resize itself.

This function is only useful for widget implementations and should never be called by an application.


def clipboard : Gdk::Clipboard #

Gets the clipboard object for the widget.

This is a utility function to get the clipboard object for the display that widget is using.

Note that this function always works, even when widget is not realized yet.


def color : Gdk::RGBA #

Gets the current foreground color for the widget’s style.

This function should only be used in snapshot implementations that need to do custom drawing with the foreground color.


def compute_bounds(target : Gtk::Widget) : Graphene::Rect #

Computes the bounds for widget in the coordinate space of target.

The bounds of widget are (the bounding box of) the region that it is expected to draw in. See the coordinate system overview to learn more.

If the operation is successful, true is returned. If widget has no bounds or the bounds cannot be expressed in target's coordinate space (for example if both widgets are in different windows), false is returned and bounds is set to the zero rectangle.

It is valid for widget and target to be the same widget.


def compute_expand(orientation : Gtk::Orientation) : Bool #

Computes whether a parent widget should give this widget extra space when possible.

Widgets with children should check this, rather than looking at Gtk::Widget#hexpand or Gtk::Widget#vexpand.

This function already checks whether the widget is visible, so visibility does not need to be checked separately. Non-visible widgets are not expanded.

The computed expand value uses either the expand setting explicitly set on the widget itself, or, if none has been explicitly set, the widget may expand if some of its children do.


def compute_point(target : Gtk::Widget, point : Graphene::Point) : Graphene::Point #

Translates the given point in widget's coordinates to coordinates in target’s coordinate system.

In order to perform this operation, both widgets must share a a common ancestor. If that is not the case, out_point is set to (0, 0) and false is returned.


def compute_transform(target : Gtk::Widget) : Graphene::Matrix #

Computes a matrix suitable to describe a transformation from widget's coordinate system into target's coordinate system.

The transform can not be computed in certain cases, for example when widget and target do not share a common ancestor. In that case out_transform gets set to the identity matrix.

To learn more about widget coordinate systems, see the coordinate system overview.


def contains(x : Float64, y : Float64) : Bool #

Tests if a given point is contained in the widget.

The coordinates for (x, y) must be in widget coordinates, so (0, 0) is assumed to be the top left of widget's content area.


def create_pango_context : Pango::Context #

Creates a new Pango::Context that is configured for the widget.

The Pango::Context will have the appropriate font map, font options, font description, and base direction set.

See also Gtk::Widget#pango_context.


def create_pango_layout(text : String | Nil) : Pango::Layout #

Creates a new Pango::Layout that is configured for the widget.

The Pango::Layout will have the appropriate font map, font description, and base direction set.

If you keep a Pango::Layout created in this way around, you need to re-create it when the widgets Pango::Context is replaced. This can be tracked by listening to changes of the Gtk::Widget#root property on the widget.


def css_classes : Enumerable(String) #

Returns the list of style classes applied to the widget.


def css_classes=(classes : Enumerable(String)) : Nil #

Replaces the current style classes of the widget with classes.


def css_name : String #

Returns the CSS name of the widget.


def css_name=(value : String) : String #

def css_name=(value : Nil) : Nil #

Set #css_name property to nil.


def css_name? : String | Nil #

Same as #css_name, but can return nil.


def cursor : Gdk::Cursor | Nil #

Gets the cursor set on the widget.

See Gtk::Widget#cursor= for details.


def cursor=(cursor : Gdk::Cursor | Nil) : Nil #

Sets the cursor to be shown when the pointer hovers over the widget.

If the cursor is NULL, widget will use the cursor inherited from its parent.


def cursor_from_name=(name : String | Nil) : Nil #

Sets the cursor to be shown when the pointer hovers over the widget.

This is a utility function that creates a cursor via Gdk::Cursor#new_from_name and then sets it on widget with Gtk::Widget#cursor=. See those functions for details.

On top of that, this function allows name to be NULL, which will do the same as calling Gtk::Widget#cursor= with a NULL cursor.


def destroy_signal #

def direction : Gtk::TextDirection #

Gets the reading direction for the widget.

See Gtk::Widget#direction=.


def direction=(dir : Gtk::TextDirection) : Nil #

Sets the reading direction on the widget.

This direction controls the primary direction for widgets containing text, and also the direction in which the children of a container are packed. The ability to set the direction is present in order so that correct localization into languages with right-to-left reading directions can be done.

Generally, applications will let the default reading direction prevail, except for widgets where the children are arranged in an order that is explicitly visual rather than logical (such as buttons for text justification).

If the direction is set to Gtk::TextDirection#none, then the value set by Gtk::Widget#default_direction= will be used.


def direction_changed_signal #

def display : Gdk::Display #

Get the display for the window that the widget belongs to.

This function can only be called after the widget has been added to a widget hierarchy with a Gtk::Root at the top.

In general, you should only create display-specific resources when a widget has been realized, and you should free those resources when the widget is unrealized.


def dispose_template(widget_type : UInt64) : Nil #

Clears the template children for the widget.

This function is the opposite of Gtk::Widget#init_template, and it is used to clear all the template children from a widget instance. If you bound a template child to a field in the instance structure, or in the instance private data structure, the field will be set to NULL after this function returns.

You should call this function inside the GObjectClass.dispose() implementation of any widget that called Gtk::Widget#init_template. Typically, you will want to call this function last, right before chaining up to the parent type's dispose implementation, e.g.

WARNING ⚠️ The following code is in c ⚠️

static void
some_widget_dispose (GObject *gobject)
{
  SomeWidget *self = SOME_WIDGET (gobject);

  // Clear the template data for SomeWidget
  gtk_widget_dispose_template (GTK_WIDGET (self), SOME_TYPE_WIDGET);

  G_OBJECT_CLASS (some_widget_parent_class)->dispose (gobject);
}

def drag_check_threshold(start_x : Int32, start_y : Int32, current_x : Int32, current_y : Int32) : Bool #

Checks to see if a drag movement has passed the GTK drag threshold.


def error_bell : Nil #

Notifies the user about an input-related error on the widget.

If the [property@Gtk.Settings:gtk-error-bell] setting is true, it calls Gdk::Surface#beep, otherwise it does nothing.

Note that the effect of Gdk::Surface#beep can be configured in many ways, depending on the windowing backend and the desktop environment or window manager that is used.


def first_child : Gtk::Widget | Nil #

Returns the widget’s first child.

This function is primarily meant for widget implementations.


def focus_child : Gtk::Widget | Nil #

Returns the focus child of the widget.


def focus_child=(child : Gtk::Widget | Nil) : Nil #

Set the focus child of the widget.

This function is only suitable for widget implementations. If you want a certain widget to get the input focus, call Gtk::Widget#grab_focus on it.


def focus_on_click : Bool #

Returns whether the widget should grab focus when it is clicked with the mouse.

See Gtk::Widget#focus_on_click=.


def focus_on_click=(focus_on_click : Bool) : Nil #

Sets whether the widget should grab focus when it is clicked with the mouse.

Making mouse clicks not grab focus is useful in places like toolbars where you don’t want the keyboard focus removed from the main area of the application.


def focus_on_click? : Bool #

def focusable : Bool #

Determines whether the widget can own the input focus.

See Gtk::Widget#focusable=.


def focusable=(focusable : Bool) : Nil #

Sets whether the widget can own the input focus.

Widget implementations should set focusable to true in their init() function if they want to receive keyboard input.

Note that having focusable be true is only one of the necessary conditions for being focusable. A widget must also be sensitive and can-focus and not have an ancestor that is marked as not can-focus in order to receive input focus.

See Gtk::Widget#grab_focus for actually setting the input focus on a widget.


def focusable? : Bool #

def font_map : Pango::FontMap | Nil #

Gets the font map of the widget.

See Gtk::Widget#font_map=.


def font_map=(font_map : Pango::FontMap | Nil) : Nil #

Sets the font map to use for text rendering in the widget.

The font map is the object that is used to look up fonts. Setting a custom font map can be useful in special situations, e.g. when you need to add application-specific fonts to the set of available fonts.

When not set, the widget will inherit the font map from its parent.


def font_options : Cairo::FontOptions | Nil #

Returns the cairo_::font_options_t of the widget.

Seee Gtk::Widget#font_options=.

DEPRECATED


def font_options=(options : Cairo::FontOptions | Nil) : Nil #

Sets the cairo_::font_options_t used for text rendering in the widget.

When not set, the default font options for the Gdk::Display will be used.

DEPRECATED


def frame_clock : Gdk::FrameClock | Nil #

Obtains the frame clock for a widget.

The frame clock is a global “ticker” that can be used to drive animations and repaints. The most common reason to get the frame clock is to call Gdk::FrameClock#frame_time, in order to get a time to use for animating. For example you might record the start of the animation with an initial value from Gdk::FrameClock#frame_time, and then update the animation by calling Gdk::FrameClock#frame_time again during each repaint.

Gdk::FrameClock#request_phase will result in a new frame on the clock, but won’t necessarily repaint any widgets. To repaint a widget, you have to use Gtk::Widget#queue_draw which invalidates the widget (thus scheduling it to receive a draw on the next frame). Gtk::Widget#queue_draw will also end up requesting a frame on the appropriate frame clock.

A widget’s frame clock will not change while the widget is mapped. Reparenting a widget (which implies a temporary unmap) can change the widget’s frame clock.

Unrealized widgets do not have a frame clock.


def grab_focus : Bool #

Causes widget to have the keyboard focus for the window that it belongs to.

If widget is not focusable, or its Gtk::Widget#grab_focus implementation cannot transfer the focus to a descendant of widget that is focusable, it will not take focus and false will be returned.

Calling Gtk::Widget#grab_focus on an already focused widget is allowed, should not have an effect, and return true.


def halign : Gtk::Align #

Gets the horizontal alignment of the widget.

For backwards compatibility reasons this method will never return one of the baseline alignments, but instead it will convert it to Gtk::Align#fill or Gtk::Align#center.

Baselines are not supported for horizontal alignment.


def halign=(align : Gtk::Align) : Nil #

Sets the horizontal alignment of the widget.


def has_css_class(css_class : String) : Bool #

Returns whether a style class is currently applied to the widget.


def has_default : Bool #

Determines whether the widget is the current default widget within its toplevel.


def has_default? : Bool #

def has_focus : Bool #

Determines if the widget has the global input focus.

See Gtk::Widget#is_focus? for the difference between having the global input focus, and only having the focus within a toplevel.


def has_focus? : Bool #

def has_tooltip : Bool #

Returns the current value of the has-tooltip property.


def has_tooltip=(has_tooltip : Bool) : Nil #

Sets the has-tooltip property on the widget.


def has_tooltip? : Bool #

def has_visible_focus : Bool #

Determines if the widget should show a visible indication that it has the global input focus.

This is a convenience function that takes into account whether focus indication should currently be shown in the toplevel window of widget. See Gtk::Window#focus_visible for more information about focus indication.

To find out if the widget has the global input focus, use Gtk::Widget#has_focus.


def hash(hasher) #
Description copied from class Reference

See Object#hash(hasher)


def height : Int32 #

Returns the content height of the widget.

This function returns the height passed to its size-allocate implementation, which is the height you should be using in Gtk::Widget#snapshot.

For pointer events, see Gtk::Widget#contains.

To learn more about widget sizes, see the coordinate system overview.


def height_request : Int32 #

def height_request=(value : Int32) : Int32 #

def hexpand : Bool #

Gets whether the widget would like any available extra horizontal space.

When a user resizes a window, widgets with expand set to true generally receive the extra space. For example, a list or scrollable area or document in your window would often be set to expand.

Widgets with children should use Gtk::Widget#compute_expand rather than this function, to see whether any of its children, has the expand flag set. If any child of a widget wants to expand, the parent may ask to expand also.

This function only looks at the widget’s own hexpand flag, rather than computing whether the entire widget tree rooted at this widget wants to expand.


def hexpand=(expand : Bool) : Nil #

Sets whether the widget would like any available extra horizontal space.

When a user resizes a window, widgets with expand set to true generally receive the extra space. For example, a list or scrollable area or document in your window would often be set to expand.

Call this function to set the expand flag if you would like your widget to become larger horizontally when the window has extra room.

By default, widgets automatically expand if any of their children want to expand. (To see if a widget will automatically expand given its current children and state, call Gtk::Widget#compute_expand. A widget can decide how the expandability of children affects its own expansion by overriding the #compute_expand virtual method on Gtk::Widget.).

Setting hexpand explicitly with this function will override the automatic expand behavior.

This function forces the widget to expand or not to expand, regardless of children. The override occurs because Gtk::Widget#hexpand= sets the hexpand-set property (see Gtk::Widget#hexpand_set=) which causes the widget’s hexpand value to be used, rather than looking at children and widget state.


def hexpand? : Bool #

def hexpand_set : Bool #

Gets whether the #hexpand flag has been explicitly set.

If Gtk::Widget#hexpand property is set, then it overrides any computed expand value based on child widgets. If #hexpand is not set, then the expand value depends on whether any children of the widget would like to expand.

There are few reasons to use this function, but it’s here for completeness and consistency.


def hexpand_set=(set : Bool) : Nil #

Sets whether the hexpand flag will be used.

The [property@Gtk.Widget:hexpand-set] property will be set automatically when you call Gtk::Widget#hexpand= to set hexpand, so the most likely reason to use this function would be to unset an explicit expand flag.

If hexpand is set, then it overrides any computed expand value based on child widgets. If hexpand is not set, then the expand value depends on whether any children of the widget would like to expand.

There are few reasons to use this function, but it’s here for completeness and consistency.


def hexpand_set? : Bool #

def hide : Nil #

Reverses the effects of [method.Gtk.Widget.show].

This is causing the widget to be hidden (invisible to the user).

DEPRECATED


def hide_signal #

def in_destruction : Bool #

Returns whether the widget is currently being destroyed.

This information can sometimes be used to avoid doing unnecessary work.


def init_template : Nil #

Creates and initializes child widgets defined in templates.

This function must be called in the instance initializer for any class which assigned itself a template using Gtk::WidgetClass#template=.

It is important to call this function in the instance initializer of a widget subclass and not in GObject.constructed() or GObject.constructor() for two reasons:

  • derived widgets will assume that the composite widgets defined by its parent classes have been created in their relative instance initializers
  • when calling g_object_new() on a widget with composite templates, it’s important to build the composite widgets before the construct properties are set. Properties passed to g_object_new() should take precedence over properties set in the private template XML

A good rule of thumb is to call this function as the first thing in an instance initialization function.


def insert_action_group(name : String, group : Gio::ActionGroup | Nil) : Nil #

Inserts an action group into the widget's actions.

Children of widget that implement Gtk::Actionable can then be associated with actions in group by setting their “action-name” to prefix.action-name.

Note that inheritance is defined for individual actions. I.e. even if you insert a group with prefix prefix, actions with the same prefix will still be inherited from the parent, unless the group contains an action with the same name.

If group is NULL, a previously inserted group for name is removed from widget.


def insert_after(parent : Gtk::Widget, previous_sibling : Gtk::Widget | Nil) : Nil #

Sets the parent widget of the widget.

In contrast to Gtk::Widget#parent=, this function inserts widget at a specific position into the list of children of the parent widget.

It will be placed after previous_sibling, or at the beginning if previous_sibling is NULL.

After calling this function, gtk_widget_get_prev_sibling (widget) will return previous_sibling.

If parent is already set as the parent widget of widget, this function can also be used to reorder widget in the child widget list of parent.

This function is primarily meant for widget implementations; if you are just using a widget, you must use its own API for adding children.


def insert_before(parent : Gtk::Widget, next_sibling : Gtk::Widget | Nil) : Nil #

Sets the parent widget of the widget.

In contrast to Gtk::Widget#parent=, this function inserts widget at a specific position into the list of children of the parent widget.

It will be placed before next_sibling, or at the end if next_sibling is NULL.

After calling this function, gtk_widget_get_next_sibling (widget) will return next_sibling.

If parent is already set as the parent widget of widget, this function can also be used to reorder widget in the child widget list of parent.

This function is primarily meant for widget implementations; if you are just using a widget, you must use its own API for adding children.


def is_ancestor(ancestor : Gtk::Widget) : Bool #

Determines whether the widget is a descendent of ancestor.


def is_drawable : Bool #

Determines whether the widget can be drawn to.

A widget can be drawn if it is mapped and visible.


def is_focus : Bool #

Determines if the widget is the focus widget within its toplevel.

This does not mean that the [property@Gtk.Widget:has-focus] property is necessarily set; [property@Gtk.Widget:has-focus] will only be set if the toplevel widget additionally has the global input focus.


def is_sensitive? : Bool #

Returns the widget’s effective sensitivity.

This means it is sensitive itself and also its parent widget is sensitive.


def is_visible? : Bool #

Determines whether the widget and all its parents are marked as visible.

This function does not check if the widget is obscured in any way.

See also Gtk::Widget#visible and Gtk::Widget#visible=.


def keynav_failed(direction : Gtk::DirectionType) : Bool #

Emits the [signal@Gtk.Widget::keynav-failed] signal on the widget.

This function should be called whenever keyboard navigation within a single widget hits a boundary.

The return value of this function should be interpreted in a way similar to the return value of Gtk::Widget#child_focus. When true is returned, stay in the widget, the failed keyboard navigation is ok and/or there is nowhere we can/should move the focus to. When false is returned, the caller should continue with keyboard navigation outside the widget, e.g. by calling Gtk::Widget#child_focus on the widget’s toplevel.

The default [signal@Gtk.Widget::keynav-failed] handler returns false for [enum@Gtk.DirectionType.tab-forward] and [enum@Gtk.DirectionType.tab-backward]. For the other values of Gtk::DirectionType it returns true.

Whenever the default handler returns true, it also calls Gtk::Widget#error_bell to notify the user of the failed keyboard navigation.

A use case for providing an own implementation of ::keynav-failed (either by connecting to it or by overriding it) would be a row of Gtk::Entry widgets where the user should be able to navigate the entire row with the cursor keys, as e.g. known from user interfaces that require entering license keys.


def keynav_failed_signal #

def last_child : Gtk::Widget | Nil #

Returns the widget’s last child.

This function is primarily meant for widget implementations.


def layout_manager : Gtk::LayoutManager | Nil #

Retrieves the layout manager of the widget.

See Gtk::Widget#layout_manager=.


def layout_manager=(layout_manager : Gtk::LayoutManager | Nil) : Nil #

Sets the layout manager to use for measuring and allocating children of the widget.


def limit_events : Bool #

Gets the value of the [property@Gtk.Widget:limit-events] property.


def limit_events=(limit_events : Bool) : Nil #

Sets whether the widget acts like a modal dialog, with respect to event delivery.


def limit_events? : Bool #

def list_mnemonic_labels : GLib::List #

Returns the widgets for which this widget is the target of a mnemonic.

Typically, these widgets will be labels. See, for example, Gtk::Label#mnemonic_widget=.

The widgets in the list are not individually referenced. If you want to iterate through the list and perform actions involving callbacks that might destroy the widgets, you must call g_list_foreach (result, (GFunc)g_object_ref, NULL) first, and then unref all the widgets afterwards.


def map : Nil #

Causes a widget to be mapped if it isn’t already.

This function is only for use in widget implementations.


def map_signal #

def mapped : Bool #

Returns whether the widget is mapped.


def margin_bottom : Int32 #

Gets the bottom margin of the widget.


def margin_bottom=(margin : Int32) : Nil #

Sets the bottom margin of the widget.


def margin_end : Int32 #

Gets the end margin of the widget.


def margin_end=(margin : Int32) : Nil #

Sets the end margin of the widget.


def margin_start : Int32 #

Gets the start margin of the widget.


def margin_start=(margin : Int32) : Nil #

Sets the start margin of the widget.


def margin_top : Int32 #

Gets the top margin of the widget.


def margin_top=(margin : Int32) : Nil #

Sets the top margin of the widget.


def measure(orientation : Gtk::Orientation, for_size : Int32) : Nil #

Measures widget in the orientation orientation and for the given for_size.

As an example, if orientation is %GTK_ORIENTATION_HORIZONTAL and for_size is 300, this functions will compute the minimum and natural width of widget if it is allocated at a height of 300 pixels.

See Gtk::Widget’s geometry management section for a more details on implementing Gtk::WidgetClass.measure().


def mnemonic_activate(group_cycling : Bool) : Bool #

Emits the [signal@Gtk.Widget::mnemonic-activate] signal.


def mnemonic_activate_signal #

def move_focus_signal #

def name : String #

Retrieves the name of a widget.

See Gtk::Widget#name= for the significance of widget names.


def name=(name : String) : Nil #

Sets a widgets name.

Setting a name allows you to refer to the widget from a CSS file. You can apply a style to widgets with a particular name in the CSS file. See the documentation for the CSS syntax (on the same page as the docs for Gtk::StyleContext.

Note that the CSS syntax has certain special characters to delimit and represent elements in a selector (period, #, >, *...), so using these will make your widget impossible to match by name. Any combination of alphanumeric symbols, dashes and underscores will suffice.


def name=(value : Nil) : Nil #

Set #name property to nil.


def name? : String | Nil #

Same as #name, but can return nil.


def native : Gtk::Native | Nil #

Returns the nearest Gtk::Native ancestor of the widget.

This function will return NULL if the widget is not contained inside a widget tree with a native ancestor.

Gtk::Native widgets will return themselves here.


def next_sibling : Gtk::Widget | Nil #

Returns the widget’s next sibling.

This function is primarily meant for widget implementations.


def observe_children : Gio::ListModel #

Returns a list model to track the children of the widget.

Calling this function will enable extra internal bookkeeping to track children and emit signals on the returned listmodel. It may slow down operations a lot.

Applications should try hard to avoid calling this function because of the slowdowns.


def observe_controllers : Gio::ListModel #

Returns a list model to track the event controllers of the widget.

Calling this function will enable extra internal bookkeeping to track controllers and emit signals on the returned listmodel. It may slow down operations a lot.

Applications should try hard to avoid calling this function because of the slowdowns.


def opacity : Float64 #

Fetches the requested opacity for the widget.

See Gtk::Widget#opacity=.


def opacity=(opacity : Float64) : Nil #

Requests the widget to be rendered partially transparent.

An opacity of 0 is fully transparent and an opacity of 1 is fully opaque.

Opacity works on both toplevel widgets and child widgets, although there are some limitations: For toplevel widgets, applying opacity depends on the capabilities of the windowing system. On X11, this has any effect only on X displays with a compositing manager, see Gdk::Display#is_composited?. On Windows and Wayland it will always work, although setting a window’s opacity after the window has been shown may cause some flicker.

Note that the opacity is inherited through inclusion — if you set a toplevel to be partially translucent, all of its content will appear translucent, since it is ultimatively rendered on that toplevel. The opacity value itself is not inherited by child widgets (since that would make widgets deeper in the hierarchy progressively more translucent). As a consequence, Gtk::Popover instances and other Gtk::Native widgets with their own surface will use their own opacity value, and thus by default appear non-translucent, even if they are attached to a toplevel that is translucent.


def overflow : Gtk::Overflow #

Returns the widget’s overflow value.


def overflow=(overflow : Gtk::Overflow) : Nil #

Sets how the widget treats content that is drawn outside the it's content area.

See the definition of Gtk::Overflow for details.

This setting is provided for widget implementations and should not be used by application code.

The default value is Gtk::Overflow#visible.


def pango_context : Pango::Context #

Gets a Pango::Context that is configured for the widget.

The Pango::Context will have the appropriate font map, font description, and base direction set.

Unlike the context returned by Gtk::Widget#create_pango_context, this context is owned by the widget (it can be used until the screen for the widget changes or the widget is removed from its toplevel), and will be updated to match any changes to the widget’s attributes. This can be tracked by listening to changes of the Gtk::Widget#root property on the widget.


def parent : Gtk::Widget | Nil #

Returns the parent widget of the widget.


def parent=(parent : Gtk::Widget) : Nil #

Sets the parent widget of the widget.

This takes care of details such as updating the state and style of the child to reflect its new location and resizing the parent. The opposite function is Gtk::Widget#unparent.

This function is useful only when implementing subclasses of Gtk::Widget.


def pick(x : Float64, y : Float64, flags : Gtk::PickFlags) : Gtk::Widget | Nil #

Finds the descendant of the widget closest to a point.

The point (x, y) must be given in widget coordinates, so (0, 0) is assumed to be the top left of widget's content area.

Usually widgets will return NULL if the given coordinate is not contained in widget checked via Gtk::Widget#contains. Otherwise they will recursively try to find a child that does not return NULL. Widgets are however free to customize their picking algorithm.

This function is used on the toplevel to determine the widget below the mouse cursor for purposes of hover highlighting and delivering events.


def preferred_size : Gtk::Requisition #

Retrieves the minimum and natural size of a widget, taking into account the widget’s preference for height-for-width management.

This is used to retrieve a suitable size by container widgets which do not impose any restrictions on the child placement. It can be used to deduce toplevel window and menu sizes as well as child widgets in free-form containers such as Gtk::Fixed.

Handle with care. Note that the natural height of a height-for-width widget will generally be a smaller size than the minimum height, since the required height for the natural width is generally smaller than the required height for the minimum width.

Use Gtk::Widget#measure if you want to support baseline alignment.


def prev_sibling : Gtk::Widget | Nil #

Returns the widget’s previous sibling.

This function is primarily meant for widget implementations.


def primary_clipboard : Gdk::Clipboard #

Gets the primary clipboard of the widget.

This is a utility function to get the primary clipboard object for the display that widget is using.

Note that this function always works, even when widget is not realized yet.


def query_tooltip_signal #

def queue_allocate : Nil #

Flags the widget for a rerun of the Gtk::Widget#size_allocate function.

Use this function instead of Gtk::Widget#queue_resize when the widget's size request didn't change but it wants to reposition its contents.

An example user of this function is Gtk::Widget#halign=.

This function is only for use in widget implementations.


def queue_draw : Nil #

Schedules this widget to be redrawn.

The redraw will happen in the paint phase of the current or the next frame.

This means widget's Gtk::Widget#snapshot implementation will be called.


def queue_resize : Nil #

Flags a widget to have its size renegotiated.

This should be called when a widget for some reason has a new size request. For example, when you change the text in a Gtk::Label, the label queues a resize to ensure there’s enough space for the new text.

Note that you cannot call gtk_widget_queue_resize() on a widget from inside its implementation of the Gtk::Widget#size_allocate virtual method. Calls to gtk_widget_queue_resize() from inside Gtk::Widget#size_allocate will be silently ignored.

This function is only for use in widget implementations.


def realize : Nil #

Creates the GDK resources associated with a widget.

Normally realization happens implicitly; if you show a widget and all its parent containers, then the widget will be realized and mapped automatically.

Realizing a widget requires all the widget’s parent widgets to be realized; calling this function realizes the widget’s parents in addition to widget itself. If a widget is not yet inside a toplevel window when you realize it, bad things will happen.

This function is primarily used in widget implementations, and isn’t very useful otherwise. Many times when you think you might need it, a better approach is to connect to a signal that will be called after the widget is realized automatically, such as Gtk::Widget::#realize.


def realize_signal #

def realized : Bool #

Determines whether the widget is realized.


def receives_default : Bool #

Determines whether the widget is always treated as the default widget within its toplevel when it has the focus, even if another widget is the default.

See Gtk::Widget#receives_default=.


def receives_default=(receives_default : Bool) : Nil #

Sets whether the widget will be treated as the default widget within its toplevel when it has the focus, even if another widget is the default.


def receives_default? : Bool #

def remove_controller(controller : Gtk::EventController) : Nil #

Removes an event controller from the widget.

The removed event controller will not receive any more events, and should not be used again.

Widgets will remove all event controllers automatically when they are destroyed, there is normally no need to call this function.


def remove_css_class(css_class : String) : Nil #

Removes a style from the widget.

After this, the style of widget will stop matching for css_class.


def remove_mnemonic_label(label : Gtk::Widget) : Nil #

Removes a widget from the list of mnemonic labels for this widget.

See Gtk::Widget#list_mnemonic_labels.

The widget must have previously been added to the list with Gtk::Widget#add_mnemonic_label.


def remove_tick_callback(id : UInt32) : Nil #

Removes a tick callback previously registered with Gtk::Widget#add_tick_callback.


def request_mode : Gtk::SizeRequestMode #

Gets whether the widget prefers a height-for-width layout or a width-for-height layout.

Single-child widgets generally propagate the preference of their child, more complex widgets need to request something either in context of their children or in context of their allocation capabilities.


def root : Gtk::Root | Nil #

Returns the Gtk::Root widget of the widget.

This function will return NULL if the widget is not contained inside a widget tree with a root widget.

Gtk::Root widgets will return themselves here.


def scale_factor : Int32 #

Retrieves the internal scale factor that maps from window coordinates to the actual device pixels.

On traditional systems this is 1, on high density outputs, it can be a higher value (typically 2).

See Gdk::Surface#scale_factor.

Note that modern systems may support fractional scaling, where the scale factor is not an integer. On such systems, this function will return the next higher integer value, but you probably want to use Gdk::Surface#scale to get the fractional scale value.


def sensitive : Bool #

Returns the widget’s sensitivity.

This function returns the value that has been set using Gtk::Widget#sensitive=).

The effective sensitivity of a widget is however determined by both its own and its parent widget’s sensitivity. See Gtk::Widget#is_sensitive?.


def sensitive=(sensitive : Bool) : Nil #

Sets the sensitivity of the widget.

A widget is sensitive if the user can interact with it. Insensitive widgets are “grayed out” and the user can’t interact with them. Insensitive widgets are known as “inactive”, “disabled”, or “ghosted” in some other toolkits.


def sensitive? : Bool #

def set_size_request(width : Int32, height : Int32) : Nil #

Sets the minimum size of the widget.

That is, the widget’s size request will be at least width by height. You can use this function to force a widget to be larger than it normally would be.

In most cases, Gtk::Window#default_size= is a better choice for toplevel windows than this function; setting the default size will still allow users to shrink the window. Setting the size request will force them to leave the window at least as large as the size request.

Note the inherent danger of setting any fixed size - themes, translations into other languages, different fonts, and user action can all change the appropriate size for a given widget. So, it is basically impossible to hardcode a size that will always work.

The size request of a widget is the smallest size a widget can accept while still functioning well and drawing itself correctly. However in some strange cases a widget may be allocated less than its requested size, and in many cases a widget may be allocated more space than it requested.

If the size request in a given direction is -1 (unset), then the “natural” size request of the widget will be used instead.

The size request set here does not include any margin from the properties [property@Gtk.Widget:margin-start], [property@Gtk.Widget:margin-end], [property@Gtk.Widget:margin-top], and [property@Gtk.Widget:margin-bottom], but it does include pretty much all other padding or border properties set by any subclass of Gtk::Widget.


def set_state_flags(flags : Gtk::StateFlags, clear : Bool) : Nil #

Turns on flag values in the current widget state.

Typical widget states are insensitive, prelighted, etc.

This function accepts the values [flags@Gtk.StateFlags.dir-ltr] and [flags@Gtk.StateFlags.dir-rtl] but ignores them. If you want to set the widget's direction, use Gtk::Widget#direction=.

This function is for use in widget implementations.


def settings : Gtk::Settings #

Gets the settings object holding the settings used for the widget.

Note that this function can only be called when the Gtk::Widget is attached to a toplevel, since the settings object is specific to a particular display. If you want to monitor the widget for changes in its settings, connect to the notify::display signal.


def should_layout : Bool #

Returns whether the widget should contribute to the measuring and allocation of its parent.

This is false for invisible children, but also for children that have their own surface, such as Gtk::Popover instances.


def show : Nil #

Flags a widget to be displayed.

Any widget that isn’t shown will not appear on the screen.

Remember that you have to show the containers containing a widget, in addition to the widget itself, before it will appear onscreen.

When a toplevel widget is shown, it is immediately realized and mapped; other shown widgets are realized and mapped when their toplevel widget is realized and mapped.

DEPRECATED


def show_signal #

def size(orientation : Gtk::Orientation) : Int32 #

Returns the content width or height of the widget.

Which dimension is returned depends on orientation.

This is equivalent to calling Gtk::Widget#width for Gtk::Orientation#horizontal or Gtk::Widget#height for Gtk::Orientation#vertical, but can be used when writing orientation-independent code, such as when implementing Gtk::Orientable widgets.

To learn more about widget sizes, see the coordinate system overview.


def size_allocate(allocation : Gdk::Rectangle, baseline : Int32) : Nil #

Allocates widget with a transformation that translates the origin to the position in allocation.

This is a simple form of Gtk::Widget#allocate.


def size_request : Nil #

Gets the size request that was explicitly set for the widget.

A value of -1 stored in width or height indicates that that dimension has not been set explicitly and the natural requisition of the widget will be used instead.

See Gtk::Widget#size_request=.

To get the size a widget will actually request, call Gtk::Widget#measure instead of this function.


def snapshot_child(child : Gtk::Widget, snapshot : Gtk::Snapshot) : Nil #

Snapshots a child of the widget.

When a widget receives a call to the snapshot function, it must send synthetic Gtk::Widget#snapshot calls to all children. This function provides a convenient way of doing this. A widget, when it receives a call to its Gtk::Widget#snapshot function, calls gtk_widget_snapshot_child() once for each child, passing in the snapshot the widget received.

This function takes care of translating the origin of snapshot, and deciding whether the child needs to be snapshot.

It does nothing for children that implement Gtk::Native.


def state_flags : Gtk::StateFlags #

Returns the widget state as a flag set.

It is worth mentioning that the effective Gtk::StateFlags#insensitive state will be returned, that is, also based on parent insensitivity, even if widget itself is sensitive.

Also note that if you are looking for a way to obtain the Gtk::StateFlags to pass to a Gtk::StyleContext method, you should look at Gtk::StyleContext#state.


def state_flags_changed_signal #

def style_context : Gtk::StyleContext #

Returns the style context associated to the widget.

The returned object is guaranteed to be the same for the lifetime of widget.

DEPRECATED


def tooltip_markup : String | Nil #

Gets the contents of the tooltip for the widget.

If the tooltip has not been set using Gtk::Widget#tooltip_markup=, this function returns NULL.


def tooltip_markup=(value : String) : String #

def tooltip_markup=(value : Nil) : Nil #

Set #tooltip_markup property to nil.


def tooltip_markup=(markup : String | Nil) : Nil #

Sets the contents of the tooltip for widget. markup must contain Pango markup.

This function will take care of setting the [property@Gtk.Widget:has-tooltip] as a side effect, and of the default handler for the [signal@Gtk.Widget::query-tooltip] signal.

See also Gtk::Tooltip#markup=.


def tooltip_markup? : String | Nil #

Same as #tooltip_markup, but can return nil.


def tooltip_text : String | Nil #

Gets the contents of the tooltip for the widget.

If the widget's tooltip was set using Gtk::Widget#tooltip_markup=, this function will return the escaped text.


def tooltip_text=(value : String) : String #

def tooltip_text=(value : Nil) : Nil #

Set #tooltip_text property to nil.


def tooltip_text=(text : String | Nil) : Nil #

Sets the contents of the tooltip for the widget.

If text contains any markup, it will be escaped.

This function will take care of setting [property@Gtk.Widget:has-tooltip] as a side effect, and of the default handler for the [signal@Gtk.Widget::query-tooltip] signal.

See also Gtk::Tooltip#text=.


def tooltip_text? : String | Nil #

Same as #tooltip_text, but can return nil.


def translate_coordinates(dest_widget : Gtk::Widget, src_x : Float64, src_y : Float64) : Bool #

Translates coordinates relative to src_widget’s allocation to coordinates relative to dest_widget’s allocations.

In order to perform this operation, both widget must share a common ancestor. If that is not the case, dest_x and dest_y are set to 0 and false is returned.

DEPRECATED


def trigger_tooltip_query : Nil #

Triggers a tooltip query on the display of the widget.


def unmap : Nil #

Causes a widget to be unmapped if it’s currently mapped.

This function is only for use in widget implementations.


def unmap_signal #

def unparent : Nil #

Removes widget from its parent.

This function is only for use in widget implementations, typically in dispose.


def unrealize : Nil #

Causes a widget to be unrealized.

This frees all GDK resources associated with the widget.

This function is only useful in widget implementations.


def unrealize_signal #

def unset_state_flags(flags : Gtk::StateFlags) : Nil #

Turns off flag values for the current widget state.

See Gtk::Widget#state_flags=.

This function is for use in widget implementations.


def valign : Gtk::Align #

Gets the vertical alignment of the widget.


def valign=(align : Gtk::Align) : Nil #

Sets the vertical alignment of the widget.


def vexpand : Bool #

Gets whether the widget would like any available extra vertical space.

See Gtk::Widget#hexpand for more detail.


def vexpand=(expand : Bool) : Nil #

Sets whether the widget would like any available extra vertical space.

See Gtk::Widget#hexpand= for more detail.


def vexpand? : Bool #

def vexpand_set : Bool #

Gets whether the #vexpand flag has been explicitly set.

See Gtk::Widget#hexpand_set for more detail.


def vexpand_set=(set : Bool) : Nil #

Sets whether the vexpand flag will be used.

See Gtk::Widget#hexpand_set= for more detail.


def vexpand_set? : Bool #

def visible : Bool #

Determines whether the widget is visible.

If you want to take into account whether the widget’s parent is also marked as visible, use Gtk::Widget#is_visible? instead.

This function does not check if the widget is obscured in any way.

See Gtk::Widget#visible=.


def visible=(visible : Bool) : Nil #

Sets the visibility state of widget.

Note that setting this to true doesn’t mean the widget is actually viewable, see Gtk::Widget#visible.


def visible? : Bool #

def width : Int32 #

Returns the content width of the widget.

This function returns the width passed to its size-allocate implementation, which is the width you should be using in Gtk::Widget#snapshot.

For pointer events, see Gtk::Widget#contains.

To learn more about widget sizes, see the coordinate system overview.


def width_request : Int32 #

def width_request=(value : Int32) : Int32 #