Crate nines

9-Slice scaling math.

left             right   ┌──→ +x
 ┊←──── outer ────→┊     │
 ┊                 ┊     ↓
 ┊  ┊←─ inner ─→┊  ┊    + y
 ┊  ┊           ┊  ┊
 ┌──┬───────────┬──┐┈┈┈┈┈┈┈┈ top
 │  │           │  │          ↑
 ├──┼───────────┼──┤┈┈┈┈      │
 │  │           │  │   ↑      │
 │  │           │  │ inner  outer
 │  │           │  │   ↓      │
 ├──┼───────────┼──┤┈┈┈┈      │
 │  │           │  │          ↓
 └──┴───────────┴──┘┈┈┈┈┈┈ bottom

References

• Wikipedia: 9-slice scaling
• Unity: 9-slicing Sprites
• CSS Backgrounds and Borders ML3: ¶6 Border Images

Crate Features

feature	Overview
debug	Enable extra asserts for debugging nines itself.
unsigned-scalar	Allow Scalar to use underflow-prone uNN types.

Structs

Axises

A { horizontal, vertical } pair.

Dimensions

The dimensions of a nine-square layout. See also ValidDimensions.

Error

A generic nines error. Currently opaque by design.

Layout

Describe a layout to render with. You’ll probably start with a:

Rect

A rectangle. See also ValidRect. Generally not inclusive of the right/bottom edge.

Style

The scaling style of a nine-square layout.

ValidDimensions

Slice dimensions with non-negative & non-NAN dimensions (including borders.)

ValidRect

A rectangle with non-negative & non-NAN dimensions.

Enums

Scale

How to scale images. Based roughly off of the CSS3 border-image-repeat property values.

Traits

Scalar

iNN or fNN intrinsics. Opt-in to underflow-prone uNN support via "unsigned-scalars" feature.