SuperSimplePDF

Define the layout once. Feed it JSON. The core is blind to both and does all the math.

The theme does not know what the content says. The JSON does not know how it looks. The core does not know it is rendering a newspaper, an invoice, or a certificate. Three blind components, one coherent output.

Source JSON  +  Theme  =  PDF

Install

npm install h17-sspdf

Requires Node.js 18 or newer. The engine vendors a single self-contained UMD build of jsPDF (which bundles fflate, fast-png, iobuffer internally) plus Chart.js and chartjs-node-canvas. The only install-time dependency is canvas (native C++ addon, used by the chart plugin) — no transitive dependency tree beyond that.

The problem it solves

Generating PDFs imperatively means tracking the cursor yourself. Every element you place shifts everything below it. Line wrapping, page breaks, font resets, all manual.

This engine inverts that. You describe what to render and how it looks. The cursor, the math, the page breaks happen automatically.

How it works

Every operation has a type and a label. The label maps to a style in the theme. The engine looks up the style, lays out the content, advances the cursor by an exact calculated amount, and moves to the next operation.

operation → label → theme style → layout → cursor advance → next operation

Page breaks happen automatically when content reaches the bottom margin. Style resets after every operation, nothing leaks.

Quick start

const { renderDocument } = require('h17-sspdf');

renderDocument({
  source: {
    operations: [
      { type: 'text', label: 'doc.title', text: 'My Document' },
      { type: 'divider', label: 'doc.rule' },
      { type: 'text', label: 'doc.body', text: 'First paragraph.' }
    ]
  },
  theme: {
    name: 'My Theme',
    page: {
      format: 'a4',
      orientation: 'portrait',
      unit: 'mm',
      marginTopMm: 20,
      marginBottomMm: 20,
      marginLeftMm: 20,
      marginRightMm: 20,
      backgroundColor: [255, 255, 255],
      defaultText:      { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 10, color: [0,0,0], lineHeight: 1.4 },
      defaultStroke:    { color: [200,200,200], lineWidth: 0.3, lineCap: 'butt', lineJoin: 'miter' },
      defaultFillColor: [255, 255, 255],
    },
    labels: {
      'doc.title': { fontFamily: 'helvetica', fontStyle: 'bold', fontSize: 22, color: [0,0,0], lineHeight: 1.2, marginBottomMm: 4 },
      'doc.rule':  { color: [200,200,200], lineWidth: 0.3, marginBottomMm: 4 },
      'doc.body':  { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 10, color: [40,40,40], lineHeight: 1.5 },
    }
  },
  outputPath: 'output/doc.pdf'
});

Building a layout

The newspaper front page

The most complex built-in layout is a newspaper front page. It has a masthead, edition line, heavy rule, headline hierarchy, byline, multi-paragraph body, pull quote, stat scoreboard, and a footer that repeats on every page. Here is how it is built.

Page template (repeating footer)

Declare it once. The engine stamps it on every page at the specified Y position.

{
  "pageTemplates": {
    "footer": [
      { "type": "divider", "label": "news.footer.rule", "x1Mm": 18, "x2Mm": 192 },
      {
        "type": "row",
        "leftLabel":  "news.footer.left",
        "rightLabel": "news.footer.right",
        "leftText":   "The Meridian Times | Civic Desk",
        "rightText":  "Page {{page}}",
        "xLeftMm": 18,
        "xRightMm": 192
      }
    ],
    "footerHeightMm": 8,
    "footerStartMm": 284
  }
}

{{page}} is replaced with the current page number at render time.

Masthead block

The masthead, edition row, heavy rule, kicker, headline, deck, and byline are all inside a section. A section allows page breaks inside it but groups the content logically.

{
  "type": "section",
  "content": [
    { "type": "text",  "label": "news.masthead", "text": "The Meridian Times", "xMm": 18, "maxWidthMm": 174 },
    {
      "type": "row",
      "leftLabel":  "news.edition.left",
      "rightLabel": "news.edition.right",
      "leftText":   "Saturday, March 7, 2026",
      "rightText":  "Late City Edition",
      "xLeftMm": 18,
      "xRightMm": 192
    },
    { "type": "divider", "label": "news.rule.heavy", "x1Mm": 18, "x2Mm": 192 },
    { "type": "text", "label": "news.kicker",   "text": "Infrastructure & Society", "xMm": 18, "maxWidthMm": 174 },
    { "type": "text", "label": "news.headline", "text": "Local Governments Are Finally Rewriting How They Publish Public Records", "xMm": 18, "maxWidthMm": 174 },
    { "type": "text", "label": "news.deck",     "text": "A quiet wave of procurement reform...", "xMm": 18, "maxWidthMm": 174 },
    {
      "type": "row",
      "leftLabel":  "news.byline",
      "rightLabel": "news.timestamp",
      "leftText":   "By Marta Ruiz",
      "rightText":  "Updated 6:40 PM",
      "xLeftMm": 18,
      "xRightMm": 192
    },
    { "type": "divider", "label": "news.rule.light", "x1Mm": 18, "x2Mm": 192 }
  ]
}

xMm and maxWidthMm override the page margins for this operation. This is how you position content independently of the theme margins.

Multi-paragraph body text

Pass text as an array. Each string becomes a paragraph with the label's spacing applied between them.

{
  "type": "text",
  "label": "news.body",
  "text": [
    "First paragraph.",
    "Second paragraph.",
    "Third paragraph."
  ],
  "xMm": 18,
  "maxWidthMm": 174
}

Keeping a heading with its content

keepWithNext: N tells the engine this operation must stay on the same page as the next N operations. Use it on section headings so they never strand at the bottom of a page.

{ "type": "text", "label": "news.section.title", "text": "Inside the shift", "keepWithNext": 3 }

Stat scoreboard

A repeating pattern of row + text pairs. The row carries the label/value, the text below carries the annotation.

{
  "type": "row",
  "leftLabel":  "news.stat.label",
  "rightLabel": "news.stat.value",
  "leftText":   "Harbor City planning notices",
  "rightText":  "42% faster"
},
{
  "type": "text",
  "label": "news.stat.note",
  "text": "Review time fell after zoning notices moved to a single contract."
}

Pull quote

{
  "type": "quote",
  "label": "news.pullquote",
  "text": "When the format becomes a system instead of a template, agencies stop re-solving the same layout problem every week.",
  "attribution": "— Elena Ward, public records modernization lead",
  "xMm": 22,
  "maxWidthMm": 166
}

xMm and maxWidthMm indent it from the body column, the indentation is in the source, not the theme.

Hidden text (ATS / search metadata)

Invisible in the rendered PDF, present in text extraction.

{
  "type": "hiddenText",
  "label": "news.hidden.tags",
  "text": "public records procurement modernization searchable notices"
}

The theme labels for this layout

Each label the source uses must exist in the theme. These are the ones the newspaper source uses:

labels: {
  'news.masthead':     { fontFamily: 'custom', fontStyle: 'bold', fontSize: 36, color: [0,0,0], lineHeight: 1.1, marginBottomMm: 2 },
  'news.edition.left': { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 8, color: [80,80,80], lineHeight: 1 },
  'news.edition.right':{ fontFamily: 'helvetica', fontStyle: 'italic', fontSize: 8, color: [80,80,80], lineHeight: 1, marginBottomMm: 1 },
  'news.rule.heavy':   { color: [0,0,0], lineWidth: 1.2, marginBottomMm: 2 },
  'news.rule.light':   { color: [160,160,160], lineWidth: 0.3, marginBottomMm: 3 },
  'news.kicker':       { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 9, color: [100,100,100], lineHeight: 1, textTransform: 'uppercase', marginBottomMm: 1 },
  'news.headline':     { fontFamily: 'custom', fontStyle: 'bold', fontSize: 28, color: [0,0,0], lineHeight: 1.15, marginBottomMm: 3 },
  'news.deck':         { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 11, color: [40,40,40], lineHeight: 1.4, marginBottomMm: 2 },
  'news.byline':       { fontFamily: 'helvetica', fontStyle: 'bold', fontSize: 8, color: [0,0,0], lineHeight: 1 },
  'news.timestamp':    { fontFamily: 'helvetica', fontStyle: 'italic', fontSize: 8, color: [80,80,80], lineHeight: 1, marginBottomMm: 2 },
  'news.body':         { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 10, color: [20,20,20], lineHeight: 1.55, marginBottomMm: 3 },
  'news.section.title':{ fontFamily: 'helvetica', fontStyle: 'bold', fontSize: 11, color: [0,0,0], lineHeight: 1.2, marginTopMm: 3, marginBottomMm: 1 },
  'news.pullquote':    { fontFamily: 'custom', fontStyle: 'italic', fontSize: 13, color: [30,30,30], lineHeight: 1.5,
                         leftBorder: { widthMm: 1.5, color: [0,0,0], paddingMm: 4 }, marginTopMm: 4, marginBottomMm: 4 },
  'news.stat.label':   { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 9, color: [40,40,40], lineHeight: 1 },
  'news.stat.value':   { fontFamily: 'helvetica', fontStyle: 'bold', fontSize: 9, color: [0,0,0], lineHeight: 1 },
  'news.stat.note':    { fontFamily: 'helvetica', fontStyle: 'italic', fontSize: 8, color: [100,100,100], lineHeight: 1.3, marginBottomMm: 3 },
  'news.brief.text':   { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 10, color: [20,20,20], lineHeight: 1.5 },
  'news.brief.marker': { color: [0,0,0] },
  'news.footer.rule':  { color: [160,160,160], lineWidth: 0.3, marginBottomMm: 1 },
  'news.footer.left':  { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 7, color: [120,120,120], lineHeight: 1 },
  'news.footer.right': { fontFamily: 'helvetica', fontStyle: 'normal', fontSize: 7, color: [120,120,120], lineHeight: 1 },
  'news.hidden.tags':  { fontSize: 0.1, color: [255,255,255] },
}

Operation types

| Type | Purpose | Key fields | |------|---------|------------| | text | Wrapped text block | label, text (string or array of strings) | | row | Left/right pair on one line | leftLabel, rightLabel, leftText, rightText | | bullet | Marker + wrapped text | label, markerLabel, bullets (array) | | divider | Horizontal rule | label, x1Mm, x2Mm | | image | Embedded PNG/JPEG | src, width (percentage or mm), caption | | spacer | Vertical gap | mm, px, or label | | pageBreak | Force new page | (none) | | hiddenText | Invisible text | label, text | | quote | Blockquote with attribution | label, text, attribution | | block | Group children, optional background + border | children, keepTogether | | section | Logical group, allows breaks inside | content | | columns | Two-column side-by-side layout | column1, column2, gutterMm |

Position overrides

Any operation accepts xMm and maxWidthMm to override the theme margins for that operation only.

Page break control

• keepWithNext: N - keep this operation on the same page as the next N operations
• block with keepTogether: true - all children stay on the same page

Label style properties

{
  // Typography
  fontFamily: 'helvetica',       // or any registered custom font family
  fontStyle: 'normal',           // 'normal' | 'bold' | 'italic' | 'bolditalic'
  fontSize: 10,                  // pt
  color: [0, 0, 0],              // RGB
  lineHeight: 1.4,               // multiplier
  textTransform: 'uppercase',    // 'uppercase' | 'lowercase' | undefined

  // Spacing
  marginTopMm: 0,
  marginBottomMm: 0,
  marginTopPx: 0,
  marginBottomPx: 0,
  paddingTopMm: 0,
  paddingBottomMm: 0,
  paddingTopPx: 0,
  paddingBottomPx: 0,

  // Dividers
  lineWidth: 0.3,

  // Container (block/section)
  backgroundColor: [245, 245, 245],
  borderColor: [200, 200, 200],
  borderWidthMm: 0.3,
  paddingMm: 4,

  // Left border accent (quote, callout)
  leftBorder: {
    widthMm: 1.5,
    color: [0, 0, 0],
    paddingMm: 4,
  },
}

Built-in fonts

20 Google Fonts ship with the package as base64 TTF. Each exports { Regular, Bold }.

Sans-serif: Inter, Roboto, Open Sans, Montserrat, Lato, Raleway, Nunito, Work Sans, IBM Plex Sans, PT Sans, Oswald

Serif: Merriweather, Lora, Playfair Display, Crimson Text, Libre Baskerville, Source Serif 4

Monospace: Fira Code, JetBrains Mono, Source Code Pro

const INTER = require('h17-sspdf/fonts/inter.js');

customFonts: [{
  family: 'Inter',
  faces: [
    { style: 'normal', fileName: 'Inter-Regular.ttf', data: INTER.Regular },
    { style: 'bold',   fileName: 'Inter-Bold.ttf',    data: INTER.Bold },
  ],
}],

List all fonts: npx h17-sspdf --fonts

Vector shapes

20 built-in vector shapes rendered via jsPDF drawing primitives. No text encoding, no font dependencies.

Use as bullet markers by setting shape on a marker label:

// Theme
'bullet.arrow': { shape: 'arrow', shapeColor: [0, 128, 255], shapeSize: 0.8 }

// Source JSON (same bullet operation as always)
{ "type": "bullet", "label": "doc.body", "markerLabel": "bullet.arrow", "bullets": ["Point one"] }

Available: arrow, circle, square, diamond, triangle, dash, chevron, doubleColon, commentSlash, hashComment, bracketChevron, treeBranch, terminalPrompt, checkmark, cross, star, plus, minus, warning, infoCircle

List all shapes: npx h17-sspdf --shapes

Custom fonts

Embed your own TTF as base64 and register in the theme:

customFonts: [
  {
    family: 'MyFont',
    faces: [
      { style: 'normal', fileName: 'MyFont-Regular.ttf', data: '<base64>' },
      { style: 'bold',   fileName: 'MyFont-Bold.ttf',    data: '<base64>' },
    ],
  },
],

Then use fontFamily: 'MyFont' in any label.

Chart plugin

Renders any Chart.js configuration to a PNG and embeds it in the PDF.

Requirements

The chart plugin requires the canvas npm package (native C++ addon). Chart.js and chartjs-node-canvas are vendored and ship with the engine.

npm install canvas

Register

const { registerPlugin, plugins } = require('h17-sspdf');
registerPlugin('chart', plugins.chart);

Operation format

{
  "type": "chart",
  "chartType": "bar",
  "widthMm": 160,
  "heightMm": 80,
  "canvasWidth": 1600,
  "canvasHeight": 800,
  "data": {
    "labels": ["Q1", "Q2", "Q3", "Q4"],
    "datasets": [
      {
        "label": "Revenue",
        "data": [120000, 145000, 138000, 172000],
        "backgroundColor": "rgba(110, 158, 210, 0.80)"
      }
    ]
  },
  "options": {
    "scales": {
      "y": { "beginAtZero": true }
    }
  }
}

data and options are passed directly to Chart.js, the plugin does not abstract the Chart.js API. canvasWidth/canvasHeight control render resolution (default 1600×800). widthMm/heightMm control the slot size in the PDF.

CLI

npx h17-sspdf -s source.json -t theme.js -o output.pdf

| Flag | Short | Description | |------|-------|-------------| | --source | -s | Path to source JSON (or pipe via stdin) | | --theme | -t | Path to theme .js file or built-in name | | --output | -o | Output PDF path | | --fonts | | List built-in fonts | | --shapes | | List built-in vector shapes | | --help | -h | Show help |

AI skills

Claude Code skills for generating PDFs and themes are available in the skills/ directory of the GitHub repository:

• skills/sspdf/ - Generate PDF documents from a task description
• skills/sspdf-theme-generator/ - Generate theme files from brand specs

Constraints

• Page format defaults to A4; custom dimensions supported via pageWidthMm/pageHeightMm (e.g. 16:9 presentations)
• Single-line row cells, no multi-line column pairs
• {{page}} gives the current page number; {{pages}} (total page count) is not supported because keep-together rules make the final page count unpredictable until the last operation is laid out
• Charts require the canvas npm package (native C++ addon) for server-side rendering; everything else is zero native dependencies
• A jspdf.umd.js build is vendored for client-side/browser use. It bundles all dependencies internally but requires wiring up your own entry point — pdf-core.js uses the Node build by default

Hugo Palma, 2026

Third-party

This project vendors the following MIT-licensed libraries:

• jsPDF - PDF generation (UMD build, bundles fflate, fast-png, iobuffer internally). Copyright (c) 2010-2025 James Hall, yWorks GmbH.
• Chart.js - Chart rendering. Copyright (c) 2014-2024 Chart.js Contributors.
• chartjs-node-canvas - Server-side Chart.js rendering. Copyright (c) 2018 Sean Sobey.

Full license texts are in vendor/*/LICENSE.