hyper-render 0.2.2

A Chromium-free HTML rendering engine for generating PNG and PDF outputs
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

//! Integration tests for PNG rendering.

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

use hyper_render::{render, render_to_png, Config, OutputFormat};

/// PNG header magic bytes
const PNG_SIGNATURE: [u8; 8] = [0x89, b'P', b'N', b'G', 0x0D, 0x0A, 0x1A, 0x0A];

/// Parse PNG dimensions from the IHDR chunk.
/// Returns (width, height) or None if parsing fails.
fn parse_png_dimensions(data: &[u8]) -> Option<(u32, u32)> {
    // PNG structure: 8-byte signature, then chunks
    // IHDR is always the first chunk after signature
    // Chunk format: 4-byte length, 4-byte type, data, 4-byte CRC
    if data.len() < 24 {
        return None;
    }

    // Skip signature (8 bytes) and length (4 bytes)
    // Check for IHDR type
    if &data[12..16] != b"IHDR" {
        return None;
    }

    // Width and height are the first 8 bytes of IHDR data (big-endian u32s)
    let width = u32::from_be_bytes([data[16], data[17], data[18], data[19]]);
    let height = u32::from_be_bytes([data[20], data[21], data[22], data[23]]);

    Some((width, height))
}

#[test]
fn test_png_basic_render() {
    let html = "<html><body><h1>Hello</h1></body></html>";
    let config = Config::new().width(400).height(300);

    let result = render(html, config);
    assert!(result.is_ok(), "render should succeed");

    let bytes = result.unwrap();
    assert!(!bytes.is_empty(), "output should not be empty");
    assert!(
        bytes.starts_with(&PNG_SIGNATURE),
        "output should be valid PNG"
    );
}

#[test]
fn test_png_render_to_png_convenience() {
    let html = "<html><body><p>Test</p></body></html>";
    let config = Config::new();

    let result = render_to_png(html, config);
    assert!(result.is_ok(), "render_to_png should succeed");

    let bytes = result.unwrap();
    assert!(
        bytes.starts_with(&PNG_SIGNATURE),
        "output should be valid PNG"
    );
}

#[test]
fn test_png_dimensions_match_config() {
    let html = "<html><body></body></html>";
    let config = Config::new().width(640).height(480).scale(1.0);

    let bytes = render(html, config).expect("render should succeed");
    let (width, height) = parse_png_dimensions(&bytes).expect("should parse PNG dimensions");

    assert_eq!(width, 640, "PNG width should match config");
    assert_eq!(height, 480, "PNG height should match config");
}

#[test]
fn test_png_scale_factor_doubles_dimensions() {
    let html = "<html><body></body></html>";
    let config = Config::new().width(100).height(100).scale(2.0);

    let bytes = render(html, config).expect("render should succeed");
    let (width, height) = parse_png_dimensions(&bytes).expect("should parse PNG dimensions");

    // With scale=2.0, output dimensions should be doubled
    assert_eq!(width, 200, "PNG width should be 2x config width");
    assert_eq!(height, 200, "PNG height should be 2x config height");
}

#[test]
fn test_png_auto_height() {
    // Create HTML with content that should be taller than 100px
    let html = r#"
        <html>
        <body style="margin: 0; padding: 0;">
            <div style="height: 500px; background: red;"></div>
        </body>
        </html>
    "#;

    let config = Config::new().width(200).height(100).auto_height(true);

    let bytes = render(html, config).expect("render should succeed");
    let (_, height) = parse_png_dimensions(&bytes).expect("should parse PNG dimensions");

    // With auto_height, the output should be taller than the configured 100px
    assert!(
        height > 100,
        "auto_height should produce taller output: got {}",
        height
    );
}

#[test]
fn test_png_transparent_background() {
    let html = "<html><body></body></html>";
    let config = Config::new()
        .width(Config::MIN_DIMENSION)
        .height(Config::MIN_DIMENSION)
        .transparent();

    let result = render(html, config);
    assert!(result.is_ok(), "transparent background should work");

    let bytes = result.unwrap();
    assert!(
        bytes.starts_with(&PNG_SIGNATURE),
        "output should be valid PNG"
    );
}

#[test]
fn test_png_custom_background() {
    let html = "<html><body></body></html>";
    let config = Config::new()
        .width(Config::MIN_DIMENSION)
        .height(Config::MIN_DIMENSION)
        .background([255, 0, 0, 255]); // Red

    let result = render(html, config);
    assert!(result.is_ok(), "custom background should work");

    let bytes = result.unwrap();
    assert!(
        bytes.starts_with(&PNG_SIGNATURE),
        "output should be valid PNG"
    );
}

#[test]
fn test_png_format_enum() {
    let html = "<html><body></body></html>";
    let config = Config::new().format(OutputFormat::Png);

    let bytes = render(html, config).expect("render should succeed");
    assert!(
        bytes.starts_with(&PNG_SIGNATURE),
        "OutputFormat::Png should produce PNG"
    );
}

#[test]
fn test_png_unicode_content() {
    let html = r#"<html><body><p>Hello δΈ–η•Œ 🌍</p></body></html>"#;
    let config = Config::new();

    let result = render(html, config);
    assert!(result.is_ok(), "unicode content should render");

    let bytes = result.unwrap();
    assert!(
        bytes.starts_with(&PNG_SIGNATURE),
        "output should be valid PNG"
    );
}

#[test]
fn test_png_styled_content() {
    let html = r#"
        <html>
        <body style="background: #f0f0f0; padding: 20px;">
            <div style="background: white; border-radius: 8px; padding: 16px;">
                <h1 style="color: navy;">Styled Content</h1>
                <p style="color: #666;">With CSS styling</p>
            </div>
        </body>
        </html>
    "#;
    let config = Config::new().width(400).height(300);

    let result = render(html, config);
    assert!(result.is_ok(), "styled content should render");

    let bytes = result.unwrap();
    assert!(
        bytes.starts_with(&PNG_SIGNATURE),
        "output should be valid PNG"
    );
}

#[test]
fn test_png_minimum_dimensions() {
    let html = "<html><body></body></html>";
    let config = Config::new()
        .width(Config::MIN_DIMENSION)
        .height(Config::MIN_DIMENSION);

    let result = render(html, config);
    assert!(result.is_ok(), "minimum dimensions should work");

    let bytes = result.unwrap();
    let (width, height) = parse_png_dimensions(&bytes).expect("should parse PNG dimensions");
    assert_eq!(width, Config::MIN_DIMENSION);
    assert_eq!(height, Config::MIN_DIMENSION);
}