App Inventor supports scanning of product identification “bar codes” and QR codes. Bar codes are typically found on consumer product packaging. QR codes are used for web addresses (so you can scan the QR code and go directly to the web address), part and product inventory tracking, and to deliver short messages.
In this tutorial, we create a simple App Inventor app to scan bar and QR codes.
Update: José Luis Núñez provides his own tutorial (in Spanish) for a bar code scanning app to check seating in a theater (written in App Inventor). Watch it on Youtube here:
Our App Inventor app has a simple user interface – a single button to scan either a bar or QR code. When pressed, the app activates the camera to scan the code and then returns a result value.
If the code is a numeric bar code value, the app displays a web page of information about the item corresponding to the bar code. If the returned code contains a web address, then that web address is displayed on screen. Here is an example from scanning the UPC code on a package of tea:
In the next example, a QR code containing is scanned:
And here is the result:
Drag a WebViewer component from the Palette’s User Interface section, and drag a BarCodeScanner component from the Sensor’s section. The WebViewer is the “earth” icon in this screen, and the BarCodeScanner is an invisible component, below the canvas area.
Two labels are used – one to display the text “Result:” and the other to display the returned code.
To activate the BarCodeScanner, we call the DoScan method:
The above activates the camera and displays a view on screen (in Landscape mode). Once a bar code or QR code is successfully scanned, the camera is automatically turned off and an AfterScan event is generated.
The AfterScan event has one parameter named result; this contains the converted scan code – a numeric value for a bar code or an URL for a web address (anything else is displayed in the lblBarCodeResult label, on screen).
Creating QR Codes To create your own QR Code images use any of the QR code generators available online – just search for “Create QR Code free” – I used Download Source Right Click (or Ctrl-Click on Mac OS X) and choose “Save as” (or similar wording):