Class (GI Class)

Gtk-3.0 ▶ Gtk ▶ CellAreaAbstract

The Gtk.CellArea is an abstract class for Gtk.CellLayout widgets (also referred to as "layouting widgets") to interface with an arbitrary number of GtkCellRenderers and interact with the user for a given Gtk.TreeModel row.

The cell area handles events, focus navigation, drawing and size requests and allocations for a given row of data.

Usually users dont have to interact with the Gtk.CellArea directly unless they are implementing a cell-layouting widget themselves.

Requesting area sizes

As outlined in [GtkWidget’s geometry management section][geometry-management], GTK+ uses a height-for-width geometry management system to compute the sizes of widgets and user interfaces. Gtk.CellArea uses the same semantics to calculate the size of an area for an arbitrary number of Gtk.TreeModel rows.

When requesting the size of a cell area one needs to calculate the size for a handful of rows, and this will be done differently by different layouting widgets. For instance a Gtk.TreeViewColumn always lines up the areas from top to bottom while a Gtk.IconView on the other hand might enforce that all areas received the same width and wrap the areas around, requesting height for more cell areas when allocated less width.

It’s also important for areas to maintain some cell alignments with areas rendered for adjacent rows (cells can appear “columnized” inside an area even when the size of cells are different in each row). For this reason the Gtk.CellArea uses a Gtk.CellAreaContext object to store the alignments and sizes along the way (as well as the overall largest minimum and natural size for all the rows which have been calculated with the said context).

The Gtk.CellAreaContext is an opaque object specific to the Gtk.CellArea which created it (see gtk_cell_area_create_context()). The owning cell-layouting widget can create as many contexts as it wishes to calculate sizes of rows which should receive the same size in at least one orientation (horizontally or vertically), However, it’s important that the same Gtk.CellAreaContext which was used to request the sizes for a given Gtk.TreeModel row be used when rendering or processing events for that row.

In order to request the width of all the rows at the root level of a Gtk.TreeModel one would do the following:

GtkTreeIter iter;
gint        minimum_width;
gint        natural_width;

valid = gtk_tree_model_get_iter_first (model, &iter);
while (valid)
  {
    gtk_cell_area_apply_attributes (area, model, &iter, FALSE, FALSE);
    gtk_cell_area_get_preferred_width (area, context, widget, NULL, NULL);

    valid = gtk_tree_model_iter_next (model, &iter);
  }
gtk_cell_area_context_get_preferred_width (context, &minimum_width, &natural_width);

Note that in this example it’s not important to observe the returned minimum and natural width of the area for each row unless the cell-layouting object is actually interested in the widths of individual rows. The overall width is however stored in the accompanying Gtk.CellAreaContext object and can be consulted at any time.

This can be useful since Gtk.CellLayout widgets usually have to support requesting and rendering rows in treemodels with an exceedingly large amount of rows. The Gtk.CellLayout widget in that case would calculate the required width of the rows in an idle or timeout source (see g_timeout_add()) and when the widget is requested its actual width in Gtk.WidgetClass.get_preferred_width() it can simply consult the width accumulated so far in the Gtk.CellAreaContext object.

A simple example where rows are rendered from top to bottom and take up the full width of the layouting widget would look like:

static void
foo_get_preferred_width (GtkWidget       *widget,
                         gint            *minimum_size,
                         gint            *natural_size)
{
  Foo        *foo  = FOO (widget);
  FooPrivate *priv = foo->priv;

  foo_ensure_at_least_one_handfull_of_rows_have_been_requested (foo);

  gtk_cell_area_context_get_preferred_width (priv->context, minimum_size, natural_size);
}

In the above example the Foo widget has to make sure that some row sizes have been calculated (the amount of rows that Foo judged was appropriate to request space for in a single timeout iteration) before simply returning the amount of space required by the area via the Gtk.CellAreaContext.

Requesting the height for width (or width for height) of an area is a similar task except in this case the Gtk.CellAreaContext does not store the data (actually, it does not know how much space the layouting widget plans to allocate it for every row. It’s up to the layouting widget to render each row of data with the appropriate height and width which was requested by the Gtk.CellArea).

In order to request the height for width of all the rows at the root level of a Gtk.TreeModel one would do the following:

GtkTreeIter iter;
gint        minimum_height;
gint        natural_height;
gint        full_minimum_height = 0;
gint        full_natural_height = 0;

valid = gtk_tree_model_get_iter_first (model, &iter);
while (valid)
  {
    gtk_cell_area_apply_attributes (area, model, &iter, FALSE, FALSE);
    gtk_cell_area_get_preferred_height_for_width (area, context, widget,
                                                  width, &minimum_height, &natural_height);

    if (width_is_for_allocation)
       cache_row_height (&iter, minimum_height, natural_height);

    full_minimum_height += minimum_height;
    full_natural_height += natural_height;

    valid = gtk_tree_model_iter_next (model, &iter);
  }

Note that in the above example we would need to cache the heights returned for each row so that we would know what sizes to render the areas for each row. However we would only want to really cache the heights if the request is intended for the layouting widgets real allocation.

In some cases the layouting widget is requested the height for an arbitrary for_width, this is a special case for layouting widgets who need to request size for tens of thousands of rows. For this case it’s only important that the layouting widget calculate one reasonably sized chunk of rows and return that height synchronously. The reasoning here is that any layouting widget is at least capable of synchronously calculating enough height to fill the screen height (or scrolled window height) in response to a single call to Gtk.WidgetClass.get_preferred_height_for_width(). Returning a perfect height for width that is larger than the screen area is inconsequential since after the layouting receives an allocation from a scrolled window it simply continues to drive the scrollbar values while more and more height is required for the row heights that are calculated in the background.

Rendering Areas

Once area sizes have been aquired at least for the rows in the visible area of the layouting widget they can be rendered at Gtk.WidgetClass.draw() time.

A crude example of how to render all the rows at the root level runs as follows:

GtkAllocation allocation;
GdkRectangle  cell_area = { 0, };
GtkTreeIter   iter;
gint          minimum_width;
gint          natural_width;

gtk_widget_get_allocation (widget, &allocation);
cell_area.width = allocation.width;

valid = gtk_tree_model_get_iter_first (model, &iter);
while (valid)
  {
    cell_area.height = get_cached_height_for_row (&iter);

    gtk_cell_area_apply_attributes (area, model, &iter, FALSE, FALSE);
    gtk_cell_area_render (area, context, widget, cr,
                          &cell_area, &cell_area, state_flags, FALSE);

    cell_area.y += cell_area.height;

    valid = gtk_tree_model_iter_next (model, &iter);
  }

Note that the cached height in this example really depends on how the layouting widget works. The layouting widget might decide to give every row its minimum or natural height or, if the model content is expected to fit inside the layouting widget without scrolling, it would make sense to calculate the allocation for each row at Gtk.Widget.SignalSignatures.size_allocate | Gtk.Widget::size-allocate time using gtk_distribute_natural_allocation().

Handling Events and Driving Keyboard Focus

Passing events to the area is as simple as handling events on any normal widget and then passing them to the gtk_cell_area_event() API as they come in. Usually Gtk.CellArea is only interested in button events, however some customized derived areas can be implemented who are interested in handling other events. Handling an event can trigger the Gtk.CellArea.SignalSignatures.focus_changed | Gtk.CellArea::focus-changed signal to fire; as well as Gtk.CellArea.SignalSignatures.add_editable | Gtk.CellArea::add-editable in the case that an editable cell was clicked and needs to start editing. You can call gtk_cell_area_stop_editing() at any time to cancel any cell editing that is currently in progress.

The Gtk.CellArea drives keyboard focus from cell to cell in a way similar to Gtk.Widget. For layouting widgets that support giving focus to cells it’s important to remember to pass Gtk.CellRendererState.FOCUSED to the area functions for the row that has focus and to tell the area to paint the focus at render time.

Layouting widgets that accept focus on cells should implement the Gtk.WidgetClass.focus() virtual method. The layouting widget is always responsible for knowing where Gtk.TreeModel rows are rendered inside the widget, so at Gtk.WidgetClass.focus() time the layouting widget should use the Gtk.CellArea methods to navigate focus inside the area and then observe the GtkDirectionType to pass the focus to adjacent rows and areas.

A basic example of how the Gtk.WidgetClass.focus() virtual method should be implemented:

static gboolean
foo_focus (GtkWidget       *widget,
           GtkDirectionType direction)
{
  Foo        *foo  = FOO (widget);
  FooPrivate *priv = foo->priv;
  gint        focus_row;
  gboolean    have_focus = FALSE;

  focus_row = priv->focus_row;

  if (!gtk_widget_has_focus (widget))
    gtk_widget_grab_focus (widget);

  valid = gtk_tree_model_iter_nth_child (priv->model, &iter, NULL, priv->focus_row);
  while (valid)
    {
      gtk_cell_area_apply_attributes (priv->area, priv->model, &iter, FALSE, FALSE);

      if (gtk_cell_area_focus (priv->area, direction))
        {
           priv->focus_row = focus_row;
           have_focus = TRUE;
           break;
        }
      else
        {
          if (direction == GTK_DIR_RIGHT ||
              direction == GTK_DIR_LEFT)
            break;
          else if (direction == GTK_DIR_UP ||
                   direction == GTK_DIR_TAB_BACKWARD)
           {
              if (focus_row == 0)
                break;
              else
               {
                  focus_row--;
                  valid = gtk_tree_model_iter_nth_child (priv->model, &iter, NULL, focus_row);
               }
            }
          else
            {
              if (focus_row == last_row)
                break;
              else
                {
                  focus_row++;
                  valid = gtk_tree_model_iter_next (priv->model, &iter);
                }
            }
        }
    }
    return have_focus;
}

Note that the layouting widget is responsible for matching the GtkDirectionType values to the way it lays out its cells.

Cell Properties

The Gtk.CellArea introduces cell properties for GtkCellRenderers in very much the same way that Gtk.Container introduces [child properties][child-properties] for GtkWidgets. This provides some general interfaces for defining the relationship cell areas have with their cells. For instance in a Gtk.CellAreaBox a cell might “expand” and receive extra space when the area is allocated more than its full natural request, or a cell might be configured to “align” with adjacent rows which were requested and rendered with the same Gtk.CellAreaContext.

Use gtk_cell_area_class_install_cell_property() to install cell properties for a cell area class and gtk_cell_area_class_find_cell_property() or gtk_cell_area_class_list_cell_properties() to get information about existing cell properties.

To set the value of a cell property, use gtk_cell_area_cell_set_property(), gtk_cell_area_cell_set() or gtk_cell_area_cell_set_valist(). To obtain the value of a cell property, use gtk_cell_area_cell_get_property(), gtk_cell_area_cell_get() or gtk_cell_area_cell_get_valist().

Hierarchy (View Summary)

Implements

Index

Constructors

constructor

Properties

$signals $gtype

Accessors

edit_widget edited_cell editedCell editWidget focus_cell focusCell

Methods

_init activate activate_cell add add_attribute add_child add_focus_sibling apply_attributes attribute_connect attribute_disconnect attribute_get_column bind_property bind_property_full block_signal_handler cell_get_property cell_set_property clear clear_attributes connect connect_after construct_child copy_context create_context custom_finished custom_tag_end custom_tag_start disconnect emit event focus force_floating foreach foreach_alloc freeze_notify get_area get_cell_allocation get_cell_at_position get_cells get_current_path_string get_data get_edit_widget get_edited_cell get_focus_cell get_focus_from_sibling get_focus_siblings get_internal_child get_name get_preferred_height get_preferred_height_for_width get_preferred_width get_preferred_width_for_height get_property get_qdata get_request_mode getv has_renderer inner_cell_area is_activatable is_floating is_focus_sibling notify notify_by_pspec pack_end pack_start parser_finished ref ref_sink remove remove_focus_sibling render reorder request_renderer run_dispose set set_buildable_property set_cell_data_func set_data set_focus_cell set_name set_property steal_data steal_qdata stop_editing stop_emission_by_name thaw_notify unblock_signal_handler unref vfunc_activate vfunc_add vfunc_add_attribute vfunc_add_child vfunc_apply_attributes vfunc_clear vfunc_clear_attributes vfunc_construct_child vfunc_constructed vfunc_copy_context vfunc_create_context vfunc_custom_finished vfunc_custom_tag_end vfunc_custom_tag_start vfunc_dispatch_properties_changed vfunc_dispose vfunc_event vfunc_finalize vfunc_focus vfunc_foreach vfunc_foreach_alloc vfunc_get_area vfunc_get_cell_property vfunc_get_cells vfunc_get_internal_child vfunc_get_name vfunc_get_preferred_height vfunc_get_preferred_height_for_width vfunc_get_preferred_width vfunc_get_preferred_width_for_height vfunc_get_property vfunc_get_request_mode vfunc_is_activatable vfunc_notify vfunc_pack_end vfunc_pack_start vfunc_parser_finished vfunc_remove vfunc_render vfunc_reorder vfunc_set_buildable_property vfunc_set_cell_data_func vfunc_set_cell_property vfunc_set_name vfunc_set_property watch_closure find_cell_property install_cell_property list_cell_properties

Methods - Inherited from GObject

_classInit compat_control find_property install_properties install_property interface_find_property interface_install_property interface_list_properties list_properties newv override_property

Constructors

Properties

$signals: Gtk.CellArea.SignalSignatures

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.

$gtype: GType<Gtk.CellArea>

Accessors

Methods

_init

  • Adds an attribute mapping to the list in cell_layout.

    The column is the column of the model to get a value from, and the attribute is the parameter on cell to be set from the value. So for example if column 2 of the model contains strings, you could have the “text” attribute of a Gtk.CellRendererText get its values from column 2.

    Parameters

    • cell: Gtk.CellRenderer

      a Gtk.CellRenderer

    • attribute: string

      an attribute on the renderer

    • column: number

      the column position on the model to get the attribute from

    Returns void

  • Applies any connected attributes to the renderers in area by pulling the values from tree_model.

    Parameters

    • tree_model: Gtk.TreeModel

      the Gtk.TreeModel to pull values from

    • iter: Gtk.TreeIter

      the Gtk.TreeIter in tree_model to apply values for

    • is_expander: boolean

      whether iter has children

    • is_expanded: boolean

      whether iter is expanded in the view and children are visible

    Returns void

  • Disconnects attribute for the renderer in area so that attribute will no longer be updated with values from the model.

    Parameters

    Returns void

  • 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

    • ...args: never[]

      the property on source to bind

    Returns any

    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.

  • Gets the value of a cell property for renderer in area.

    Parameters

    Returns void

  • Sets a cell property for renderer in area.

    Parameters

    • renderer: Gtk.CellRenderer

      a Gtk.CellRenderer inside area

    • property_name: string

      the name of the cell property to set

    • value: any

      the value to set the cell property to

    Returns void

  • 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 should be called by the area’s owning layout widget when focus is to be passed to area, or moved within area for a given direction and row data.

    Implementing Gtk.CellArea classes should implement this method to receive and navigate focus in its own way particular to how it lays out cells.

    Parameters

    Returns boolean

    true if focus remains inside area as a result of this call.

  • 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 the current Gtk.TreePath string for the currently applied Gtk.TreeIter, this is implicitly updated when gtk_cell_area_apply_attributes() is called and can be used to interact with renderers from Gtk.CellArea subclasses.

    Returns string

    The current Gtk.TreePath string for the current attributes applied to area. This string belongs to the area and should not be freed.

  • 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.

  • Gets the name of the buildable object.

    Gtk.Builder sets the name based on the [GtkBuilder UI definition][BUILDER-UI] used to construct the buildable.

    Returns string

    the name set with gtk_buildable_set_name()

  • Retrieves a cell area’s initial minimum and natural height.

    area will store some geometrical information in context along the way; when requesting sizes over an arbitrary number of rows, it’s not important to check the minimum_height and natural_height of this call but rather to consult gtk_cell_area_context_get_preferred_height() after a series of requests.

    Parameters

    Returns [number, number]

  • Retrieves a cell area’s minimum and natural height if it would be given the specified width.

    area stores some geometrical information in context along the way while calling gtk_cell_area_get_preferred_width(). It’s important to perform a series of gtk_cell_area_get_preferred_width() requests with context first and then call gtk_cell_area_get_preferred_height_for_width() on each cell area individually to get the height for width of each fully requested row.

    If at some point, the width of a single row changes, it should be requested with gtk_cell_area_get_preferred_width() again and then the full width of the requested rows checked again with gtk_cell_area_context_get_preferred_width().

    Parameters

    Returns [number, number]

  • Retrieves a cell area’s initial minimum and natural width.

    area will store some geometrical information in context along the way; when requesting sizes over an arbitrary number of rows, it’s not important to check the minimum_width and natural_width of this call but rather to consult gtk_cell_area_context_get_preferred_width() after a series of requests.

    Parameters

    Returns [number, number]

  • Retrieves a cell area’s minimum and natural width if it would be given the specified height.

    area stores some geometrical information in context along the way while calling gtk_cell_area_get_preferred_height(). It’s important to perform a series of gtk_cell_area_get_preferred_height() requests with context first and then call gtk_cell_area_get_preferred_width_for_height() on each cell area individually to get the height for width of each fully requested row.

    If at some point, the height of a single row changes, it should be requested with gtk_cell_area_get_preferred_height() again and then the full height of the requested rows checked again with gtk_cell_area_context_get_preferred_height().

    Parameters

    Returns [number, number]

  • Gets a property of an object.

    The value can be:

    • an empty GObject.Value initialized by G_VALUE_INIT, which will be automatically initialized with the expected type of the property (since GLib 2.60)
    • a GObject.Value initialized with the expected type of the property
    • a GObject.Value initialized with a type to which the expected type of the property can be transformed

    In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling GObject.Value.unset.

    Note that GObject.Object.get_property is really intended for language bindings, GObject.Object.get is much more convenient for C programming.

    Parameters

    • property_name: string

      The name of the property to get

    • value: any

      Return location for the property value. Can be an empty GObject.Value initialized by G_VALUE_INIT (auto-initialized with expected type since GLib 2.60), a GObject.Value initialized with the expected property type, or a GObject.Value initialized with a transformable type

    Returns any

  • 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

  • Returns whether the area can do anything when activated, after applying new attributes to area.

    Returns boolean

    whether area can do anything when activated.

  • 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

  • Adds the cell to the end of cell_layout. If expand is false, then the cell is allocated no more space than it needs. Any unused space is divided evenly between cells for which expand is true.

    Note that reusing the same cell renderer is not supported.

    Parameters

    Returns void

  • Packs the cell into the beginning of cell_layout. If expand is false, then the cell is allocated no more space than it needs. Any unused space is divided evenly between cells for which expand is true.

    Note that reusing the same cell renderer is not supported.

    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

  • This is a convenience function for Gtk.CellArea implementations to request size for cell renderers. It’s important to use this function to request size and then use gtk_cell_area_inner_cell_area() at render and event time since this function will add padding around the cell for focus painting.

    Parameters

    Returns [number, number]

  • 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

  • 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

  • Explicitly stops the editing of the currently edited cell.

    If canceled is true, the currently edited cell renderer will emit the ::editing-canceled signal, otherwise the the ::editing-done signal will be emitted on the current edit widget.

    See gtk_cell_area_get_edited_cell() and gtk_cell_area_get_edit_widget().

    Parameters

    • canceled: boolean

      whether editing was canceled.

    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

  • Adds an attribute mapping to the list in cell_layout.

    The column is the column of the model to get a value from, and the attribute is the parameter on cell to be set from the value. So for example if column 2 of the model contains strings, you could have the “text” attribute of a Gtk.CellRendererText get its values from column 2.

    Parameters

    • cell: Gtk.CellRenderer

      a Gtk.CellRenderer

    • attribute: string

      an attribute on the renderer

    • column: number

      the column position on the model to get the attribute from

    Returns void

  • Applies any connected attributes to the renderers in area by pulling the values from tree_model.

    Parameters

    • tree_model: Gtk.TreeModel

      the Gtk.TreeModel to pull values from

    • iter: Gtk.TreeIter

      the Gtk.TreeIter in tree_model to apply values for

    • is_expander: boolean

      whether iter has children

    • is_expanded: boolean

      whether iter is expanded in the view and children are visible

    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

  • This is sometimes needed for cases where rows need to share alignments in one orientation but may be separately grouped in the opposing orientation.

    For instance, Gtk.IconView creates all icons (rows) to have the same width and the cells theirin to have the same horizontal alignments. However each row of icons may have a separate collective height. Gtk.IconView uses this to request the heights of each row based on a context which was already used to request all the row widths that are to be displayed.

    Parameters

    Returns Gtk.CellAreaContext

  • 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

  • This should be called by the area’s owning layout widget when focus is to be passed to area, or moved within area for a given direction and row data.

    Implementing Gtk.CellArea classes should implement this method to receive and navigate focus in its own way particular to how it lays out cells.

    Parameters

    Returns boolean

  • Retrieves a cell area’s initial minimum and natural height.

    area will store some geometrical information in context along the way; when requesting sizes over an arbitrary number of rows, it’s not important to check the minimum_height and natural_height of this call but rather to consult gtk_cell_area_context_get_preferred_height() after a series of requests.

    Parameters

    Returns [number, number]

  • Retrieves a cell area’s minimum and natural height if it would be given the specified width.

    area stores some geometrical information in context along the way while calling gtk_cell_area_get_preferred_width(). It’s important to perform a series of gtk_cell_area_get_preferred_width() requests with context first and then call gtk_cell_area_get_preferred_height_for_width() on each cell area individually to get the height for width of each fully requested row.

    If at some point, the width of a single row changes, it should be requested with gtk_cell_area_get_preferred_width() again and then the full width of the requested rows checked again with gtk_cell_area_context_get_preferred_width().

    Parameters

    Returns [number, number]

  • Retrieves a cell area’s initial minimum and natural width.

    area will store some geometrical information in context along the way; when requesting sizes over an arbitrary number of rows, it’s not important to check the minimum_width and natural_width of this call but rather to consult gtk_cell_area_context_get_preferred_width() after a series of requests.

    Parameters

    Returns [number, number]

  • Retrieves a cell area’s minimum and natural width if it would be given the specified height.

    area stores some geometrical information in context along the way while calling gtk_cell_area_get_preferred_height(). It’s important to perform a series of gtk_cell_area_get_preferred_height() requests with context first and then call gtk_cell_area_get_preferred_width_for_height() on each cell area individually to get the height for width of each fully requested row.

    If at some point, the height of a single row changes, it should be requested with gtk_cell_area_get_preferred_height() again and then the full height of the requested rows checked again with gtk_cell_area_context_get_preferred_height().

    Parameters

    Returns [number, number]

  • Returns whether the area can do anything when activated, after applying new attributes to area.

    Returns boolean

  • 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

  • Adds the cell to the end of cell_layout. If expand is false, then the cell is allocated no more space than it needs. Any unused space is divided evenly between cells for which expand is true.

    Note that reusing the same cell renderer is not supported.

    Parameters

    Returns void

  • Packs the cell into the beginning of cell_layout. If expand is false, then the cell is allocated no more space than it needs. Any unused space is divided evenly between cells for which expand is true.

    Note that reusing the same cell renderer is not supported.

    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

Methods - Inherited from GObject

Static_classInit

  • 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

Interfaces

ConstructorProps
SignalSignatures