Desktop-capture-js

A native desktop capture library for Node.js that leverages N-API and DirectX libraries to capture desktop on Windows rapidly and efficiently. Ideal for applications requiring real-time screen capturing, such as screenshot taking, streaming, recording, or automated testing tools.

Table of Contents

• Installation
• Usage
  • Capturing a Frame as Buffer
  • Capturing a Frame as JPEG
• API Reference
• Examples

Installation

Ensure you have Node.js installed. Then, install the package via npm:

npm install desktop-capture-js

Usage

First, require the library in your project:

const { captureFrameAsBuffer, captureFrameAsJpeg } = require('desktop-capture-js');

Capturing a Frame as Buffer

Capture the current desktop frame as a raw buffer along with its dimensions.

const result = captureFrameAsBuffer();

if (result.status === 1) {
    const frameBuffer = result.message;
    const width = result.width;
    const height = result.height;
    // Process the frame buffer as needed
} else {
    console.error('Capture failed:', result.message);
}

Capturing a Frame as JPEG

Capture the current desktop frame and convert it to a JPEG image. You can specify the quality (default is 80).

captureFrameAsJpeg(90)
    .then(result => {
        if (result.status === 1) {
            const jpegBuffer = result.message;
            const width = result.width;
            const height = result.height;
            // Save or process the JPEG buffer as needed
        } else {
            console.error('No new frame available');
        }
    })
    .catch(error => {
        console.error('Capture failed:', error.message);
    });

API Reference

captureFrameAsBuffer()

Captures the current desktop frame as a raw buffer.

Returns:

• An object containing:
  • status (number): 1 for success, 0 for failure.
  • message (Buffer | string): The frame data buffer on success, or an error message.
  • width (number): Width of the captured frame.
  • height (number): Height of the captured frame.

captureFrameAsJpeg(quality)

Captures the current desktop frame and converts it to a JPEG image.

Parameters:

• quality (number, optional): JPEG quality (1-100). Defaults to 80.

Returns:

• A Promise that resolves to an object containing:
  • status (number): 1 for success, 0 for failure.
  • message (Buffer | string): The JPEG data buffer on success, or an error message.
  • width (number): Width of the captured frame.
  • height (number): Height of the captured frame.

Examples

Save Captured Frame as JPEG

const fs = require('fs');
const { captureFrameAsJpeg } = require('desktop-capture-js');

captureFrameAsJpeg(85)
    .then(result => {
        if (result.status === 1) {
            fs.writeFileSync('screenshot.jpg', result.message);
            console.log(`Screenshot saved: ${result.width}x${result.height}`);
        } else {
            console.error('No new frame available');
        }
    })
    .catch(error => {
        console.error('Error capturing frame:', error.message);
    });

Stream Desktop Frames

const { captureFrameAsBuffer } = require('desktop-capture-js');

setInterval(() => {
    const result = captureFrameAsBuffer();
    if (result.status === 1) {
        // Stream the frame buffer to a server or process it
        console.log(`Captured frame: ${result.width}x${result.height}`);
    } else {
        console.warn(result.message);
    }
}, 17); // Capture in 60 fps