figgy-model 0.10.0

figgy chart model — option SSoT, interaction contracts, preset policies.
Documentation 
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#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum LineStylePreset {
    /// Solid line (no pattern).
    #[default]
    Solid,
    /// Standard dash: `[8, 4]`.
    Dash,
    /// Dotted: `[2, 3]`.
    Dot,
    /// Dash-dot: `[8, 4, 2, 4]`.
    DashDot,
    /// Dash-dot-dot: `[8, 4, 2, 4, 2, 4]`.
    DashDotDot,
    /// Short dash: `[4, 3]`.
    ShortDash,
    /// Short dot (dense dots): `[1, 2]`.
    ShortDot,
    /// Short dash-dot: `[4, 3, 1, 3]`.
    ShortDashDot,
    /// Long dash: `[14, 4]`.
    LongDash,
    /// Long dash-dot: `[14, 4, 2, 4]`.
    LongDashDot,
    /// Long dash-dot-dot: `[14, 4, 2, 4, 2, 4]`.
    LongDashDotDot,
}

impl LineStylePreset {
    /// Dash pattern as sequential `[on, off, ...]` pixel lengths at 1× scale.
    /// Empty slice = solid. Consumers (CPU raster dash, GPU `Style.dash`)
    /// apply their own scale factor to each entry.
    pub fn pattern(&self) -> &'static [f32] {
        match self {
            LineStylePreset::Solid => &[],
            LineStylePreset::Dash => &[8.0, 4.0],
            LineStylePreset::Dot => &[2.0, 3.0],
            LineStylePreset::DashDot => &[8.0, 4.0, 2.0, 4.0],
            LineStylePreset::DashDotDot => &[8.0, 4.0, 2.0, 4.0, 2.0, 4.0],
            LineStylePreset::ShortDash => &[4.0, 3.0],
            LineStylePreset::ShortDot => &[1.0, 2.0],
            LineStylePreset::ShortDashDot => &[4.0, 3.0, 1.0, 3.0],
            LineStylePreset::LongDash => &[14.0, 4.0],
            LineStylePreset::LongDashDot => &[14.0, 4.0, 2.0, 4.0],
            LineStylePreset::LongDashDotDot => &[14.0, 4.0, 2.0, 4.0, 2.0, 4.0],
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn solid_pattern_is_empty() {
        assert!(LineStylePreset::Solid.pattern().is_empty());
    }

    #[test]
    fn dash_presets_are_positive_on_off_pairs() {
        for preset in [
            LineStylePreset::Dash,
            LineStylePreset::Dot,
            LineStylePreset::DashDot,
            LineStylePreset::DashDotDot,
            LineStylePreset::ShortDash,
            LineStylePreset::ShortDot,
            LineStylePreset::ShortDashDot,
            LineStylePreset::LongDash,
            LineStylePreset::LongDashDot,
            LineStylePreset::LongDashDotDot,
        ] {
            let pattern = preset.pattern();
            assert!(!pattern.is_empty());
            assert_eq!(pattern.len() % 2, 0, "{preset:?}");
            assert!(pattern.iter().all(|length| *length > 0.0), "{preset:?}");
        }
    }
}