Feature suggestion: Import from Gallery

[nathanfallet]

Description of the problem:

I would like to add a method to trigger the recognition from a file imported from Gallery/Camera Roll.
That way, when embedding the scanner in a custom Activity, we can place a button to allow the user to import a QR code from Gallery instead of scanning one.

[nathanfallet]

I found a way to implement it:

I open the gallery this way: (this function is called when a button is pressed)

    private fun openGallery() {
        val intent = Intent()
        intent.type = "image/*"
        intent.action = Intent.ACTION_GET_CONTENT
        openGalleryRequest.launch(Intent.createChooser(intent, getString(R.string.scanner_gallery)))
    }

Using this request:

    private val openGalleryRequest =
        registerForActivityResult(ActivityResultContracts.StartActivityForResult()) {
            if (it.resultCode == RESULT_OK) {
                it.data?.data?.let { uri -> handleImage(uri) }
            }
        }

And then I handle the result with this function:

    private fun handleImage(uri: Uri) {
        try {
            val image = if (Build.VERSION.SDK_INT < 28) {
                MediaStore.Images.Media.getBitmap(this.contentResolver, uri)
            } else {
                val source = ImageDecoder.createSource(this.contentResolver, uri)
                ImageDecoder.decodeBitmap(source).copy(Bitmap.Config.RGBA_F16, true)
            }

            val intArray = IntArray(image.width * image.height)
            image.getPixels(intArray, 0, image.width, 0, 0, image.width, image.height)

            val source = RGBLuminanceSource(image.width, image.height, intArray)
            val reader = MixedDecoder(MultiFormatReader())
            var result = reader.decode(source)
            if (result == null) {
                result = reader.decode(source)
            }

            val intent = CaptureManager.resultIntent(BarcodeResult(result, null), null)
            setResult(RESULT_OK, intent)
            finish()
        } catch (e: Exception) {
            e.printStackTrace()
        }
    }

Note that I decode twice the result to allow to get inverted codes as well (white codes on a colored background) with the MixedDecoder.

What do you think of this implementation? Do you have any suggestion or feedback? And also, now we found how to do it, any path to implement it in the library? (in which class, how it would be called, ...)

Does adding a function to BarcodeView to handle a Bitmap imported from gallery (the developer has to fetch the image himself) is a great idea of implementation? @rkistner

[sachin-varshney]

Here is the solution

private val openGalleryRequest =
        registerForActivityResult(ActivityResultContracts.StartActivityForResult()) {
            if (it.resultCode == AppCompatActivity.RESULT_OK) {
                it.data?.data?.let { uri -> decodeQRCode(uri) }
            }
        }

    private fun openGallery() {
        val intent = Intent()
        intent.type = "image/*"
        intent.action = Intent.ACTION_GET_CONTENT
        openGalleryRequest.launch(Intent.createChooser(intent, "Scan Gallery"))
    }

    private fun decodeQRCode(imageUri: Uri) {
        try {
            val inputStream = context?.contentResolver?.openInputStream(imageUri)
            val bitmap = BitmapFactory.decodeStream(inputStream)

            val intArray = IntArray(bitmap.width * bitmap.height)
            bitmap.getPixels(intArray, 0, bitmap.width, 0, 0, bitmap.width, bitmap.height)

            val source: LuminanceSource = RGBLuminanceSource(bitmap.width, bitmap.height, intArray)
            val binaryBitmap = BinaryBitmap(HybridBinarizer(source))

            val reader = QRCodeReader()
            val result = reader.decode(binaryBitmap)

            // The QR code content is in result.text
            val qrCodeContent = result.text
            proceedQrData(qrCodeContent)

        } catch (e: Exception) {
            // Handle exceptions (e.g., QR code not found)
           
        }
    }