Enum Affordance 

#[non_exhaustive]
pub enum Affordance {
    Hover,
    Hint,
    Ancillary,
    Detail,
    Anchored,
    Overflow,
}

An affordance whose existence depends on the surface it is offered on.

Six members, drawn from what the two measured apps already gate by hand rather than from a taxonomy. makeover-layout’s warning applies and is the reason for stopping here: guessing at eight is how a description becomes a framework.

Each answers Self::available against the two axes and nothing else. An affordance that is always available is not an affordance this crate has anything to say about, and every_member_is_an_adaptation asserts none has snuck in.

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.

Hover

Anything a consumer reveals on hover: a row’s action cluster, a hover toolbar, a preview popover.

Both webview apps arrived at hover-revealed row actions independently (goingson .task-row-action, Balanced Breakfast .row-actions), which is why makeover-layout records the reveal as behaviour of RowPart::Actions rather than as app policy. What neither app can say is that a fingertip has no hover state at all, so the affordance is not hidden on touch — it does not exist there, and something else has to carry the same actions.

Hint

Chrome documenting a keyboard interaction: shortcut badges, key hints, a “press / to search” line.

goingson hides .kbd-hint on touch. Strictly this is a claim about having a keyboard rather than about the contact patch, and Density is the closest honest proxy the family carries. Stated rather than hidden, because a detachable-keyboard tablet is where the proxy breaks and a third axis is what fixing it would cost.

Ancillary

A secondary panel standing beside the primary content: a saved-views rail, a filter sidebar, an inspector.

goingson hides .saved-views-sidebar below its widest layout. Purely a screen-budget claim — a touchscreen laptop should keep it — so this reads SizeClass alone.

Detail

The detail half of a list-detail split, shown alongside the list rather than navigated to.

goingson’s .main-content and Balanced Breakfast’s .detail-panel. Unavailable is not the same as absent: the detail still exists, it is reached by navigation instead of by adjacency, and which of the two a screen gets is what makeover-layout’s Arrangement is describing.

Anchored

Navigation or a primary action cluster pinned to a fixed screen edge instead of sitting in the flow of the page.

The reposition bucket, and the largest single one in goingson at 20%. It exists to compensate for what a compact window cannot hold in flow, so unlike the two above it is available at the narrow end and not the wide one. That inversion is the point: an adaptation that only ever removes things describes a degraded layout rather than a different one.

Overflow

An action cluster collapsed behind one control rather than laid out inline.

The other compensating member. makeover-layout’s Column::kept_at already handles a table narrowing by dropping columns; this is the same pressure on a cluster of controls, which cannot drop any of them and folds instead.

Implementations

impl Affordance

pub const fn available(self, density: Density, size: SizeClass) -> bool

Whether this affordance exists on a surface with the given input class and screen budget.

The whole crate in one call. A renderer asks per affordance and never branches on a width.

pub const fn reads_density(self) -> bool

Whether this affordance’s availability reads Density at all.

Exposed rather than kept private because it is the crate’s own claim about itself: exactly the members gating a contact-patch interaction say yes. A renderer with one density can skip the rest entirely.

pub const fn reads_size(self) -> bool

Whether this affordance’s availability reads SizeClass at all.

pub const fn all() -> [Self; 6]

Every member, in declaration order.

pub const fn token(self) -> &'static str

The CSS class name an app may hang off this, without the leading dot.

Present for the same reason SizeClass::token is: a webview renderer needs a stable name, and minting it per app is how two apps end up with has-hover and hover-capable.

Trait Implementations

impl Clone for Affordance

fn clone(&self) -> Affordance

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Affordance

impl Debug for Affordance

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

Formats the value using the given formatter.

impl Eq for Affordance

impl Hash for Affordance

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for Affordance

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Affordance