Struct gio::ListModel

pub struct ListModel { /* private fields */ }

ListModel is an interface that represents a mutable list of GObjects. 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 notify signal). Taken together with the 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 ListModel 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 ListModel are of (or derived from) the same type. ListModelExt::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: ListModelExt::n_items() returns the number of items in the list and g_list_model_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 g_list_model_get_item() until it returns None.

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][g-main-context-push-thread-default] in effect at the time that the model was created.

Over time, it has established itself as good practice for listmodel 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 ListModelExt::item_type() and ListModelExt::n_items() respectively and be defined as such:

⚠️ The following code is in C ⚠️

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

Signals

items-changed

This signal is emitted whenever items were added to or removed from list. At position, removed items were removed and added items were added in their place.

Note: If removed != added, the positions of all later items in the model change.

Implements

ListModelExt, ListModelExtManual

Implementations

impl ListModel

pub const NONE: Option<&'static ListModel> = None

Trait Implementations

impl Clone for ListModel

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ListModel

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for ListModel

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl HasParamSpec for ListModel

type ParamSpec = ParamSpecObject

type SetValue = ListModel

Preferred value to be used as setter for the associated ParamSpec.

type BuilderFn = fn(_: &str) -> ParamSpecObjectBuilder<'_, ListModel>

fn param_spec_builder() -> Self::BuilderFn

impl Hash for ListModel

fn hash<H>(&self, state: &mut H)

where H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<'a> IntoIterator for &'a ListModel

type Item = Result<Object, ListModelMutatedDuringIter>

The type of the elements being iterated over.

type IntoIter = ListModelIter<'a, Object>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<T: ListModelImpl> IsImplementable<T> for ListModel

where <T as ObjectSubclass>::Type: IsA<Object>,

fn interface_init(iface: &mut Interface<Self>)

Override the virtual methods of this interface for the given subclass and do other interface initialization.

fn instance_init(_instance: &mut InitializingObject<T>)

Instance specific initialization.

impl Ord for ListModel

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl<OT: ObjectType> PartialEq<OT> for ListModel

fn eq(&self, other: &OT) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<OT: ObjectType> PartialOrd<OT> for ListModel

fn partial_cmp(&self, other: &OT) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl StaticType for ListModel

fn static_type() -> Type

Returns the type identifier of Self.

impl Eq for ListModel

impl IsA<ListModel> for ListStore