Struct VirtualViewport 

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

Variable-height virtual collection geometry, keyed by model identity.

Implementations

impl<K> VirtualViewport<K>

where K: Clone + Eq + Hash,

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

Create an empty viewport. Estimates and measurements are clamped to at least one logical pixel so prefix sums remain strictly increasing.

pub fn len(&self) -> usize

pub fn is_empty(&self) -> bool

pub fn estimated_height(&self) -> f64

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

Change the fallback height for rows that have not been measured. The first visible stable key stays at the same screen position.

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 content_extent(&self) -> f64

pub fn max_offset(&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 reconcile<I>(&mut self, keys: I) -> Result<(), ReconcileError>

where I: IntoIterator<Item = K>,

Replace model order while retaining measurements and the visible anchor by stable key.

Errors

Returns ReconcileError::DuplicateKey without changing the viewport when keys contains duplicates.

pub fn key(&self, index: usize) -> Option<&K>

pub fn index_of(&self, key: &K) -> Option<usize>

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>

Top of an item in viewport coordinates (0 is the viewport’s top).

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

Cache a measured height. Returns whether geometry changed.

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

Cache a measured height by stable key. Returns whether geometry changed.

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

Half-open item range intersecting the viewport plus pixel overscan.

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

Resolve a y coordinate relative to the viewport top to an item index.

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

Trait Implementations

impl<K> Clone for VirtualViewport<K>

where K: Clone,

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<K> Debug for VirtualViewport<K>

where K: Debug,

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

Formats the value using the given formatter.