[pos] migrate to view binding

14 files changed, 177 insertions, 152 deletions

diff --git a/merchant-terminal/build.gradle b/merchant-terminal/build.gradle
index f7bbc1c..df8cee5 100644
--- a/merchant-terminal/build.gradle
+++ b/merchant-terminal/build.gradle
@@ -1,7 +1,6 @@
 plugins {
     id 'com.android.application'
     id 'kotlin-android'
-    id 'kotlin-android-extensions'
     id 'kotlinx-serialization'
     id 'androidx.navigation.safeargs.kotlin'
 }
@@ -13,7 +12,7 @@ android {
 
     defaultConfig {
         applicationId "net.taler.merchantpos"
-        minSdkVersion 26
+        minSdkVersion 24
         targetSdkVersion 29
         versionCode 1
         versionName "1.0"
@@ -40,6 +39,10 @@ android {
         jvmTarget = "1.8"
     }
 
+    buildFeatures {
+        viewBinding = true
+    }
+
     testOptions {
         unitTests {
             includeAndroidResources = true
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/MainActivity.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/MainActivity.kt
index 533c540..47da74e 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/MainActivity.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/MainActivity.kt
@@ -28,21 +28,20 @@ import android.widget.Toast.LENGTH_SHORT
 import androidx.activity.viewModels
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.view.GravityCompat.START
-import androidx.lifecycle.Observer
 import androidx.navigation.NavController
 import androidx.navigation.fragment.NavHostFragment
 import androidx.navigation.ui.AppBarConfiguration
 import androidx.navigation.ui.setupWithNavController
 import com.google.android.material.navigation.NavigationView.OnNavigationItemSelectedListener
-import kotlinx.android.synthetic.main.activity_main.*
-import kotlinx.android.synthetic.main.app_bar_main.*
 import net.taler.common.NfcManager
+import net.taler.merchantpos.databinding.ActivityMainBinding
 
 class MainActivity : AppCompatActivity(), OnNavigationItemSelectedListener {
 
     private val model: MainViewModel by viewModels()
     private val nfcManager = NfcManager()
 
+    private lateinit var ui: ActivityMainBinding
     private lateinit var nav: NavController
 
     private var reallyExit = false
@@ -53,9 +52,10 @@ class MainActivity : AppCompatActivity(), OnNavigationItemSelectedListener {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_main)
+        ui = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(ui.root)
 
-        model.paymentManager.payment.observe(this, Observer { payment ->
+        model.paymentManager.payment.observe(this, { payment ->
             payment?.talerPayUri?.let {
                 nfcManager.setTagString(it)
             }
@@ -65,12 +65,12 @@ class MainActivity : AppCompatActivity(), OnNavigationItemSelectedListener {
             supportFragmentManager.findFragmentById(R.id.navHostFragment) as NavHostFragment
         nav = navHostFragment.navController
 
-        nav_view.setupWithNavController(nav)
-        nav_view.setNavigationItemSelectedListener(this)
+        ui.navView.setupWithNavController(nav)
+        ui.navView.setNavigationItemSelectedListener(this)
 
-        setSupportActionBar(toolbar)
-        val appBarConfiguration = AppBarConfiguration(nav.graph, drawer_layout)
-        toolbar.setupWithNavController(nav, appBarConfiguration)
+        setSupportActionBar(ui.main.toolbar)
+        val appBarConfiguration = AppBarConfiguration(nav.graph, ui.drawerLayout)
+        ui.main.toolbar.setupWithNavController(nav, appBarConfiguration)
     }
 
     override fun onStart() {
@@ -99,14 +99,14 @@ class MainActivity : AppCompatActivity(), OnNavigationItemSelectedListener {
             R.id.nav_history -> nav.navigate(R.id.action_global_merchantHistory)
             R.id.nav_settings -> nav.navigate(R.id.action_global_merchantSettings)
         }
-        drawer_layout.closeDrawer(START)
+        ui.drawerLayout.closeDrawer(START)
         return true
     }
 
     override fun onBackPressed() {
         val currentDestination = nav.currentDestination?.id
-        if (drawer_layout.isDrawerOpen(START)) {
-            drawer_layout.closeDrawer(START)
+        if (ui.drawerLayout.isDrawerOpen(START)) {
+            ui.drawerLayout.closeDrawer(START)
         } else if (currentDestination == R.id.nav_settings && !model.configManager.config.isValid()) {
             // we are in the configuration screen and need a config to continue
             val intent = Intent(ACTION_MAIN).apply {
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFetcherFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFetcherFragment.kt
index 8231052..87004d8 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFetcherFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFetcherFragment.kt
@@ -27,20 +27,23 @@ import com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_SHORT
 import com.google.android.material.snackbar.Snackbar
 import net.taler.common.navigate
 import net.taler.merchantpos.MainViewModel
-import net.taler.merchantpos.R
 import net.taler.merchantpos.config.ConfigFetcherFragmentDirections.Companion.actionConfigFetcherToMerchantSettings
 import net.taler.merchantpos.config.ConfigFetcherFragmentDirections.Companion.actionConfigFetcherToOrder
+import net.taler.merchantpos.databinding.FragmentConfigFetcherBinding
 
 class ConfigFetcherFragment : Fragment() {
 
     private val model: MainViewModel by activityViewModels()
     private val configManager by lazy { model.configManager }
 
+    private lateinit var ui: FragmentConfigFetcherBinding
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_config_fetcher, container, false)
+        ui = FragmentConfigFetcherBinding.inflate(inflater)
+        return ui.root
     }
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFragment.kt
index daddbff..c31eb61 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/config/ConfigFragment.kt
@@ -30,11 +30,11 @@ import androidx.fragment.app.activityViewModels
 import androidx.lifecycle.Observer
 import com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_LONG
 import com.google.android.material.snackbar.Snackbar
-import kotlinx.android.synthetic.main.fragment_merchant_config.*
 import net.taler.common.navigate
 import net.taler.merchantpos.MainViewModel
 import net.taler.merchantpos.R
 import net.taler.merchantpos.config.ConfigFragmentDirections.Companion.actionSettingsToOrder
+import net.taler.merchantpos.databinding.FragmentMerchantConfigBinding
 import net.taler.merchantpos.topSnackbar
 
 /**
@@ -45,86 +45,89 @@ class ConfigFragment : Fragment() {
     private val model: MainViewModel by activityViewModels()
     private val configManager by lazy { model.configManager }
 
+    private lateinit var ui: FragmentMerchantConfigBinding
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_merchant_config, container, false)
+        ui = FragmentMerchantConfigBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        configUrlView.editText!!.setOnFocusChangeListener { _, hasFocus ->
+        ui.configUrlView.editText!!.setOnFocusChangeListener { _, hasFocus ->
             if (!hasFocus) checkForUrlCredentials()
         }
-        okButton.setOnClickListener {
+        ui.okButton.setOnClickListener {
             checkForUrlCredentials()
-            val inputUrl = configUrlView.editText!!.text
+            val inputUrl = ui.configUrlView.editText!!.text
             val url = if (inputUrl.startsWith("http")) {
                 inputUrl.toString()
             } else {
-                "https://$inputUrl".also { configUrlView.editText!!.setText(it) }
+                "https://$inputUrl".also { ui.configUrlView.editText!!.setText(it) }
             }
-            progressBar.visibility = VISIBLE
-            okButton.visibility = INVISIBLE
+            ui.progressBar.visibility = VISIBLE
+            ui.okButton.visibility = INVISIBLE
             val config = Config(
                 configUrl = url,
-                username = usernameView.editText!!.text.toString(),
-                password = passwordView.editText!!.text.toString()
+                username = ui.usernameView.editText!!.text.toString(),
+                password = ui.passwordView.editText!!.text.toString()
             )
-            configManager.fetchConfig(config, true, savePasswordCheckBox.isChecked)
+            configManager.fetchConfig(config, true, ui.savePasswordCheckBox.isChecked)
             configManager.configUpdateResult.observe(viewLifecycleOwner, Observer { result ->
                 if (onConfigUpdate(result)) {
                     configManager.configUpdateResult.removeObservers(viewLifecycleOwner)
                 }
             })
         }
-        forgetPasswordButton.setOnClickListener {
+        ui.forgetPasswordButton.setOnClickListener {
             configManager.forgetPassword()
-            passwordView.editText!!.text = null
-            forgetPasswordButton.visibility = GONE
+            ui.passwordView.editText!!.text = null
+            ui.forgetPasswordButton.visibility = GONE
         }
-        configDocsView.movementMethod = LinkMovementMethod.getInstance()
+        ui.configDocsView.movementMethod = LinkMovementMethod.getInstance()
         updateView(savedInstanceState == null)
     }
 
     override fun onStart() {
         super.onStart()
         // focus password if this is the only empty field
-        if (passwordView.editText!!.text.isBlank()
-            && !configUrlView.editText!!.text.isBlank()
-            && !usernameView.editText!!.text.isBlank()
+        if (ui.passwordView.editText!!.text.isBlank()
+            && !ui.configUrlView.editText!!.text.isBlank()
+            && !ui.usernameView.editText!!.text.isBlank()
         ) {
-            passwordView.requestFocus()
+            ui.passwordView.requestFocus()
         }
     }
 
     private fun updateView(isInitialization: Boolean = false) {
         val config = configManager.config
-        configUrlView.editText!!.setText(
+        ui.configUrlView.editText!!.setText(
             if (isInitialization && config.configUrl.isBlank()) CONFIG_URL_DEMO
             else config.configUrl
         )
-        usernameView.editText!!.setText(
+        ui.usernameView.editText!!.setText(
             if (isInitialization && config.username.isBlank()) CONFIG_USERNAME_DEMO
             else config.username
         )
-        passwordView.editText!!.setText(
+        ui.passwordView.editText!!.setText(
             if (isInitialization && config.password.isBlank()) CONFIG_PASSWORD_DEMO
             else config.password
         )
-        forgetPasswordButton.visibility = if (config.hasPassword()) VISIBLE else GONE
+        ui.forgetPasswordButton.visibility = if (config.hasPassword()) VISIBLE else GONE
     }
 
     private fun checkForUrlCredentials() {
-        val text = configUrlView.editText!!.text.toString()
+        val text = ui.configUrlView.editText!!.text.toString()
         Uri.parse(text)?.userInfo?.let { userInfo ->
             if (userInfo.contains(':')) {
                 val (user, pass) = userInfo.split(':')
                 val strippedUrl = text.replace("${userInfo}@", "")
-                configUrlView.editText!!.setText(strippedUrl)
-                usernameView.editText!!.setText(user)
-                passwordView.editText!!.setText(pass)
+                ui.configUrlView.editText!!.setText(strippedUrl)
+                ui.usernameView.editText!!.setText(user)
+                ui.passwordView.editText!!.setText(pass)
             }
         }
     }
@@ -157,8 +160,8 @@ class ConfigFragment : Fragment() {
     }
 
     private fun onResultReceived() {
-        progressBar.visibility = INVISIBLE
-        okButton.visibility = VISIBLE
+        ui.progressBar.visibility = INVISIBLE
+        ui.okButton.visibility = VISIBLE
     }
 
 }
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/history/HistoryFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/history/HistoryFragment.kt
index 8cc435a..3ef48e1 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/history/HistoryFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/history/HistoryFragment.kt
@@ -23,18 +23,16 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.DividerItemDecoration
 import androidx.recyclerview.widget.DividerItemDecoration.VERTICAL
 import androidx.recyclerview.widget.LinearLayoutManager
 import com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_LONG
 import com.google.android.material.snackbar.Snackbar
-import kotlinx.android.synthetic.main.fragment_merchant_history.*
 import net.taler.common.exhaustive
 import net.taler.common.navigate
 import net.taler.merchantlib.OrderHistoryEntry
 import net.taler.merchantpos.MainViewModel
-import net.taler.merchantpos.R
+import net.taler.merchantpos.databinding.FragmentMerchantHistoryBinding
 import net.taler.merchantpos.history.HistoryFragmentDirections.Companion.actionGlobalMerchantSettings
 import net.taler.merchantpos.history.HistoryFragmentDirections.Companion.actionNavHistoryToRefundFragment
 
@@ -55,31 +53,33 @@ class HistoryFragment : Fragment(), RefundClickListener {
     private val historyManager by lazy { model.historyManager }
     private val refundManager by lazy { model.refundManager }
 
+    private lateinit var ui: FragmentMerchantHistoryBinding
     private val historyListAdapter = HistoryItemAdapter(this)
 
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_merchant_history, container, false)
+        ui = FragmentMerchantHistoryBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        list_history.apply {
+        ui.listHistory.apply {
             layoutManager = LinearLayoutManager(requireContext())
             addItemDecoration(DividerItemDecoration(context, VERTICAL))
             adapter = historyListAdapter
         }
 
-        swipeRefresh.setOnRefreshListener {
+        ui.swipeRefresh.setOnRefreshListener {
             Log.v(TAG, "refreshing!")
             historyManager.fetchHistory()
         }
-        historyManager.isLoading.observe(viewLifecycleOwner, Observer { loading ->
+        historyManager.isLoading.observe(viewLifecycleOwner, { loading ->
             Log.v(TAG, "setting refreshing to $loading")
-            swipeRefresh.isRefreshing = loading
+            ui.swipeRefresh.isRefreshing = loading
         })
-        historyManager.items.observe(viewLifecycleOwner, Observer { result ->
+        historyManager.items.observe(viewLifecycleOwner, { result ->
             when (result) {
                 is HistoryResult.Error -> onError(result.msg)
                 is HistoryResult.Success -> historyListAdapter.setData(result.items)
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/CategoriesFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/CategoriesFragment.kt
index 4f8e5af..69e74ce 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/order/CategoriesFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/CategoriesFragment.kt
@@ -23,12 +23,10 @@ import android.view.View.INVISIBLE
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.LinearLayoutManager
-import kotlinx.android.synthetic.main.fragment_categories.*
 import net.taler.merchantpos.MainViewModel
-import net.taler.merchantpos.R
 import net.taler.merchantpos.config.Category
+import net.taler.merchantpos.databinding.FragmentCategoriesBinding
 
 interface CategorySelectionListener {
     fun onCategorySelected(category: Category)
@@ -38,6 +36,8 @@ class CategoriesFragment : Fragment(), CategorySelectionListener {
 
     private val viewModel: MainViewModel by activityViewModels()
     private val orderManager by lazy { viewModel.orderManager }
+
+    private lateinit var ui: FragmentCategoriesBinding
     private val adapter = CategoryAdapter(this)
 
     override fun onCreateView(
@@ -45,18 +45,19 @@ class CategoriesFragment : Fragment(), CategorySelectionListener {
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_categories, container, false)
+        ui = FragmentCategoriesBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        categoriesList.apply {
+        ui.categoriesList.apply {
             adapter = this@CategoriesFragment.adapter
             layoutManager = LinearLayoutManager(requireContext())
         }
 
-        orderManager.categories.observe(viewLifecycleOwner, Observer { categories ->
+        orderManager.categories.observe(viewLifecycleOwner, { categories ->
             adapter.setItems(categories)
-            progressBar.visibility = INVISIBLE
+            ui.progressBar.visibility = INVISIBLE
         })
     }
 
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderFragment.kt
index 7291a23..1335b65 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderFragment.kt
@@ -22,12 +22,11 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
-import androidx.lifecycle.Observer
 import androidx.transition.TransitionManager.beginDelayedTransition
-import kotlinx.android.synthetic.main.fragment_order.*
 import net.taler.common.navigate
 import net.taler.merchantpos.MainViewModel
 import net.taler.merchantpos.R
+import net.taler.merchantpos.databinding.FragmentOrderBinding
 import net.taler.merchantpos.order.OrderFragmentDirections.Companion.actionGlobalConfigFetcher
 import net.taler.merchantpos.order.OrderFragmentDirections.Companion.actionOrderToMerchantSettings
 import net.taler.merchantpos.order.OrderFragmentDirections.Companion.actionOrderToProcessPayment
@@ -40,17 +39,20 @@ class OrderFragment : Fragment() {
     private val orderManager by lazy { viewModel.orderManager }
     private val paymentManager by lazy { viewModel.paymentManager }
 
+    private lateinit var ui: FragmentOrderBinding
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_order, container, false)
+        ui = FragmentOrderBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         super.onActivityCreated(savedInstanceState)
-        orderManager.currentOrderId.observe(viewLifecycleOwner, Observer { orderId ->
+        orderManager.currentOrderId.observe(viewLifecycleOwner, { orderId ->
             val liveOrder = orderManager.getOrder(orderId)
             onOrderSwitched(orderId, liveOrder)
             // add a new OrderStateFragment for each order
@@ -72,39 +74,39 @@ class OrderFragment : Fragment() {
 
     private fun onOrderSwitched(orderId: Int, liveOrder: LiveOrder) {
         // order title
-        liveOrder.order.observe(viewLifecycleOwner, Observer { order ->
+        liveOrder.order.observe(viewLifecycleOwner, { order ->
             activity?.title = getString(R.string.order_label_title, order.title)
         })
         // restart button
-        restartButton.setOnClickListener { liveOrder.restartOrUndo() }
-        liveOrder.restartState.observe(viewLifecycleOwner, Observer { state ->
+        ui.restartButton.setOnClickListener { liveOrder.restartOrUndo() }
+        liveOrder.restartState.observe(viewLifecycleOwner, { state ->
             beginDelayedTransition(view as ViewGroup)
             if (state == UNDO) {
-                restartButton.setText(R.string.order_undo)
-                restartButton.isEnabled = true
-                completeButton.isEnabled = false
+                ui.restartButton.setText(R.string.order_undo)
+                ui.restartButton.isEnabled = true
+                ui.completeButton.isEnabled = false
             } else {
-                restartButton.setText(R.string.order_restart)
-                restartButton.isEnabled = state == ENABLED
-                completeButton.isEnabled = state == ENABLED
+                ui.restartButton.setText(R.string.order_restart)
+                ui.restartButton.isEnabled = state == ENABLED
+                ui.completeButton.isEnabled = state == ENABLED
             }
         })
         // -1 and +1 buttons
-        liveOrder.modifyOrderAllowed.observe(viewLifecycleOwner, Observer { allowed ->
-            minusButton.isEnabled = allowed
-            plusButton.isEnabled = allowed
+        liveOrder.modifyOrderAllowed.observe(viewLifecycleOwner, { allowed ->
+            ui.minusButton.isEnabled = allowed
+            ui.plusButton.isEnabled = allowed
         })
-        minusButton.setOnClickListener { liveOrder.decreaseSelectedOrderLine() }
-        plusButton.setOnClickListener { liveOrder.increaseSelectedOrderLine() }
+        ui.minusButton.setOnClickListener { liveOrder.decreaseSelectedOrderLine() }
+        ui.plusButton.setOnClickListener { liveOrder.increaseSelectedOrderLine() }
         // previous and next button
-        prevButton.isEnabled = orderManager.hasPreviousOrder(orderId)
-        orderManager.hasNextOrder(orderId).observe(viewLifecycleOwner, Observer { hasNextOrder ->
-            nextButton.isEnabled = hasNextOrder
+        ui.prevButton.isEnabled = orderManager.hasPreviousOrder(orderId)
+        orderManager.hasNextOrder(orderId).observe(viewLifecycleOwner, { hasNextOrder ->
+            ui.nextButton.isEnabled = hasNextOrder
         })
-        prevButton.setOnClickListener { orderManager.previousOrder() }
-        nextButton.setOnClickListener { orderManager.nextOrder() }
+        ui.prevButton.setOnClickListener { orderManager.previousOrder() }
+        ui.nextButton.setOnClickListener { orderManager.nextOrder() }
         // complete button
-        completeButton.setOnClickListener {
+        ui.completeButton.setOnClickListener {
             val order = liveOrder.order.value ?: return@setOnClickListener
             paymentManager.createPayment(order)
             navigate(actionOrderToProcessPayment())
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt
index b60f3a5..93c4f97 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/OrderStateFragment.kt
@@ -22,16 +22,15 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
-import androidx.lifecycle.Observer
 import androidx.recyclerview.selection.SelectionPredicates
 import androidx.recyclerview.selection.SelectionTracker
 import androidx.recyclerview.selection.StorageStrategy
 import androidx.recyclerview.widget.LinearLayoutManager
-import kotlinx.android.synthetic.main.fragment_order_state.*
 import net.taler.common.fadeIn
 import net.taler.common.fadeOut
 import net.taler.merchantpos.MainViewModel
 import net.taler.merchantpos.R
+import net.taler.merchantpos.databinding.FragmentOrderStateBinding
 import net.taler.merchantpos.order.OrderAdapter.OrderLineLookup
 
 class OrderStateFragment : Fragment() {
@@ -39,6 +38,8 @@ class OrderStateFragment : Fragment() {
     private val viewModel: MainViewModel by activityViewModels()
     private val orderManager by lazy { viewModel.orderManager }
     private val liveOrder by lazy { orderManager.getOrder(orderManager.currentOrderId.value!!) }
+
+    private lateinit var ui: FragmentOrderStateBinding
     private val adapter = OrderAdapter()
     private var tracker: SelectionTracker<String>? = null
 
@@ -47,18 +48,19 @@ class OrderStateFragment : Fragment() {
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_order_state, container, false)
+        ui = FragmentOrderStateBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        orderList.apply {
+        ui.orderList.apply {
             adapter = this@OrderStateFragment.adapter
             layoutManager = LinearLayoutManager(requireContext())
         }
-        val detailsLookup = OrderLineLookup(orderList)
+        val detailsLookup = OrderLineLookup(ui.orderList)
         val tracker = SelectionTracker.Builder(
             "order-selection-id",
-            orderList,
+            ui.orderList,
             adapter.keyProvider,
             detailsLookup,
             StorageStrategy.createStringStorage()
@@ -80,16 +82,16 @@ class OrderStateFragment : Fragment() {
                 liveOrder.selectOrderLine(item)
             }
         })
-        liveOrder.order.observe(viewLifecycleOwner, Observer { order ->
+        liveOrder.order.observe(viewLifecycleOwner, { order ->
             onOrderChanged(order, tracker)
         })
-        liveOrder.orderTotal.observe(viewLifecycleOwner, Observer { orderTotal ->
+        liveOrder.orderTotal.observe(viewLifecycleOwner, { orderTotal ->
             if (orderTotal.isZero()) {
-                totalView.fadeOut()
-                totalView.text = null
+                ui.totalView.fadeOut()
+                ui.totalView.text = null
             } else {
-                totalView.text = getString(R.string.order_total, orderTotal)
-                totalView.fadeIn()
+                ui.totalView.text = getString(R.string.order_total, orderTotal)
+                ui.totalView.fadeIn()
             }
         })
     }
@@ -104,9 +106,8 @@ class OrderStateFragment : Fragment() {
             liveOrder.lastAddedProduct?.let {
                 val position = adapter.findPosition(it)
                 if (position >= 0) {
-                    // orderList can be null m(
-                    orderList?.scrollToPosition(position)
-                    orderList?.post { this.tracker?.select(it.id) }
+                    ui.orderList.scrollToPosition(position)
+                    ui.orderList.post { this.tracker?.select(it.id) }
                 }
             }
             // workaround for bug: SelectionObserver doesn't update when removing selected item
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/order/ProductsFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/order/ProductsFragment.kt
index 00eb509..a3898fd 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/order/ProductsFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/order/ProductsFragment.kt
@@ -24,14 +24,13 @@ import android.view.ViewGroup
 import android.widget.TextView
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
-import androidx.lifecycle.Observer
 import androidx.recyclerview.widget.GridLayoutManager
 import androidx.recyclerview.widget.RecyclerView.Adapter
 import androidx.recyclerview.widget.RecyclerView.ViewHolder
-import kotlinx.android.synthetic.main.fragment_products.*
 import net.taler.merchantpos.MainViewModel
 import net.taler.merchantpos.R
 import net.taler.merchantpos.config.ConfigProduct
+import net.taler.merchantpos.databinding.FragmentProductsBinding
 import net.taler.merchantpos.order.ProductAdapter.ProductViewHolder
 
 interface ProductSelectionListener {
@@ -44,27 +43,30 @@ class ProductsFragment : Fragment(), ProductSelectionListener {
     private val orderManager by lazy { viewModel.orderManager }
     private val adapter = ProductAdapter(this)
 
+    private lateinit var ui: FragmentProductsBinding
+
     override fun onCreateView(
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_products, container, false)
+        ui = FragmentProductsBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        productsList.apply {
+        ui.productsList.apply {
             adapter = this@ProductsFragment.adapter
             layoutManager = GridLayoutManager(requireContext(), 3)
         }
 
-        orderManager.products.observe(viewLifecycleOwner, Observer { products ->
+        orderManager.products.observe(viewLifecycleOwner, { products ->
             if (products == null) {
                 adapter.setItems(emptyList())
             } else {
                 adapter.setItems(products)
             }
-            progressBar.visibility = INVISIBLE
+            ui.progressBar.visibility = INVISIBLE
         })
     }
 
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentSuccessFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentSuccessFragment.kt
index 10d538d..5b95dea 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentSuccessFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/PaymentSuccessFragment.kt
@@ -22,21 +22,23 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.navigation.fragment.findNavController
-import kotlinx.android.synthetic.main.fragment_payment_success.*
-import net.taler.merchantpos.R
+import net.taler.merchantpos.databinding.FragmentPaymentSuccessBinding
 
 class PaymentSuccessFragment : Fragment() {
 
+    private lateinit var ui: FragmentPaymentSuccessBinding
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_payment_success, container, false)
+        ui = FragmentPaymentSuccessBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
         super.onActivityCreated(savedInstanceState)
-        paymentButton.setOnClickListener {
+        ui.paymentButton.setOnClickListener {
             findNavController().navigateUp()
         }
     }
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/ProcessPaymentFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/ProcessPaymentFragment.kt
index 27ef366..5c0a894 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/payment/ProcessPaymentFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/payment/ProcessPaymentFragment.kt
@@ -22,10 +22,8 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
-import androidx.lifecycle.Observer
 import androidx.navigation.fragment.findNavController
 import com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_LONG
-import kotlinx.android.synthetic.main.fragment_process_payment.*
 import net.taler.common.NfcManager.Companion.hasNfc
 import net.taler.common.QrCodeManager.makeQrCode
 import net.taler.common.fadeIn
@@ -33,6 +31,7 @@ import net.taler.common.fadeOut
 import net.taler.common.navigate
 import net.taler.merchantpos.MainViewModel
 import net.taler.merchantpos.R
+import net.taler.merchantpos.databinding.FragmentProcessPaymentBinding
 import net.taler.merchantpos.payment.ProcessPaymentFragmentDirections.Companion.actionProcessPaymentToPaymentSuccess
 import net.taler.merchantpos.topSnackbar
 
@@ -41,21 +40,24 @@ class ProcessPaymentFragment : Fragment() {
     private val model: MainViewModel by activityViewModels()
     private val paymentManager by lazy { model.paymentManager }
 
+    private lateinit var ui: FragmentProcessPaymentBinding
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_process_payment, container, false)
+        ui = FragmentProcessPaymentBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         val introRes =
             if (hasNfc(requireContext())) R.string.payment_intro_nfc else R.string.payment_intro
-        payIntroView.setText(introRes)
-        paymentManager.payment.observe(viewLifecycleOwner, Observer { payment ->
+        ui.payIntroView.setText(introRes)
+        paymentManager.payment.observe(viewLifecycleOwner, { payment ->
             onPaymentStateChanged(payment)
         })
-        cancelPaymentButton.setOnClickListener {
+        ui.cancelPaymentButton.setOnClickListener {
             onPaymentCancel()
         }
     }
@@ -76,17 +78,17 @@ class ProcessPaymentFragment : Fragment() {
             navigate(actionProcessPaymentToPaymentSuccess())
             return
         }
-        payIntroView.fadeIn()
-        amountView.text = payment.order.total.toString()
+        ui.payIntroView.fadeIn()
+        ui.amountView.text = payment.order.total.toString()
         payment.orderId?.let {
-            orderRefView.text = getString(R.string.payment_order_id, it)
-            orderRefView.fadeIn()
+            ui.orderRefView.text = getString(R.string.payment_order_id, it)
+            ui.orderRefView.fadeIn()
         }
         payment.talerPayUri?.let {
             val qrcodeBitmap = makeQrCode(it)
-            qrcodeView.setImageBitmap(qrcodeBitmap)
-            qrcodeView.fadeIn()
-            progressBar.fadeOut()
+            ui.qrcodeView.setImageBitmap(qrcodeBitmap)
+            ui.qrcodeView.fadeIn()
+            ui.progressBar.fadeOut()
         }
     }
 
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/refund/RefundFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/refund/RefundFragment.kt
index 752b7aa..91e68e6 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/refund/RefundFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/refund/RefundFragment.kt
@@ -22,11 +22,9 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
-import androidx.lifecycle.Observer
 import androidx.navigation.fragment.findNavController
 import com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_LONG
 import com.google.android.material.snackbar.Snackbar
-import kotlinx.android.synthetic.main.fragment_refund.*
 import net.taler.common.fadeIn
 import net.taler.common.fadeOut
 import net.taler.common.navigate
@@ -35,6 +33,7 @@ import net.taler.lib.common.AmountParserException
 import net.taler.merchantlib.OrderHistoryEntry
 import net.taler.merchantpos.MainViewModel
 import net.taler.merchantpos.R
+import net.taler.merchantpos.databinding.FragmentRefundBinding
 import net.taler.merchantpos.refund.RefundFragmentDirections.Companion.actionRefundFragmentToRefundUriFragment
 import net.taler.merchantpos.refund.RefundResult.AlreadyRefunded
 import net.taler.merchantpos.refund.RefundResult.Error
@@ -46,44 +45,47 @@ class RefundFragment : Fragment() {
     private val model: MainViewModel by activityViewModels()
     private val refundManager by lazy { model.refundManager }
 
+    private lateinit var ui: FragmentRefundBinding
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_refund, container, false)
+        ui = FragmentRefundBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         val item = refundManager.toBeRefunded ?: throw IllegalStateException()
-        amountInputView.setText(item.amount.amountStr)
-        currencyView.text = item.amount.currency
-        abortButton.setOnClickListener { findNavController().navigateUp() }
-        refundButton.setOnClickListener { onRefundButtonClicked(item) }
+        ui.amountInputView.setText(item.amount.amountStr)
+        ui.currencyView.text = item.amount.currency
+        ui.abortButton.setOnClickListener { findNavController().navigateUp() }
+        ui.refundButton.setOnClickListener { onRefundButtonClicked(item) }
 
-        refundManager.refundResult.observe(viewLifecycleOwner, Observer { result ->
+        refundManager.refundResult.observe(viewLifecycleOwner, { result ->
             onRefundResultChanged(result)
         })
     }
 
     private fun onRefundButtonClicked(item: OrderHistoryEntry) {
         val inputAmount = try {
-            Amount.fromString(item.amount.currency, amountInputView.text.toString())
+            Amount.fromString(item.amount.currency, ui.amountInputView.text.toString())
         } catch (e: AmountParserException) {
-            amountView.error = getString(R.string.refund_error_invalid_amount)
+            ui.amountView.error = getString(R.string.refund_error_invalid_amount)
             return
         }
         if (inputAmount > item.amount) {
-            amountView.error = getString(R.string.refund_error_max_amount, item.amount.amountStr)
+            ui.amountView.error = getString(R.string.refund_error_max_amount, item.amount.amountStr)
             return
         }
         if (inputAmount.isZero()) {
-            amountView.error = getString(R.string.refund_error_zero)
+            ui.amountView.error = getString(R.string.refund_error_zero)
             return
         }
-        amountView.error = null
-        refundButton.fadeOut()
-        progressBar.fadeIn()
-        refundManager.refund(item, inputAmount, reasonInputView.text.toString())
+        ui.amountView.error = null
+        ui.refundButton.fadeOut()
+        ui.progressBar.fadeIn()
+        refundManager.refund(item, inputAmount, ui.reasonInputView.text.toString())
     }
 
     private fun onRefundResultChanged(result: RefundResult?): Any = when (result) {
@@ -91,8 +93,8 @@ class RefundFragment : Fragment() {
         PastDeadline -> onError(getString(R.string.refund_error_deadline))
         AlreadyRefunded -> onError(getString(R.string.refund_error_already_refunded))
         is Success -> {
-            progressBar.fadeOut()
-            refundButton.fadeIn()
+            ui.progressBar.fadeOut()
+            ui.refundButton.fadeIn()
             navigate(actionRefundFragmentToRefundUriFragment())
         }
         null -> { // no-op
@@ -101,8 +103,8 @@ class RefundFragment : Fragment() {
 
     private fun onError(msg: String) {
         Snackbar.make(requireView(), msg, LENGTH_LONG).show()
-        progressBar.fadeOut()
-        refundButton.fadeIn()
+        ui.progressBar.fadeOut()
+        ui.refundButton.fadeIn()
     }
 
 }
diff --git a/merchant-terminal/src/main/java/net/taler/merchantpos/refund/RefundUriFragment.kt b/merchant-terminal/src/main/java/net/taler/merchantpos/refund/RefundUriFragment.kt
index b8e8997..5e52404 100644
--- a/merchant-terminal/src/main/java/net/taler/merchantpos/refund/RefundUriFragment.kt
+++ b/merchant-terminal/src/main/java/net/taler/merchantpos/refund/RefundUriFragment.kt
@@ -23,22 +23,25 @@ import android.view.ViewGroup
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
 import androidx.navigation.fragment.findNavController
-import kotlinx.android.synthetic.main.fragment_refund_uri.*
 import net.taler.common.NfcManager.Companion.hasNfc
 import net.taler.common.QrCodeManager.makeQrCode
 import net.taler.merchantpos.MainViewModel
 import net.taler.merchantpos.R
+import net.taler.merchantpos.databinding.FragmentRefundUriBinding
 
 class RefundUriFragment : Fragment() {
 
     private val model: MainViewModel by activityViewModels()
     private val refundManager by lazy { model.refundManager }
 
+    private lateinit var ui: FragmentRefundUriBinding
+
     override fun onCreateView(
         inflater: LayoutInflater, container: ViewGroup?,
         savedInstanceState: Bundle?
     ): View? {
-        return inflater.inflate(R.layout.fragment_refund_uri, container, false)
+        ui = FragmentRefundUriBinding.inflate(inflater, container, false)
+        return ui.root
     }
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
@@ -46,19 +49,19 @@ class RefundUriFragment : Fragment() {
         val result = refundManager.refundResult.value
         if (result !is RefundResult.Success) throw IllegalStateException()
 
-        refundQrcodeView.setImageBitmap(makeQrCode(result.refundUri))
+        ui.refundQrcodeView.setImageBitmap(makeQrCode(result.refundUri))
 
         val introRes =
             if (hasNfc(requireContext())) R.string.refund_intro_nfc else R.string.refund_intro
-        refundIntroView.setText(introRes)
+        ui.refundIntroView.setText(introRes)
 
-        refundAmountView.text = result.amount.toString()
+        ui.refundAmountView.text = result.amount.toString()
 
-        refundRefView.text =
+        ui.refundRefView.text =
             getString(R.string.refund_order_ref, result.item.orderId, result.reason)
 
-        cancelRefundButton.setOnClickListener { findNavController().navigateUp() }
-        completeButton.setOnClickListener { findNavController().navigateUp() }
+        ui.cancelRefundButton.setOnClickListener { findNavController().navigateUp() }
+        ui.completeButton.setOnClickListener { findNavController().navigateUp() }
     }
 
     override fun onDestroy() {
diff --git a/merchant-terminal/src/main/res/layout/activity_main.xml b/merchant-terminal/src/main/res/layout/activity_main.xml
index 1285b19..c801563 100644
--- a/merchant-terminal/src/main/res/layout/activity_main.xml
+++ b/merchant-terminal/src/main/res/layout/activity_main.xml
@@ -24,6 +24,7 @@
     tools:openDrawer="start">
 
     <include
+        android:id="@+id/main"
         layout="@layout/app_bar_main"
         android:layout_width="match_parent"
         android:layout_height="match_parent" />