PaperForge

PaperForge is a pure Elixir PDF generation engine. It builds PDF object graphs, page content streams, resources, cross-reference tables, trailers, text layout, vector graphics, metadata, and image XObjects directly in Elixir.

No browser, wkhtmltopdf, Chromium, ImageMagick, Ghostscript, or external rendering service is required.

PaperForge is currently pre-1.0. The 0.3.x API is usable, but some details may still change while layout and image support mature.

Highlights

• Pure Elixir PDF generation
• Multi-page documents
• PDF 1.4, 1.5, 1.6, and 1.7 headers
• Flate compression enabled by default
• A3, A4, A5, Letter, Legal, and custom page sizes
• Portrait and landscape orientation
• Bottom-left and top-left coordinate systems
• Uniform and side-specific page margins
• Text drawing with color, alignment, and width-aware positioning
• Multiline text boxes with wrapping, explicit line breaks, line height, height limits, and overflow reporting
• The 14 standard PDF Type 1 fonts
• Embedded TrueType fonts loaded from paths or binaries
• TrueType PDF width and /ToUnicode subsetting for used glyphs
• Font-family registration with regular, bold, italic, and bold italic variants
• Document-level default font selection
• Visible Unicode text through Type 0 / CIDFontType2 fonts
• Identity-H encoding and /ToUnicode maps for embedded fonts
• Real TrueType metrics for width, wrapping, and alignment
• Vertical text flow with automatic page breaks
• Basic tables
• URI link annotations
• Lines, rectangles, circles, fill, stroke, and line widths
• RGB and grayscale colors
• JPEG image XObjects with RGB, grayscale, and CMYK support
• PNG image XObjects for non-interlaced 8-bit grayscale, RGB, grayscale-alpha, and RGBA images
• PNG transparency through PDF soft masks (/SMask)
• Image deduplication by SHA-256 hash
• Unicode-aware document metadata using Latin-1 or UTF-16BE as needed
• Traditional PDF xref table generation

Installation

PaperForge can be used from GitHub:

def deps do
  [
    {:paper_forge,
     github: "Manuel1471/paper_forge",
     tag: "v0.3.0"}
  ]
end

For local development against main:

def deps do
  [
    {:paper_forge,
     github: "Manuel1471/paper_forge",
     branch: "main"}
  ]
end

After PaperForge is published to Hex, installation will use:

def deps do
  [
    {:paper_forge, "~> 0.3.0"}
  ]
end

Then run:

mix deps.get

Quick Start

alias PaperForge.Color
alias PaperForge.Page

document =
  PaperForge.new(compress: true, pdf_version: "1.7")
  |> PaperForge.register_font(
    :inter,
    path: "assets/fonts/Inter-Regular.ttf"
  )
  |> PaperForge.metadata(
    title: "PaperForge Example",
    author: "Manuel Garcia",
    subject: "Pure Elixir PDF generation",
    keywords: ["Elixir", "PDF", "PaperForge"]
  )
  |> PaperForge.add_page(
    [
      size: :a4,
      origin: :top_left,
      margins: 72
    ],
    fn page ->
      page
      |> Page.text(
        "Informacion del usuario — 你好 — Привет",
        y: 72,
        width: Page.content_width(page),
        align: :center,
        font: :inter,
        size: 28,
        color: Color.rgb255(35, 60, 120)
      )
      |> Page.text_box(
        "PaperForge creates PDF files directly from Elixir data structures, with embedded fonts for visible Unicode text.",
        y: 120,
        width: Page.content_width(page),
        font: :inter,
        size: 12,
        line_height: 17
      )
    end
  )

PaperForge.write!(document, "example.pdf")

Document Options

PaperForge.new/1 accepts:

• :compress - enables Flate compression for page content streams. Defaults to true.
• :pdf_version - sets the PDF header version. Supported values are "1.4", "1.5", "1.6", and "1.7". Defaults to "1.7".

PaperForge.new()
PaperForge.new(compress: false)
PaperForge.new(pdf_version: "1.4")
PaperForge.new(default_font: :helvetica)

Pages

Add a page with default options:

document =
  PaperForge.new()
  |> PaperForge.add_page(fn page ->
    Page.text(page, "Default A4 page", x: 72, y: 750)
  end)

Add a page with options:

document =
  PaperForge.new()
  |> PaperForge.add_page(
    [
      size: :letter,
      orientation: :landscape,
      origin: :top_left,
      margins: [top: 48, right: 54, bottom: 48, left: 54]
    ],
    fn page ->
      Page.text(page, "Landscape page", y: 48)
    end
  )

Supported page sizes:

:a3
:a4
:a5
:letter
:legal

Custom page sizes use {width, height} in PDF points:

Page.new(size: {500, 700})

All dimensions are expressed in PDF points.

1 point = 1/72 inch

Coordinates And Margins

PaperForge supports both PDF-native bottom-left coordinates and top-left coordinates.

Page.new(origin: :bottom_left)
Page.new(origin: :top_left)

You can also set the origin per operation:

Page.rectangle(page, x: 72, y: 72, width: 100, height: 40, origin: :top_left)

Margins can be uniform:

Page.new(margins: 72)

Or side-specific:

Page.new(margins: [top: 40, right: 50, bottom: 40, left: 50])

Content helpers:

Page.content_width(page)
Page.content_height(page)
Page.content_left(page)
Page.content_top(page)
Page.content_bottom(page)

Text

Draw a single line of text:

Page.text(
  page,
  "Centered title",
  x: Page.content_left(page),
  y: 72,
  width: Page.content_width(page),
  align: :center,
  font: :helvetica_bold,
  size: 24,
  color: Color.black()
)

Draw wrapped multiline text:

Page.text_box(
  page,
  """
  PaperForge wraps text into multiple lines using built-in font metrics.

  Explicit line breaks are preserved.
  """,
  x: Page.content_left(page),
  y: 120,
  width: Page.content_width(page),
  height: 160,
  font: :times_roman,
  size: 12,
  line_height: 17,
  align: :left
)

Supported alignment values:

:left
:center
:right

Fonts And Unicode Text

PaperForge supports two font paths: the 14 standard PDF Type 1 fonts and embedded TrueType fonts.

Standard Type 1 fonts are registered automatically when used:

:helvetica
:helvetica_bold
:helvetica_oblique
:helvetica_bold_oblique
:times_roman
:times_bold
:times_italic
:times_bold_italic
:courier
:courier_bold
:courier_oblique
:courier_bold_oblique
:symbol
:zapf_dingbats

Standard Type 1 fonts are convenient for simple Latin text, but they are not full Unicode fonts. For visible Unicode text, register a TrueType .ttf font before adding pages:

document =
  PaperForge.new()
  |> PaperForge.register_font(
    :inter,
    path: "assets/fonts/Inter-Regular.ttf"
  )

You can also register a font from an in-memory binary:

document =
  PaperForge.register_font(
    document,
    :inter,
    data: File.read!("assets/fonts/Inter-Regular.ttf")
  )

Then use the registered key in text operations:

Page.text(
  page,
  "El pingüino comió camarón — ¿listo? — Привет — Ω",
  x: 72,
  y: 720,
  font: :inter,
  size: 18
)

Embedded TrueType fonts are written as PDF Type 0 fonts with a CIDFontType2 descendant, Identity-H encoding, a /FontFile2 stream, widths from the TTF hmtx table, and a /ToUnicode CMap so text extraction and search can recover Unicode characters.

Supported embedded font input:

• TrueType outlines (.ttf)
• Unicode cmap format 4 or 12
• 8-bit and Unicode text strings supported by the font's glyph coverage

Current limitations:

• OpenType CFF (OTTO) and TrueType Collection (.ttc) files are not supported yet.
• Complex text shaping is not performed, so scripts such as Arabic, Devanagari, and advanced ligatures may not render as expected.
• PaperForge subsets the generated PDF width arrays and /ToUnicode maps to the glyphs used by the document. Physical TTF table reconstruction is not implemented yet, so the full .ttf program is still embedded in /FontFile2.
• A missing glyph raises PaperForge.FontError.

Font Families

Register related TrueType files as a family:

document =
  PaperForge.new()
  |> PaperForge.register_font_family(
    :inter,
    regular: [path: "assets/fonts/Inter-Regular.ttf"],
    bold: [path: "assets/fonts/Inter-Bold.ttf"],
    italic: [path: "assets/fonts/Inter-Italic.ttf"],
    bold_italic: [path: "assets/fonts/Inter-BoldItalic.ttf"]
  )

Then select a variant with :weight and :style:

Page.text(
  page,
  "Important",
  x: 72,
  y: 720,
  font: :inter,
  weight: :bold,
  style: :italic
)

Set a document default font when most text should use the same font:

document =
  PaperForge.new()
  |> PaperForge.register_font(:inter, path: "assets/fonts/Inter-Regular.ttf")
  |> PaperForge.default_font(:inter)

Shapes

Lines

Page.line(
  page,
  x1: 72,
  y1: 700,
  x2: 300,
  y2: 700,
  width: 2,
  color: Color.rgb255(40, 70, 140)
)

Rectangles

Page.rectangle(
  page,
  x: 72,
  y: 560,
  width: 220,
  height: 100,
  fill: true,
  stroke: true,
  fill_color: Color.rgb255(235, 240, 250),
  stroke_color: Color.rgb255(40, 70, 140),
  line_width: 2
)

Circles

Page.circle(
  page,
  x: 400,
  y: 610,
  radius: 50,
  fill: true,
  stroke: true,
  fill_color: Color.rgb255(245, 180, 70),
  stroke_color: Color.rgb255(120, 70, 20),
  line_width: 2
)

PaperForge approximates circles using four cubic Bezier curves because PDF does not provide a native circle operator.

Colors

RGB values can be expressed from 0 to 1:

Color.rgb(1.0, 0.0, 0.0)

Or from 0 to 255:

Color.rgb255(255, 0, 0)

Grayscale helpers:

Color.gray(0.5)
Color.black()
Color.white()

Images

Page.image/3 accepts a supported image binary or a file path.

png = File.read!("logo.png")

page
|> Page.image(png, x: 72, y: 120, width: 200)
|> Page.image("photo.jpg", x: 72, y: 360, width: 200, height: 120)

When only one dimension is supplied, PaperForge preserves the source aspect ratio:

Page.image(page, "logo.png", x: 72, y: 120, width: 200)
Page.image(page, "logo.png", x: 72, y: 120, height: 80)

Supported JPEGs:

• grayscale
• RGB
• CMYK

Supported PNGs:

• non-interlaced 8-bit grayscale
• non-interlaced 8-bit RGB
• non-interlaced 8-bit grayscale with alpha
• non-interlaced 8-bit RGBA

PNG alpha is written as a PDF soft mask (/SMask). PNG grayscale/RGB images without alpha use the original compressed IDAT data directly with /FlateDecode and PNG predictor decode parameters. JPEG image data is embedded directly with /DCTDecode.

Images are deduplicated by SHA-256 hash, so drawing the same image several times does not embed duplicate image streams.

Flow, Tables, And Links

Flow text blocks across pages:

document =
  PaperForge.new()
  |> PaperForge.add_flow(
    [
      "First paragraph with enough text to wrap.",
      "Second paragraph. PaperForge creates new pages as needed."
    ],
    [size: :letter, margins: 72],
    font: :helvetica,
    size: 11,
    line_height: 15,
    gap: 8
  )

Draw a basic table:

page =
  page
  |> Page.table(
    [
      ["Name", "Score"],
      ["Ana", 10],
      ["Luis", 9]
    ],
    x: Page.content_left(page),
    y: 96,
    width: Page.content_width(page),
    header: true
  )

Add a URI link annotation:

page =
  page
  |> Page.text("Project", x: 72, y: 720)
  |> Page.link(
    "https://github.com/Manuel1471/paper_forge",
    x: 72,
    y: 700,
    width: 180,
    height: 24
  )

Metadata

document =
  PaperForge.new()
  |> PaperForge.metadata(
    title: "Reporte de Mexico",
    author: "Manuel Garcia",
    subject: "Informacion \u65E5\u672C\u8A9E",
    keywords: ["report", "elixir", "pdf"],
    creator: "PaperForge",
    producer: "PaperForge",
    creation_date: DateTime.utc_now(),
    modification_date: DateTime.utc_now()
  )

Metadata is written into the PDF Info dictionary and referenced from the document trailer. Latin-1-compatible strings are stored as PDF literal strings. Other Unicode strings are stored as UTF-16BE hexadecimal strings.

Binary Output

PaperForge can return the complete PDF as a binary:

pdf_binary =
  PaperForge.to_binary(document)

This can be used in Phoenix or Plug responses:

conn
|> put_resp_content_type("application/pdf")
|> put_resp_header(
  "content-disposition",
  ~s(attachment; filename="document.pdf")
)
|> send_resp(200, PaperForge.to_binary(document))

Write to disk:

PaperForge.write(document, "document.pdf")
PaperForge.write!(document, "document.pdf")

Architecture

PaperForge separates public drawing operations from low-level PDF objects.

PaperForge
|-- Document
|   |-- object allocation
|   |-- font registry
|   |-- image registry
|   `-- metadata reference
|-- Page
|   `-- high-level drawing operations
|-- PageCompiler
|   |-- coordinate transforms
|   |-- font registration
|   |-- image registration
|   `-- resource dictionaries
|-- Graphics
|   |-- Text
|   |-- TextBox
|   |-- Line
|   |-- Rectangle
|   |-- Circle
|   `-- Image
|-- Serializer
|   `-- Elixir values to PDF syntax
`-- Writer
    |-- PDF header
    |-- indirect objects
    |-- cross-reference table
    |-- trailer
    `-- EOF marker

The generated PDF uses traditional cross-reference tables. Tests verify that xref offsets point to the start of their corresponding indirect objects.

Examples

Run the included examples:

mix run examples/hello.exs
mix run examples/graphics.exs
mix run examples/two_pages.exs
mix run examples/new_features.exs
mix run examples/png.exs
mix run examples/multilingual_layout.exs
mix run examples/complete_showcase.exs

Generated files are written under tmp/.

Development

Clone the repository:

git clone git@github.com:Manuel1471/paper_forge.git
cd paper_forge

Run the test suite:

mix test

Compile with warnings treated as errors:

mix compile --warnings-as-errors

Format the source code:

mix format

Run all checks:

mix do format, compile --warnings-as-errors, test

Run the TrueType and Unicode benchmark script:

mix run benchmarks/truetype.exs

Roadmap

0.4.x

• Better paragraph layout APIs
• Physical TrueType table subsetting for smaller /FontFile2 streams

Future

• OpenType CFF fonts
• PNG palette support
• Reusable Form XObjects
• HTML parsing
• CSS style resolution
• HTML/CSS layout engine
• Existing PDF parsing
• Incremental updates
• Digital signatures

Project Status

PaperForge is experimental and currently intended for learning, testing, and early integration.

The public API may change before version 1.0.0.

Contributing

Contributions, bug reports, architecture discussions, and PDF examples are welcome.

Before opening a pull request:

mix format
mix compile --warnings-as-errors
mix test

License

PaperForge is available under the terms specified in the LICENSE.