Struct CumulativeHeightCache 

pub struct CumulativeHeightCache { /* private fields */ }

Prefix-sum cumulative height cache.

Stores per-row heights and lazily rebuilds a prefix-sum array whenever the heights are mutated. All lookup operations are O(log n) via binary search.

Implementations

impl CumulativeHeightCache

pub fn new() -> Self

Create an empty, dirty cache.

pub fn set_heights(&mut self, heights: Vec<f32>)

Replace all row heights with heights. Marks the cache dirty.

pub fn set_uniform_height(&mut self, row_count: usize, height: f32)

Set row_count rows all to the same height. Marks the cache dirty.

pub fn mark_dirty(&mut self)

Mark the cache dirty so the prefix-sum array is rebuilt on the next access.

pub fn row_at_offset(&mut self, y: f32) -> usize

Find the row index whose vertical span contains offset y. O(log n).

Returns 0 when the cache is empty or y < 0.

pub fn row_y_range(&mut self, row: usize) -> (f32, f32)

Return the (top, bottom) Y-coordinate range for row.

pub fn visible_range( &mut self, viewport_y: f32, viewport_height: f32, ) -> Range<usize>

Return the range of row indices at least partially visible in the viewport [viewport_y, viewport_y + viewport_height).

pub fn total_height(&mut self) -> f32

Total height of all rows in logical pixels.

pub fn row_count(&self) -> usize

Number of rows in the cache.

Trait Implementations

impl Default for CumulativeHeightCache

fn default() -> Self

Returns the “default value” for a type.