eulumdat 0.6.0

Eulumdat (LDT) and IES photometric file parser, writer, and validator for Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

//! Unit system for photometric output (SI / Imperial).
//!
//! All internal values remain in SI (lux, meters, millimeters).
//! This module provides conversion and formatting helpers so that
//! CLI output, SVG labels, and UI displays can show either system.

/// Conversion factor: 1 foot-candle = 10.764 lux
const LUX_PER_FC: f64 = 10.764;

/// Conversion factor: 1 foot = 0.3048 meters
const M_PER_FT: f64 = 0.3048;

/// Conversion factor: 1 inch = 25.4 millimeters
const MM_PER_IN: f64 = 25.4;

/// Unit system for photometric output.
///
/// Internal data is always stored in SI units. This enum selects
/// which unit system to use when *displaying* values.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub enum UnitSystem {
    /// SI / Metric: lux, meters, millimeters
    #[default]
    Metric,
    /// Imperial: foot-candles, feet, inches
    Imperial,
}

impl UnitSystem {
    // ── Illuminance ────────────────────────────────────────────

    /// Unit abbreviation for illuminance ("lx" or "fc").
    pub fn illuminance_label(&self) -> &'static str {
        match self {
            Self::Metric => "lx",
            Self::Imperial => "fc",
        }
    }

    /// Convert a value from lux to the selected unit.
    pub fn convert_lux(&self, lux: f64) -> f64 {
        match self {
            Self::Metric => lux,
            Self::Imperial => lux / LUX_PER_FC,
        }
    }

    // ── Distance (meters) ──────────────────────────────────────

    /// Unit abbreviation for macro distances ("m" or "ft").
    pub fn distance_label(&self) -> &'static str {
        match self {
            Self::Metric => "m",
            Self::Imperial => "ft",
        }
    }

    /// Convert a value from meters to the selected unit.
    pub fn convert_meters(&self, m: f64) -> f64 {
        match self {
            Self::Metric => m,
            Self::Imperial => m / M_PER_FT,
        }
    }

    // ── Dimensions (millimeters) ───────────────────────────────

    /// Unit abbreviation for small dimensions ("mm" or "in").
    pub fn dimension_label(&self) -> &'static str {
        match self {
            Self::Metric => "mm",
            Self::Imperial => "in",
        }
    }

    /// Convert a value from millimeters to the selected unit.
    pub fn convert_mm(&self, mm: f64) -> f64 {
        match self {
            Self::Metric => mm,
            Self::Imperial => mm / MM_PER_IN,
        }
    }

    /// Convert a value from the selected unit back to millimeters.
    pub fn to_mm(&self, val: f64) -> f64 {
        match self {
            Self::Metric => val,
            Self::Imperial => val * MM_PER_IN,
        }
    }

    // ── Format helpers ─────────────────────────────────────────

    /// Format an illuminance value (input in lux).
    pub fn format_lux(&self, lux: f64) -> String {
        let v = self.convert_lux(lux);
        format!("{v:.1} {}", self.illuminance_label())
    }

    /// Format a macro distance (input in meters).
    pub fn format_distance(&self, m: f64) -> String {
        let v = self.convert_meters(m);
        format!("{v:.1} {}", self.distance_label())
    }

    /// Format a small dimension (input in millimeters).
    pub fn format_dimension(&self, mm: f64) -> String {
        match self {
            Self::Metric => format!("{mm:.0} mm"),
            Self::Imperial => format!("{:.1} in", mm / MM_PER_IN),
        }
    }
}

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

    #[test]
    fn metric_is_identity() {
        let u = UnitSystem::Metric;
        assert!((u.convert_lux(100.0) - 100.0).abs() < 1e-9);
        assert!((u.convert_meters(5.0) - 5.0).abs() < 1e-9);
        assert!((u.convert_mm(200.0) - 200.0).abs() < 1e-9);
    }

    #[test]
    fn imperial_conversions() {
        let u = UnitSystem::Imperial;
        // 10.764 lux = 1 fc
        assert!((u.convert_lux(10.764) - 1.0).abs() < 1e-3);
        // 0.3048 m = 1 ft
        assert!((u.convert_meters(0.3048) - 1.0).abs() < 1e-6);
        // 25.4 mm = 1 in
        assert!((u.convert_mm(25.4) - 1.0).abs() < 1e-9);
    }

    #[test]
    fn labels() {
        assert_eq!(UnitSystem::Metric.illuminance_label(), "lx");
        assert_eq!(UnitSystem::Imperial.illuminance_label(), "fc");
        assert_eq!(UnitSystem::Metric.distance_label(), "m");
        assert_eq!(UnitSystem::Imperial.distance_label(), "ft");
        assert_eq!(UnitSystem::Metric.dimension_label(), "mm");
        assert_eq!(UnitSystem::Imperial.dimension_label(), "in");
    }

    #[test]
    fn format_helpers() {
        let m = UnitSystem::Metric;
        assert_eq!(m.format_lux(100.0), "100.0 lx");
        assert_eq!(m.format_distance(5.0), "5.0 m");
        assert_eq!(m.format_dimension(200.0), "200 mm");

        let i = UnitSystem::Imperial;
        assert_eq!(i.format_lux(10.764), "1.0 fc");
        assert_eq!(i.format_distance(0.3048), "1.0 ft");
        assert_eq!(i.format_dimension(25.4), "1.0 in");
    }

    #[test]
    fn default_is_metric() {
        assert_eq!(UnitSystem::default(), UnitSystem::Metric);
    }
}