Package ch.bailu.gtk.gio

Klasse MenuModel

java.lang.Object
ch.bailu.gtk.type.Type
ch.bailu.gtk.type.Pointer
ch.bailu.gtk.gobject.Object
ch.bailu.gtk.type.PropertyHolder
ch.bailu.gtk.gio.MenuModel
Alle implementierten Schnittstellen:
PointerInterface
Bekannte direkte Unterklassen:
DBusMenuModel, Menu
public class MenuModel extends PropertyHolder
`GMenuModel` represents the contents of a menu — an ordered list of
menu items. The items are associated with actions, which can be
activated through them. Items can be grouped in sections, and may
have submenus associated with them. Both items and sections usually
have some representation data, such as labels or icons. The type of
the associated action (ie whether it is stateful, and what kind of
state it has) can influence the representation of the item.

The conceptual model of menus in `GMenuModel` is hierarchical:
sections and submenus are again represented by `GMenuModel`s.
Menus themselves do not define their own roles. Rather, the role
of a particular `GMenuModel` is defined by the item that references
it (or, in the case of the ‘root’ menu, is defined by the context
in which it is used).

As an example, consider the visible portions of this menu:

## An example menu

![](menu-example.png)

While this kind of deeply nested menu is no longer considered good UI
practice, it serves as a good example of the concepts in `GMenuModel`.
There are 8 ‘menus’ visible in the screenshot: one menubar, two
submenus and 5 sections:

- the toplevel menubar (containing 4 items)
- the View submenu (containing 3 sections)
- the first section of the View submenu (containing 2 items)
- the second section of the View submenu (containing 1 item)
- the final section of the View submenu (containing 1 item)
- the Highlight Mode submenu (containing 2 sections)
- the Sources section (containing 2 items)
- the Markup section (containing 2 items)

The [example](#a-menu-example) illustrates the conceptual connection between
these 8 menus. Each large block in the figure represents a menu and the
smaller blocks within the large block represent items in that menu. Some
items contain references to other menus.

## A menu example

<picture>
<source srcset="menu-model-dark.svg" media="(prefers-color-scheme: dark)">
<img src="menu-model-light.svg" alt="menu model">
</picture>

Notice that the separators visible in the [example](#an-example-menu)
appear nowhere in the [menu model](#a-menu-example). This is because
separators are not explicitly represented in the menu model. Instead,
a separator is inserted between any two non-empty sections of a menu.
Section items can have labels just like any other item. In that case,
a display system may show a section header instead of a separator.

The motivation for this abstract model of application controls is
that modern user interfaces tend to make these controls available
outside the application. Examples include global menus, jumplists,
dash boards, etc. To support such uses, it is necessary to ‘export’
information about actions and their representation in menus, which
is exactly what the action group exporter and the menu model exporter do for
[iface@Gio.ActionGroup] and [class@Gio.MenuModel]. The client-side
counterparts to make use of the exported information are
[class@Gio.DBusActionGroup] and [class@Gio.DBusMenuModel].

The API of `GMenuModel` is very generic, with iterators for the
attributes and links of an item, see
[method@Gio.MenuModel.iterate_item_attributes] and
[method@Gio.MenuModel.iterate_item_links]. The ‘standard’ attributes and
link types have predefined names: `G_MENU_ATTRIBUTE_LABEL`,
`G_MENU_ATTRIBUTE_ACTION`, `G_MENU_ATTRIBUTE_TARGET`, `G_MENU_LINK_SECTION`
and `G_MENU_LINK_SUBMENU`.

Items in a `GMenuModel` represent active controls if they refer to
an action that can get activated when the user interacts with the
menu item. The reference to the action is encoded by the string ID
in the `G_MENU_ATTRIBUTE_ACTION` attribute. An action ID uniquely
identifies an action in an action group. Which action group(s) provide
actions depends on the context in which the menu model is used.
E.g. when the model is exported as the application menu of a
[`GtkApplication`](https://docs.gtk.org/gtk4/class.Application.html),
actions can be application-wide or window-specific (and thus come from
two different action groups). By convention, the application-wide actions
have names that start with `app.`, while the names of window-specific
actions start with `win.`.

While a wide variety of stateful actions is possible, the following
is the minimum that is expected to be supported by all users of exported
menu information:
- an action with no parameter type and no state
- an action with no parameter type and boolean state
- an action with string parameter type and string state

## Stateless

A stateless action typically corresponds to an ordinary menu item.

Selecting such a menu item will activate the action (with no parameter).

## Boolean State

An action with a boolean state will most typically be used with a ‘toggle’
or ‘switch’ menu item. The state can be set directly, but activating the
action (with no parameter) results in the state being toggled.

Selecting a toggle menu item will activate the action. The menu item should
be rendered as ‘checked’ when the state is true.

## String Parameter and State

Actions with string parameters and state will most typically be used to
represent an enumerated choice over the items available for a group of
radio menu items. Activating the action with a string parameter is
equivalent to setting that parameter as the state.

Radio menu items, in addition to being associated with the action, will
have a target value. Selecting that menu item will result in activation
of the action with the target value as the parameter. The menu item should
be rendered as ‘selected’ when the state of the action is equal to the
target value of the menu item.

https://docs.gtk.org/gio/class.MenuModel.html

  • Felddetails

  • Konstruktordetails

  • Methodendetails

    • getClassHandler

      public static ClassHandler getClassHandler()

    • getItemAttribute

      public boolean getItemAttribute(int item_index, @Nonnull Str attribute, @Nonnull Str format_string, Object... _ellipsis)
      Queries item at position @item_index in @model for the attribute
      specified by @attribute.

      If the attribute exists and matches the #GVariantType corresponding
      to @format_string then @format_string is used to deconstruct the
      value into the positional parameters and %TRUE is returned.

      If the attribute does not exist, or it does exist but has the wrong
      type, then the positional parameters are ignored and %FALSE is
      returned.

      This function is a mix of g_menu_model_get_item_attribute_value() and
      g_variant_get(), followed by a g_variant_unref(). As such,
      @format_string must make a complete copy of the data (since the
      #GVariant may go away after the call to g_variant_unref()). In
      particular, no '&' characters are allowed in @format_string.
      Parameter:
      item_index - the index of the item
      attribute - the attribute to query
      format_string - a #GVariant format string
      _ellipsis - positional parameters, as per @format_string
      Gibt zurück:
      %TRUE if the named attribute was found with the expected type

    • getItemAttribute

      public boolean getItemAttribute(int item_index, String attribute, String format_string, Object... _ellipsis)
      Queries item at position @item_index in @model for the attribute
      specified by @attribute.

      If the attribute exists and matches the #GVariantType corresponding
      to @format_string then @format_string is used to deconstruct the
      value into the positional parameters and %TRUE is returned.

      If the attribute does not exist, or it does exist but has the wrong
      type, then the positional parameters are ignored and %FALSE is
      returned.

      This function is a mix of g_menu_model_get_item_attribute_value() and
      g_variant_get(), followed by a g_variant_unref(). As such,
      @format_string must make a complete copy of the data (since the
      #GVariant may go away after the call to g_variant_unref()). In
      particular, no '&' characters are allowed in @format_string.
      Parameter:
      item_index - the index of the item
      attribute - the attribute to query
      format_string - a #GVariant format string
      _ellipsis - positional parameters, as per @format_string
      Gibt zurück:
      %TRUE if the named attribute was found with the expected type

    • getItemAttributeValue

      public Variant getItemAttributeValue(int item_index, @Nonnull Str attribute, @Nullable VariantType expected_type)
      Queries the item at position @item_index in @model for the attribute
      specified by @attribute.

      If @expected_type is non-%NULL then it specifies the expected type of
      the attribute. If it is %NULL then any type will be accepted.

      If the attribute exists and matches @expected_type (or if the
      expected type is unspecified) then the value is returned.

      If the attribute does not exist, or does not match the expected type
      then %NULL is returned.
      Parameter:
      item_index - the index of the item
      attribute - the attribute to query
      expected_type - the expected type of the attribute, or %NULL
      Gibt zurück:
      the value of the attribute

    • getItemAttributeValue

      public Variant getItemAttributeValue(int item_index, String attribute, @Nullable VariantType expected_type)
      Queries the item at position @item_index in @model for the attribute
      specified by @attribute.

      If @expected_type is non-%NULL then it specifies the expected type of
      the attribute. If it is %NULL then any type will be accepted.

      If the attribute exists and matches @expected_type (or if the
      expected type is unspecified) then the value is returned.

      If the attribute does not exist, or does not match the expected type
      then %NULL is returned.
      Parameter:
      item_index - the index of the item
      attribute - the attribute to query
      expected_type - the expected type of the attribute, or %NULL
      Gibt zurück:
      the value of the attribute

    • getItemLink

      public MenuModel getItemLink(int item_index, @Nonnull Str link)
      Queries the item at position @item_index in @model for the link
      specified by @link.

      If the link exists, the linked #GMenuModel is returned. If the link
      does not exist, %NULL is returned.
      Parameter:
      item_index - the index of the item
      link - the link to query
      Gibt zurück:
      the linked #GMenuModel, or %NULL

    • getItemLink

      public MenuModel getItemLink(int item_index, String link)
      Queries the item at position @item_index in @model for the link
      specified by @link.

      If the link exists, the linked #GMenuModel is returned. If the link
      does not exist, %NULL is returned.
      Parameter:
      item_index - the index of the item
      link - the link to query
      Gibt zurück:
      the linked #GMenuModel, or %NULL

    • getNItems

      public int getNItems()
      Query the number of items in @model.
      Gibt zurück:
      the number of items

    • isMutable

      public boolean isMutable()
      Queries if @model is mutable.

      An immutable #GMenuModel will never emit the #GMenuModel::items-changed
      signal. Consumers of the model may make optimisations accordingly.
      Gibt zurück:
      %TRUE if the model is mutable (ie: "items-changed" may be emitted).

    • itemsChanged

      public void itemsChanged(int position, int removed, int added)
      Requests emission of the #GMenuModel::items-changed signal on @model.

      This function should never be called except by #GMenuModel
      subclasses. Any other calls to this function will very likely lead
      to a violation of the interface of the model.

      The implementation should update its internal representation of the
      menu before emitting the signal. The implementation should further
      expect to receive queries about the new state of the menu (and
      particularly added menu items) while signal handlers are running.

      The implementation must dispatch this call directly from a mainloop
      entry and not in response to calls -- particularly those from the
      #GMenuModel API. Said another way: the menu must not change while
      user code is running without returning to the mainloop.
      Parameter:
      position - the position of the change
      removed - the number of items removed
      added - the number of items added

    • iterateItemAttributes

      public MenuAttributeIter iterateItemAttributes(int item_index)
      Creates a #GMenuAttributeIter to iterate over the attributes of
      the item at position @item_index in @model.

      You must free the iterator with g_object_unref() when you are done.
      Parameter:
      item_index - the index of the item
      Gibt zurück:
      a new #GMenuAttributeIter

    • iterateItemLinks

      public MenuLinkIter iterateItemLinks(int item_index)
      Creates a #GMenuLinkIter to iterate over the links of the item at
      position @item_index in @model.

      You must free the iterator with g_object_unref() when you are done.
      Parameter:
      item_index - the index of the item
      Gibt zurück:
      a new #GMenuLinkIter

    • onItemsChanged

      public SignalHandler onItemsChanged(MenuModel.OnItemsChanged signal)
      Connect to signal "items-changed".
      See MenuModel.OnItemsChanged.onItemsChanged(int, int, int) for signal description.
      Field SIGNAL_ON_ITEMS_CHANGED contains original signal name and can be used as resource reference.
      Parameter:
      signal - callback function (lambda).
      Gibt zurück:
      SignalHandler. Can be used to disconnect signal and to release callback function.

    • getTypeID

      public static long getTypeID()

    • getParentTypeID

      public static long getParentTypeID()

    • getTypeSize

      public static TypeSystem.TypeSize getTypeSize()

    • getParentTypeSize

      public static TypeSystem.TypeSize getParentTypeSize()

    • getInstanceSize

      public static int getInstanceSize()