simple_gal/imaging/
params.rs

1//! Parameter types for image operations.
2//!
3//! These structs describe *what* to do, not *how* to do it. They are the
4//! interface between the high-level [`operations`](super::operations) module
5//! (which decides what images to create) and the [`backend`](super::backend)
6//! (which does the actual pixel work). This separation allows swapping backends
7//! (e.g. for testing with a mock) without changing operation logic.
8//!
9//! ## Types
10//!
11//! - [`Quality`] — Lossy encoding quality (1–100, default 90). Clamped on construction.
12//! - [`Sharpening`] — Unsharp-mask parameters (sigma + threshold) for thumbnail crispness.
13//! - [`ResizeParams`] — Full specification for a resize: source, output path, target dimensions, quality.
14//! - [`ThumbnailParams`] — Full specification for a thumbnail: source, output, crop dimensions, quality, optional sharpening.
15
16use std::path::PathBuf;
17
18/// Quality setting for lossy image encoding (1-100).
19#[derive(Debug, Clone, Copy, PartialEq, Eq)]
20pub struct Quality(pub u32);
21
22impl Quality {
23    pub fn new(value: u32) -> Self {
24        Self(value.clamp(1, 100))
25    }
26
27    pub fn value(self) -> u32 {
28        self.0
29    }
30}
31
32impl Default for Quality {
33    fn default() -> Self {
34        Self(90)
35    }
36}
37
38/// Sharpening parameters for unsharp mask.
39///
40/// - `sigma`: Standard deviation of the Gaussian blur (higher = more sharpening)
41/// - `threshold`: Minimum brightness difference to sharpen (0 = sharpen all pixels)
42#[derive(Debug, Clone, Copy, PartialEq)]
43pub struct Sharpening {
44    pub sigma: f32,
45    pub threshold: i32,
46}
47
48impl Sharpening {
49    /// Light sharpening suitable for thumbnails.
50    pub fn light() -> Self {
51        Self {
52            sigma: 0.5,
53            threshold: 0,
54        }
55    }
56}
57
58/// Parameters for a simple resize operation.
59#[derive(Debug, Clone, PartialEq)]
60pub struct ResizeParams {
61    pub source: PathBuf,
62    pub output: PathBuf,
63    pub width: u32,
64    pub height: u32,
65    pub quality: Quality,
66}
67
68/// Parameters for a thumbnail operation (resize + center crop).
69#[derive(Debug, Clone, PartialEq)]
70pub struct ThumbnailParams {
71    pub source: PathBuf,
72    pub output: PathBuf,
73    /// Final crop dimensions.
74    pub crop_width: u32,
75    pub crop_height: u32,
76    pub quality: Quality,
77    pub sharpening: Option<Sharpening>,
78}
79
80#[cfg(test)]
81mod tests {
82    use super::*;
83
84    #[test]
85    fn quality_clamps_to_valid_range() {
86        assert_eq!(Quality::new(0).value(), 1);
87        assert_eq!(Quality::new(50).value(), 50);
88        assert_eq!(Quality::new(150).value(), 100);
89    }
90
91    #[test]
92    fn quality_default_is_90() {
93        assert_eq!(Quality::default().value(), 90);
94    }
95
96    #[test]
97    fn sharpening_light_values() {
98        let s = Sharpening::light();
99        assert_eq!(s.sigma, 0.5);
100        assert_eq!(s.threshold, 0);
101    }
102}
simple_gal/imaging/params.rs

simple_gal/imaging/
params.rs
