An Android app (written in Kotlin) that scans a receipt and calculates how much an individual should pay/tip. Let's imagine for a moment how easy will it be to use this app as opposed to everyone having to calculate its share. The very first advantage is the fact that there will be no mistakes and we must be realistic, more often than not, splitting the bill results in a lot of mistakes. We either forgot to add a product or we even forgot that we have consumed it or virtually we mistype a number when we try to calculate and just with a simple mistake like that, everything goes south. This app makes it everything easy for us, which I believe is just the primary scope of day-to-day technology.
- every current version of Android (works on 99.58% of the devices)
Once the app will have every feature ready, it will be published on Android Store and be available to the public.
Describing the app - (non-tehnical description - user stories, backlog creation, features list, design description, behavior description)
- As a waiter, I want a faster way to receive a higher tip so that I can put aside some money for a vacation.
- As Karen, I want to organise my tips better so I can feel more in control.
- As a restaurateur (restaurant owner), I want an app that increases the chance of my employees getting a tip after their service.
- As Alex, I want to know how much I have to pay so that my friends won't discover that I don't know maths.
- As an accountant, I want to make sure that the waiters don't make a mistake when they calculate change back to customers so that I have to pay less attention to that aspect.
- As a waitress, I would like an app that makes customers pay a tip so that I can pay off my loans.
- As a HR manager, I need to view the employees' tips so I can manage company personnel needs.
- As Susan, I want to use an app when eating out so that I look younger.
- As a customer, I want to view a list of products so I can select what I ordered.
- As John, I want to link my credit card to my profile so that I can pay for a meal faster, easier and without using cash.
- As Mary, I want to use an app that makes it easy so split a bill when going out with my friends.
- As a math addict, I want to use a tip calculator so that I can get the formula behind the app.
- As a customer, I don't want to worry about who is going to foot the bill so that I can enjoy my going out.
- As an user I want an app which will make my life easier so that I won't worry about how much I have to pay.
- As a young teenager, I want to not stress myself about the bill so that I can have fun with my friends.
- As a good mathematician, I don't want to constantly calculate how much should everyone pay, so as to get the split right.
- As a waiter, I want the customers to have a great time so that I will receive tips.
We monitorized our backlog creation using Trello. It can be found here.
- Scanning a receipt and extracting the product's name and price
- Creating a checklist from scratch
- Chosing a photo from the gallery/ from Drive
- Creating a checklist based on the scan
- Editing a checklist
- Calculating the total sum that a individual has to pay based on his selection from the checklist
- Deleting an individual's selected products
- Clearing a checklist
Basically, the user can either opt for scanning a receipt or create a checklist. If he chose to scan an receipt, he will be asked to chose a photo from the drice or use a photo from the gallery. Either way, the scanner will build a list containing the products (name and price). The user can modify this checklist should it contain any mistakes by adding/deleting a product or clearing the list. These operations can be done by pressing the buttons having the same names. Alongside with the name of the product and the price, the checklist also contains a checkbox which allows the user to select that product. After the checklist is finalised, each buyer will select the products that he consumed by pressing the checkbox of the product. When he finishes, he will press 'Done' button and the total sum will appear on the screen. After he finishes, he will press delete and everything that he consumed and paid will be deleted. The next user takes the phone and begin the same process by selecting his products from the remaining ones.
As a following implementation, the developers will add a new column called quantity which will let the individual select how many products of this kind he has consumed. His part will be subtracted from the total after he presses 'Done' button. Another idea is to enable split option as a product could have been shared by multiple individual and once paid, it should be subtracted from the total. As a final step, we would like to merge everything and update the app so as to calculate how much should everyone pay and then invites the user to pay his share using a credit card. This thing can be implemented in accordance with restaurant's personnel. If the bill will come in this form instead of as a receipt on a paper. The consumer will not need to scan the receipt and then calculate. The restaurant's personnel should bring the bill in this format and the user should select their products and pay them using a credit card. Just like that the weiter's job gets easier because nobody will ask for a separate bill which is a daunting job when you have a lot of customers. Needless to say, the consumers will be deprived of having to calculate a lot in order to see how much he has to pay and the risk of making a mistake is virtually inexistent.
When the app is installed, the user will see the three pictures which presents the app's basic features. The app has also a navigation drawer whose purpose is to redirect the user to either the homepage, the Scanner or the Checklist. The homepage invites the user to select one of the app's functions (Load scanner or Open Checklist).
- App icon
-
Installation Pages design - consists of three pictures aiming to present the app's functionalities.These apeears only the first time the app is installed. Every page has two buttons (Skip and Next) which can be found in activity_slider.xml.
- welcome_slider1.xml
      - ImageView
      - TextView - Welcome -
      - TextView - Ever felt tired of keeping track of the receipt? -
- welcome_slider2.xml
      - ImageView
      - TextView - We got you -
      - TextView - Just take a quick photo or chose one from your gallery -
- welcome_slider3.xml
      - ImageView
      - TextView - Sync -
      - TextView - Remember to save your information over the cloud with a simple login -
- welcome_slider1.xml
-
Welcome Page design - appears every time the app is opened
- activity_splash.xml
      - ImageView
      - ProgressBar -
- activity_splash.xml
-
Home Page design -
- app_bar_main_drawer.xml
      - ImageView
      - Twp Buttons (Load Scanner and Open Checklist) -
- app_bar_main_drawer.xml
-
Navigation drawer
- activity_main_drawer.xml
      - NavigationView implemented by Android
      - ImageView
      - Two TextViews for username and passward
- activity_main_drawer.xml
-
Scanner page
- content_main_drawer.xml
      - ImageView (here will appear the image)
      - Twp Buttons (Select image - takes the user to the gallery in order to select an image and Recognise Text - scans the image that was selected) -
      - EditText (here will appear the text - names and prices of the products-)
Chose an image option
After the image was chosen
Chose an image option
Text recognition function
Transform image into checklist
- content_main_drawer.xml
-
Checklist - activity_checklist.xml - a relative Layout which contains:
- TextView - title of the page - Receipt List
- EditText - textbox in which we write the name of the product we want to add. The product is created based on list_products.xml which has two TextViews (Name and Price) and a checkbox.
- EditText - textbox in which we write the price of the product we want to add
- LinearLayout - contains 3 Buttons (Add, Delete, Clear, Done) each of them having a specific functionality. Add adds a new product (written in EditText box), Delete removes the selected item, Clear (deletes every instance of the list, Done prints the total sum that has to be paid by an individual)
- TextView - marks the beginning the receipt list - My Receipt List
- ListView - dynamic list which contains the added items resulted from scanning and/or added through the Checklist
Select an item using the checkbox
Calculating the total sum by pressing Done
Deleting an item by pressing Delete
Adding an item
Item added
Clearing the list by pressing Clear
Branches: https://github.com/AndraRaco/App-Receipt-Scanner/branches
- branch text-recognition - contains code that allows the user to select an image from the gallery or to take a picture which will be scanned. The scanner is programmed to extract the name of the product and its price;
- branch pickfromgallery has code that allows the user to pick an image from gallery when pressing a button;
- branch ui-update - was used to create a friendly-looking interface for the user;
- branch checklist - allows the user to add an item (name + value) to a list, to remove it from the list or to clear the whole list; then the app calculates the total price for the chosen products;
Commits: https://github.com/AndraRaco/App-Receipt-Scanner/commits
Describing the code (tehnical - Classes Diagram in reference to features, Design Scheme, Functions and proprieties, Tehnical Description of behaviour)
-
Splash
- info: the first activity that starts when the app launches and acts as a welcome message/ loading page
- type: AppCompatActivity
- behaviour: starts every time the app launches, runs for 2 seconds and then reddirects to either slider activity or main activity, depending on wether or not the isFirstTime variable is true or false
-
Slider
- info: a sliding welcome message that briefly describes the app
- type: AppCompatActivity
- behaviour: loads the first time the user opens the app after an install/update and contains short messages to inform the user about new app functionalities
- contains a skip button and a next button
Code for Next Button
btnNext.setOnClickListener(View.OnClickListener { if (viewPager.getCurrentItem() + 1 < layouts.size) { viewPager.setCurrentItem(viewPager.getCurrentItem() + 1) } else { //go to main activity //launcherManager.setFirstLaunch(false); startActivity(Intent(applicationContext, MainDrawer::class.java)) } })Code for Skip Button
btnSkip.setOnClickListener(View.OnClickListener { startActivity( Intent( applicationContext, MainDrawer::class.java ) ) })These functions can be found in Slider.kt file.
-
HomeFragment
- info: part of the main activity, the app's homepage, with two buttons to load the checklist and scan activities
- type: Fragment
- behaviour: serves as the homepage and links to the checklist and scan functionalities of the app using
- elements:
-
openchecklistpart
-
type: button
-
use: links the homepage to the checklist activity
-
code:
openchecklistpart.setOnClickListener { var intent = Intent( view.context, ChecklistActivity::class.java ) startActivity(intent) }
-
-
openscanpart
-
type: button
-
use: links the homepage to the checklist activity
-
code:
openscanpart.setOnClickListener { var intent = Intent( view.context, MainTextRecognizer::class.java ) startActivity(intent) }
-
-
These functions can be found in GallertActivity.kt file.
-
GalleryActivity
- info: the app activity that extracts an image from the gallery or from a google drive account
- type: AppCompatActivity
- behaviour: the user selects an image, either from the camera or from the gallery or from a google drive account
override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) //BUTTON CLICK img_pick_btn.setOnClickListener { //check runtime permission if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_DENIED) { //permission denied val permissions = arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE); //show popup to request runtime permission requestPermissions(permissions, PERMISSION_CODE); } else { //permission already granted pickImageFromGallery(); } } else { //system OS is < Marshmallow pickImageFromGallery(); } } }Functions used:
-
Picks an image from Gallery
private fun pickImageFromGallery() {
//Intent to pick image
val intent = Intent(Intent.ACTION_PICK)
intent.type = "image/*"
startActivityForResult(intent, IMAGE_PICK_CODE)
}
- Select an image
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
//BUTTON CLICK
img_pick_btn.setOnClickListener {
//check runtime permission
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_DENIED) {
//permission denied
val permissions = arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE);
//show popup to request runtime permission
requestPermissions(permissions, PERMISSION_CODE);
} else {
//permission already granted
pickImageFromGallery();
}
} else {
//system OS is < Marshmallow
pickImageFromGallery();
}
}
}
These functions can be found in GallertActivity.kt file.
- MainTextRecognizer
- info: the app activity that scans a given image
- type: AppCompatActivity
- behaviour: the user selects an image, either from the camera or from the gallery, then, using google's firebase ml ocr algorithms, the image is processed as text and saved as a list
Functions used:
- Select an image
fun selectImage(v: View) {
val intent = Intent()
intent.type = "image/*"
intent.action = Intent.ACTION_GET_CONTENT
startActivityForResult(Intent.createChooser(intent, "Select Picture"), 1)
}
- Scanning the text
fun startRecognizing(v: View) {
if (imageView.drawable != null) {
editText.setText("")
v.isEnabled = false
val bitmap = (imageView.drawable as BitmapDrawable).bitmap
val image = FirebaseVisionImage.fromBitmap(bitmap)
val detector = FirebaseVision.getInstance().onDeviceTextRecognizer
detector.processImage(image)
.addOnSuccessListener { firebaseVisionText ->
v.isEnabled = true
processResultText(firebaseVisionText)
var toCheckList: List<String?> // list to send to checklist activity
toCheckList = ArrayList(50)
var products: List<Pair<Double, String>> // auxiliary list to make tochecklist
products = processResultText(firebaseVisionText)
for (x in products)
toCheckList.add(x.first.toString() + ',' + x.second)
// pass the products array to checklist for merging
val Checklist = Intent(this, ChecklistActivity::class.java)
Checklist.putExtra("Products", toCheckList)
startActivity(Checklist)
}
.addOnFailureListener {
v.isEnabled = true
editText.setText("Failed")
}
} else {
Toast.makeText(this, "Select an Image First", Toast.LENGTH_LONG).show()
}
}
Other functions:
- Function for Processing the text
private fun processResultText(resultText: FirebaseVisionText): List<Pair<Double, String>> {
var products: List<Pair<Double, String>>
products = ArrayList(50)
if (resultText.textBlocks.size == 0) {
editText.setText("No Text Found")
return products
}
for (block in resultText.textBlocks) {
val blockText = block.text
editText.append(blockText + "\n")
}
val tuples = getTuples(editText.text.toString())
products = getTuples(editText.text.toString())
editText.setText("")
for (t in tuples) {
editText.append(t.toString() + "\n")
}
return products
}
- Function for extracting the price and name of the products
// returns a list of pairs (price, product_name), given the text of the receipt
fun getTuples(text: String): List<Pair<Double, String>> {
var products = mutableListOf<Pair<Double, String>>()
var produs_crt = 0
var pret_crt = 0
var nume_crt = 0
var started =
false // all the text from the upper part of the receipt is unnecessary and it should be skipped
val lines = text.split("\n")
for (line in lines) {
if ("total" == line.toLowerCase(Locale.getDefault())
|| "*" in line.toLowerCase(Locale.getDefault())
) {
break
}
if ("x " in line.toLowerCase(Locale.getDefault())) {
val trimmedLine = line.drop(line.toLowerCase(Locale.getDefault()).indexOf("x ") + 2)
if (trimmedLine.isEmpty()) {
continue
}
val words = trimmedLine.split(' ')
if (words.isNotEmpty()) {
if (words[0].toDoubleOrNull() != null) {
val nr = words[0].toDouble()
if (pret_crt == produs_crt) {
products.add(Pair(nr, ""))
produs_crt += 1
pret_crt += 1
} else {
products[pret_crt] = Pair(nr, products[pret_crt].second)
pret_crt += 1
}
started = true
}
}
} else if (started
&& !line[0].isDigit()
&& "discount" !in line.toLowerCase(Locale.getDefault())
&& "total" !in line.toLowerCase(Locale.getDefault())
&& "lei" != line.toLowerCase(Locale.getDefault())
&& "lel" != line.toLowerCase(Locale.getDefault())
) { // the text recognizer might confuse i for l
if (nume_crt == produs_crt) {
products.add(Pair(0.toDouble(), line))
produs_crt += 1
nume_crt += 1
} else {
products[nume_crt] = Pair(products[nume_crt].first, line)
nume_crt += 1
}
}
}
return products
}
These functions can be found in MainTextRecogniser.kt file.
- ChecklistActivity
- info: app activity that creates a checklist for easy recipie management
- type: AppCompatActivity
- behaviour: adds items from userimput as a pair < name, price >, stores them in a list and calculates the total of the selected items
Functions used:
- Add function which functions by pressing Add button
// Adding the items to the list when the add button is pressed
add.setOnClickListener {
addRow()
}
// Adding a new row to the CheckList
fun addRow() {
// Create product with name and prace
val name = editText.text.toString()
val price = et_price.text.toString().toDouble()
val p = Product(name, price)
// Add product to the list of Products
itemList.add(p)
// Notify the attached observers that the underlying data has been changed and
// the listView should refresh itself
(listView.adapter as ProductAdapter).notifyDataSetChanged()
// After adding the item, the edit texts for name and for price will be cleared
editText.text.clear()
et_price.text.clear()
}
- Clear function which functions by pressing Clear button
// Delete the all rows form the listView
clear.setOnClickListener {
clearRows()
}
// Delete the all rows form the listView
fun clearRows() {
itemList.clear()
// Notify the attached observers that the underlying data has been changed and
// the listView should refresh itself
(listView.adapter as ProductAdapter).notifyDataSetChanged()
}
- Delete function which functions by pressing Delete button
// Selecting and Deleting the items from the list when the delete button is pressed
delete.setOnClickListener {
deleteRow()
}
// Delete the selected rows form the listView
fun deleteRow() {
val position: SparseBooleanArray =
listView.checkedItemPositions // Map with indices of the items from listView
// and true/false if the item is checked/ is not checked
val count = listView.count // size of the listView
var item = count - 1 // index for the list
// Removing the selected items
while (item >= 0) {
if (position.get(item)) {
itemList.removeAt(item)
}
item--
}
position.clear()
// Notify the attached observers that the underlying data has been changed and
// the listView should refresh itself
(listView.adapter as ProductAdapter).notifyDataSetChanged()
}
- Calculate sum function which functions by pressing Done button
// Calculate how much has the person to pay
calculate.setOnClickListener {
var sum = calculatePriceToPay()
// Show a text with the sum
android.widget.Toast.makeText(
this,
"You have to pay $sum",
android.widget.Toast.LENGTH_SHORT
).show()
}
// Calculate how much the user has to pay
fun calculatePriceToPay(): Double {
val position: SparseBooleanArray =
listView.checkedItemPositions // Map with indices of the items from listView
// and true/false if the item is checked/ is not checked
val count = listView.count // Size of the listView
var pricesOfProducts: ArrayList<Double> = ArrayList<Double>()
// Select the products that are checked
var item = count - 1
while (item >= 0) {
if (position.get(item)) {
pricesOfProducts.add(itemList[item].price)
}
item--
}
// Calculate the sum of the selected products
return sumAux(pricesOfProducts)
}
These functions can be found in ChecklistActivity.kt file.
Our project is developed using Andorid Studio IDE that has a Gradle-based building tool. When we want to build our project in an APK, so that we can give it to our users to install the application and use it, we go to:
and click Build APK. Then, in the folder our project is in, it generates 2 files:
One of the file, "app-debug.apk", is the apk that will install our application, the other one, "output.json", is a message that tells us if the apk was generated succesfully or not. We then transfer the APK to our mobile device and run it to install the application.
1. Test if the product ("mere", 4.5) can be added
@Test
fun user_add_product_correct() {
// Write product information in typeTexts
onView(withId(R.id.editText)).perform(typeText("mere"))
onView(withId(R.id.et_price)).perform(typeText("4.5"))
var sizeBeforeAdd =
rule.activity.getItemListSize() // Size of the Checklist before inserting a new element
// Click on add button
onView(withId(R.id.add)).perform(click())
var sizeAfterAdd =
rule.activity.getItemListSize() // Size of the Checklist after inserting a new element
// Check if the product was added, the size after add should be equal with the initial size + one
Assert.assertEquals(
"The product was not insert in the CheckList",
(sizeBeforeAdd + 1).toDouble(), sizeAfterAdd.toDouble(), 0.0
)
}
2. Test if the product ("mere", "ciocolata") can be added
@Test
fun user_add_product_wrong() {
// Product name and price
var nameProduct = "mere"
var priceProduct = "ciocolata"
// Write product information in typeTexts
onView(withId(R.id.editText)).perform(typeText(nameProduct))
onView(withId(R.id.et_price)).perform(typeText(priceProduct))
var ok: Boolean = true // Check whether the input was correct or not
if (priceProduct.toDoubleOrNull() == null) // if price is not double
ok = false
if (priceProduct == "" || nameProduct == "") // if price or name is not written
ok = false
// Check if the product was added, the size after add should be equal with the initial size + one
Assert.assertTrue("The product was not insert in the CheckList", ok)
}
3. Test if the user can delete product from the CheckList
@Test
fun user_add_and_delete_product_correct() {
// Add 2 products to the CheckList
// Write product information in typeTexts
onView(withId(R.id.editText)).perform(typeText("mere"))
onView(withId(R.id.et_price)).perform(typeText("4.5"))
// Click on add button
onView(withId(R.id.add)).perform(click())
// Write product information in typeTexts
onView(withId(R.id.editText)).perform(typeText("pere"))
onView(withId(R.id.et_price)).perform(typeText("5.0"))
// Click on add button
onView(withId(R.id.add)).perform(click())
var sizeBeforeDelete =
rule.activity.getItemListSize() // Size of the Checklist before deleting an element
// Select "mere" from list
onView(withText("mere")).perform(click())
// Delete selected products from CheckList
onView(withId(R.id.delete)).perform(click())
var sizeAfterDelete =
rule.activity.getItemListSize() // Size of the Checklist after deleting an element
// Check if the product was added, the size after add should be equal with the initial size + one
Assert.assertEquals(
"The product was not deleted from the CheckList",
(sizeBeforeDelete - 1).toDouble(), sizeAfterDelete.toDouble(), 0.0
)
}
4. Test if the user can clear the CheckLsit
@Test
fun user_add_and_clear_product_correct() {
// Add 2 products to the CheckList
// Write product information in typeTexts
onView(withId(R.id.editText)).perform(typeText("mere"))
onView(withId(R.id.et_price)).perform(typeText("4.5"))
// Click on add button
onView(withId(R.id.add)).perform(click())
// Write product information in typeTexts
onView(withId(R.id.editText)).perform(typeText("pere"))
onView(withId(R.id.et_price)).perform(typeText("5.0"))
// Click on add button
onView(withId(R.id.add)).perform(click())
// Click on clear button
onView(withId(R.id.clear)).perform(click())
var sizeAfterClear =
rule.activity.getItemListSize() // Size of the Checklist after deleting an element
// Check if the product was added, the size after add should be equal with the initial size + one
Assert.assertEquals(
"The product was not deleted from the CheckList",
0.0, sizeAfterClear.toDouble(), 0.0
)
}
5. Test if the sum of the selected items is calculated correctly
@Test
fun user_calculate_correct() {
// Add 2 products to the CheckList
// Write product information in typeTexts
onView(withId(R.id.editText)).perform(typeText("mere"))
onView(withId(R.id.et_price)).perform(typeText("4.5"))
// Click on add button
onView(withId(R.id.add)).perform(click())
// Write product information in typeTexts
onView(withId(R.id.editText)).perform(typeText("pere"))
onView(withId(R.id.et_price)).perform(typeText("5.0"))
// Click on add button
onView(withId(R.id.add)).perform(click())
// Select "mere" from list
onView(withText("mere")).perform(click())
// Select "pere" from list
onView(withText("pere")).perform(click())
var correctSum: Double = 4.5 + 5.0
// How much has the user to pay for selected items
var sum = rule.activity.calculatePriceToPay()
// Check if the product was added, the size after add should be equal with the initial size + one
Assert.assertEquals(
"The sum is wrong",
correctSum, sum, 0.0
)
}
Unit Testing Results:
