Enum Samples 

#[non_exhaustive]
pub enum Samples {
    Packed(Packed),
    Whole(Pixels),
}

An image’s samples, in whichever state the decode ladder left them.

The two states are genuinely different things, not one thing with a flag. Samples::Packed is what every path that does not run a codec of its own produces: the filter chain’s bytes, still at the dictionary’s /BitsPerComponent, which the row pipeline widens as it walks (Unpacked). Samples::Whole is what a codec produced — DCT, JPEG 2000 and JBIG2 all hand back eight-bit samples — together with the two arms that cannot be lazy at all: a stencil’s bits, and the palettes an indexed or tint image resolves once.

Nothing widens a packed image until someone asks for whole-image Pixels, which is Samples::to_pixels and nowhere else.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Packed(Packed)

Still packed, walked by Unpacked.

Whole(Pixels)

Already one byte per component, or a shape that has no packed form.

Implementations

impl Samples

pub fn components(&self) -> usize

How many components each pixel carries.

pub fn byte_size(&self) -> usize

Bytes held, for the render cache’s budget.

Honest about what is actually held: a packed image is its packed bytes and its decode table, which is what the cache is keeping alive, and is smaller than the widened form it never builds.

pub const fn is_stencil(&self) -> bool

Whether these samples are a stencil mask’s bits.

A stencil never has a packed form — its bits are its representation — so this is a question about the Whole arm alone.

pub fn palette(&self) -> Option<&[Rgb]>

The resolved palette, when these samples are indices into one.

Only Pixels::Indexed has one; every other representation carries its colours in the samples themselves.

pub fn to_pixels(&self) -> Pixels

The whole image as Pixels, widening a packed one if it has to.

The one place the full-size buffer the row pipeline exists to avoid is built. Three callers want it and no more: the CLI’s image export, the facade’s edit path, and a test that names the representation.

Trait Implementations

impl Clone for Samples

fn clone(&self) -> Samples

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Samples

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

Formats the value using the given formatter.

impl PartialEq for Samples

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Samples