Struct ScrollViewport 

pub struct ScrollViewport { /* private fields */ }

A handle to the enclosing scroll area’s live viewport, handed to the content builder by LayoutScrollArea::new_with. Because a scroll area lays its content out as its OWN layout root, every descendant’s tracked rect is already in the same content-local space the scroll offset indexes into — so visible is a plain rect overlap, no scroll-transform math.

Implementations

impl ScrollViewport

pub fn offset(&self) -> (ReadSignal<f32>, ReadSignal<f32>)

The live scroll offset (x, y) in content-local px.

pub fn reveal(&self, item: NodeId, margin: f32)

Scrolls the minimum distance needed to bring item fully into view, leaving margin px of breathing room at whichever edge it entered from. A no-op when the item is already visible.

This is what keyboard navigation needs and what a scroll offset alone cannot express: moving a selection down a list should follow it, without yanking the view when the item was on screen all along. item must be a node inside this scroll’s content, so its tracked rect shares the content-local space the offset indexes into.

pub fn rect(&self) -> ReadSignal<Rect>

The live viewport rect; its width/height are the visible window’s size.

pub fn scroll_to_top(&self)

Puts the view back at the top-left.

For content that has been replaced rather than resized — a page swapped for another one — which is the one thing the scroll area cannot tell on its own: a shorter page is clamped back into range automatically, but only the caller knows that what is in the viewport is now a different thing, and that being three screens down someone else’s page is not where the reader left off.

peek for the same reason as reveal, and this is where it bites hardest: “the page changed” is noticed by an effect, so a reactive read of the offset would make every wheel tick re-run the effect that puts the offset back — the viewport pinned to the top for good.

Trait Implementations

impl Clone for ScrollViewport

fn clone(&self) -> ScrollViewport

Returns a duplicate of the value.

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

Performs copy-assignment from source.