bgone 0.6.0

Ultra-fast CLI tool for removing solid background colors from images
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

use anyhow::{Context, Result};

/// Multiplier to expand hex color shorthand (e.g., F -> FF)
const HEX_SHORTHAND_MULTIPLIER: u8 = 17;

/// RGB color represented as [R, G, B] with values 0-255
pub type Color = [u8; 3];

/// Normalized RGB color with values 0.0-1.0
pub type NormalizedColor = [f64; 3];

/// A foreground color specification - either known or unknown
#[derive(Debug, Clone, PartialEq)]
pub enum ForegroundColorSpec {
    /// A known color specified by the user
    Known(Color),
    /// An unknown color to be deduced by the algorithm
    Unknown,
}

/// Parse a hex color string into RGB
/// Supports: "#ff0000", "ff0000", "#f00", "f00"
pub fn parse_hex_color(hex: &str) -> Result<Color> {
    let hex = hex.trim_start_matches('#');

    let (r, g, b) = match hex.len() {
        3 => {
            // Expand shorthand: "f00" -> "ff0000"
            let r = u8::from_str_radix(&hex[0..1], 16).context("Invalid red component")?;
            let g = u8::from_str_radix(&hex[1..2], 16).context("Invalid green component")?;
            let b = u8::from_str_radix(&hex[2..3], 16).context("Invalid blue component")?;
            (
                r * HEX_SHORTHAND_MULTIPLIER,
                g * HEX_SHORTHAND_MULTIPLIER,
                b * HEX_SHORTHAND_MULTIPLIER,
            )
        }
        6 => {
            // Full hex color
            let r = u8::from_str_radix(&hex[0..2], 16).context("Invalid red component")?;
            let g = u8::from_str_radix(&hex[2..4], 16).context("Invalid green component")?;
            let b = u8::from_str_radix(&hex[4..6], 16).context("Invalid blue component")?;
            (r, g, b)
        }
        _ => anyhow::bail!("Hex color must be 3 or 6 characters long (got: {})", hex),
    };

    Ok([r, g, b])
}

/// Parse a foreground color specification
/// Can be either a hex color or "auto" for unknown
pub fn parse_foreground_spec(spec: &str) -> Result<ForegroundColorSpec> {
    if spec == "auto" {
        Ok(ForegroundColorSpec::Unknown)
    } else {
        parse_hex_color(spec).map(ForegroundColorSpec::Known)
    }
}

/// Convert a Color to NormalizedColor
pub fn normalize_color(color: Color) -> NormalizedColor {
    [
        color[0] as f64 / 255.0,
        color[1] as f64 / 255.0,
        color[2] as f64 / 255.0,
    ]
}

/// Convert a NormalizedColor back to Color
pub fn denormalize_color(color: NormalizedColor) -> Color {
    [
        (color[0] * 255.0).round().clamp(0.0, 255.0) as u8,
        (color[1] * 255.0).round().clamp(0.0, 255.0) as u8,
        (color[2] * 255.0).round().clamp(0.0, 255.0) as u8,
    ]
}

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

    #[test]
    fn test_parse_hex_color() {
        // Full format with # prefix
        assert_eq!(parse_hex_color("#ff0000").unwrap(), [255, 0, 0]);
        assert_eq!(parse_hex_color("#00ff00").unwrap(), [0, 255, 0]);
        assert_eq!(parse_hex_color("#0000ff").unwrap(), [0, 0, 255]);

        // Full format without # prefix
        assert_eq!(parse_hex_color("ff0000").unwrap(), [255, 0, 0]);
        assert_eq!(parse_hex_color("00ff00").unwrap(), [0, 255, 0]);
        assert_eq!(parse_hex_color("0000ff").unwrap(), [0, 0, 255]);

        // Shorthand with # prefix
        assert_eq!(parse_hex_color("#f00").unwrap(), [255, 0, 0]);
        assert_eq!(parse_hex_color("#0f0").unwrap(), [0, 255, 0]);
        assert_eq!(parse_hex_color("#00f").unwrap(), [0, 0, 255]);
        assert_eq!(parse_hex_color("#fff").unwrap(), [255, 255, 255]);
        assert_eq!(parse_hex_color("#000").unwrap(), [0, 0, 0]);
        assert_eq!(parse_hex_color("#369").unwrap(), [51, 102, 153]); // 3*17=51, 6*17=102, 9*17=153

        // Shorthand without # prefix
        assert_eq!(parse_hex_color("f00").unwrap(), [255, 0, 0]);
        assert_eq!(parse_hex_color("0f0").unwrap(), [0, 255, 0]);
        assert_eq!(parse_hex_color("00f").unwrap(), [0, 0, 255]);

        // Error cases
        assert!(parse_hex_color("ff").is_err()); // Wrong length
        assert!(parse_hex_color("ffff").is_err()); // Wrong length
        assert!(parse_hex_color("#gggggg").is_err()); // Invalid hex
        assert!(parse_hex_color("#ggg").is_err()); // Invalid hex shorthand
    }

    #[test]
    fn test_normalize_color() {
        assert_eq!(normalize_color([255, 127, 0]), [1.0, 127.0 / 255.0, 0.0]);
    }

    #[test]
    fn test_parse_foreground_spec() {
        // Test unknown placeholder
        assert_eq!(
            parse_foreground_spec("auto").unwrap(),
            ForegroundColorSpec::Unknown
        );

        // Test known colors
        assert_eq!(
            parse_foreground_spec("#ff0000").unwrap(),
            ForegroundColorSpec::Known([255, 0, 0])
        );
        assert_eq!(
            parse_foreground_spec("f00").unwrap(),
            ForegroundColorSpec::Known([255, 0, 0])
        );

        // Test invalid input
        assert!(parse_foreground_spec("invalid").is_err());
    }
}