Fix part of #138: Topic train fragment Low-fi UI (Part 3)

app/build.gradle

@@ -61,6 +61,7 @@ dependencies {
       'androidx.constraintlayout:constraintlayout:1.1.3',
       'androidx.core:core-ktx:1.0.2',
       'androidx.lifecycle:lifecycle-runtime-ktx:2.2.0-alpha03',
+      'androidx.recyclerview:recyclerview:1.0.0',
       'com.google.dagger:dagger:2.24',
       "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version",
       "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.2.1",

app/src/main/java/org/oppia/app/topic/train/SkillInterface.kt

@@ -0,0 +1,9 @@
+package org.oppia.app.topic.train
+
+/** Interface to update the selectedSkillList in [TopicTrainFragmentPresenter]. */
+interface SkillInterface {
+  /** This skill will get added to selectedSkillList in [TopicTrainFragmentPresenter] */
+  fun skillSelected(skill: String)
+  /** This skill will get removed from selectedSkillList in [TopicTrainFragmentPresenter] */
+  fun skillUnselected(skill: String)
+}

app/src/main/java/org/oppia/app/topic/train/SkillSelectionAdapter.kt

@@ -0,0 +1,52 @@
+package org.oppia.app.topic.train;
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.databinding.DataBindingUtil
+import androidx.databinding.ViewDataBinding
+import androidx.databinding.library.baseAdapters.BR
+import androidx.recyclerview.widget.RecyclerView
+import kotlinx.android.synthetic.main.topic_train_skill_view.view.*
+import org.oppia.app.R
+import org.oppia.app.databinding.TopicTrainSkillViewBinding
+
+/** Adapter to bind skills to [RecyclerView] inside [TopicTrainFragment]. **/
+class SkillSelectionAdapter(
+  private val skillList: List<String>,
+  private val skillInterface: SkillInterface
+) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
+
+  override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
+    val inflater = LayoutInflater.from(parent.context)
+    val binding =
+      DataBindingUtil.inflate<TopicTrainSkillViewBinding>(
+        inflater,
+        R.layout.topic_train_skill_view,
+        parent,
+        false
+      )
+    return SkillViewHolder(binding)
+  }
+
+  override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
+    (holder as SkillViewHolder).bind(skillList[position], position)
+  }
+
+  override fun getItemCount(): Int {
+    return skillList.size
+  }
+
+  private inner class SkillViewHolder(val binding: ViewDataBinding) : RecyclerView.ViewHolder(binding.root) {
+    internal fun bind(rawString: String?, position: Int) {
+      binding.setVariable(BR.skill, rawString)
+      binding.root.skill_check_box.setOnCheckedChangeListener { buttonView, isChecked ->
+        val skill = skillList[position]
+        if (isChecked) {
+          skillInterface.skillSelected(skill)
+        } else {
+          skillInterface.skillUnselected(skill)
+        }
+      }
+    }
+  }
+}

app/src/main/java/org/oppia/app/topic/train/TopicTrainFragment.kt

@@ -21,4 +21,9 @@ class TopicTrainFragment : InjectableFragment() {
   override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
     return topicTrainFragmentPresenter.handleCreateView(inflater, container)
   }
+
+  fun submitButtonClicked(){
+    // List of selected skills when submit button is clicked.
+    val skillList = topicTrainFragmentPresenter.getSelectedSkillList()
+  }
 }

app/src/main/java/org/oppia/app/topic/train/TopicTrainFragmentPresenter.kt

@@ -4,20 +4,61 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
+import androidx.recyclerview.widget.LinearLayoutManager
 import org.oppia.app.databinding.TopicTrainFragmentBinding
 import org.oppia.app.fragment.FragmentScope
+import org.oppia.app.viewmodel.ViewModelProvider
 import javax.inject.Inject
 
 /** The presenter for [TopicTrainFragment]. */
 @FragmentScope
 class TopicTrainFragmentPresenter @Inject constructor(
-  private val fragment: Fragment
-) {
+  private val fragment: Fragment,
+  private val viewModelProvider: ViewModelProvider<TopicTrainViewModel>
+) : SkillInterface {
+  private val selectedSkillList = ArrayList<String>()
+
   fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
+    val skillAdapter = SkillSelectionAdapter(dummySkillList(), this)
+
     val binding = TopicTrainFragmentBinding.inflate(inflater, container, /* attachToRoot= */ false)
+    binding.skillRecyclerView.apply {
+      adapter = skillAdapter
+      layoutManager = LinearLayoutManager(context)
+    }
     binding.let {
+      it.viewModel = getTopicTrainViewModel()
       it.lifecycleOwner = fragment
     }
     return binding.root
   }
+
+  private fun getTopicTrainViewModel(): TopicTrainViewModel {
+    return viewModelProvider.getForFragment(fragment, TopicTrainViewModel::class.java)
+  }
+
+  override fun skillSelected(skill: String) {
+    selectedSkillList.add(skill)
+    getTopicTrainViewModel().selectedSkillList(selectedSkillList)
+  }
+
+  override fun skillUnselected(skill: String) {
+    selectedSkillList.remove(skill)
+    getTopicTrainViewModel().selectedSkillList(selectedSkillList)
+  }
+
+  private fun dummySkillList(): List<String> {
+    val skillList = ArrayList<String>()
+    skillList.add("Identify the Parts of a Fraction")
+    skillList.add("Writing Fractions")
+    skillList.add("Equivalent Fractions")
+    skillList.add("Mixed Numbers and Improper Fractions")
+    skillList.add("Comparing Fractions")
+    skillList.add("Adding and Subtracting Fractions")
+    skillList.add("Multiplying Fractions")
+    skillList.add("Dividing Fractions")
+    return skillList
+  }
+
+  fun getSelectedSkillList() = selectedSkillList
 }

app/src/main/java/org/oppia/app/topic/train/TopicTrainViewModel.kt

@@ -0,0 +1,16 @@
+package org.oppia.app.topic.train
+
+import androidx.databinding.ObservableField
+import androidx.lifecycle.ViewModel
+import org.oppia.app.fragment.FragmentScope
+import javax.inject.Inject
+
+/** [ViewModel] for showing skills in train fragment. */
+@FragmentScope
+class TopicTrainViewModel @Inject constructor() : ViewModel() {
+  var isSubmitButtonActive = ObservableField<Boolean>(false)
+
+  fun selectedSkillList(selectedSkillList: ArrayList<String>) {
+    isSubmitButtonActive.set(selectedSkillList.isNotEmpty())
+  }
+}

app/src/main/res/drawable/state_button_primary_background.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  android:shape="rectangle">
+  <corners
+    android:radius="@dimen/state_previous_next_button_radius"/>
+  <solid
+    android:color="@color/colorPrimary"/>
+</shape>

app/src/main/res/drawable/state_button_transparent_background.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  android:shape="rectangle">
+  <solid
+    android:color="@android:color/transparent"/>
+</shape>

app/src/main/res/layout/topic_train_fragment.xml

@@ -2,17 +2,64 @@
 <layout
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto">
+  <data>
+    <import type="android.view.View"/>
+    <variable
+      name="topicTrainFragment"
+      type="org.oppia.app.topic.train.TopicTrainFragment"/>
+    <variable
+      name="viewModel"
+      type="org.oppia.app.topic.train.TopicTrainViewModel"/>
+  </data>
   <androidx.constraintlayout.widget.ConstraintLayout
     android:layout_width="match_parent"
     android:layout_height="match_parent">
-    <TextView
-      android:id="@+id/dummy_text_view"
-      android:layout_width="wrap_content"
-      android:layout_height="wrap_content"
-      android:text="This is dummy TextView for testing"
+    <ScrollView
+      android:layout_width="match_parent"
+      android:layout_height="match_parent"
+      android:overScrollMode="never"
+      android:scrollbars="none"
       app:layout_constraintBottom_toBottomOf="parent"
       app:layout_constraintEnd_toEndOf="parent"
       app:layout_constraintStart_toStartOf="parent"
-      app:layout_constraintTop_toTopOf="parent"/>
+      app:layout_constraintTop_toTopOf="parent">
+      <LinearLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:padding="32dp">
+        <TextView
+          android:id="@+id/master_skills_text_view"
+          android:layout_width="wrap_content"
+          android:layout_height="wrap_content"
+          android:text="@string/topic_train_master_these_skills"
+          android:textColor="@color/oppiaPrimaryText"
+          android:textSize="20sp"/>
+        <TextView
+          android:id="@+id/skills_description_text_view"
+          android:layout_width="wrap_content"
+          android:layout_height="wrap_content"
+          android:layout_marginTop="16dp"
+          android:text="@string/topic_train_skills_description"
+          android:textColor="@color/oppiaSecondaryText"
+          android:textSize="16sp"/>
+        <androidx.recyclerview.widget.RecyclerView
+          android:id="@+id/skill_recycler_view"
+          android:layout_width="match_parent"
+          android:layout_height="wrap_content"
+          android:layout_marginTop="16dp"
+          app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"/>
+        <Button
+          android:id="@+id/topic_train_start_button"
+          style="@style/StateButtonInactive"
+          android:layout_gravity="center_horizontal"
+          android:layout_marginTop="24dp"
+          android:background="@{viewModel.isSubmitButtonActive() ? @drawable/state_button_primary_background :@drawable/state_button_transparent_background}"
+          android:clickable="@{viewModel.isSubmitButtonActive()}"
+          android:onClick="@{(v) -> topicTrainFragment.submitButtonClicked()}"
+          android:text="@string/topic_train_start"
+          android:textColor="@{viewModel.isSubmitButtonActive()? @color/white : @color/submitButtonInactive}"/>
+      </LinearLayout>
+    </ScrollView>
   </androidx.constraintlayout.widget.ConstraintLayout>
 </layout>

app/src/main/res/layout/topic_train_skill_view.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<layout
+  xmlns:android="http://schemas.android.com/apk/res/android"
+  xmlns:app="http://schemas.android.com/apk/res-auto">
+  <data>
+    <variable
+      name="skill"
+      type="java.lang.String"/>
+  </data>
+  <androidx.constraintlayout.widget.ConstraintLayout
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content">
+    <CheckBox
+      android:id="@+id/skill_check_box"
+      android:layout_width="match_parent"
+      android:layout_height="wrap_content"
+      android:layout_margin="4dp"
+      android:drawablePadding="4dp"
+      android:gravity="center_vertical"
+      android:text="@{skill}"
+      android:textColor="@color/oppiaPrimaryText"
+      android:textSize="16sp"
+      app:layout_constraintBottom_toBottomOf="parent"
+      app:layout_constraintEnd_toEndOf="parent"
+      app:layout_constraintStart_toStartOf="parent"
+      app:layout_constraintTop_toTopOf="parent"/>
+  </androidx.constraintlayout.widget.ConstraintLayout>
+</layout>

app/src/main/res/values/colors.xml

@@ -9,8 +9,12 @@
   <color name="ic_launcher_background">#26A69A</color>
   <!-- OPPIA COLORS -->
   <color name="oppiaDarkBlue">#2D4A9D</color>
+  <color name="oppiaPrimaryText">#333333</color>
+  <color name="oppiaSecondaryText">#666666</color>
   <!-- BASIC COLORS -->
   <color name="white">#FFFFFF</color>
   <!-- AUDIO COMPONENT -->
   <color name="audioComponentBackground">@color/oppiaDarkBlue</color>
+  <!-- SUBMIT BUTTON INACTIVE -->
+  <color name="submitButtonInactive">#56000000</color>
 </resources>

app/src/main/res/values/dimens.xml

@@ -6,4 +6,5 @@
   <dimen name="audio_fragment_corner_radius">8dp</dimen>
   <dimen name="audio_fragment_margin">32dp</dimen>
   <dimen name="cellular_data_dialog_padding">24dp</dimen>
+  <dimen name="state_previous_next_button_radius">4dp</dimen>
 </resources>

app/src/main/res/values/strings.xml

@@ -12,4 +12,7 @@
   <string name="cellular_data_alert_dialog_title">Currently on Cellular Data</string>
   <string name="cellular_data_alert_dialog_description">Streaming audio may use a lot of cellular data.</string>
   <string name="cellular_data_alert_dialog_checkbox">Don\'t show this message again</string>
+  <string name="topic_train_master_these_skills">Master These Skills</string>
+  <string name="topic_train_skills_description">Select or unselect skills that you want to practice</string>
+  <string name="topic_train_start">Start</string>
 </resources>

app/src/main/res/values/styles.xml

@@ -43,4 +43,31 @@
     <item name="android:windowEnterAnimation">@anim/slide_up</item>
     <item name="android:windowExitAnimation">@anim/slide_down</item>
   </style>
+
+  <!-- STATE BUTTON ACTIVE STYLE -->
+  <style name="StateButtonActive" parent="TextAppearance.AppCompat.Widget.Button">
+    <item name="android:layout_width">wrap_content</item>
+    <item name="android:layout_height">wrap_content</item>
+    <item name="android:background">@drawable/state_button_primary_background</item>
+    <item name="android:paddingTop">8dp</item>
+    <item name="android:paddingBottom">8dp</item>
+    <item name="android:paddingStart">16dp</item>
+    <item name="android:paddingEnd">16dp</item>
+    <item name="android:textAllCaps">true</item>
+    <item name="android:textColor">@color/white</item>
+    <item name="android:textSize">14sp</item>
+    <item name="android:clickable">true</item>
+  </style>
+
+  <!-- STATE BUTTON INACTIVE STYLE -->
+  <style name="StateButtonInactive" parent="TextAppearance.AppCompat.Widget.Button">
+    <item name="android:layout_width">wrap_content</item>
+    <item name="android:layout_height">wrap_content</item>
+    <item name="android:padding">8dp</item>
+    <item name="android:textAllCaps">true</item>
+    <item name="android:background">@android:color/transparent</item>
+    <item name="android:textColor">#56000000</item>
+    <item name="android:textSize">14sp</item>
+    <item name="android:clickable">false</item>
+  </style>
 </resources>