SeriesPattern

SeriesPattern — the non-colour channel that identifies a chart series.

A chart that tells its series apart by colour and nothing else fails WCAG 1.4.1 (Use of Color), whatever palette it uses. A CVD-safe palette like Okabe–Ito answers a different question — whether the colours are distinguishable from one another — and does not answer this one: a reader with monochrome vision, a monochrome printout, a display in bright sun, or a forced-colours setting has no colour channel at all. It also does not answer the wrap-around problem, where a ninth series repeats the first's colour exactly.

So every series carries a second, orthogonal identity: a pattern. One value drives all three renderings a chart needs, so a series looks like itself whether it is drawn as a line, a bar, a slice, or a legend swatch:

Six patterns against the theme palette's eight colours means the pair (colour, pattern) does not repeat until the 24th series — where colour alone repeated at the 9th.

A series with no explicit pattern is assigned one from its position by SeriesPattern::for_index, so the channel exists without any application code. Whether a chart draws it is the chart's decision (the stock charts draw it once more than one series is visible, since a single-series chart has nothing to disambiguate).

Builder methods at a glance

ALL, for_index, dash, marker, hatch

API reference

📖 Full rustdoc API for this module

pub enum SeriesPattern

The non-colour visual channel identifying one chart series.

See the module docs for the rendering table and the reasoning.

#![allow(unused)]
fn main() {
pub enum SeriesPattern { /* variants */ }
}

Variants

• Solid — Unbroken line, round marker, plain fill.
• Dashed — Long dash, square marker, forward (45°) hatch.
• Dotted — Dotted line, triangular marker, back (135°) hatch.
• DashDot — Dash-dot line, diamond marker, cross-hatch.
• ShortDash — Short dash, ×-shaped marker, horizontal hatch.
• WideDash — Wide-spaced dash, +-shaped marker, vertical hatch.

Methods

pub const ALL: SeriesPattern;`

Every pattern, in assignment order. The order is the cycle [`for_index`` walks.

pub fn for_index(index: usize) -> Self

The pattern a series at index gets when it declares none.

Wraps, like ChartPalette::color_for does with colours — but at a different period (6 against the theme palette's 8), so the wrap points do not coincide and (colour, pattern) stays unique far longer than either channel alone.

pub fn dash(self, line_width: f32) -> Option<(f32, f32)>

The dash pattern for a stroked line, as (dash, gap) in logical pixels, or None for an unbroken line.

Scaled by line_width so a 1 dp line and a 4 dp line read as the same pattern rather than the thick one looking almost solid.

pub fn marker(self) -> SeriesMarker

The marker glyph for this pattern.

pub fn hatch(self) -> SeriesHatch

The hatch for a filled region carrying this pattern.

pub enum SeriesMarker

The marker glyph drawn at a line chart's data points, and next to a series in a legend. Shape, not colour — that is the whole point.

#![allow(unused)]
fn main() {
pub enum SeriesMarker { /* variants */ }
}

Variants

• Circle
• Square
• Triangle
• Diamond
• Cross
• Plus

pub enum SeriesHatch

How a filled region (a bar, an area, a pie slice) carries its series' pattern. None is a plain fill; the rest are line hatches at the named angle, drawn in a contrasting tone over the fill.

#![allow(unused)]
fn main() {
pub enum SeriesHatch { /* variants */ }
}

Variants

• None — No hatch — a plain fill.
• Forward — Parallel lines rising to the right (45°).
• Backward — Parallel lines falling to the right (135°).
• Cross — Both diagonals.
• Horizontal — Parallel horizontal lines.
• Vertical — Parallel vertical lines.