### Measuring Text Size (JavaScript)

Source: https://github.com/hopding/react-native-pdf-lib/blob/master/README.md

Shows how to use the measureText function to get the dimensions of a string based on a specified font name and size. This is useful for layout calculations like centering text.

```javascript
return PDFLib.measureText(
  "My Centered Title",
  "Franklin Gothic Medium",
  14
).then(result => {
  console.log("The text size is: ", result);
});
```

--------------------------------

### Creating a New PDF Document with react-native-pdf-lib (JavaScript)

Source: https://github.com/hopding/react-native-pdf-lib/blob/master/README.md

This snippet demonstrates how to create a new PDF document using `react-native-pdf-lib`. It shows how to create `PDFPage` objects, add text and shapes, include images from file paths, and then combine these pages into a new `PDFDocument` which is written to the device's documents directory. It requires importing `PDFLib`, `PDFDocument`, and `PDFPage`.

```JavaScript
// Import from 'react-native-pdf-lib'
import PDFLib, { PDFDocument, PDFPage } from 'react-native-pdf-lib';

// Create a PDF page with text and rectangles
const page1 = PDFPage
  .create()
  .setMediaBox(200, 200)
  .drawText('You can add text and rectangles to the PDF!', {
    x: 5,
    y: 235,
    color: '#007386',
  })
  .drawRectangle({
    x: 25,
    y: 25,
    width: 150,
    height: 150,
    color: '#FF99CC',
  })
  .drawRectangle({
    x: 75,
    y: 75,
    width: 50,
    height: 50,
    color: '#99FFCC',
  });

// Create a PDF page with text and images
const jpgPath = // Path to a JPG image on the file system...
const pngPath = // Path to a PNG image on the file system...
const page2 = PDFPage
  .create()
  .setMediaBox(250, 250)
  .drawText('You can add JPG images too!')
  .drawImage(jpgPath, 'jpg', {
     x: 5,
     y: 125,
     width: 200,
     height: 100,
  })
  .drawImage(pngPath, 'png', {
     x: 5,
     y: 25,
     width: 200,
     height: 100,
  });

// Create a new PDF in your app's private Documents directory
const docsDir = await PDFLib.getDocumentsDirectory();
const pdfPath = `${docsDir}/sample.pdf`;
PDFDocument
  .create(pdfPath)
  .addPages(page1, page2)
  .write() // Returns a promise that resolves with the PDF's path
  .then(path => {
    console.log('PDF created at: ' + path);
    // Do stuff with your shiny new PDF!
  });
```

--------------------------------

### Configuring Custom Font Assets (rnpm)

Source: https://github.com/hopding/react-native-pdf-lib/blob/master/README.md

Configures the react-native packager (rnpm) to include the custom fonts directory in the app's assets, ensuring they are bundled correctly for use within the application.

```json
  "rnpm": {
    "assets": [
      "./assets/fonts"
    ]
  }
```

--------------------------------

### Modifying an Existing PDF Document with react-native-pdf-lib (JavaScript)

Source: https://github.com/hopding/react-native-pdf-lib/blob/master/README.md

This snippet illustrates how to modify an existing PDF file. It shows how to use `PDFPage.modify()` to target specific pages by index, add new elements like text and images, and also how to add entirely new pages using `PDFPage.create()`. The modified pages and new pages are then applied to the existing document using `PDFDocument.modify()` and `addPage()`, and the changes are written back to the file system. It requires importing `PDFLib`, `PDFDocument`, and `PDFPage`.

```JavaScript
// Import from 'react-native-pdf-lib'
import PDFLib, { PDFDocument, PDFPage } from 'react-native-pdf-lib';

// Modify first page in document
const page1 = PDFPage
  .modify(0)
  .drawText('This is a modification on the first page!', {
    x: 5,
    y: 235,
    color: '#F62727',
  })
  .drawRectangle({
    x: 150,
    y: 150,
    width: 50,
    height: 50,
    color: '#81C744',
  });

// Modify second page in document
const jpgPath = // in iOS Path to a JPG image on the file system... in Android path to the assert
const pngPath = // in iOS Path to a PNG image on the file system... in Android path to the assert
const page2 = PDFPage
  .modify(1)
  .drawText('You can add images to modified pages too!')
  .drawImage(
    jpgPath,
    'jpg',
    {
      x: 5,
      y: 125,
      width: 200,
      height: 100,
      source: 'assets' // 'assets' to get image from Android assets 'path' to get image from imagePath
    }
  )
  .drawImage(
    pngPath,
    'png',
    {
      x: 5,
      y: 25,
      width: 200,
      height: 100,
      source: 'path' // 'assets' to get image from Android assets 'path' to get image from imagePath
    }
   );

// Create a PDF page to add to document
const page3 = PDFPage
  .create()
  .setMediaBox(200, 200)
  .drawText('You can add new pages to a modified PDF as well!', {
    x: 5,
    y: 235,
    color: '#007386',
  });

const existingPDF = 'path/to/existing.pdf';
PDFDocument
  .modify(existingPDF)
  .modifyPages(page1, page2)
  .addPage(page3)
  .write() // Returns a promise that resolves with the PDF's path
  .then(path => {
    console.log('PDF modified at: ' + path);
  });
```

--------------------------------

### Drawing Text with Custom Font (JavaScript)

Source: https://github.com/hopding/react-native-pdf-lib/blob/master/README.md

Demonstrates how to create a PDF page and draw text using a previously linked custom font ('Franklin Gothic Medium'). It sets the text position, color, and specifies the font name.

```javascript
const page1 = PDFPage.create()
  .setMediaBox(200, 200)
  .drawText("This text is using the font Franklin Gothic Medium!", {
    x: 5,
    y: 235,
    color: "#F62727",
    fontName: "Franklin Gothic Medium"
  });
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.