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Documentation Index

Fetch the complete documentation index at: https://docs.formepdf.com/llms.txt

Use this file to discover all available pages before exploring further.

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Installation

cargo add forme-pdf
The crate is published as forme-pdf on crates.io. The library name is forme: 
use forme::{render_json, Document, Style, FormeError};

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Quick start

use forme::{render_json, FormeError};

fn main() -> Result<(), FormeError> {
    let json = r#"{
        "pages": [{ "size": "A4" }],
        "children": [{
            "kind": "text",
            "content": "Hello from Forme!",
            "style": { "fontSize": 24, "margin": { "top": 72, "left": 72 } }
        }]
    }"#;

    let pdf_bytes = render_json(json)?;
    std::fs::write("hello.pdf", pdf_bytes).unwrap();
    Ok(())
}

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API

FunctionDescription
render(&Document)Render a Document struct to PDF bytes
render_json(&str)Parse JSON and render to PDF
render_with_layout(&Document)Render and return layout metadata
render_json_with_layout(&str)Parse JSON, render, and return layout metadata
render_template(&str, &str)Evaluate a template with data, then render
render_template_with_layout(&str, &str)Evaluate a template with data, render, and return layout metadata

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PDF operations

FunctionDescription
merge_pdfs(&[&[u8]])Combine multiple PDFs into one
certify_pdf(&[u8], &str, &str, ...)Apply a PKCS#7 digital signature to an existing PDF
redact_pdf(&[u8], &[RedactionRegion])Redact regions from a PDF (removes underlying text)
redact_text(&[u8], &[TextSearchRedaction])Find text by pattern and redact matching regions
find_text_regions(&[u8], &[TextSearchPattern])Find text regions in a PDF without redacting
All functions return Result<Vec<u8>, FormeError> (or Result<(Vec<u8>, LayoutInfo), FormeError> for the _with_layout variants).

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Working with the Document struct

For full control, build a Document directly instead of using JSON: 
use forme::{Document, Node, NodeKind, PageConfig, PageSize, Style, Metadata, render};

let document = Document {
    children: vec![Node {
        kind: NodeKind::Text {
            content: "Hello from Forme!".to_string(),
        },
        style: Some(Style {
            font_size: Some(24.0),
            ..Default::default()
        }),
        children: vec![],
        ..Default::default()
    }],
    pages: vec![PageConfig {
        size: Some(PageSize::A4),
        ..Default::default()
    }],
    metadata: Metadata::default(),
    ..Default::default()
};

let pdf_bytes = render(&document)?;

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Templates

Render dynamic documents by combining a template (with $ref, $each, $if expressions) and a data object: 
use forme::render_template;

let template = r#"{
    "pages": [{ "size": "A4" }],
    "children": [{
        "kind": "text",
        "content": { "$ref": "greeting" },
        "style": { "fontSize": 24 }
    }]
}"#;

let data = r#"{ "greeting": "Hello, world!" }"#;

let pdf_bytes = render_template(template, data)?;
See the templates guide for the full expression language.

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Layout metadata

The _with_layout variants return a LayoutInfo struct describing the position and dimensions of every element on every page. Useful for overlays, click-to-inspect, and testing: 
use forme::render_json_with_layout;

let (pdf_bytes, layout) = render_json_with_layout(json)?;
println!("Pages: {}", layout.pages.len());
for page in &layout.pages {
    for element in &page.elements {
        println!("  {} at ({}, {})", element.id, element.x, element.y);
    }
}

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Features

The engine supports:
  • Flexbox layout — row, column, wrap, grow/shrink, all alignment modes
  • CSS Grid — track sizing, auto/explicit placement, repeat() syntax
  • Text — OpenType shaping, Knuth-Plass line breaking, hyphenation (35+ languages), BiDi, per-character font fallback
  • Tables — automatic header repetition on page breaks
  • Images — JPEG, PNG, WebP
  • SVG — inline rendering (rect, circle, line, path, arc)
  • Charts — BarChart, LineChart, PieChart, AreaChart, DotPlot
  • QR codes & barcodes — Code128, Code39, EAN13, EAN8, Codabar
  • AcroForms — fillable PDF forms (TextField, Checkbox, Dropdown, RadioButton) with form flattening
  • Digital signatures — PKCS#7 detached signatures with X.509 certificates (PKCS#1 and PKCS#8 keys)
  • PDF/UA-1 — accessibility compliance with structure tree and artifact tagging
  • PDF/A — archival compliance (PDF/A-2b, PDF/A-2a)
  • PDF operations — merge, certify, redact, and text search on existing PDFs
  • Embedded data — attach JSON inside the PDF for round-tripping

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WASM

The crate compiles to WebAssembly. Enable the wasm feature for wasm-bindgen support: 
[dependencies]
forme-pdf = { version = "0.9", features = ["wasm"] }
This is how @formepdf/core works under the hood — the same engine, compiled to WASM and called from JavaScript.