hnc-rn-image-overlay

Native module to add white overlay with text watermark to images on iOS and Android.

Features

• ✅ Native performance - No JavaScript bridge for image processing
• ✅ Multiple text lines - Support for any number of text lines
• ✅ Auto-scaling - Font size automatically scales based on image dimensions
• ✅ EXIF orientation handling - Correctly handles rotated images (Android)
• ✅ Modern native code - Written in Swift (iOS) and Kotlin (Android)
• ✅ TypeScript support - Fully typed API

Installation

npm install hnc-rn-image-overlay
# or
yarn add hnc-rn-image-overlay

iOS

cd ios && pod install

Android

No additional steps required. Auto-linking will handle the setup.

Usage

import ImageOverlayModule from 'hnc-rn-image-overlay';

const processImage = async () => {
  try {
    const imagePath = '/path/to/image.jpg';
    const textLines = [
      '🕕 John Doe - 14:30    14/01/2026',
      '📍 123 Main Street, Hanoi, Vietnam'
    ];

    const resultPath = await ImageOverlayModule.addOverlayAndText(
      imagePath,
      textLines
    );

    console.log('Processed image:', resultPath);
  } catch (error) {
    console.error('Failed to process image:', error);
  }
};

API

addOverlayAndText(imagePath: string, textLines: string[]): Promise<string>

Adds a white semi-transparent overlay with text to an image.

Parameters:

• imagePath (string) - Absolute path to the input image
• textLines (string[]) - Array of text strings to render on the overlay

Returns:

• Promise<string> - Resolves to the output image path (in cache directory)

Technical Details

Overlay Specifications

• Position: Bottom of the image
• Color: White with 75% opacity
• Text color: Black
• Font: System default
• Font size: Automatically calculated based on image size
• Output format: JPEG with 100% quality

Image Processing

Android:

• Reads EXIF orientation data and applies rotation before processing
• Handles all EXIF orientation values (1-8)

iOS:

• Uses Core Graphics (UIKit) for drawing

License

MIT

Credits

Developed by HopNhat Team.