Struct CoherenceCache 

pub struct CoherenceCache { /* private fields */ }

Stores previous layout allocations for temporal coherence.

When terminal size changes, the layout solver re-computes positions from scratch. Without coherence, rounding tie-breaks can cause widgets to “jump” between frames even when the total size change is small.

The CoherenceCache feeds previous allocations to round_layout_stable so that tie-breaking favours keeping elements where they were.

Usage

use ftui_layout::{CoherenceCache, CoherenceId, round_layout_stable, Constraint, Direction};

let mut coherence = CoherenceCache::new(64);

let id = CoherenceId::new(&constraints, Direction::Horizontal);
let prev = coherence.get(&id);
let alloc = round_layout_stable(&targets, total, prev);
coherence.store(id, alloc.clone());

Eviction

Entries are evicted on a least-recently-stored basis when the cache reaches capacity. The cache does not grow unboundedly.

Implementations

impl CoherenceCache

pub fn new(max_entries: usize) -> Self

Create a new coherence cache with the specified capacity.

pub fn get(&self, id: &CoherenceId) -> Option<Vec<u16>>

Retrieve the previous allocation for a layout, if available.

Returns Some(allocation) suitable for passing directly to round_layout_stable.

pub fn store(&mut self, id: CoherenceId, allocation: Vec<u16>)

Store a layout allocation for future coherence lookups.

If the cache is at capacity, evicts the oldest entry.

pub fn clear(&mut self)

Clear all stored allocations.

pub fn len(&self) -> usize

Number of entries in the cache.

pub fn is_empty(&self) -> bool

Returns true if the cache is empty.

pub fn displacement(&self, id: &CoherenceId, new_alloc: &[u16]) -> (u64, u32)

Compute displacement between a new allocation and the previously stored one.

Returns (sum_displacement, max_displacement) in cells. If no previous allocation exists for the ID, returns (0, 0).

Trait Implementations

impl Debug for CoherenceCache

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

Formats the value using the given formatter.

impl Default for CoherenceCache

fn default() -> Self

Returns the “default value” for a type.