pick_closest

Picks the face that CSS would use for a request, among the faces of one family: the CSS Fonts Level 4 matching algorithm (§5.2), as a pure function. The stretch is matched first, then the style, then the weight; each step keeps only the faces closest to what was asked.

• Stretch: at or below 100, narrower faces first (nearest), then wider ones; above 100, the other way round.
• Style: normal prefers normal, then oblique, then italic; italic prefers italic, then oblique, then normal; oblique prefers oblique, then italic, then normal.
• Weight: a variable face whose range covers the weight is an exact match. Otherwise, from 400 to 500, the nearest heavier weight up to 500, then lighter ones, then heavier ones above 500; below 400, lighter first then heavier; above 500, heavier first then lighter. A variable face counts for the bound of its range closest to the weight.

Import

use helpers4::font::pick_closest;

Cargo feature font (enabled by default). To compile only this module:

cargo add helpers4 --no-default-features --features font

or in Cargo.toml:

[dependencies]
helpers4 = { version = "0.0.11", default-features = false, features = ["font"] }

Signature

pub fn pick_closest(faces: &[FontFace], wanted: FontRequest) -> Option<usize>

Parameters

Parameter	Type	Description
faces	&[FontFace]	The faces of one family.
wanted	FontRequest	What was asked.

Returns

Option<usize> — The index of the closest face, the first one when several are equally close, or None for no face.

Examples

use helpers4::font::{pick_closest, FontFace, FontRequest, FontStyle};

let faces = [
    FontFace::new(300.0, FontStyle::Normal),
    FontFace::new(400.0, FontStyle::Normal),
    FontFace::new(700.0, FontStyle::Normal),
];
assert_eq!(pick_closest(&faces, FontRequest::new(600.0, FontStyle::Normal)), Some(2));

let variable = [FontFace::variable(100.0, 900.0, FontStyle::Normal), FontFace::new(600.0, FontStyle::Normal)];
assert_eq!(pick_closest(&variable, FontRequest::new(450.0, FontStyle::Normal)), Some(0));

Source

src/font/pick_closest.rs