Function generate_pdf_from_html

Source

pub fn generate_pdf_from_html(
    pool: &Mutex<BrowserPool>,
    request: &PdfFromHtmlRequest,
) -> Result<PdfResponse, PdfServiceError>

Expand description

Generate a PDF from HTML content.

Loads the provided HTML content into a browser tab using a data URL, waits for any JavaScript execution, and generates a PDF.

§Thread Safety

This function is thread-safe and can be called concurrently from multiple threads. See generate_pdf_from_url for details.

§Blocking Behavior

This function blocks the calling thread. See generate_pdf_from_url for guidance on async usage.

§How It Works

The HTML content is converted to a data URL:

data:text/html;charset=utf-8,<encoded-html-content>

This allows loading HTML directly without a web server. The browser renders the HTML as if it were loaded from a regular URL.

§Arguments

pool - Reference to the mutex-wrapped browser pool
request - HTML content and generation parameters. See PdfFromHtmlRequest.

§Returns

Ok(PdfResponse) - Successfully generated PDF
Err(PdfServiceError) - Error details

§Errors

Error	Cause	Resolution
`EmptyHtml`	HTML content is empty/whitespace	Provide HTML content
`PoolLockFailed`	Mutex poisoned	Restart service
`BrowserUnavailable`	Pool exhausted	Retry or increase pool size
`NavigationFailed`	HTML parsing issue	Check HTML validity
`PdfGenerationFailed`	Rendering issue	Simplify HTML

§Limitations

§External Resources

Since HTML is loaded via data URL, relative URLs don’t work:

<!-- ❌ Won't work - relative URL -->
<img src="/images/logo.png">

<!-- ✅ Works - absolute URL -->
<img src="https://example.com/images/logo.png">

<!-- ✅ Works - inline base64 -->
<img src="data:image/png;base64,iVBORw0KGgo...">

§Size Limits

Data URLs have browser-specific size limits. For very large HTML documents (> 1MB), consider:

Hosting the HTML on a temporary server
Using generate_pdf_from_url instead
Splitting into multiple PDFs

§Examples

§Simple HTML

use html2pdf_api::service::{generate_pdf_from_html, PdfFromHtmlRequest};

let request = PdfFromHtmlRequest {
    html: "<h1>Hello World</h1><p>This is a test.</p>".to_string(),
    ..Default::default()
};

let response = generate_pdf_from_html(&pool, &request)?;
std::fs::write("output.pdf", &response.data)?;

§Complete Document with Styling

let html = r#"
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <style>
        body {
            font-family: 'Arial', sans-serif;
            margin: 40px;
            color: #333;
        }
        h1 {
            color: #0066cc;
            border-bottom: 2px solid #0066cc;
            padding-bottom: 10px;
        }
        table {
            width: 100%;
            border-collapse: collapse;
            margin-top: 20px;
        }
        th, td {
            border: 1px solid #ddd;
            padding: 12px;
            text-align: left;
        }
        th {
            background-color: #f5f5f5;
        }
    </style>
</head>
<body>
    <h1>Monthly Report</h1>
    <p>Generated on: 2024-01-15</p>
    <table>
        <tr><th>Metric</th><th>Value</th></tr>
        <tr><td>Revenue</td><td>$50,000</td></tr>
        <tr><td>Users</td><td>1,234</td></tr>
    </table>
</body>
</html>
"#;

let request = PdfFromHtmlRequest {
    html: html.to_string(),
    filename: Some("monthly-report.pdf".to_string()),
    print_background: Some(true), // Include styled backgrounds
    ..Default::default()
};

let response = generate_pdf_from_html(&pool, &request)?;

§With Embedded Images

// Base64 encode an image
let image_base64 = base64::encode(std::fs::read("logo.png")?);

let html = format!(r#"
<!DOCTYPE html>
<html>
<body>
    <img src="data:image/png;base64,{}" alt="Logo">
    <h1>Company Report</h1>
</body>
</html>
"#, image_base64);

let request = PdfFromHtmlRequest {
    html,
    ..Default::default()
};

let response = generate_pdf_from_html(&pool, &request)?;

generate_pdf_from_html

Function generate_pdf_from_html Copy item path