pdf-generator

PDF Generator

When to Use This Skill

Use this skill when:

• Creating PDF documents programmatically from data or specifications
• Filling PDF forms with dynamic data
• Adding watermarks, stamps, or overlays to existing PDFs
• Extracting text and metadata from PDF files
• Merging multiple PDFs into one document
• Analyzing PDF structure and form fields

Do NOT use this skill when:

• User wants to open/view PDFs (use native PDF viewer)
• Complex page layout with flowing text is needed (consider HTML-to-PDF tools)
• Working with password-protected PDFs (limited support)
• OCR is needed for scanned documents

Prerequisites

• Deno installed (https://deno.land/)
• Input PDF files for template-based operations
• JSON specification for scratch generation

Quick Start

Two Modes of Operation

1. Template Mode: Modify existing PDF templates

• Fill form fields (text, checkbox, dropdown)
• Add overlays (text, images, shapes)
• Merge and combine PDFs

1. Scratch Mode: Create PDFs from nothing using JSON specifications

Instructions

Mode 1: Template-Based Generation

Step 1a: Analyze the Template

Extract form fields and structure from an existing PDF:

deno run --allow-read scripts/analyze-template.ts form-template.pdf > inventory.json

Output (inventory.json):

{
  "filename": "form-template.pdf",
  "pageCount": 2,
  "title": "Application Form",
  "author": "Company Inc",
  "pages": [
    { "pageNumber": 1, "width": 612, "height": 792, "text": "..." }
  ],
  "formFields": [
    { "name": "FullName", "type": "text", "value": "" },
    { "name": "Email", "type": "text", "value": "" },
    { "name": "AgreeToTerms", "type": "checkbox", "value": false }
  ],
  "placeholders": [
    { "tag": "{{DATE}}", "location": "page 1", "pageNumber": 1 }
  ],
  "hasFormFields": true
}

Step 1b: Create Fill Specification

Create form-data.json:

{
  "formFields": [
    { "name": "FullName", "value": "John Smith" },
    { "name": "Email", "value": "john@example.com" },
    { "name": "AgreeToTerms", "value": true }
  ],
  "flattenForm": true
}

Step 1c: Generate Filled PDF

deno run --allow-read --allow-write scripts/generate-from-template.ts \
  form-template.pdf form-data.json filled-form.pdf

Adding Overlays (Watermarks, Stamps)

Create watermark-spec.json:

{
  "overlays": [
    {
      "type": "text",
      "page": 1,
      "x": 200,
      "y": 400,
      "text": "CONFIDENTIAL",
      "fontSize": 48,
      "color": { "r": 1, "g": 0, "b": 0 },
      "rotate": 45
    },
    {
      "type": "image",
      "page": 1,
      "x": 450,
      "y": 700,
      "path": "logo.png",
      "width": 100,
      "height": 50
    }
  ]
}

Merging PDFs

Create merge-spec.json:

{
  "prependPdfs": [
    { "path": "cover-page.pdf" }
  ],
  "appendPdfs": [
    { "path": "appendix-a.pdf", "pages": [1, 2, 3] },
    { "path": "appendix-b.pdf" }
  ],
  "excludePages": [5, 6]
}

Mode 2: From-Scratch Generation

Step 2a: Create Specification

Create spec.json:

{
  "title": "Quarterly Report",
  "author": "Finance Team",
  "pages": [
    {
      "size": "A4",
      "elements": [
        {
          "type": "text",
          "x": 50,
          "y": 750,
          "text": "Q4 2024 Financial Report",
          "fontSize": 28,
          "font": "HelveticaBold",
          "color": { "r": 0, "g": 0, "b": 0.5 }
        },
        {
          "type": "line",
          "startX": 50,
          "startY": 740,
          "endX": 550,
          "endY": 740,
          "thickness": 2
        },
        {
          "type": "text",
          "x": 50,
          "y": 700,
          "text": "Executive Summary",
          "fontSize": 18,
          "font": "HelveticaBold"
        },
        {
          "type": "text",
          "x": 50,
          "y": 670,
          "text": "This quarter showed strong growth across all divisions...",
          "fontSize": 12,
          "maxWidth": 500,
          "lineHeight": 16
        }
      ]
    }
  ]
}

Step 2b: Generate PDF

deno run --allow-read --allow-write scripts/generate-scratch.ts spec.json output.pdf

Examples

Example 1: Fill Application Form

Scenario: Automatically fill a job application form.

# 1. Analyze form to find field names
deno run --allow-read scripts/analyze-template.ts application.pdf --pretty

# 2. Create form-data.json with applicant info
# 3. Generate filled form
deno run --allow-read --allow-write scripts/generate-from-template.ts \
  application.pdf form-data.json john-smith-application.pdf

Example 2: Add Approval Stamp

Scenario: Add an "APPROVED" stamp to a document.

stamp-spec.json:

{
  "overlays": [
    {
      "type": "rectangle",
      "page": 1,
      "x": 400,
      "y": 700,
      "width": 150,
      "height": 50,
      "color": { "r": 0.9, "g": 1, "b": 0.9 }
    },
    {
      "type": "text",
      "page": 1,
      "x": 410,
      "y": 720,
      "text": "APPROVED",
      "fontSize": 20,
      "font": "HelveticaBold",
      "color": { "r": 0, "g": 0.5, "b": 0 }
    },
    {
      "type": "text",
      "page": 1,
      "x": 410,
      "y": 705,
      "text": "2024-12-15",
      "fontSize": 10
    }
  ]
}

Example 3: Create Report with Table

Scenario: Generate a simple report with a data table.

report-spec.json:

{
  "title": "Sales Report",
  "pages": [{
    "size": "Letter",
    "elements": [
      {
        "type": "text",
        "x": 72,
        "y": 720,
        "text": "Monthly Sales Report",
        "fontSize": 24,
        "font": "HelveticaBold"
      },
      {
        "type": "table",
        "x": 72,
        "y": 680,
        "rows": [
          ["Product", "Units", "Revenue"],
          ["Widget A", "150", "$15,000"],
          ["Widget B", "75", "$11,250"],
          ["Widget C", "200", "$8,000"]
        ],
        "columnWidths": [150, 80, 100],
        "rowHeight": 25,
        "headerBackground": { "r": 0.9, "g": 0.9, "b": 0.9 }
      }
    ]
  }]
}

Script Reference

Element Types (Scratch Mode)

Available Fonts

• Helvetica (default)
• HelveticaBold
• HelveticaOblique
• TimesRoman
• TimesBold
• Courier
• CourierBold

Page Sizes

• A4 (595.28 x 841.89 points)
• Letter (612 x 792 points)
• Legal (612 x 1008 points)
• Custom: [width, height] in points

Common Issues and Solutions

Issue: Form fields not found

Symptoms: Error saying field name doesn't exist.

Solution:

1. Run analyze-template.ts to get exact field names
2. Field names are case-sensitive
3. Some PDFs have non-fillable text that looks like form fields

Issue: Text positioning is off

Symptoms: Text appears in wrong location.

Solution:

• PDF coordinates start from bottom-left (0,0)
• Y increases upward, X increases rightward
• Use analyze-template.ts to see page dimensions

Issue: Images not appearing

Symptoms: Image overlay not visible.

Solution:

1. Check file path is relative to spec.json location
2. Verify image is PNG or JPEG format
3. Ensure coordinates are within page bounds

Issue: Merged PDF has wrong page order

Symptoms: Pages appear in unexpected order.

Solution:

• prependPdfs add pages before template
• appendPdfs add pages after template
• Use pages array to select specific pages: [1, 3, 5]

Limitations

• No built-in table layout: Tables require manual column width specification
• Standard fonts only: Custom font embedding not supported in scratch mode
• No flowing text: Text doesn't automatically wrap to next page
• Limited form field creation: Can fill existing forms, not create new fields
• No encryption: Cannot create password-protected PDFs
• Basic graphics: No gradients, patterns, or complex paths
• Text extraction: May not work perfectly on all PDFs (depends on PDF structure)

Related Skills

• pptx-generator: For creating PowerPoint presentations
• docx-generator: For creating Word documents
• xlsx-generator: For creating Excel spreadsheets