Struct Virtualized 

pub struct Virtualized<T> { /* private fields */ }

A virtualized content container that tracks scroll state and computes visible ranges.

Design Rationale

• Generic over item type for flexibility
• Supports both owned storage and external data sources
• Computes visible ranges for O(visible) rendering
• Optional overscan for smooth scrolling
• Momentum scrolling support

Implementations

impl<T> Virtualized<T>

pub fn new(capacity: usize) -> Self

Create a new virtualized container with owned storage.

Arguments

• capacity - Maximum items to retain in memory.

pub fn external(len: usize, cache_capacity: usize) -> Self

Create with external storage reference.

pub fn with_item_height(self, height: ItemHeight) -> Self

Set item height strategy.

pub fn with_fixed_height(self, height: u16) -> Self

Set fixed item height.

pub fn with_variable_heights_fenwick( self, default_height: u16, capacity: usize, ) -> Self

Set variable heights with O(log n) Fenwick tree tracking.

This is more efficient than Variable(HeightCache) for large lists as scroll-to-index mapping is O(log n) instead of O(visible).

pub fn with_overscan(self, overscan: usize) -> Self

Set overscan amount.

pub fn with_follow(self, follow: bool) -> Self

Enable follow mode.

pub fn len(&self) -> usize

Get total number of items.

pub fn is_empty(&self) -> bool

Check if empty.

pub fn scroll_offset(&self) -> usize

Get current scroll offset.

pub fn visible_count(&self) -> usize

Get current visible count (from last render).

pub fn follow_mode(&self) -> bool

Check if follow mode is enabled.

pub fn visible_range(&self, viewport_height: u16) -> Range<usize>

Calculate visible range for given viewport height.

pub fn render_range(&self, viewport_height: u16) -> Range<usize>

Get render range with overscan for smooth scrolling.

pub fn scroll(&mut self, delta: i32)

Scroll by delta (positive = down/forward).

pub fn scroll_to(&mut self, idx: usize)

Scroll to specific item index.

pub fn scroll_to_bottom(&mut self)

Scroll to bottom.

pub fn scroll_to_top(&mut self)

Scroll to top.

pub fn scroll_to_start(&mut self)

Alias for scroll_to_top (Home key).

pub fn scroll_to_end(&mut self)

Scroll to bottom and enable follow mode (End key).

pub fn page_up(&mut self)

Page up (scroll by visible count - 1).

pub fn page_down(&mut self)

Page down (scroll by visible count - 1).

pub fn set_follow(&mut self, follow: bool)

Set follow mode.

pub fn is_at_bottom(&self) -> bool

Check if scrolled to bottom.

pub fn fling(&mut self, velocity: f32)

Start momentum scroll.

pub fn tick(&mut self, dt: Duration)

Apply momentum scroll tick.

pub fn set_visible_count(&mut self, count: usize)

Update visible count (called during render).

impl<T> Virtualized<T>

pub fn push(&mut self, item: T)

Push an item (owned storage only).

pub fn get(&self, idx: usize) -> Option<&T>

Get item by index (owned storage only).

pub fn get_mut(&mut self, idx: usize) -> Option<&mut T>

Get mutable item by index (owned storage only).

pub fn clear(&mut self)

Clear all items (owned storage only).

pub fn trim_front(&mut self, max: usize) -> usize

Trim items from the front to keep at most max items (owned storage only).

Returns the number of items removed.

pub fn iter(&self) -> Box<dyn Iterator<Item = &T> + '_>

Iterate over items (owned storage only). Returns empty iterator for external storage.

pub fn set_external_len(&mut self, len: usize)

Update external storage length.

Trait Implementations

impl<T: Clone> Clone for Virtualized<T>

fn clone(&self) -> Virtualized<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for Virtualized<T>

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

Formats the value using the given formatter.