qrcode-rs 0.5.0

QR code encoder in Rust，Generate QR Code matrices and images in RAW, PNG and SVG formats.
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
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234

//! HTML rendering support.
//!
//! Generates HTML `<table>` or CSS Grid output for embedding QR codes in web pages.
//!
//! # Example
//!
//! ```
//! use qrcode_rs::QrCode;
//! use qrcode_rs::render::html::Color;
//!
//! let code = QrCode::new(b"Hello").unwrap();
//! let html = code.render::<Color>().build();
//! println!("{}", html);
//! ```

#![cfg(feature = "html")]

use std::marker::PhantomData;

use crate::cast::As;
use crate::render::{Canvas as RenderCanvas, Pixel};
use crate::types::Color as ModuleColor;

/// Rendering mode for HTML output.
#[derive(Copy, Clone, Default, PartialEq, Eq)]
pub enum Mode {
    /// Generate HTML `<table>` (default).
    #[default]
    Table,
    /// Generate `<div>` with CSS Grid layout.
    Grid,
}

/// An HTML color.
#[derive(Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Color<'a>(pub &'a str);

impl<'a> Pixel for Color<'a> {
    type Image = String;
    type Canvas = Canvas<'a>;

    fn default_unit_size() -> (u32, u32) {
        (1, 1)
    }

    fn default_color(color: ModuleColor) -> Self {
        Color(color.select("#000", "#fff"))
    }
}

#[doc(hidden)]
pub struct Canvas<'a> {
    dark_pixels: Vec<bool>,
    width: u32,
    height: u32,
    dark_color: &'a str,
    light_color: &'a str,
    mode: Mode,
    marker: PhantomData<Color<'a>>,
}

impl<'a> Canvas<'a> {
    /// Sets the HTML rendering mode (Table or Grid).
    pub fn set_mode(&mut self, mode: Mode) {
        self.mode = mode;
    }
}

impl<'a> RenderCanvas for Canvas<'a> {
    type Pixel = Color<'a>;
    type Image = String;

    fn new(width: u32, height: u32, dark_pixel: Color<'a>, light_pixel: Color<'a>) -> Self {
        Canvas {
            dark_pixels: vec![false; (width * height).as_usize()],
            width,
            height,
            dark_color: dark_pixel.0,
            light_color: light_pixel.0,
            mode: Mode::default(),
            marker: PhantomData,
        }
    }

    fn draw_dark_pixel(&mut self, x: u32, y: u32) {
        let idx = (y * self.width + x).as_usize();
        if idx < self.dark_pixels.len() {
            self.dark_pixels[idx] = true;
        }
    }

    fn into_image(self) -> String {
        match self.mode {
            Mode::Table => self.into_table(),
            Mode::Grid => self.into_grid(),
        }
    }
}

impl<'a> Canvas<'a> {
    fn into_table(self) -> String {
        let cap = 512 + (self.width * self.height * 20) as usize;
        let mut html = String::with_capacity(cap);
        html.push_str(r#"<!DOCTYPE html><html><head><meta charset="UTF-8"></head><body><table style="border-collapse:collapse;line-height:0">"#);

        for y in 0..self.height {
            html.push_str("<tr>");
            for x in 0..self.width {
                let idx = (y * self.width + x).as_usize();
                let color = if self.dark_pixels[idx] { self.dark_color } else { self.light_color };
                html.push_str(r#"<td style="width:1px;height:1px;background:"#);
                html.push_str(color);
                html.push_str(r#""></td>"#);
            }
            html.push_str("</tr>");
        }

        html.push_str("</table></body></html>");
        html
    }

    fn into_grid(self) -> String {
        let cap = 512 + (self.width * self.height * 10) as usize;
        let mut html = String::with_capacity(cap);
        html.push_str(r#"<!DOCTYPE html><html><head><meta charset="UTF-8"></head><body><div style="display:grid;grid-template-columns:repeat("#);
        html.push_str(&self.width.to_string());
        html.push_str(r#",1px);line-height:0">"#);

        for y in 0..self.height {
            for x in 0..self.width {
                let idx = (y * self.width + x).as_usize();
                let color = if self.dark_pixels[idx] { self.dark_color } else { self.light_color };
                html.push_str(r#"<div style="width:1px;height:1px;background:"#);
                html.push_str(color);
                html.push_str(r#""></div>"#);
            }
        }

        html.push_str("</div></body></html>");
        html
    }
}

/// Injects custom attributes into the QR container element (`<table>` in
/// [`Mode::Table`], `<div>` in [`Mode::Grid`]). If no container is found the
/// input is returned unchanged.
///
/// # Example
///
/// ```
/// use qrcode_rs::QrCode;
/// use qrcode_rs::render::html::{self, Color};
///
/// let code = QrCode::new(b"Hello").unwrap();
/// let html = code.render::<Color>().build();
/// let html = html::inject_attributes(&html, &[("class", "qr")]);
/// let start = html.find("<table").unwrap();
/// let tag_end = start + html[start..].find('>').unwrap();
/// assert!(html[start..tag_end].contains(r#"class="qr""#));
/// ```
pub fn inject_attributes(html: &str, attrs: &[(&str, &str)]) -> String {
    let Some(start) = html.find("<table").or_else(|| html.find("<div")) else {
        return html.to_owned();
    };
    let Some(close) = html[start..].find('>').map(|p| start + p) else {
        return html.to_owned();
    };
    let mut result = String::with_capacity(html.len() + attrs.len() * 16);
    result.push_str(&html[..close]);
    for (key, value) in attrs {
        result.push(' ');
        result.push_str(key);
        result.push_str(r#"=""#);
        result.push_str(value);
        result.push('"');
    }
    result.push_str(&html[close..]);
    result
}

/// Adds screen-reader accessibility attributes (`role="img"` and
/// `aria-label="<label>"`) to the QR container element.
///
/// # Example
///
/// ```
/// use qrcode_rs::QrCode;
/// use qrcode_rs::render::html::{self, Color};
///
/// let code = QrCode::new(b"Hello").unwrap();
/// let html = code.render::<Color>().build();
/// let html = html::aria_label(&html, "QR code saying Hello");
/// assert!(html.contains(r#"aria-label="QR code saying Hello""#));
/// ```
pub fn aria_label(html: &str, label: &str) -> String {
    inject_attributes(html, &[("role", "img"), ("aria-label", label)])
}

#[cfg(test)]
mod tests {
    use crate::QrCode;
    use crate::render::html::Color;

    #[test]
    fn test_html_table_render() {
        let code = QrCode::new(b"Hello").unwrap();
        let html = code.render::<Color>().build();
        assert!(html.contains("<!DOCTYPE html>"));
        assert!(html.contains("<table"));
        assert!(html.contains("</table>"));
        assert!(html.contains("#000"));
        assert!(html.contains("#fff"));
    }

    #[test]
    fn test_html_custom_colors() {
        let code = QrCode::new(b"Hi").unwrap();
        let html = code.render::<Color>().dark_color(Color("#333")).light_color(Color("#eee")).build();
        assert!(html.contains("#333"));
        assert!(html.contains("#eee"));
    }

    #[test]
    fn test_aria_label_injected_into_container() {
        let code = QrCode::new(b"Hi").unwrap();
        let html = code.render::<Color>().build();
        let html = super::aria_label(&html, "a QR code");
        // both attributes land inside the <table …> opening tag
        let start = html.find("<table").unwrap();
        let tag_end = start + html[start..].find('>').unwrap();
        assert!(html[start..tag_end].contains(r#"role="img""#));
        assert!(html[start..tag_end].contains(r#"aria-label="a QR code""#));
    }
}