PPTX Generator Agent Skill

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

• Template Mode: Modify existing branded templates
• Analyze & Replace: Find {{PLACEHOLDERS}} and replace with content
• Slide Library: Select and combine slides from a template library

• 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:

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

Output (inventory.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:

{
  "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

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:

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

For visual preview, extract the thumbnail:

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:

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

Step 2c: Generate Combined Presentation

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:

{
  "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

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:

# 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:

# 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:

# 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:

• Run analyze-template.ts to verify exact tag text
• Tags may be split across XML runs - ensure your template has tags in single text runs
• 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:

• Use absolute paths or paths relative to spec.json location
• Verify image file exists and is readable
• 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

• 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.

• 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>.

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

• 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):

<!-- 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:

<!-- 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

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