# PptxGenJS Tutorial

> **Pull colors from Fractal.** Reference [`../color/color-guide.md`](../color/color-guide.md) for palettes used in `pres.layout`, slide masters, chart series, and text styles. PptxGenJS hex strings drop the `#` prefix (see Common Pitfalls).
>
> **For fonts, decks use `'Roboto'` and `'Roboto Mono'`** — *not* Fractal's app-UI default of Figtree. See the Typography section in [`presentations-guide.md`](./presentations-guide.md) for the rationale (Roboto ships pre-installed with PowerPoint and Keynote; Figtree does not).

## Setup & Basic Structure

```javascript
const pptxgen = require("pptxgenjs");

let pres = new pptxgen();
pres.layout = 'LAYOUT_16x9';  // or 'LAYOUT_16x10', 'LAYOUT_4x3', 'LAYOUT_WIDE'
pres.author = 'Your Name';
pres.title = 'Presentation Title';

let slide = pres.addSlide();
slide.addText("Hello World!", { x: 0.5, y: 0.5, fontSize: 36, color: "363636" });

pres.writeFile({ fileName: "Presentation.pptx" });
```

## Layout Dimensions

Slide dimensions (coordinates in inches):
- `LAYOUT_16x9`: 10" × 5.625" (default)
- `LAYOUT_16x10`: 10" × 6.25"
- `LAYOUT_4x3`: 10" × 7.5"
- `LAYOUT_WIDE`: 13.3" × 7.5"

---

## Text & Formatting

```javascript
// Basic text
slide.addText("Simple Text", {
  x: 1, y: 1, w: 8, h: 2, fontSize: 24, fontFace: "Arial",
  color: "363636", bold: true, align: "center", valign: "middle"
});

// Character spacing (use charSpacing, not letterSpacing which is silently ignored)
slide.addText("SPACED TEXT", { x: 1, y: 1, w: 8, h: 1, charSpacing: 6 });

// Rich text arrays
slide.addText([
  { text: "Bold ", options: { bold: true } },
  { text: "Italic ", options: { italic: true } }
], { x: 1, y: 3, w: 8, h: 1 });

// Multi-line text (requires breakLine: true)
slide.addText([
  { text: "Line 1", options: { breakLine: true } },
  { text: "Line 2", options: { breakLine: true } },
  { text: "Line 3" }  // Last item doesn't need breakLine
], { x: 0.5, y: 0.5, w: 8, h: 2 });

// Text box margin (internal padding)
slide.addText("Title", {
  x: 0.5, y: 0.3, w: 9, h: 0.6,
  margin: 0  // Use 0 when aligning text with other elements like shapes or icons
});
```

**Tip:** Text boxes have internal margin by default. Set `margin: 0` when you need text to align precisely with shapes, lines, or icons at the same x-position.

---

## Text Box Sizing

> ⚠️ **Single most common cause of bad-looking decks.**

PptxGenJS text boxes are **fixed-size containers** — they do **not** shrink to fit their content. If you write `addText('Title', { y: 1.0, h: 0.5, fontSize: 13 })`, the box reserves 0.5" of vertical space, but the rendered 13pt text only occupies ~0.25". Any element placed at `y + h` (i.e. `1.5`) sits 0.25" below where the title visually ends — creating dead space and orphaned headers.

The user-visible symptom is always the same: a **header floating away from the body it belongs to**. See [presentations-guide.md → Proximity](./presentations-guide.md#proximity--keep-titles-tight-to-their-bodies) for the design-side rule.

### Match `h` to the rendered text height

Approximate rendered height per line (sans-serif, normal line-height):

| `fontSize` | h per line |
|------------|------------|
| 10 pt      | 0.22"      |
| 12 pt      | 0.26"      |
| 14 pt      | 0.31"      |
| 16 pt      | 0.35"      |
| 18 pt      | 0.40"      |
| 22 pt      | 0.48"      |
| 28 pt      | 0.62"      |
| 36 pt      | 0.79"      |
| 48 pt      | 1.06"      |
| 64 pt      | 1.41"      |

Quick formula: `h ≈ fontSize × 0.022` per line (1.4 line-height + small descender pad, calibrated against pptxgenjs + LibreOffice). Multiply by line count for wrapping text. For wrapping body paragraphs, estimate line count from `w`: characters per line ≈ `w_inches × 84 / fontSize`.

### Wrong vs. right

❌ **Orphan header — 0.35" of dead space between title and body:**

```javascript
slide.addText('Section Header', {
  x: 0.6, y: 1.0, w: 6, h: 0.6,        // h=0.6 reserves too much
  fontSize: 13, fontFace: 'Roboto', bold: true,
});
slide.addText('Body paragraph that explains the section.', {
  x: 0.6, y: 1.6, w: 6, h: 1,          // body sits 0.6" below the title's TOP
  fontSize: 11, fontFace: 'Roboto',
});
```

✅ **Tight pairing — title and body visually connected:**

```javascript
slide.addText('Section Header', {
  x: 0.6, y: 1.0, w: 6, h: 0.25,       // h matches 13pt rendered height
  fontSize: 13, fontFace: 'Roboto', bold: true,
});
slide.addText('Body paragraph that explains the section.', {
  x: 0.6, y: 1.30, w: 6, h: 0.4,       // body starts 0.05" below title end
  fontSize: 11, fontFace: 'Roboto',
});
```

### When you don't know the line count

Two escape hatches:

1. `valign: 'bottom'` on the title box — anchors the title to the bottom of its container, so an over-tall `h` won't push the body away. Use when the title might wrap and you'd rather pad above than below.
2. Use the `titlePair` recipe in [presentations-guide.md → Common Patterns](./presentations-guide.md#common-patterns) — encapsulates the height math so it can't drift.

---

## Lists & Bullets

```javascript
// ✅ CORRECT: Multiple bullets
slide.addText([
  { text: "First item", options: { bullet: true, breakLine: true } },
  { text: "Second item", options: { bullet: true, breakLine: true } },
  { text: "Third item", options: { bullet: true } }
], { x: 0.5, y: 0.5, w: 8, h: 3 });

// ❌ WRONG: Never use unicode bullets
slide.addText("• First item", { ... });  // Creates double bullets

// Sub-items and numbered lists
{ text: "Sub-item", options: { bullet: true, indentLevel: 1 } }
{ text: "First", options: { bullet: { type: "number" }, breakLine: true } }
```

---

## Shapes

```javascript
slide.addShape(pres.shapes.RECTANGLE, {
  x: 0.5, y: 0.8, w: 1.5, h: 3.0,
  fill: { color: "FF0000" }, line: { color: "000000", width: 2 }
});

slide.addShape(pres.shapes.OVAL, { x: 4, y: 1, w: 2, h: 2, fill: { color: "0000FF" } });

slide.addShape(pres.shapes.LINE, {
  x: 1, y: 3, w: 5, h: 0, line: { color: "FF0000", width: 3, dashType: "dash" }
});

// With transparency
slide.addShape(pres.shapes.RECTANGLE, {
  x: 1, y: 1, w: 3, h: 2,
  fill: { color: "0088CC", transparency: 50 }
});

// Rounded rectangle (rectRadius only works with ROUNDED_RECTANGLE, not RECTANGLE)
// ⚠️ Don't pair with rectangular accent overlays — they won't cover rounded corners. Use RECTANGLE instead.
slide.addShape(pres.shapes.ROUNDED_RECTANGLE, {
  x: 1, y: 1, w: 3, h: 2,
  fill: { color: "FFFFFF" }, rectRadius: 0.1
});

// With shadow
slide.addShape(pres.shapes.RECTANGLE, {
  x: 1, y: 1, w: 3, h: 2,
  fill: { color: "FFFFFF" },
  shadow: { type: "outer", color: "000000", blur: 6, offset: 2, angle: 135, opacity: 0.15 }
});
```

Shadow options:

| Property | Type | Range | Notes |
|----------|------|-------|-------|
| `type` | string | `"outer"`, `"inner"` | |
| `color` | string | 6-char hex (e.g. `"000000"`) | No `#` prefix, no 8-char hex — see Common Pitfalls |
| `blur` | number | 0-100 pt | |
| `offset` | number | 0-200 pt | **Must be non-negative** — negative values corrupt the file |
| `angle` | number | 0-359 degrees | Direction the shadow falls (135 = bottom-right, 270 = upward) |
| `opacity` | number | 0.0-1.0 | Use this for transparency, never encode in color string |

To cast a shadow upward (e.g. on a footer bar), use `angle: 270` with a positive offset — do **not** use a negative offset.

**Note**: Gradient fills are not natively supported. Use a gradient image as a background instead.

---

## Images

### Image Sources

```javascript
// From file path
slide.addImage({ path: "images/photo.jpg", x: 1, y: 1, w: 5, h: 3 });

// From URL
slide.addImage({ path: "https://example.com/image.jpg", x: 1, y: 1, w: 5, h: 3 });

// From base64 (faster, no file I/O)
slide.addImage({ data: "image/png;base64,iVBORw0KGgo...", x: 1, y: 1, w: 5, h: 3 });
```

### Image Options

```javascript
slide.addImage({
  path: "image.png",
  x: 1, y: 1, w: 5, h: 3,
  rotate: 45,              // 0-359 degrees
  rounding: true,          // Circular crop
  transparency: 50,        // 0-100
  flipH: true,             // Horizontal flip
  flipV: false,            // Vertical flip
  altText: "Description",  // Accessibility
  hyperlink: { url: "https://example.com" }
});
```

### Image Sizing Modes

```javascript
// Contain - fit inside, preserve ratio
{ sizing: { type: 'contain', w: 4, h: 3 } }

// Cover - fill area, preserve ratio (may crop)
{ sizing: { type: 'cover', w: 4, h: 3 } }

// Crop - cut specific portion
{ sizing: { type: 'crop', x: 0.5, y: 0.5, w: 2, h: 2 } }
```

### Calculate Dimensions (preserve aspect ratio)

```javascript
const origWidth = 1978, origHeight = 923, maxHeight = 3.0;
const calcWidth = maxHeight * (origWidth / origHeight);
const centerX = (10 - calcWidth) / 2;

slide.addImage({ path: "image.png", x: centerX, y: 1.2, w: calcWidth, h: maxHeight });
```

### Supported Formats

- **Standard**: PNG, JPG, GIF (animated GIFs work in Microsoft 365)
- **SVG**: Works in modern PowerPoint/Microsoft 365

---

## Icons

Use react-icons to generate SVG icons, then rasterize to PNG for universal compatibility.

### Setup

```javascript
const React = require("react");
const ReactDOMServer = require("react-dom/server");
const sharp = require("sharp");
const { FaCheckCircle, FaChartLine } = require("react-icons/fa");

function renderIconSvg(IconComponent, color = "#000000", size = 256) {
  return ReactDOMServer.renderToStaticMarkup(
    React.createElement(IconComponent, { color, size: String(size) })
  );
}

async function iconToBase64Png(IconComponent, color, size = 256) {
  const svg = renderIconSvg(IconComponent, color, size);
  const pngBuffer = await sharp(Buffer.from(svg)).png().toBuffer();
  return "image/png;base64," + pngBuffer.toString("base64");
}
```

### Add Icon to Slide

```javascript
const iconData = await iconToBase64Png(FaCheckCircle, "#4472C4", 256);

slide.addImage({
  data: iconData,
  x: 1, y: 1, w: 0.5, h: 0.5  // Size in inches
});
```

**Note**: Use size 256 or higher for crisp icons. The size parameter controls the rasterization resolution, not the display size on the slide (which is set by `w` and `h` in inches).

### Icon Libraries

Install: `npm install -g react-icons react react-dom sharp`

Popular icon sets in react-icons:
- `react-icons/fa` - Font Awesome
- `react-icons/md` - Material Design
- `react-icons/hi` - Heroicons
- `react-icons/bi` - Bootstrap Icons

---

## Slide Backgrounds

```javascript
// Solid color
slide.background = { color: "F1F1F1" };

// Color with transparency
slide.background = { color: "FF3399", transparency: 50 };

// Image from URL
slide.background = { path: "https://example.com/bg.jpg" };

// Image from base64
slide.background = { data: "image/png;base64,iVBORw0KGgo..." };
```

---

## Tables

```javascript
slide.addTable([
  ["Header 1", "Header 2"],
  ["Cell 1", "Cell 2"]
], {
  x: 1, y: 1, w: 8, h: 2,
  border: { pt: 1, color: "999999" }, fill: { color: "F1F1F1" }
});

// Advanced with merged cells
let tableData = [
  [{ text: "Header", options: { fill: { color: "6699CC" }, color: "FFFFFF", bold: true } }, "Cell"],
  [{ text: "Merged", options: { colspan: 2 } }]
];
slide.addTable(tableData, { x: 1, y: 3.5, w: 8, colW: [4, 4] });
```

---

## Charts

**Keep charts native and editable. Choose your approach by what PowerPoint can represent, not by what's quickest to code:**

1. **Library-native** (bar, column, line, pie, area, scatter, bubble, radar, doughnut, combo): use `addChart()` below. For combo charts pass an array of `{type, data, options}` objects. Never render these to an image.
2. **PowerPoint-native but not exposed by the library** (trendlines, error bars): stay native — either compute the extra series yourself (e.g., regression line as a second `LINE`/`SCATTER` series) or inject the OOXML element (e.g., `<c:trendline>`) by post-processing the generated `.pptx` XML. Do **not** fall back to a matplotlib PNG; the user loses editability.
3. **Genuinely no native PowerPoint representation** (Sankey, network/graph, chord, complex statistical plots): only here is rendering to an image and inserting via `addImage()` appropriate.

```javascript
// Bar chart
slide.addChart(pres.charts.BAR, [{
  name: "Sales", labels: ["Q1", "Q2", "Q3", "Q4"], values: [4500, 5500, 6200, 7100]
}], {
  x: 0.5, y: 0.6, w: 6, h: 3, barDir: 'col',
  showTitle: true, title: 'Quarterly Sales'
});

// Line chart
slide.addChart(pres.charts.LINE, [{
  name: "Temp", labels: ["Jan", "Feb", "Mar"], values: [32, 35, 42]
}], { x: 0.5, y: 4, w: 6, h: 3, lineSize: 3, lineSmooth: true });

// Pie chart
slide.addChart(pres.charts.PIE, [{
  name: "Share", labels: ["A", "B", "Other"], values: [35, 45, 20]
}], { x: 7, y: 1, w: 5, h: 4, showPercent: true });

// Scatter with a computed trend line (tier-2: stay native, add regression as a second series)
const xs = [8, 12, 18, 22, 25, 31], ys = [102, 145, 198, 241, 267, 312];
const n = xs.length, sx = xs.reduce((a,b)=>a+b), sy = ys.reduce((a,b)=>a+b);
const sxy = xs.reduce((a,x,i)=>a+x*ys[i],0), sxx = xs.reduce((a,x)=>a+x*x,0);
const m = (n*sxy - sx*sy)/(n*sxx - sx*sx), b = (sy - m*sx)/n;
slide.addChart(pres.charts.SCATTER, [
  { name: "X",     values: xs },
  { name: "Data",  values: ys },
  { name: "Trend", values: xs.map(x => m*x + b) },
], { x: 0.5, y: 1, w: 9, h: 4 });
```

### Better-Looking Charts

Default charts look dated. Apply these options for a modern, clean appearance:

```javascript
slide.addChart(pres.charts.BAR, chartData, {
  x: 0.5, y: 1, w: 9, h: 4, barDir: "col",

  // Custom colors (match your presentation palette)
  chartColors: ["0D9488", "14B8A6", "5EEAD4"],

  // Clean background
  chartArea: { fill: { color: "FFFFFF" }, roundedCorners: true },

  // Muted axis labels
  catAxisLabelColor: "64748B",
  valAxisLabelColor: "64748B",

  // Subtle grid (value axis only)
  valGridLine: { color: "E2E8F0", size: 0.5 },
  catGridLine: { style: "none" },

  // Data labels on bars
  showValue: true,
  dataLabelPosition: "outEnd",
  dataLabelColor: "1E293B",

  // Hide legend for single series
  showLegend: false,
});
```

**Key styling options:**
- `chartColors: [...]` - hex colors for series/segments
- `chartArea: { fill, border, roundedCorners }` - chart background
- `catGridLine/valGridLine: { color, style, size }` - grid lines (`style: "none"` to hide)
- `lineSmooth: true` - curved lines (line charts)
- `legendPos: "r"` - legend position: "b", "t", "l", "r", "tr"

---

## Slide Masters

```javascript
pres.defineSlideMaster({
  title: 'TITLE_SLIDE', background: { color: '283A5E' },
  objects: [{
    placeholder: { options: { name: 'title', type: 'title', x: 1, y: 2, w: 8, h: 2 } }
  }]
});

let titleSlide = pres.addSlide({ masterName: "TITLE_SLIDE" });
titleSlide.addText("My Title", { placeholder: "title" });
```

---

## Common Pitfalls

⚠️ These issues cause file corruption, visual bugs, or broken output. Avoid them.

1. **NEVER use "#" with hex colors** - causes file corruption
   ```javascript
   color: "FF0000"      // ✅ CORRECT
   color: "#FF0000"     // ❌ WRONG
   ```

2. **NEVER encode opacity in hex color strings** - 8-char colors (e.g., `"00000020"`) corrupt the file. Use the `opacity` property instead.
   ```javascript
   shadow: { type: "outer", blur: 6, offset: 2, color: "00000020" }          // ❌ CORRUPTS FILE
   shadow: { type: "outer", blur: 6, offset: 2, color: "000000", opacity: 0.12 }  // ✅ CORRECT
   ```

3. **Use `bullet: true`** - NEVER unicode symbols like "•" (creates double bullets)

4. **Use `breakLine: true`** between array items or text runs together

5. **Avoid `lineSpacing` with bullets** - causes excessive gaps; use `paraSpaceAfter` instead

6. **Each presentation needs fresh instance** - don't reuse `pptxgen()` objects

7. **NEVER reuse option objects across calls** - PptxGenJS mutates objects in-place (e.g. converting shadow values to EMU). Sharing one object between multiple calls corrupts the second shape.
   ```javascript
   const shadow = { type: "outer", blur: 6, offset: 2, color: "000000", opacity: 0.15 };
   slide.addShape(pres.shapes.RECTANGLE, { shadow, ... });  // ❌ second call gets already-converted values
   slide.addShape(pres.shapes.RECTANGLE, { shadow, ... });

   const makeShadow = () => ({ type: "outer", blur: 6, offset: 2, color: "000000", opacity: 0.15 });
   slide.addShape(pres.shapes.RECTANGLE, { shadow: makeShadow(), ... });  // ✅ fresh object each time
   slide.addShape(pres.shapes.RECTANGLE, { shadow: makeShadow(), ... });
   ```

8. **Don't use `ROUNDED_RECTANGLE` with accent borders** - rectangular overlay bars won't cover rounded corners. Use `RECTANGLE` instead.
   ```javascript
   // ❌ WRONG: Accent bar doesn't cover rounded corners
   slide.addShape(pres.shapes.ROUNDED_RECTANGLE, { x: 1, y: 1, w: 3, h: 1.5, fill: { color: "FFFFFF" } });
   slide.addShape(pres.shapes.RECTANGLE, { x: 1, y: 1, w: 0.08, h: 1.5, fill: { color: "0891B2" } });

   // ✅ CORRECT: Use RECTANGLE for clean alignment
   slide.addShape(pres.shapes.RECTANGLE, { x: 1, y: 1, w: 3, h: 1.5, fill: { color: "FFFFFF" } });
   slide.addShape(pres.shapes.RECTANGLE, { x: 1, y: 1, w: 0.08, h: 1.5, fill: { color: "0891B2" } });
   ```

---

## Quick Reference

- **Shapes**: RECTANGLE, OVAL, LINE, ROUNDED_RECTANGLE
- **Charts**: BAR, COLUMN, LINE, AREA, PIE, DOUGHNUT, SCATTER, BUBBLE, RADAR, combo (array of `{type, data, options}`)
- **Layouts**: LAYOUT_16x9 (10"×5.625"), LAYOUT_16x10, LAYOUT_4x3, LAYOUT_WIDE
- **Alignment**: "left", "center", "right"
- **Chart data labels**: "outEnd", "inEnd", "center"