Struct LayerCache 

pub struct LayerCache { /* private fields */ }

A pool of off-screen render targets, keyed by layer_id: u64.

Implementations

impl LayerCache

pub fn new(max_layers: usize) -> Self

Create a new cache that holds at most max_layers layers simultaneously.

pub fn set_max_idle_frames(&mut self, frames: u64)

Set the number of idle frames after which a layer is evicted.

A larger value trades GPU memory for reduced re-render cost when a layer goes temporarily off-screen.

pub fn begin_frame(&mut self)

Advance the internal frame counter and evict any layers that have not been accessed for max_idle_frames frames.

Must be called once per frame, before any get/get_or_create calls for that frame.

pub fn get(&mut self, layer_id: u64) -> Option<&mut RenderTarget>

Look up an existing layer by layer_id.

Updates the last-access frame counter. Returns None if no layer with this id is currently cached.

pub fn get_or_create( &mut self, device: &Device, layer_id: u64, width: u32, height: u32, sample_count: u32, ) -> Result<&mut RenderTarget, UiError>

Return the RenderTarget for layer_id, creating a new one if absent.

If a new target is created it is width × height pixels with the given sample_count. If the layer already exists but has different dimensions it is not resized — the existing target is returned as-is. Call LayerCache::invalidate + LayerCache::remove then re-create if you need a different size.

When the cache is at capacity (max_layers), the LRU layer is evicted before creating the new entry.

Errors

Propagates RenderTarget::new errors.

pub fn invalidate(&mut self, layer_id: u64)

Invalidate a layer by layer_id, marking it dirty and bumping its generation counter. If the layer is not cached, this is a no-op.

pub fn invalidate_all(&mut self)

Invalidate all cached layers.

pub fn remove(&mut self, layer_id: u64)

Remove a layer by layer_id, freeing the associated GPU texture.

pub fn clear(&mut self)

Remove all cached layers, freeing all associated GPU textures.

pub fn len(&self) -> usize

Return the number of live layers currently in the cache.

pub fn is_empty(&self) -> bool

Return true if the cache is empty.

pub fn current_frame(&self) -> u64

Return the current frame counter.