Struct druid::WidgetId

pub struct WidgetId(_);

A unique identifier for a single Widget.

WidgetIds are generated automatically for all widgets that participate in layout. More specifically, each WidgetPod has a unique WidgetId.

These ids are used internally to route events, and can be used to communicate between widgets, by submitting a command (as with EventCtx::submit_command) and passing a WidgetId as the Target.

A widget can retrieve its id via methods on the various contexts, such as LifeCycleCtx::widget_id.

Explicit WidgetIds.

Sometimes, you may want to know a widget's id when constructing the widget. You can give a widget an explicit id by wrapping it in an IdentityWrapper widget, or by using the WidgetExt::with_id convenience method.

If you set a WidgetId directly, you are resposible for ensuring that it is unique in time. That is: only one widget can exist with a given id at a given time.

Implementations

impl WidgetId

pub fn next() -> WidgetId

Allocate a new, unique WidgetId.

All widgets are assigned ids automatically; you should only create an explicit id if you need to know it ahead of time, for instance if you want two sibling widgets to know each others' ids.

You must ensure that a given WidgetId is only ever used for one widget at a time.

pub const fn reserved(raw: u16) -> WidgetId

Create a reserved WidgetId, suitable for reuse.

The caller is responsible for ensuring that this ID is in fact assigned to a single widget at any time, or your code may become haunted.

The actual inner representation of the returned WidgetId will not be the same as the raw value that is passed in; it will be u64::max_value() - raw.

Trait Implementations

impl Clone for WidgetId

fn clone(&self) -> WidgetId

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Copy for WidgetId

impl Debug for WidgetId

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

Formats the value using the given formatter.

impl Eq for WidgetId

impl From<WidgetId> for Target

fn from(id: WidgetId) -> Target

Performs the conversion.

impl Hash for WidgetId

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

Feeds this value into the given [Hasher].

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

Feeds a slice of this type into the given [Hasher].

impl Into<Option<Target>> for WidgetId

fn into(self) -> Option<Target>

Performs the conversion.

impl PartialEq<WidgetId> for WidgetId

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

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

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

This method tests for !=.

impl StructuralEq for WidgetId

impl StructuralPartialEq for WidgetId