Simple QR code scanning app

I need an Android app for scanning QR codes to take attendance. The QR codes contains user ID-s (number). The result of scanning (user ID) should be sent to a .Net web service and the result of the web service should be displayed on the screen (the web service is developed and available and does all work in marking attendance in our database and returns "welcome" message if the user is successfully checked in). The screens are: #1 screen: Login screen - two textboxes to enter username and password and a button to login. A checkbox "remember me" to remember the un/pwd. After a button click the un/pwd are sent to our web service. The web service returns true or false. If true the user proceeds to screen #2. If false, the warning is displayed. #2 screen: Select group screen - a dropdown select box displays available groups which user needs to select before scanning the QR code. The list of available groups is returned by our webservice. When a user selects a group he can go to second screen. #3 screen: Scanning screen - this screen is divided in two parts: the upper part is reserved for displaying the result of scanning (the returned string message from web service). In screen title there should be displayed the group name the user selected in previous step. Below the upper part is the scanning screen displaying camera view. There should be a button to switch between front and back camera of the device. When the user puts the QR code in front of camera the app should read the code which contains a number (user ID) and send it with group ID selected on previous screen to web service. The web service returns a string message that is displayed in upper part of the screen. Immediately after this the app is ready for next qr code scanning. There should be no pop ups, all must be visible on one screen (the message and the camera view). This screen must work in portrait or landscape mode (depending on device orientation). Also, there should be a small button to clear the displayed message. That's it. It's a simple app - all work is done by our web service, you only need to call it and display the results. The important points are: - front/back camera switch feature - portrait/landscape mode support - fast reading of QR codes - support of various phone and tablet screen size We will provide links to web service functions. We require source code and build APK file ready for deployment after the work is done.