Package ch.bailu.gtk.gio

Klasse ListModel

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.type.Interface
ch.bailu.gtk.gio.ListModel
Alle implementierten Schnittstellen:
PointerInterface
public class ListModel extends Interface
`GListModel` is an interface that represents a mutable list of
[class@GObject.Object]. Its main intention is as a model for various widgets
in user interfaces, such as list views, but it can also be used as a
convenient method of returning lists of data, with support for
updates.

Each object in the list may also report changes in itself via some
mechanism (normally the [signal@GObject.Object::notify] signal). Taken
together with the [signal@Gio.ListModel::items-changed] signal, this provides
for a list that can change its membership, and in which the members can
change their individual properties.

A good example would be the list of visible wireless network access
points, where each access point can report dynamic properties such as
signal strength.

It is important to note that the `GListModel` itself does not report
changes to the individual items. It only reports changes to the list
membership. If you want to observe changes to the objects themselves
then you need to connect signals to the objects that you are
interested in.

All items in a `GListModel` are of (or derived from) the same type.
[method@Gio.ListModel.get_item_type] returns that type. The type may be an
interface, in which case all objects in the list must implement it.

The semantics are close to that of an array:
[method@Gio.ListModel.get_n_items] returns the number of items in the list
and [method@Gio.ListModel.get_item] returns an item at a (0-based) position.
In order to allow implementations to calculate the list length lazily,
you can also iterate over items: starting from 0, repeatedly call
[method@Gio.ListModel.get_item] until it returns `NULL`.

An implementation may create objects lazily, but must take care to
return the same object for a given position until all references to
it are gone.

On the other side, a consumer is expected only to hold references on
objects that are currently ‘user visible’, in order to facilitate the
maximum level of laziness in the implementation of the list and to
reduce the required number of signal connections at a given time.

This interface is intended only to be used from a single thread. The
thread in which it is appropriate to use it depends on the particular
implementation, but typically it will be from the thread that owns
the thread-default main context (see
[method@GLib.MainContext.push_thread_default]) in effect at the time that the
model was created.

Over time, it has established itself as good practice for list model
implementations to provide properties `item-type` and `n-items` to
ease working with them. While it is not required, it is recommended
that implementations provide these two properties. They should return
the values of [method@Gio.ListModel.get_item_type] and
[method@Gio.ListModel.get_n_items] respectively and be defined as such:

```c
properties[PROP_ITEM_TYPE] =
g_param_spec_gtype ("item-type", NULL, NULL, G_TYPE_OBJECT,
G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS);
properties[PROP_N_ITEMS] =
g_param_spec_uint ("n-items", NULL, NULL, 0, G_MAXUINT, 0,
G_PARAM_READABLE | G_PARAM_STATIC_STRINGS);
```

https://docs.gtk.org/gio/iface.ListModel.html

  • Felddetails

  • Konstruktordetails

  • Methodendetails

    • getClassHandler

      public static ClassHandler getClassHandler()

    • getItem

      public Pointer getItem(int position)
      Get the item at @position.

      If @position is greater than the number of items in @list, %NULL is
      returned.

      %NULL is never returned for an index that is smaller than the length
      of the list.

      See also: g_list_model_get_n_items()
      Parameter:
      position - the position of the item to fetch
      Gibt zurück:
      the item at @position.

    • getItemType

      public long getItemType()
      Gets the type of the items in @list.

      All items returned from g_list_model_get_item() are of the type
      returned by this function, or a subtype, or if the type is an
      interface, they are an implementation of that interface.

      The item type of a #GListModel can not change during the life of the
      model.
      Gibt zurück:
      the #GType of the items contained in @list.

    • getNItems

      public int getNItems()
      Gets the number of items in @list.

      Depending on the model implementation, calling this function may be
      less efficient than iterating the list with increasing values for
      @position until g_list_model_get_item() returns %NULL.
      Gibt zurück:
      the number of items in @list.

    • getObject

      public Object getObject(int position)
      Get the item at @position.

      If @position is greater than the number of items in @list, %NULL is
      returned.

      %NULL is never returned for an index that is smaller than the length
      of the list.

      This function is meant to be used by language bindings in place
      of g_list_model_get_item().

      See also: g_list_model_get_n_items()
      Parameter:
      position - the position of the item to fetch
      Gibt zurück:
      the object at @position.

    • itemsChanged

      public void itemsChanged(int position, int removed, int added)
      Emits the #GListModel::items-changed signal on @list.

      This function should only be called by classes implementing
      #GListModel. It has to be called after the internal representation
      of @list has been updated, because handlers connected to this signal
      might query the new state of the list.

      Implementations must only make changes to the model (as visible to
      its consumer) in places that will not cause problems for that
      consumer. For models that are driven directly by a write API (such
      as #GListStore), changes can be reported in response to uses of that
      API. For models that represent remote data, changes should only be
      made from a fresh mainloop dispatch. It is particularly not
      permitted to make changes in response to a call to the #GListModel
      consumer API.

      Stated another way: in general, it is assumed that code making a
      series of accesses to the model via the API, without returning to the
      mainloop, and without calling other code, will continue to view the
      same contents of the model.
      Parameter:
      position - the position at which @list changed
      removed - the number of items removed
      added - the number of items added

    • onItemsChanged

      public SignalHandler onItemsChanged(ListModel.OnItemsChanged signal)
      Connect to signal "items-changed".
      See ListModel.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()