Enum StateContext 

pub enum StateContext {
    Project,
    Preset {
        path: Option<String>,
    },
}

Why a plugin is being handed a state blob.

VST3 lets a plugin ask where the state it is being given came from: the host attaches an IStreamAttributes list to the IBStream it passes to setState, and the plugin reads the PresetAttributes::kStateType key from it. The SDK ships Vst::Helpers::isProjectState() for exactly this — it answers “yes” only for StateType::kProject and “this came from a preset” for every other value — and plugins use the answer to decide what to restore (a preset should not, for instance, drag a project’s per-instance routing along with it).

Pass this to Plugin::load_state_with_context. Plugin::load_state uses StateContext::Project; Plugin::load_vstpreset and Plugin::load_preset use StateContext::Preset with the file they read.

Variants

Project

The blob is part of a host session/project restore.

Tags the stream StateType::kProject — “the state is restored from a project loading or it is saved in a project”.

Preset

The blob came from a standalone preset file.

Tags the stream StateType::kTrackPreset. Of the three values the SDK defines, kProject is explicitly the project case and kDefault is narrower than it looks — “the state is restored from a preset (marked as default) or the host wants to store a default state of the plug-in” — so claiming it for a preset the user picked would tell the plugin this is its initialization patch. kTrackPreset (“the state is restored from a track preset”) is the SDK’s remaining preset-file value, and it is what makes Vst::Helpers::isProjectState() answer “came from a preset” rather than the “host doesn’t implement this” it returns when the attribute is missing entirely.

Fields

path: Option<String>

Full path of the file the state was read from, when the caller knows it.

Published as PresetAttributes::kFilePathStringType (“full file path string (if available) where the preset comes from”); left off the stream when None.

Text rather than a PathBuf because it is published as a UTF-16 stream attribute and crosses the process-isolation boundary as JSON, neither of which can carry a non-UTF-8 path. StateContext::preset_from_path does the lossy conversion once, where it is visible.

Implementations

impl StateContext

pub fn preset() -> Self

A preset load whose source file is unknown (state handed over in memory, say).

pub fn preset_from_path(path: impl AsRef<Path>) -> Self

A preset load from path, which the plugin will see as the stream’s file path.

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

The source file this state came from, when one is known.

Trait Implementations

impl Clone for StateContext

fn clone(&self) -> StateContext

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StateContext

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

Formats the value using the given formatter.

impl Default for StateContext

fn default() -> StateContext

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for StateContext

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for StateContext

impl PartialEq for StateContext

fn eq(&self, other: &StateContext) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for StateContext

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for StateContext