KScan

A Compose Multiplatform barcode scanning library for Android, iOS, Desktop and Web.

Android	iOS	Desktop

Web (JS)	Web (Wasm)

Installation

Add the dependency to your commonMain source set:

implementation("io.github.ismai117:KScan:$version")

Platform Setup

Android - Uses zxing-cpp for barcode scanning, so every dependency is open source and the library can be used in apps published on F-Droid.

iOS - Uses AVFoundation for camera and barcode scanning.

Windows / macOS / Linux - Uses JavaCV for camera and ZXing for barcode scanning.

Web (JS / Wasm) - Uses the browser's BarcodeDetector, falling back to the MIT-licensed barcode-detector polyfill from a CDN where a browser has none. KScanWeb points it at your own copies instead.

Permissions

Android, iOS, macOS - Before displaying the ScannerView, your application must request and be granted camera permissions by the operating system. On iOS & macOS, add this to your Info.plist:

<key>NSCameraUsageDescription</key>
<string>Camera access is required for barcode scanning</string>

Web - The browser asks on the first scan, so there is nothing to declare, but the page has to be served over https. Without it the browser withholds getUserMedia and no camera opens.

Usage

Basic

ScannerView draws the camera preview and nothing else, so the controls and overlays around it are yours to build:

ScannerView(
    codeTypes = listOf(BarcodeFormat.FORMAT_QR_CODE, BarcodeFormat.FORMAT_EAN_13)
) { result ->
    when (result) {
        is BarcodeResult.OnSuccess -> {
            println("Barcode: ${result.barcode.data}")
        }
        is BarcodeResult.OnFailed -> {
            println("Error: ${result.exception.message}")
        }
    }
}

On web the preview is an HTML element the browser stacks above the Compose canvas, so place your own UI beside it rather than over it.

Custom Controls

Use ScannerController for torch and zoom:

val scannerController = remember { ScannerController() }

ScannerView(
    codeTypes = listOf(BarcodeFormat.FORMAT_ALL_FORMATS),
    scannerController = scannerController
) { result ->
    // handle result
}

// Torch control
Button(onClick = { scannerController.setTorch(!scannerController.torchEnabled) }) {
    Text("Toggle Torch")
}

// Zoom control
Slider(
    value = scannerController.zoomRatio,
    onValueChange = scannerController::setZoom,
    valueRange = 1f..scannerController.maxZoomRatio
)

Scanning from Images

Use scanImage to scan barcodes from static images (gallery, screenshots, downloaded images) instead of the live camera feed:

scanImage(
    imageBytes = imageBytes, // ByteArray of the image (PNG, JPEG)
    codeTypes = listOf(BarcodeFormat.FORMAT_ALL_FORMATS),
    filter = { barcode -> true }, // Optional: filter detected barcodes
) { result ->
    when (result) {
        is BarcodeResult.OnSuccess -> {
            println("Barcode: ${result.barcode.data}")
            println("Format: ${result.barcode.format}")
        }
        is BarcodeResult.OnFailed -> {
            println("Error: ${result.exception.message}")
        }
    }
}

Supported Formats

Format	Android	iOS	Desktop	Web
CODE_128	✅	✅	✅	✅
CODE_39	✅	✅	✅	✅
CODE_93	✅	✅	✅	✅
CODABAR	✅	✅	✅	✅
EAN_13	✅	✅	✅	✅
EAN_8	✅	✅	✅	✅
ITF	✅	✅	✅	✅
UPC_A	✅	❌	✅	✅
UPC_E	✅	✅	✅	✅
QR_CODE	✅	✅	✅	✅
PDF417	✅	✅	✅	✅
AZTEC	✅	✅	✅	✅
DATA_MATRIX	✅	✅	✅	✅

Use BarcodeFormat.FORMAT_ALL_FORMATS to scan all supported types.

License

Copyright 2024 ismai117

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Contributing

Contributions are welcome! Feel free to open issues or submit pull requests.