Generating Order QR codes in Open Event Android

Generating Order QR codes in Open Event Android

QR codes provide a very fast and convenient way to share information to other device, one device generates a bitmap image with information encoded in it, this bitmap can be easily scanned from the other device. QR codes are used in Open Event Android to share order identifier information, the latter can be used to check in attendee in Open Event Orga App. This blog post will guide you on how its implemented in Open Event Android.

Add the dependency

We use Zixing’s Barcode scanning library in Open Event Android for generating QR bitmaps. Add the following dependency in your app level gradle file. Please visit zxing GitHub page for latest version information.

implementation ‘com.journeyapps:zxing-android-embedded:3.4.0’

Create View for QR code

To display QR code we need to create and bitmap and then populate it on an Image View. The following code snippet generated an Image View on the screen, we have set the scale type to center crop so that image is scaled uniformly and the dimension of the image is equal to the corresponding dimension of the view.

    <ImageView
               android:layout_width=“200dp”
               android:layout_gravity=“center”
               android:layout_height=“200dp”
               android:id=“@+id/qrCodeView”
               android:layout_margin=“@dimen/layout_margin_medium”
               android:scaleType=“centerCrop” />

Generating the QR Bitmap

The following code snippet generates QR bitmap for order identifier.

try {
           val bitMatrix = MultiFormatWriter().encode(orderIdentifier, BarcodeFormat.QR_CODE, 200, 200)
           itemView.qrCodeView.setImageBitmap(BarcodeEncoder().createBitmap(bitMatrix))
       } catch (e: WriterException) {
           e.printStackTrace()
       }

MultiformatWriter encodes the provided string in the format specified in the second parameter of encode function and generates a bitMatrix of specified dimensions in our case orderIdentifier is the string to be encoded and the format is QR_CODE. The last two parameters in the encode method are the width and height respectively for the Image Matrix to be generated. This bitMatrix can be then used to create QR bitmaps, BarcodeEncode() function creates a bitmap from this bitMatrix which is then set on the image View using setImageBitmap method. As a writer exception may occur while encoding string to specified format this whole block of code is put inside a try catch block which catches and logs the WriterException.

References

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