Struct NavStackState 

pub struct NavStackState { /* private fields */ }

A stack of views, one visible at a time, with the pages popped off it kept for forward.

This is SwiftUI’s NavigationStack, Qt’s StackView and WinUI’s Frame: navigation between pages. Underneath it is a History of views from the root through the current page. A popped page becomes a forward entry until a push discards that forward branch, which is what WinUI’s BackStack and ForwardStack do.

The stack owns which view is current and the lifecycle of a change: after a push, pop or replace, the outgoing view stays mounted until the NavStack’s transition finishes, so the application can animate it. The views themselves, and what a transition looks like, belong to the application.

pop keeps the root, as Qt’s StackView and UIKit’s navigation controller do; clear is the way to empty the stack. A back button is shown when depth() > 1, a forward button when forward_views() is not empty.

Implementations

impl NavStackState

pub fn new() -> Self

pub fn depth(&self) -> usize

The number of views on the stack.

pub fn is_empty(&self) -> bool

pub fn current(&self) -> Option<&AnyView>

The view on top of the stack, which is the one shown once any transition has finished.

pub fn views(&self) -> impl ExactSizeIterator<Item = &AnyView>

Every view on the stack, root first.

pub fn forward_views(&self) -> impl ExactSizeIterator<Item = &AnyView>

The views popped since the last push, nearest first: the one forward would bring back is the first.

pub fn push( &mut self, view: impl Into<AnyView>, motion: NavMotion, cx: &mut Context<'_, Self>, )

Pushes view on top of the stack and discards the forward views.

Into an empty stack this is immediate, like Qt’s initialItem. Over an existing top it starts a NavOperation::Push transition, unless motion is NavMotion::Immediate.

pub fn pop( &mut self, motion: NavMotion, cx: &mut Context<'_, Self>, ) -> Option<AnyView>

Pops the top view and returns it, starting a NavOperation::Pop transition to the view below. The view waits in forward_views.

The root is never popped: this returns None at a depth of one or less.

pub fn pop_to_root( &mut self, motion: NavMotion, cx: &mut Context<'_, Self>, ) -> Vec<AnyView>

Pops every view above the root in one NavOperation::Pop transition from the previous top, and returns them root-side first.

pub fn forward( &mut self, motion: NavMotion, cx: &mut Context<'_, Self>, ) -> Option<AnyView>

Brings back the most recently popped view, starting a NavOperation::Push transition over the current top, and returns it. None when nothing has been popped since the last push.

pub fn replace( &mut self, view: impl Into<AnyView>, motion: NavMotion, cx: &mut Context<'_, Self>, ) -> Option<AnyView>

Swaps the top view for view and returns the one replaced, starting a NavOperation::Replace transition. The forward views are kept. On an empty stack this is a push.

pub fn clear(&mut self, cx: &mut Context<'_, Self>)

Empties the stack and the forward views immediately, abandoning any running transition.

Trait Implementations

impl Default for NavStackState

fn default() -> Self

Returns the “default value” for a type.

impl EventEmitter<NavStackEvent> for NavStackState