Struct GpuStateManager 

pub struct GpuStateManager {
    pub caches: BTreeMap<DomId, GpuValueCache>,
    pub fade_delay: Duration,
    pub fade_duration: Duration,
    pub scrollbar_fade_active: bool,
    pub pending_changes: GpuEventChanges,
}

Manages GPU-accelerated properties across all DOMs.

The GpuStateManager maintains caches for transform and opacity keys that are used by the GPU renderer. It handles:

• Scrollbar thumb position transforms (updated on scroll)
• Opacity fading for scrollbars (fade in on activity, fade out after delay)
• Per-DOM GPU value caches for efficient rendering

Fields

caches: BTreeMap<DomId, GpuValueCache>

GPU value caches indexed by DOM ID

fade_delay: Duration

Delay before scrollbars start fading out after last activity

fade_duration: Duration

Duration of the fade-out animation

scrollbar_fade_active: bool

Whether any scrollbar has non-zero opacity and needs continued frame generation. Set during both the fade_delay period (opacity == 1.0) and the active fade-out phase (0 < opacity < 1). Set by LayoutWindow::synchronize_scrollbar_opacity, read by the platform render loop.

pending_changes: GpuEventChanges

GPU events produced during layout (CSS transform / opacity synchronization, scrollbar transform / opacity updates) that have not yet been pushed to the renderer. Drained by the platform render path when a transaction is built.

Implementations

impl GpuStateManager

pub fn new(fade_delay: Duration, fade_duration: Duration) -> Self

Creates a new GPU state manager with specified fade timing.

pub fn take_pending_changes(&mut self) -> GpuEventChanges

Take any queued transform / opacity events that have been accumulated during layout. Clears the internal buffer.

pub fn get_cache(&self, dom_id: DomId) -> Option<&GpuValueCache>

Gets or creates the GPU cache for a specific DOM.

pub fn get_or_create_cache(&mut self, dom_id: DomId) -> &mut GpuValueCache

pub fn update_scrollbar_transforms( &mut self, dom_id: DomId, scroll_manager: &ScrollManager, layout_tree: &LayoutTree, ) -> GpuEventChanges

Updates scrollbar thumb transforms based on current scroll positions.

Calculates the transform needed to position scrollbar thumbs correctly based on the scroll offset and content/container sizes. Returns the GPU event changes that need to be applied by the renderer.

Trait Implementations

impl Clone for GpuStateManager

fn clone(&self) -> GpuStateManager

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for GpuStateManager

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

Formats the value using the given formatter.

impl Default for GpuStateManager

fn default() -> Self

Returns the “default value” for a type.

impl NodeIdRemap for GpuStateManager

fn remap_node_ids(&mut self, dom: DomId, map: &NodeIdMap)

Remap the per-node GPU caches (transform / opacity keys and values).

Without this, a rebuild that shifts NodeIds left the scrollbar/CSS transform + opacity keys attached to the wrong node — the visible symptom being a scrollbar thumb (or an animated element) that keeps painting at a stale offset, plus scrollbar_fade_active never settling because the platform loop keeps generating frames for a node that is not the one actually scrolling.