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 0.5.x API is usable, but some details may still change while layout and image support mature.

Why PaperForge?

• Generate PDFs without leaving Elixir or the BEAM.
• Avoid Chromium, Node.js, Python, native executables, and external rendering services.
• Build structured documents with automatic pagination.
• Render visible Unicode text with embedded TrueType fonts.
• Create reports, invoices, statements, contracts, and other business PDFs.
• Work with immutable Elixir data structures and process-safe APIs.

Highlights

Document Layout

• Unified block-based layout through PaperForge.Flow.
• Deterministic pagination with page-break and keep-together controls.
• Two-pass rendering with PageContext and total page counts.
• Named page templates with page size, orientation, margins, headers, and footers.
• Sections with metadata, template switching, destinations, and bookmarks.
• Multipage tables with repeated headers.
• Automatic heading destinations and outline bookmarks.
• Structured layout reports and debug reports.

PDF Engine

• 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 font-program deduplication by binary hash
• TrueType subsetting planning with composite glyph dependency resolution, table checksums, and glyf/loca/hmtx/maxp rebuild metadata
• 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
• Internal links, named destinations, outlines, and bookmarks
• 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

Which API Should I Use?

Installation

Add PaperForge to your dependencies:

def deps do
  [
    {:paper_forge, "~> 0.5.0"}
  ]
end

Then run:

mix deps.get

To use the GitHub release directly:

def deps do
  [
    {:paper_forge,
     github: "Manuel1471/paper_forge",
     tag: "v0.5.0"}
  ]
end

For local development against main:

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

Quick Start

alias PaperForge.Flow

{document, report} =
  PaperForge.new(compress: true, pdf_version: "1.7")
  |> PaperForge.page_template(
    :default,
    size: :a4,
    margins: [top: 72, right: 54, bottom: 72, left: 54],
    header: "Quarterly Report",
    footer: "Page {page} of {total}"
  )
  |> PaperForge.layout(
    fn flow ->
      flow
      |> Flow.heading("Quarterly Report", level: 1)
      |> Flow.paragraph("""
      PaperForge measures, paginates, and renders document blocks automatically.
      """)
      |> Flow.list(
        ["Unified layout", "Automatic pagination", "Reusable templates"],
        type: :unordered
      )
      |> Flow.table(
        ["Metric", "Value"],
        [
          ["Revenue", "$120K"],
          ["Margin", "24%"]
        ],
        repeat_header: true
      )
    end,
    template: :default
  )

IO.inspect(report.pages, label: "Pages")
PaperForge.write!(document, "report.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)

Low-level Page API

Use PaperForge.Page when you need manual graphics, exact coordinates, or a lower-level drawing surface. New structured documents should usually start with PaperForge.Flow and PaperForge.layout/3.

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. The physical TrueType subsetting planner can resolve composite glyph dependencies and calculate table checksums, but final /FontFile2 table reconstruction is still in progress.
• 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.

Unified Flow

PaperForge.flow/2 builds a document from layout blocks instead of manual page operations. The engine measures blocks, paginates them, calculates total pages, and then renders the final pages.

alias PaperForge.Flow

{document, report} =
  PaperForge.new()
  |> PaperForge.page_template(
    :report,
    size: :a4,
    margins: [top: 72, right: 54, bottom: 72, left: 54],
    header: "Quarterly report",
    footer: "Page {page} of {total}"
  )
  |> PaperForge.layout(
    fn flow ->
      flow
      |> Flow.heading("Quarterly report", level: 1)
      |> Flow.paragraph("Summary text that wraps and splits across pages.")
      |> Flow.list(["Revenue", "Expenses", "Cash"], type: :ordered)
      |> Flow.table(
        ["Metric", "Value"],
        [
          ["Revenue", "$120K"],
          ["Margin", "24%"]
        ],
        repeat_header: true
      )
      |> Flow.separator()
      |> Flow.page_break()
      |> Flow.section(:appendix, [title: "Appendix"], fn section ->
        section
        |> Flow.paragraph("Section content receives section metadata.")
      end)
    end,
    template: :report
  )

The report returned by PaperForge.layout/3 contains page count, block count, placements, warnings, and rendered page values. Placements include block ID, block type, page number, coordinates, dimensions, and section metadata:

{document, report} =
  PaperForge.layout(document, flow_function, template: :report)

report.pages
report.blocks
report.placements

Pagination options can be set on flow blocks:

flow
|> Flow.heading("Appendix", page_break_before: true, keep_with_next: true)
|> Flow.paragraph("This paragraph should stay visually connected.")
|> Flow.separator(page_break_after: true)

Sections group related content under a stable section ID. A section can add a title heading, start or end with page breaks, switch to a named page template, and pass section metadata into PageContext:

flow
|> Flow.section(:appendix, [title: "Appendix", template: :appendix], fn section ->
  section
  |> Flow.paragraph("Appendix content")
end)

Page templates can configure page geometry and reusable header/footer content:

document =
  PaperForge.new()
  |> PaperForge.page_template(
    :appendix,
    size: :letter,
    orientation: :landscape,
    margins: [top: 60, right: 48, bottom: 60, left: 48],
    header: fn page, context ->
      Page.text(page, "Appendix", x: context.content_left, y: 24)
    end,
    footer: "Page {page} of {total}"
  )

Custom blocks receive the current Page and PageContext:

Flow.custom(flow, fn page, context ->
  Page.text(
    page,
    "Page #{context.page_number} of #{context.total_pages}",
    x: context.content_left,
    y: context.content_top
  )
end, height: 24)

Debug reports summarize the generated document:

PaperForge.debug(document,
  show_margins: true,
  show_blocks: true,
  show_page_breaks: true
)

Existing Page, add_flow/4, and add_table/4 APIs remain supported for compatibility. New applications should prefer PaperForge.Flow and PaperForge.layout/3.

Legacy Flow And Page-level APIs

The APIs in this section remain supported for compatibility. New applications should prefer PaperForge.Flow and PaperForge.layout/3.

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
  )

Get flow overflow information:

{document, report} =
  PaperForge.layout_flow(
    PaperForge.new(),
    ["A long paragraph", "Another long paragraph"],
    [size: :letter, margins: 72],
    header: "Quarterly report",
    footer: "Generated by PaperForge",
    keep_together: true
  )

report.pages_added
report.overflow?

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
  )

Create internal navigation:

document =
  PaperForge.new()
  |> PaperForge.add_page(fn page ->
    page
    |> Page.destination(:intro, y: 720)
    |> Page.bookmark("Introduction", y: 720)
    |> Page.text("Introduction", x: 72, y: 720)
  end)
  |> PaperForge.add_page(fn page ->
    page
    |> Page.text("Back to intro", x: 72, y: 720)
    |> Page.link_to(:intro, x: 72, y: 700, width: 120, height: 24)
  end)

Add a paginated table with repeated headers:

document =
  PaperForge.add_table(
    document,
    rows,
    [size: :a4, margins: 72],
    repeat_header: true,
    row_split: :keep
  )

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
|-- Flow
|   `-- block-based document layout builder
|-- Layout
|   |-- Block
|   |-- Engine
|   `-- two-pass pagination and rendering
|-- 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
mix run examples/paper_forge_0_4_showcase.exs
mix run examples/paper_forge_0_5_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

Current Limitations

• The unified layout engine is the preferred rendering path for new applications, while page-level APIs remain available for compatibility.
• Rich text and inline mixed-style runs are not yet supported.
• Advanced widow and orphan control is not yet supported.
• Tables can continue across multiple pages, while individual rows are kept together. Content inside a single row or cell cannot yet be split across pages.
• Automatic table-of-contents generation is not yet supported.
• Advanced image cropping, fitting modes, and object positioning remain future work.
• Page-template inheritance and first, odd, even, or final-page template variants are not yet supported.
• Physical TrueType /FontFile2 reconstruction is not enabled yet. PaperForge uses the subsetting planner foundation while embedding the original TrueType font program.

Roadmap

0.6.x - Document Authoring

• Rich text and inline styles
• Physical TrueType subsetting
• Font fallback
• Automatic table of contents
• Advanced tables
• Advanced page templates
• Reusable document components

1.x - Production And Distributed Generation

• Streaming output
• Compiled templates
• Shared local caches
• Batch generation
• Telemetry
• Cancellation and timeouts
• Fault-tolerant job integration
• High-volume benchmarks

2.x - HTML And CSS

• HTML parsing
• CSS cascade and computed styles
• HTML/CSS to PaperForge Layout IR
• Paged-media layout
• Flexbox and advanced document styling

Project Status

PaperForge is pre-1.0 and suitable for experimentation, prototypes, internal tools, and early production evaluation.

The unified layout API is usable, but public API details may still 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.