Agent skill

pptx-generator

Create and manipulate PowerPoint PPTX files programmatically. Use when the user needs to generate presentations, modify PPTX templates, extract slide content, create thumbnail previews, or automate PowerPoint workflows. Supports both template-based generation (for branding compliance) and from-scratch creation. Keywords: PowerPoint, PPTX, presentation, slides, template, deck, slideshow, corporate, branding.

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Install this agent skill to your Project

npx add-skill https://github.com/jwynia/agent-skills/tree/main/skills/general/document-processing/presentation/pptx-generator

Metadata

Additional technical details for this skill

mode
generative
type
generator
author
agent-skills
domain
documents
version
1.0

SKILL.md

PPTX Generator

When to Use This Skill

Use this skill when:

  • Creating presentations programmatically from data or specifications
  • Populating branded templates with dynamic content while preserving corporate styling
  • Extracting text and structure from existing PPTX files for analysis
  • Combining slides from a library of approved templates
  • Automating presentation generation workflows

Do NOT use this skill when:

  • User wants to open/view presentations (use native PowerPoint or viewer)
  • Complex animations or transitions are required (limited support)
  • Working with older .ppt format (PPTX only)

Prerequisites

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

Quick Start

Two Modes of Operation

  1. Template Mode: Modify existing branded templates

    • Analyze & Replace: Find {{PLACEHOLDERS}} and replace with content
    • Slide Library: Select and combine slides from a template library

  2. Scratch Mode: Create presentations from nothing using JSON specifications

Instructions

Mode 1: Template-Based Generation

Step 1a: Analyze the Template

Extract text inventory to understand what can be replaced:

bash
deno run --allow-read scripts/analyze-template.ts corporate-template.pptx > inventory.json

Output (inventory.json):

json
{
  "filename": "corporate-template.pptx",
  "slideCount": 10,
  "textElements": [
    {
      "slideNumber": 1,
      "shapeId": "shape-2",
      "shapeName": "Title 1",
      "placeholderType": "ctrTitle",
      "position": { "x": 1.5, "y": 2.0, "w": 7.0, "h": 1.2 },
      "paragraphs": [
        { "text": "{{TITLE}}", "fontSize": 44, "bold": true }
      ]
    }
  ]
}

Step 1b: Create Replacement Specification

Create replacements.json:

json
{
  "textReplacements": [
    { "tag": "{{TITLE}}", "value": "Q4 2024 Results" },
    { "tag": "{{SUBTITLE}}", "value": "Financial Overview" },
    { "tag": "{{DATE}}", "value": "December 2024" },
    { "tag": "{{AUTHOR}}", "value": "Finance Team", "slideNumbers": [1] }
  ]
}

Step 1c: Generate Output

bash
deno run --allow-read --allow-write scripts/generate-from-template.ts \
  corporate-template.pptx replacements.json output.pptx

Mode 1 (Alternative): Slide Library

Step 2a: Preview Template Slides

Get information about available slides:

bash
deno run --allow-read scripts/generate-thumbnails.ts slide-library.pptx

For visual preview, extract the thumbnail:

bash
deno run --allow-read --allow-write scripts/generate-thumbnails.ts \
  slide-library.pptx --extract-thumb --output-dir ./previews

Step 2b: Select and Combine Slides

Create selections.json:

json
{
  "slideSelections": [
    { "slideNumber": 1 },
    { "slideNumber": 5 },
    { "slideNumber": 12 },
    { "slideNumber": 3 }
  ],
  "textReplacements": [
    { "tag": "{{TITLE}}", "value": "Custom Presentation" }
  ]
}

Step 2c: Generate Combined Presentation

bash
deno run --allow-read --allow-write scripts/generate-from-template.ts \
  slide-library.pptx selections.json custom-deck.pptx

Mode 2: From-Scratch Generation

Step 3a: Create Specification

Create spec.json:

json
{
  "title": "Product Launch 2025",
  "author": "Marketing Team",
  "slides": [
    {
      "background": { "color": "003366" },
      "elements": [
        {
          "type": "text",
          "x": 1, "y": 2.5, "w": 8, "h": 1.5,
          "options": {
            "text": "Product Launch 2025",
            "fontSize": 44,
            "bold": true,
            "color": "FFFFFF",
            "align": "center"
          }
        },
        {
          "type": "text",
          "x": 1, "y": 4, "w": 8, "h": 0.5,
          "options": {
            "text": "Revolutionizing the Industry",
            "fontSize": 24,
            "color": "CCCCCC",
            "align": "center"
          }
        }
      ]
    },
    {
      "elements": [
        {
          "type": "text",
          "x": 0.5, "y": 0.5, "w": 9, "h": 0.7,
          "options": {
            "text": "Key Features",
            "fontSize": 32,
            "bold": true,
            "color": "003366"
          }
        },
        {
          "type": "table",
          "x": 0.5, "y": 1.5, "w": 9, "h": 3,
          "options": {
            "rows": [
              ["Feature", "Description", "Benefit"],
              ["Speed", "2x faster processing", "Save time"],
              ["Quality", "HD output", "Better results"],
              ["Integration", "Works with existing tools", "Easy adoption"]
            ],
            "border": { "pt": 1, "color": "CCCCCC" }
          }
        }
      ]
    }
  ]
}

Step 3b: Generate Presentation

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

Examples

Example 1: Corporate Quarterly Report

Scenario: Generate quarterly report from branded template.

Steps:

bash
# 1. Analyze template for replaceable content
deno run --allow-read scripts/analyze-template.ts quarterly-template.pptx --pretty

# 2. Create replacements.json with Q4 data
# 3. Generate report
deno run --allow-read --allow-write scripts/generate-from-template.ts \
  quarterly-template.pptx replacements.json Q4-2024-Report.pptx

Example 2: Custom Pitch Deck from Slide Library

Scenario: Combine approved slides for a specific client pitch.

Steps:

bash
# 1. View available slides
deno run --allow-read scripts/generate-thumbnails.ts pitch-library.pptx

# 2. Create selections.json picking slides 1, 3, 7, 12, 15
# 3. Generate custom deck
deno run --allow-read --allow-write scripts/generate-from-template.ts \
  pitch-library.pptx selections.json acme-pitch.pptx

Example 3: Data-Driven Presentation

Scenario: Generate presentation from JSON data (e.g., API response).

Steps:

bash
# 1. Transform your data into spec.json format
# 2. Generate presentation
deno run --allow-read --allow-write scripts/generate-scratch.ts data-spec.json report.pptx

Script Reference

Script Purpose Permissions
analyze-template.ts Extract text inventory from PPTX --allow-read
generate-thumbnails.ts Get slide info and extract previews --allow-read --allow-write
generate-from-template.ts Modify templates (replace/combine) --allow-read --allow-write
generate-scratch.ts Create PPTX from JSON specification --allow-read --allow-write

Element Types (Scratch Mode)

Type Description Key Options
text Text box text, fontSize, bold, color, align
image Image from file or base64 path, data, sizing
table Data table rows, colW, border, fill
shape Geometric shapes type, fill, line, text
chart Charts and graphs type, data, title, showLegend

Common Issues and Solutions

Issue: Text not being replaced

Symptoms: Output PPTX still contains {{PLACEHOLDER}} tags.

Solution:

  1. Run analyze-template.ts to verify exact tag text
  2. Tags may be split across XML runs - ensure your template has tags in single text runs
  3. Check slideNumbers filter in replacements

Issue: Slide order incorrect

Symptoms: Slides appear in wrong order after combining.

Solution:

  • Slides are added in the order specified in slideSelections
  • Verify slide numbers match original template (1-indexed)

Issue: Images not appearing

Symptoms: Image elements are blank in output.

Solution:

  1. Use absolute paths or paths relative to spec.json location
  2. Verify image file exists and is readable
  3. Check supported formats: PNG, JPEG, GIF

OOXML Placeholder Inheritance (Advanced)

Understanding how PowerPoint's OOXML format handles placeholders is crucial for template development.

The Inheritance Chain

PowerPoint uses a hierarchical inheritance model:

Theme → Slide Master → Slide Layout → Slide
  • Theme: Defines colors, fonts, effects
  • Slide Master: Defines default placeholder positions and formatting (including bullets)
  • Slide Layout: Overrides master settings for specific layout types (e.g., Title Slide, Content)
  • Slide: Contains actual content, inherits formatting from layout

Key Principles

  1. Text Content Does NOT Inherit: Slides must contain their own text content. The {{placeholder}} text in a layout does NOT automatically appear on slides using that layout.

  2. Text Formatting CAN Inherit: When a slide shape has an empty <a:lstStyle/>, it inherits formatting (color, size, bullets) from the layout's <a:lstStyle>.

  3. Placeholder Linking: Slides link to layouts via <p:ph type="..." idx="..."/>. The type (e.g., "title", "body", "ctrTitle") and idx must match.

  4. Bullet Suppression: To prevent bullets on a placeholder that would normally inherit them from the master's bodyStyle, add <a:buNone/> in the layout's lstStyle.

Defining Inheritable Formatting

In layout placeholders, define colors in <a:lstStyle> (inheritable), not in <a:rPr> (run-specific):

xml
<!-- Layout: Color in lstStyle (GOOD - inheritable) -->
<p:txBody>
  <a:lstStyle>
    <a:lvl1pPr algn="ctr">
      <a:buNone/>  <!-- Suppress bullets -->
      <a:defRPr sz="4400" b="1">
        <a:solidFill><a:srgbClr val="FFFFFF"/></a:solidFill>
      </a:defRPr>
    </a:lvl1pPr>
  </a:lstStyle>
  <a:p>
    <a:r><a:rPr lang="en-US"/><a:t>{{placeholder}}</a:t></a:r>
  </a:p>
</p:txBody>

Slide Shape Structure

For slides to properly inherit from layouts:

xml
<!-- Slide: Empty lstStyle to inherit from layout -->
<p:sp>
  <p:nvSpPr>
    <p:cNvPr id="2" name="title 2"/>
    <p:cNvSpPr><a:spLocks noGrp="1"/></p:cNvSpPr>
    <p:nvPr>
      <p:ph type="ctrTitle"/>  <!-- Links to layout placeholder -->
    </p:nvPr>
  </p:nvSpPr>
  <p:spPr/>  <!-- Empty = inherit position from layout -->
  <p:txBody>
    <a:bodyPr/>
    <a:lstStyle/>  <!-- Empty = inherit formatting from layout -->
    <a:p>
      <a:r>
        <a:rPr lang="en-US"/>  <!-- Empty = inherit character formatting -->
        <a:t>{{placeholder}}</a:t>  <!-- Content must be here -->
      </a:r>
    </a:p>
  </p:txBody>
</p:sp>

Common Issues

Issue Cause Solution
Text shows as black instead of white Color defined in <a:rPr> not <a:lstStyle> Move color to layout's <a:defRPr> in <a:lstStyle>
Unwanted bullets appearing Master's bodyStyle has bullets, layout doesn't override Add <a:buNone/> to layout's <a:lvl1pPr>
Placeholder text not appearing Text only in layout, not in slide Include text content in slide's <p:txBody>
Formatting not applying Slide has explicit formatting Use empty <a:lstStyle/> and <a:rPr lang="en-US"/>

Reference: Placeholder Types

Type Usage
ctrTitle Centered title (title slides)
title Standard title
subTitle Subtitle
body Content area (use idx for multiple)
pic Picture placeholder
dt Date/time
ftr Footer
sldNum Slide number

Limitations

  • No slide rendering: Cannot render slides to images directly (use LibreOffice for this)
  • Limited animation support: Basic animations only in scratch mode
  • No master slide editing: Template mode preserves but doesn't modify masters
  • PPTX only: Does not support legacy .ppt format
  • Text run splitting: Complex formatting in templates may split tags across XML elements

Related Skills

  • pdf-generator: For creating PDF documents instead of presentations
  • docx-generator: For creating Word documents
  • xlsx-generator: For creating Excel spreadsheets

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