Struct ViewportWidget 

pub struct ViewportWidget { /* private fields */ }

The retained widget for a CustomScrollView: the children’s pods and what the last layout decided for each, the scroll position, and the shared scroll core (the module docs).

Implementations

impl ViewportWidget

pub fn offset(&self) -> f64

The current scroll position (in range unless a drag, settle or simulation holds it past an edge).

pub fn max_offset(&self) -> f64

The largest in-range scroll position: the children’s summed scroll extent less the viewport extent, never negative.

pub fn axis(&self) -> ScrollAxis

The axis this viewport scrolls along.

pub fn sliver_count(&self) -> usize

How many children the viewport holds.

pub fn sliver_geometry(&self, index: usize) -> Option<SliverGeometry>

The geometry child index reported from the last layout — the box adapter’s geometry for a child laid out as a box — or None past the last child.

pub fn is_flinging(&self) -> bool

Whether post-release motion is in flight (a fling or a simulation).

Trait Implementations

impl Widget for ViewportWidget

fn layout(&mut self, ctx: &mut LayoutCtx<'_>, bc: &BoxConstraints) -> Size

Choose a size within bc and return it. Under a render root the call may be skipped (see ChildPod::layout_child), so the result must depend only on bc, the context’s globals and state changed through a pod-dirtying channel: a LAYOUT rebuild, request_layout, an unpaced frame request, or a handled / redraw-requesting event.

fn paint(&mut self, ctx: &mut PaintCtx<'_>, scene: &mut dyn PaintScene)

Emit draw commands into scene. Paint may advance animation state; it must then call PaintCtx::request_frame until the animation rests.

fn event(&mut self, ctx: &mut EventCtx<'_>, event: &InputEvent) -> EventResult

Handle an input event and report whether it was consumed; defaults to EventResult::Ignored. Containers forward via ChildPod::event_child.

fn semantics(&self, ctx: &mut SemanticsCtx)

Contribute accessibility node(s) after layout; defaults to none. A container forwards via ChildPod::semantics_child.

fn visit_children(&self, visitor: &mut dyn FnMut(&ChildPod))

Visit this widget’s owned ChildPods in paint order, for read-only tooling; defaults to none and must not mutate pass state.

fn type_name(&self) -> &'static str

This widget’s concrete type name, for diagnostics only (docs/LIMITATIONS.md focus-wrapper-erasure-swap-blind); override only in a transparent wrapper.

fn is_focusable(&self) -> bool

Whether keyboard traversal (Tab / Shift+Tab at the root) may stop on this widget’s pod.

fn visit_focus_children(&self, visitor: &mut dyn FnMut(&ChildPod))

Visit the children traversal may enter, in focus order; defaults to Widget::visit_children. A container showing only some children narrows it.

fn as_sliver(&mut self) -> Option<&mut (dyn SliverWidget + 'static)>

This widget as a sliver (crate::sliver), if it speaks that protocol. Defaults to None; transparent wrappers forward it.