Struct UndoAccess 

pub struct UndoAccess { /* private fields */ }

The undo half of a widget, as one embeddable field: the last UndoStatus the host published, plus at most one pending UndoRequest.

Embed it and wire the two Widget methods:

struct MyToolbar { undo: tilo_ui::UndoAccess, /* … */ }

impl Widget for MyToolbar {
    fn set_undo_status(&mut self, s: &mut dyn FnMut() -> tilo_ui::UndoStatus) { self.undo.publish(&s()); }
    fn take_undo_request(&mut self) -> Option<tilo_ui::UndoRequest> { self.undo.take_request() }
}

Then self.undo.can_undo() decides whether the control paints enabled, and self.undo.request(UndoRequest::Undo) on activation asks the host to do it.

Implementations

impl UndoAccess

pub fn new() -> UndoAccess

A fresh access with an empty history and nothing pending.

pub fn publish(&mut self, status: &UndoStatus)

Host → widget: store the status published this frame.

pub fn status(&self) -> &UndoStatus

The last published status.

pub fn can_undo(&self) -> bool

pub fn can_redo(&self) -> bool

pub fn can(&self, which: UndoRequest) -> bool

Whether the verb which is currently available — what a control’s enabled/disabled state must be derived from.

pub fn request(&mut self, which: UndoRequest) -> bool

Ask the host to perform which. Returns false — and enqueues nothing — when the verb is unavailable, so a control that somehow got activated while empty cannot make the host attempt an undo that isn’t there.

pub fn take_request(&mut self) -> Option<UndoRequest>

Widget → host: take the pending request. Rising-edge — reading clears it, so one activation produces exactly one undo.

Trait Implementations

impl Clone for UndoAccess

fn clone(&self) -> UndoAccess

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for UndoAccess

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

Formats the value using the given formatter.

impl Default for UndoAccess

fn default() -> UndoAccess

Returns the “default value” for a type.