Struct SparseVirtualViewport 

pub struct SparseVirtualViewport<K> { /* private fields */ }

Virtual geometry for collections whose logical item count is much larger than the set of resident keys.

Unlike VirtualViewport, this type does not store one entry per logical row. Unmeasured rows share an estimate; only measured stable keys and their prefix-sum deltas consume memory. The owning model resolves keys at visible indices and indices for measured/anchored keys during reconciliation.

Implementations

impl<K> SparseVirtualViewport<K>

where K: Clone + Eq + Hash,

pub fn new(estimated_height: f64) -> SparseVirtualViewport<K>

pub fn set_edges(&mut self, lead: f64, trail: f64) -> bool

Leave lead above the first item and trail below the last, as a page’s padding is: the content’s, scrolled with the items, and hitting none. A view showing the lead (at its top) stays at its top; one scrolled past it keeps the items in view where they are. Whether they changed.

pub const fn edges(&self) -> (f64, f64)

The space above the first item and below the last.

pub fn len(&self) -> usize

pub fn is_empty(&self) -> bool

pub fn resident_measurements(&self) -> usize

pub fn estimated_height(&self) -> f64

pub fn set_estimated_height(&mut self, height: f64)

pub fn set_minimum_height(&mut self, height: f64)

Set a geometry floor without discarding authored estimates or stable measured heights. Lowering the floor restores those original values.

pub fn minimum_height(&self) -> f64

pub fn set_viewport(&mut self, height: f64)

pub fn viewport(&self) -> f64

pub fn set_overscan(&mut self, pixels: f64)

pub fn overscan(&self) -> f64

pub fn offset(&self) -> f64

pub fn set_offset(&mut self, offset: f64)

pub fn scroll_by(&mut self, delta: f64)

pub fn content_extent(&self) -> f64

pub fn max_offset(&self) -> f64

pub fn capture_anchor<F>(&self, key_at: F) -> Option<SparseAnchor<K>>

where F: FnMut(usize) -> Option<K>,

Capture the first visible stable key before a model mutation.

pub fn reconcile<F>( &mut self, count: usize, index_of: F, anchor: Option<&SparseAnchor<K>>, )

where F: FnMut(&K) -> Option<usize>,

Reconcile a new logical count. index_of is called only for resident measured keys and the captured anchor, never for every logical row.

pub fn is_measured(&self, key: &K) -> bool

Whether key has a measured height: a row that has been laid out, as against one that stands at the estimate.

pub fn measure(&mut self, index: usize, key: K, height: f64) -> bool

Store a measured height for the stable key currently at index.

pub fn collapse(&mut self, index: usize, key: K) -> bool

Cache a row folded away as taking no room at all: a closed group’s rows stand on the same offset, under their heading’s band.

pub fn expand(&mut self, index: usize, key: &K) -> bool

Forget a row’s folded-away measurement: it takes the room it measures again, as a row that was never folded does. Self::collapse’s other half.

pub fn remap_key(&mut self, old: &K, new: K) -> bool

Move a resident measurement to a replacement stable key without changing its logical position. Useful when a placeholder resolves to a real model id.

pub fn item_height(&self, index: usize) -> Option<f64>

pub fn item_top(&self, index: usize) -> Option<f64>

pub fn item_view_top(&self, index: usize) -> Option<f64>

pub fn visible_range(&self) -> Range<usize>

pub fn range_around(&self, above: f64, below: f64) -> Range<usize>

Half-open item range intersecting the viewport stretched above pixels up and below pixels down.

pub fn hit_test(&self, viewport_y: f64) -> Option<usize>

pub fn scroll_to_index( &mut self, index: usize, alignment: ScrollAlignment, ) -> bool

Trait Implementations

impl<K> Clone for SparseVirtualViewport<K>

where K: Clone,

fn clone(&self) -> SparseVirtualViewport<K>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<K> Debug for SparseVirtualViewport<K>

where K: Debug,

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

Formats the value using the given formatter.