Struct BuildContext 

pub struct BuildContext {
    pub colorspaces: ColorSpaceCache,
    pub functions: FunctionCache,
    pub images: ImageCache,
    pub decode_target: RequestedSize,
    pub fonts: Arc<FontCache>,
    pub substitution: SubstitutionOptions,
    /* private fields */
}

The caches and guards a build shares across the whole page.

Owned by the caller and passed down by &mut — no globals, no interior mutability.

Fields

colorspaces: ColorSpaceCache

Colour spaces, keyed on the reference that named them.

functions: FunctionCache

Functions, likewise.

images: ImageCache

Decoded images, keyed on (reference, requested size).

decode_target: RequestedSize

How much resolution this build’s images are wanted at.

A hint: a codec that cannot reduce returns full resolution and the image reports the size it actually decoded at. Full — the default — asks for every sample, which is what a build with no render target behind it wants.

One value per build rather than one per image: the size that matters is the render target’s, so the question a decode hint answers is how much bigger an image is than the whole page bitmap, not how small a rectangle it lands in.

fonts: Arc<FontCache>

Fonts: the loaded-font cache and the font-identity counter.

Shared by Arc rather than owned, so every session over one document — every worker of a parallel render, and a text run and a render run alike — loads each font once between them. A context built with BuildContext::new gets a fresh one, which is the right answer for a caller with no document to hang it on; the facade hands its own document-owned cache to every session it makes.

substitution: SubstitutionOptions

How a non-embedded font finds a face to draw with.

Carried here rather than passed in per call because every font load under one document must make the same choice: a substitution that varied between two Tf operators naming the same resource would give one line of text different metrics from the next. Defaults to the built-in faces alone, which is what keeps tests hermetic; the tool fills it from --font-dir and --croscore-font-names.

Implementations

impl BuildContext

pub fn new() -> Self

An empty context.

pub fn with_substitution(options: SubstitutionOptions) -> Self

An empty context whose non-embedded fonts resolve through options.

The caches start empty either way; this only fixes how substitution will answer, which must be settled before the first font loads.

pub fn form_fonts<T: Any + Send + Sync>( &mut self, key: FormFontsKey, load: impl FnOnce(&mut Self) -> T, ) -> Arc<T>

The interactive form’s faces for key, built by load on the first ask and handed back from the cache on every later one.

load is a closure, not a value, so a hit costs nothing to build. FormFontsKey::Direct is never cached and always calls load: it is the one case with no reference anywhere to key on, and reusing one document’s faces for another’s would be wrong.

pub fn forms_in_flight(&self) -> usize

How many form parses are in flight.

Trait Implementations

impl Debug for BuildContext

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

Formats the value using the given formatter.

impl Default for BuildContext

fn default() -> BuildContext

Returns the “default value” for a type.