Struct SliverGeometry 

pub struct SliverGeometry {
    pub scroll_extent: f64,
    pub paint_extent: f64,
    pub paint_origin: f64,
    pub layout_extent: f64,
    pub max_paint_extent: f64,
    pub hit_test_extent: f64,
    pub visible: bool,
    pub has_visual_overflow: bool,
    pub scroll_offset_correction: Option<f64>,
    pub cache_extent: f64,
}

The sliver protocol a scrolling viewport lays its children out with — a widget implements SliverWidget and overrides Widget::as_sliver to answer SliverConstraints with a SliverGeometry; a viewport lays such a child out through ChildPod::layout_sliver_child. Lifted so an app’s own sliver needs no direct frust-core dependency. What a sliver reports back from layout: how far it scrolls, how much of the viewport it painted, and where the next sliver starts — Flutter’s SliverGeometry.

All extents are logical pixels along the constraints’ axis.

Fields

scroll_extent: f64

The (estimated) total scrollable extent of the sliver’s content (Flutter’s scrollExtent).

paint_extent: f64

How much of the remaining paint extent the sliver painted — its visible size along the axis (Flutter’s paintExtent).

paint_origin: f64

Where the sliver’s first visible pixel sits relative to its layout position, e.g. negative to paint over an earlier sliver (Flutter’s paintOrigin).

layout_extent: f64

The distance from this sliver’s first visible pixel to the next sliver’s — usually paint_extent; less for a sliver the next one should overlap (Flutter’s layoutExtent).

max_paint_extent: f64

The (estimated) paint extent the sliver would provide given infinite remaining paint extent (Flutter’s maxPaintExtent).

hit_test_extent: f64

The distance from the paint start to the end of the region that accepts hits — usually paint_extent (Flutter’s hitTestExtent).

visible: bool

Whether the sliver should be painted at all — usually paint_extent > 0 (Flutter’s visible).

has_visual_overflow: bool

Whether the sliver painted outside its paint extent, so the viewport must clip it (Flutter’s hasVisualOverflow).

scroll_offset_correction: Option<f64>

A non-zero amount the viewport must adjust its scroll offset by before re-running the whole layout, when the sliver found its earlier extent estimate wrong (Flutter’s scrollOffsetCorrection).

cache_extent: f64

How much of the remaining cache extent the sliver consumed — at least layout_extent (Flutter’s cacheExtent).

Implementations

impl SliverGeometry

pub const ZERO: SliverGeometry

The geometry of an empty sliver: no extent of any kind and not visible (Flutter’s SliverGeometry.zero).

pub fn new( scroll_extent: f64, paint_extent: f64, max_paint_extent: f64, ) -> SliverGeometry

A geometry with Flutter’s constructor defaults for everything but the three extents: layout_extent and hit_test_extent equal paint_extent, cache_extent equals layout_extent, visible is paint_extent > 0, and the rest is zero.

pub fn debug_assert_valid(&self, constraints: &SliverConstraints)

Debug-assert the geometry is well formed and fits constraints — Flutter’s SliverGeometry.debugAssertIsValid plus the paint-extent check of RenderSliver.debugAssertDoesMeetConstraints.

Checks that scroll_extent, paint_extent, layout_extent, cache_extent and hit_test_extent are non-negative (NaN fails); that layout_extent <= paint_extent, paint_extent <= max_paint_extent, paint_extent <= constraints.remaining_paint_extent and layout_extent <= cache_extent, each within PRECISION_ERROR_TOLERANCE; and that a scroll_offset_correction is finite and non-zero. Compiles to nothing without debug_assertions.

Trait Implementations

impl Clone for SliverGeometry

fn clone(&self) -> SliverGeometry

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for SliverGeometry

impl Debug for SliverGeometry

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

Formats the value using the given formatter.

impl PartialEq for SliverGeometry

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for SliverGeometry