Struct PresetManager 

pub struct PresetManager {
    preset_queue: VecDeque<PathBuf>,
    current_index: usize,
    transition: TransitionState,
    history: History<PathBuf>,
    locked: bool,
    mode: SelectionMode,
    ratings: HashMap<PathBuf, u8>,
    ratings_path: Option<PathBuf>,
}

Preset manager handling library navigation, mode/lock/ratings, and crossfade transitions.

Fields

preset_queue: VecDeque<PathBuf>

Library queue — populated at startup by walking the preset dir.

current_index: usize

Cursor into preset_queue. Sequential navigation walks this; random navigation rewrites it before reading.

transition: TransitionState

Crossfade transition state.

history: History<PathBuf>

History ring — records every preset actually loaded via [advance] (and friends) so Backspace can walk back through what the user has seen, not just the queue order.

locked: bool

Scroll Lock state. When true, [advance] / [retreat] return None so the engine keeps showing the current preset.

mode: SelectionMode

Random vs sequential selection mode.

ratings: HashMap<PathBuf, u8>

Per-preset rating in [0, 5]. Unrated entries fall back to the default 3 when sampling. Sampling weight is 2^rating.

ratings_path: Option<PathBuf>

Where ratings persist. None disables persistence (tests).

Implementations

impl PresetManager

pub fn new() -> Self

Create a new preset manager with no persistence.

pub fn with_history_size(history_size: usize) -> Self

Create a new preset manager with a specific history cap.

pub fn attach_ratings_file(&mut self, path: PathBuf)

Point the manager at a TOML file for persisted ratings and load whatever’s already on disk. Missing / unreadable / unparseable files fall back to “no ratings” — the call never fails.

pub fn add_preset<P: AsRef<Path>>(&mut self, path: P)

Add a preset to the queue.

pub fn add_presets<P: AsRef<Path>>(&mut self, paths: &[P])

Add multiple presets to the queue.

pub fn next_preset(&mut self) -> Option<&Path>

Get the next preset path (sequential walk, ignores mode / lock).

pub fn prev_preset(&mut self) -> Option<&Path>

Get the previous preset path (sequential walk, ignores mode / lock).

pub fn current_preset(&self) -> Option<&Path>

Get the current preset path.

pub fn random_preset(&mut self) -> Option<&Path>

Pick a uniformly-random preset (ignores ratings, mode, lock). Used by the beat detector for forced cuts where the user has asked for randomness independent of selection mode.

pub fn random_weighted_by_rating(&mut self) -> Option<&Path>

Pick a rating-weighted random preset. Probability of selecting a preset is proportional to 2^rating(preset) — a rating-5 preset is 32× more likely than a rating-0 one. Unrated presets use DEFAULT_RATING.

pub fn advance(&mut self) -> Option<PathBuf>

High-level “user pressed Space / Right arrow”: respect lock, dispatch on mode, record the result in history. Returns None when locked, when the queue is empty, or when the current implementation can’t produce a candidate.

pub fn retreat(&mut self) -> Option<PathBuf>

History-aware “Backspace”: walks the history ring back one entry and returns it. Falls back to the sequential [prev_preset] when the history has no prior entry. Honours the lock.

pub fn is_locked(&self) -> bool

True when preset changes are blocked.

pub fn set_locked(&mut self, locked: bool)

Set the lock state outright (used by Scroll Lock keybind and by the GUI’s startup hydration from Settings::presets.locked).

pub fn toggle_lock(&mut self) -> bool

Flip the lock state and return the new value.

pub fn mode(&self) -> SelectionMode

pub fn set_mode(&mut self, mode: SelectionMode)

pub fn cycle_mode(&mut self) -> SelectionMode

R keybind: cycle Random ↔ Sequential and return the new mode.

pub fn rating(&self, path: &Path) -> u8

Rating of an arbitrary preset path. Unrated → DEFAULT_RATING.

pub fn current_rating(&self) -> Option<u8>

Rating of the currently-cursor’d preset.

pub fn set_rating(&mut self, path: &Path, rating: u8)

Set a preset’s rating (clamped to [0, 5]) and persist.

pub fn nudge_current_rating(&mut self, delta: i32) -> Option<u8>

Nudge the current preset’s rating by delta (+/-), clamped to [0, 5]. Returns the new rating, or None if no current preset.

fn persist_ratings(&self)

pub fn start_transition(&mut self, duration: f32)

Start a transition to the next preset.

pub fn update_transition(&mut self, delta_time: f32) -> bool

Update transition state.

pub fn transition_progress(&self) -> f32

Get transition progress (0.0 to 1.0).

pub fn is_transitioning(&self) -> bool

Check if transitioning.

pub fn clear(&mut self)

Clear all presets.

pub fn preset_count(&self) -> usize

Get number of presets in queue.

pub fn shuffle(&mut self)

Shuffle presets.

Trait Implementations

impl Default for PresetManager

fn default() -> Self

Returns the “default value” for a type.