Class (GI Class)

Gtk-3.0GtkStyleContext

Gtk.StyleContext is an object that stores styling information affecting a widget defined by Gtk.WidgetPath.

In order to construct the final style information, Gtk.StyleContext queries information from all attached GtkStyleProviders. Style providers can be either attached explicitly to the context through gtk_style_context_add_provider(), or to the screen through gtk_style_context_add_provider_for_screen(). The resulting style is a combination of all providers’ information in priority order.

For GTK+ widgets, any Gtk.StyleContext returned by gtk_widget_get_style_context() will already have a Gtk.WidgetPath, a Gdk.Screen and RTL/LTR information set. The style context will also be updated automatically if any of these settings change on the widget.

If you are using the theming layer standalone, you will need to set a widget path and a screen yourself to the created style context through gtk_style_context_set_path() and possibly gtk_style_context_set_screen(). See the “Foreign drawing“ example in gtk3-demo.

Style Classes # {#gtkstylecontext-classes}

Widgets can add style classes to their context, which can be used to associate different styles by class. The documentation for individual widgets lists which style classes it uses itself, and which style classes may be added by applications to affect their appearance.

GTK+ defines macros for a number of style classes.

Style Regions

Widgets can also add regions with flags to their context. This feature is deprecated and will be removed in a future GTK+ update. Please use style classes instead.

GTK+ defines macros for a number of style regions.

Custom styling in UI libraries and applications

If you are developing a library with custom GtkWidgets that render differently than standard components, you may need to add a Gtk.StyleProvider yourself with the GTK_STYLE_PROVIDER_PRIORITY_FALLBACK priority, either a Gtk.CssProvider or a custom object implementing the Gtk.StyleProvider interface. This way themes may still attempt to style your UI elements in a different way if needed so.

If you are using custom styling on an applications, you probably want then to make your style information prevail to the theme’s, so you must use a Gtk.StyleProvider with the GTK_STYLE_PROVIDER_PRIORITY_APPLICATION priority, keep in mind that the user settings in XDG_CONFIG_HOME/gtk-3.0/gtk.css will still take precedence over your changes, as it uses the GTK_STYLE_PROVIDER_PRIORITY_USER priority.

Hierarchy (View Summary)

Index

Constructors

Properties

Accessors

Methods

Methods - Inherited from GObject

Constructors

Properties

Compile-time signal type information.

This instance property is generated only for TypeScript type checking. It is not defined at runtime and should not be accessed in JS code.

parent_object: GObject.Object

Accessors

Methods

  • Adds a style class to context, so posterior calls to gtk_style_context_get() or any of the gtk_render_*() functions will make use of this new class for styling.

    In the CSS file format, a Gtk.Entry defining a “search” class, would be matched by:

    entry.search { ... }
    

    While any widget defining a “search” class would be matched by:

    .search { ... }
    

    Parameters

    • class_name: string

      class name to use in styling

    Returns void

  • Adds a style provider to context, to be used in style construction. Note that a style provider added by this function only affects the style of the widget to which context belongs. If you want to affect the style of all widgets, use gtk_style_context_add_provider_for_screen().

    Note: If both priorities are the same, a Gtk.StyleProvider added through this function takes precedence over another added through gtk_style_context_add_provider_for_screen().

    Parameters

    • provider: Gtk.StyleProvider
    • priority: number

      the priority of the style provider. The lower it is, the earlier it will be used in the style construction. Typically this will be in the range between GTK_STYLE_PROVIDER_PRIORITY_FALLBACK and GTK_STYLE_PROVIDER_PRIORITY_USER

    Returns void

  • Adds a region to context, so posterior calls to gtk_style_context_get() or any of the gtk_render_*() functions will make use of this new region for styling.

    In the CSS file format, a Gtk.TreeView defining a “row” region, would be matched by:

    treeview row { ... }
    

    Pseudo-classes are used for matching flags, so the two following rules:

    treeview row:nth-child(even) { ... }
    treeview row:nth-child(odd) { ... }
    

    would apply to even and odd rows, respectively.

    Region names must only contain lowercase letters and “-”, starting always with a lowercase letter.

    Parameters

    • region_name: string

      region name to use in styling

    • flags: Gtk.RegionFlags

      flags that apply to the region

    Returns void

  • Stops all running animations for region_id and all animatable regions underneath.

    A null region_id will stop all ongoing animations in context, when dealing with a Gtk.StyleContext obtained through gtk_widget_get_style_context(), this is normally done for you in all circumstances you would expect all widget to be stopped, so this should be only used in complex widgets with different animatable regions.

    Parameters

    • Optionalregion_id: any

      animatable region to stop, or null. See gtk_style_context_push_animatable_region()

    Returns void

  • Gets the background color for a given state.

    This function is far less useful than it seems, and it should not be used in newly written code. CSS has no concept of "background color", as a background can be an image, or a gradient, or any other pattern including solid colors.

    The only reason why you would call gtk_style_context_get_background_color() is to use the returned value to draw the background with it; the correct way to achieve this result is to use gtk_render_background() instead, along with CSS style classes to modify the color to be rendered.

    Parameters

    Returns Gdk.RGBA

  • Gets a style property from context for the given state.

    Note that not all CSS properties that are supported by GTK+ can be retrieved in this way, since they may not be representable as GObject.Value. GTK+ defines macros for a number of properties that can be used with this function.

    Note that passing a state other than the current state of context is not recommended unless the style context has been saved with gtk_style_context_save().

    When value is no longer needed, g_value_unset() must be called to free any allocated memory.

    Parameters

    • property: string

      style property name

    • state: Gtk.StateFlags

      state to retrieve the property value for

    Returns unknown

  • Parameters

    • ...args: never[]

    Returns any

  • Queries the location in the CSS where property was defined for the current context. Note that the state to be queried is taken from gtk_style_context_get_state().

    If the location is not available, null will be returned. The location might not be available for various reasons, such as the property being overridden, property not naming a supported CSS property or tracking of definitions being disabled for performance reasons.

    Shorthand CSS properties cannot be queried for a location and will always return null.

    Parameters

    • property: string

      style property name

    Returns Gtk.CssSection

    null or the section where a value for property was defined

  • Gets the value for a widget style property.

    When value is no longer needed, g_value_unset() must be called to free any allocated memory.

    Parameters

    • property_name: string

      the name of the widget style property

    • value: any

      Return location for the property value

    Returns void

  • Returns true if context currently has defined the given class name.

    Parameters

    • class_name: string

      a class name

    Returns boolean

    true if context has class_name defined

  • Returns true if context has the region defined. If flags_return is not null, it is set to the flags affecting the region.

    Parameters

    • region_name: string

      a region name

    Returns [boolean, Gtk.RegionFlags]

    true if region is defined

  • Invalidates context style information, so it will be reconstructed again. It is useful if you modify the context and need the new information immediately.

    Returns void

  • Returns the list of classes currently defined in context.

    Returns string[]

    a GLib.List of strings with the currently defined classes. The contents of the list are owned by GTK+, but you must free the list itself with g_list_free() when you are done with it.

  • Returns the list of regions currently defined in context.

    Returns string[]

    a GLib.List of strings with the currently defined regions. The contents of the list are owned by GTK+, but you must free the list itself with g_list_free() when you are done with it.

  • Looks up and resolves a color name in the context color map.

    Parameters

    • color_name: string

      color name to lookup

    Returns [boolean, Gdk.RGBA]

    true if color_name was found and resolved, false otherwise

  • Looks up stock_id in the icon factories associated to context and the default icon factory, returning an icon set if found, otherwise null.

    Parameters

    • stock_id: string

      an icon name

    Returns IconSet

    The looked up %GtkIconSet, or null

  • Notifies a state change on context, so if the current style makes use of transition animations, one will be started so all rendered elements under region_id are animated for state state being set to value state_value.

    The window parameter is used in order to invalidate the rendered area as the animation runs, so make sure it is the same window that is being rendered on by the gtk_render_*() functions.

    If region_id is null, all rendered elements using context will be affected by this state transition.

    As a practical example, a Gtk.Button notifying a state transition on the prelight state:

    gtk_style_context_notify_state_change (context,
                                           gtk_widget_get_window (widget),
                                           NULL,
                                           GTK_STATE_PRELIGHT,
                                           button->in_button);
    

    Can be handled in the CSS file like this:

    button {
        background-color: #f00
    }
    
    button:hover {
        background-color: #fff;
        transition: 200ms linear
    }
    

    This combination will animate the button background from red to white if a pointer enters the button, and back to red if the pointer leaves the button.

    Note that state is used when finding the transition parameters, which is why the style places the transition under the :hover pseudo-class.

    Parameters

    • window: Gdk.Window
    • region_id: any

      animatable region to notify on, or null. See gtk_style_context_push_animatable_region()

    • state: Gtk.StateType

      state to trigger transition for

    • state_value: boolean

      true if state is the state we are changing to, false if we are changing away from it

    Returns void

  • Pops an animatable region from context. See gtk_style_context_push_animatable_region().

    Returns void

  • Pushes an animatable region, so all further gtk_render_*() calls between this call and the following gtk_style_context_pop_animatable_region() will potentially show transition animations for this region if gtk_style_context_notify_state_change() is called for a given state, and the current theme/style defines transition animations for state changes.

    The region_id used must be unique in context so the themes can uniquely identify rendered elements subject to a state transition.

    Parameters

    • Optionalregion_id: any

      unique identifier for the animatable region

    Returns void

  • Removes class_name from context.

    Parameters

    • class_name: string

      class name to remove

    Returns void

  • Removes a region from context.

    Parameters

    • region_name: string

      region name to unset

    Returns void

  • Restores context state to a previous stage. See gtk_style_context_save().

    Returns void

  • Saves the context state, so temporary modifications done through gtk_style_context_add_class(), gtk_style_context_remove_class(), gtk_style_context_set_state(), etc. can quickly be reverted in one go through gtk_style_context_restore().

    The matching call to gtk_style_context_restore() must be done before GTK returns to the main loop.

    Returns void

  • This function is analogous to gdk_window_scroll(), and should be called together with it so the invalidation areas for any ongoing animation are scrolled together with it.

    Parameters

    • window: Gdk.Window

      a Gdk.Window used previously in gtk_style_context_notify_state_change()

    • dx: number

      Amount to scroll in the X axis

    • dy: number

      Amount to scroll in the Y axis

    Returns void

  • Sets the sides where rendered elements (mostly through gtk_render_frame()) will visually connect with other visual elements.

    This is merely a hint that may or may not be honored by themes.

    Container widgets are expected to set junction hints as appropriate for their children, so it should not normally be necessary to call this function manually.

    Parameters

    • sides: Gtk.JunctionSides

      sides where rendered elements are visually connected to other elements

    Returns void

  • Sets the scale to use when getting image assets for the style.

    Parameters

    • scale: number

      scale

    Returns void

  • Returns true if there is a transition animation running for the current region (see gtk_style_context_push_animatable_region()).

    If progress is not null, the animation progress will be returned there, 0.0 means the state is closest to being unset, while 1.0 means it’s closest to being set. This means transition animation will run from 0 to 1 when state is being set and from 1 to 0 when it’s being unset.

    Parameters

    Returns [boolean, number]

    true if there is a running transition animation for state.

  • Converts the style context into a string representation.

    The string representation always includes information about the name, state, id, visibility and style classes of the CSS node that is backing context. Depending on the flags, more information may be included.

    This function is intended for testing and debugging of the CSS implementation in GTK+. There are no guarantees about the format of the returned string, it may change.

    Parameters

    Returns string

    a newly allocated string representing context

  • Adds a global style provider to screen, which will be used in style construction for all GtkStyleContexts under screen.

    GTK+ uses this to make styling information from Gtk.Settings available.

    Note: If both priorities are the same, A Gtk.StyleProvider added through gtk_style_context_add_provider() takes precedence over another added through this function.

    Parameters

    • screen: Gdk.Screen
    • provider: Gtk.StyleProvider
    • priority: number

      the priority of the style provider. The lower it is, the earlier it will be used in the style construction. Typically this will be in the range between GTK_STYLE_PROVIDER_PRIORITY_FALLBACK and GTK_STYLE_PROVIDER_PRIORITY_USER

    Returns void

  • This function recomputes the styles for all widgets under a particular Gdk.Screen. This is useful when some global parameter has changed that affects the appearance of all widgets, because when a widget gets a new style, it will both redraw and recompute any cached information about its appearance. As an example, it is used when the color scheme changes in the related Gtk.Settings object.

    Parameters

    Returns void

Methods - Inherited from GObject

  • Creates a binding between source_property on source and target_property on target.

    Whenever the source_property is changed the target_property is updated using the same value. For instance:

      g_object_bind_property (action, "active", widget, "sensitive", 0);
    

    Will result in the "sensitive" property of the widget GObject.Object instance to be updated with the same value of the "active" property of the action GObject.Object instance.

    If flags contains GObject.BindingFlags.BIDIRECTIONAL then the binding will be mutual: if target_property on target changes then the source_property on source will be updated as well.

    The binding will automatically be removed when either the source or the target instances are finalized. To remove the binding without affecting the source and the target you can just call g_object_unref() on the returned GObject.Binding instance.

    Removing the binding by calling g_object_unref() on it must only be done if the binding, source and target are only used from a single thread and it is clear that both source and target outlive the binding. Especially it is not safe to rely on this if the binding, source or target can be finalized from different threads. Keep another reference to the binding and use g_binding_unbind() instead to be on the safe side.

    A GObject.Object can have multiple bindings.

    Parameters

    Returns GObject.Binding

    the GObject.Binding instance representing the binding between the two GObject.Object instances. The binding is released whenever the GObject.Binding reference count reaches zero.

  • Complete version of g_object_bind_property().

    Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.

    If flags contains GObject.BindingFlags.BIDIRECTIONAL then the binding will be mutual: if target_property on target changes then the source_property on source will be updated as well. The transform_from function is only used in case of bidirectional bindings, otherwise it will be ignored

    The binding will automatically be removed when either the source or the target instances are finalized. This will release the reference that is being held on the GObject.Binding instance; if you want to hold on to the GObject.Binding instance, you will need to hold a reference to it.

    To remove the binding, call g_binding_unbind().

    A GObject.Object can have multiple bindings.

    The same user_data parameter will be used for both transform_to and transform_from transformation functions; the notify function will be called once, when the binding is removed. If you need different data for each transformation function, please use g_object_bind_property_with_closures() instead.

    Parameters

    • source_property: string

      the property on source to bind

    • target: GObject.Object

      the target GObject.Object

    • target_property: string

      the property on target to bind

    • flags: GObject.BindingFlags

      flags to pass to GObject.Binding

    • Optionaltransform_to: BindingTransformFunc

      the transformation function from the source to the target, or null to use the default

    • Optionaltransform_from: BindingTransformFunc

      the transformation function from the target to the source, or null to use the default

    • Optionalnotify: DestroyNotify

      a function to call when disposing the binding, to free resources used by the transformation functions, or null if not required

    Returns GObject.Binding

    the GObject.Binding instance representing the binding between the two GObject.Object instances. The binding is released whenever the GObject.Binding reference count reaches zero.

  • Creates a binding between source_property on source and target_property on target, allowing you to set the transformation functions to be used by the binding.

    This function is the language bindings friendly version of g_object_bind_property_full(), using GClosures instead of function pointers.

    Parameters

    Returns GObject.Binding

    the GObject.Binding instance representing the binding between the two GObject.Object instances. The binding is released whenever the GObject.Binding reference count reaches zero.

  • Disconnects a handler from an instance so it will not be called during any future or currently ongoing emissions of the signal it has been connected to.

    Parameters

    • id: number

      Handler ID of the handler to be disconnected

    Returns void

  • This function is intended for GObject.Object implementations to re-enforce a [floating][floating-ref] object reference. Doing this is seldom required: all GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink().

    Returns void

  • Increases the freeze count on object. If the freeze count is non-zero, the emission of "notify" signals on object is stopped. The signals are queued until the freeze count is decreased to zero. Duplicate notifications are squashed so that at most one GObject.Object::notify signal is emitted for each property modified while the object is frozen.

    This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.

    Returns void

  • Gets a named field from the objects table of associations (see g_object_set_data()).

    Parameters

    • key: string

      name of the key for that association

    Returns any

    the data if found, or null if no such data exists.

  • This function gets back user data pointers stored via g_object_set_qdata().

    Parameters

    • quark: number

      A GLib.Quark, naming the user data pointer

    Returns any

    The user data pointer set, or null

  • Gets n_properties properties for an object. Obtained properties will be set to values. All properties must be valid. Warnings will be emitted and undefined behaviour may result if invalid properties are passed in.

    Parameters

    • names: string[]

      the names of each property to get

    • values: any[]

      the values of each property to get

    Returns void

  • Emits a "notify" signal for the property property_name on object.

    When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

    Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

    Parameters

    • property_name: string

      the name of a property installed on the class of object.

    Returns void

  • Emits a "notify" signal for the property specified by pspec on object.

    This function omits the property name lookup, hence it is faster than g_object_notify().

    One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with g_object_class_install_property() inside a static array, e.g.:

      typedef enum
    {
    PROP_FOO = 1,
    PROP_LAST
    } MyObjectProperty;

    static GParamSpec *properties[PROP_LAST];

    static void
    my_object_class_init (MyObjectClass *klass)
    {
    properties[PROP_FOO] = g_param_spec_int ("foo", NULL, NULL,
    0, 100,
    50,
    G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
    g_object_class_install_property (gobject_class,
    PROP_FOO,
    properties[PROP_FOO]);
    }

    and then notify a change on the "foo" property with:

      g_object_notify_by_pspec (self, properties[PROP_FOO]);
    

    Parameters

    Returns void

  • Increases the reference count of object.

    Since GLib 2.56, if GLIB_VERSION_MAX_ALLOWED is 2.56 or greater, the type of object will be propagated to the return type (using the GCC typeof() extension), so any casting the caller needs to do on the return type must be explicit.

    Returns GObject.Object

    the same object

  • Increase the reference count of object, and possibly remove the [floating][floating-ref] reference, if object has a floating reference.

    In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one.

    Since GLib 2.56, the type of object will be propagated to the return type under the same conditions as for g_object_ref().

    Returns GObject.Object

    object

  • Releases all references to other objects. This can be used to break reference cycles.

    This function should only be called from object system implementations.

    Returns void

  • Sets multiple properties of an object at once. The properties argument should be a dictionary mapping property names to values.

    Parameters

    • properties: { [key: string]: any }

      Object containing the properties to set

    Returns void

  • Each object carries around a table of associations from strings to pointers. This function lets you set an association.

    If the object already had an association with that name, the old association will be destroyed.

    Internally, the key is converted to a GLib.Quark using g_quark_from_string(). This means a copy of key is kept permanently (even after object has been finalized) — so it is recommended to only use a small, bounded set of values for key in your program, to avoid the GLib.Quark storage growing unbounded.

    Parameters

    • key: string

      name of the key

    • Optionaldata: any

      data to associate with that key

    Returns void

  • Sets a property on an object.

    Parameters

    • property_name: string

      The name of the property to set

    • value: any

      The value to set the property to

    Returns void

  • Remove a specified datum from the object's data associations, without invoking the association's destroy handler.

    Parameters

    • key: string

      name of the key

    Returns any

    the data if found, or null if no such data exists.

  • This function gets back user data pointers stored via g_object_set_qdata() and removes the data from object without invoking its destroy() function (if any was set). Usually, calling this function is only required to update user data pointers with a destroy notifier, for example:

    void
    object_add_to_user_list (GObject *object,
    const gchar *new_string)
    {
    // the quark, naming the object data
    GQuark quark_string_list = g_quark_from_static_string ("my-string-list");
    // retrieve the old string list
    GList *list = g_object_steal_qdata (object, quark_string_list);

    // prepend new string
    list = g_list_prepend (list, g_strdup (new_string));
    // this changed 'list', so we need to set it again
    g_object_set_qdata_full (object, quark_string_list, list, free_string_list);
    }
    static void
    free_string_list (gpointer data)
    {
    GList *node, *list = data;

    for (node = list; node; node = node->next)
    g_free (node->data);
    g_list_free (list);
    }

    Using g_object_get_qdata() in the above example, instead of g_object_steal_qdata() would have left the destroy function set, and thus the partial string list would have been freed upon g_object_set_qdata_full().

    Parameters

    • quark: number

      A GLib.Quark, naming the user data pointer

    Returns any

    The user data pointer set, or null

  • Stops a signal's emission by the given signal name. This will prevent the default handler and any subsequent signal handlers from being invoked.

    Parameters

    • detailedName: string

      Name of the signal to stop emission of

    Returns void

  • Reverts the effect of a previous call to g_object_freeze_notify(). The freeze count is decreased on object and when it reaches zero, queued "notify" signals are emitted.

    Duplicate notifications for each property are squashed so that at most one GObject.Object::notify signal is emitted for each property, in the reverse order in which they have been queued.

    It is an error to call this function when the freeze count is zero.

    Returns void

  • Decreases the reference count of object. When its reference count drops to 0, the object is finalized (i.e. its memory is freed).

    If the pointer to the GObject.Object may be reused in future (for example, if it is an instance variable of another object), it is recommended to clear the pointer to null rather than retain a dangling pointer to a potentially invalid GObject.Object instance. Use g_clear_object() for this.

    Returns void

  • the constructed function is called by g_object_new() as the final step of the object creation process. At the point of the call, all construction properties have been set on the object. The purpose of this call is to allow for object initialisation steps that can only be performed after construction properties have been set. constructed implementors should chain up to the constructed call of their parent class to allow it to complete its initialisation.

    Returns void

  • the dispose function is supposed to drop all references to other objects, but keep the instance otherwise intact, so that client method invocations still work. It may be run multiple times (due to reference loops). Before returning, dispose should chain up to the dispose method of the parent class.

    Returns void

  • instance finalization function, should finish the finalization of the instance begun in dispose and chain up to the finalize method of the parent class.

    Returns void

  • Emits a "notify" signal for the property property_name on object.

    When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.

    Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.

    Parameters

    Returns void

  • the generic setter for all properties of this type. Should be overridden for every type with properties. If implementations of set_property don't emit property change notification explicitly, this will be done implicitly by the type system. However, if the notify signal is emitted explicitly, the type system will not emit it a second time.

    Parameters

    Returns void

  • This function essentially limits the life time of the closure to the life time of the object. That is, when the object is finalized, the closure is invalidated by calling g_closure_invalidate() on it, in order to prevent invocations of the closure with a finalized (nonexisting) object. Also, g_object_ref() and g_object_unref() are added as marshal guards to the closure, to ensure that an extra reference count is held on object during invocation of the closure. Usually, this function will be called on closures that use this object as closure data.

    Parameters

    Returns void

  • Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created GObject.ParamSpec, but normally g_object_class_override_property() will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property.

    This function is meant to be called from the interface's default vtable initialization function (the class_init member of GObject.TypeInfo.) It must not be called after after class_init has been called for any object types implementing this interface.

    If pspec is a floating reference, it will be consumed.

    Parameters

    Returns void

  • Parameters

    • property_id: number

      the new property ID

    • name: string

      the name of a property registered in a parent class or in an interface of this class.

    Returns void

Interfaces

ConstructorProps
SignalSignatures