+

contacts/src/main/res/layout/fragment_main.xml

@@ -10,6 +10,7 @@
 
     <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/rv"
+        tools:listitem="@layout/item_contact"
         android:layout_width="match_parent"
         android:layout_height="match_parent"/>
 

contacts/src/main/res/layout/item_contact.xml

@@ -12,20 +12,23 @@
             android:paddingVertical="8dp"
             android:paddingStart="12dp"
             android:orientation="horizontal"
-            android:gravity="center_vertical">
+            android:gravity="center_vertical"
+            tools:ignore="RtlSymmetry">
 
         <ImageView
             android:id="@+id/img_avatar"
+            tools:src="@drawable/aki"
             android:layout_marginStart="10dp"
             android:layout_width="32dp"
             android:layout_height="match_parent"/>
 
         <TextView
             android:id="@+id/tv"
+            tools:text="Aki"
             android:layout_width="wrap_content"
             android:layout_height="match_parent"
             android:gravity="center_vertical"
-            android:layout_marginLeft="12dp"
+            android:layout_marginStart="12dp"
             />
     </LinearLayout>
 

stopwatch/.gitignore

@@ -0,0 +1 @@
+/build

stopwatch/build.gradle

@@ -0,0 +1,63 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+    id 'com.android.application'
+    id 'org.jetbrains.kotlin.android'
+}
+
+android {
+    namespace 'pers.shawxingkwok.stopwatch'
+    compileSdk 33
+
+    defaultConfig {
+        applicationId "pers.shawxingkwok.stopwatch"
+        minSdk 24
+        targetSdk 33
+        versionCode 1
+        versionName "1.0"
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+    buildFeatures {
+        viewBinding true
+    }
+}
+
+dependencies {
+
+    implementation 'androidx.core:core-ktx:1.9.0'
+    implementation 'androidx.appcompat:appcompat:1.6.1'
+    implementation 'com.google.android.material:material:1.9.0'
+    implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
+
+    implementation "androidx.activity:activity-ktx:1.7.2"
+
+    testImplementation 'junit:junit:4.13.2'
+    androidTestImplementation 'androidx.test.ext:junit:1.1.5'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
+}
+
+//region shawxingkwok: android-util-view
+tasks.withType(KotlinCompile).configureEach{
+    kotlinOptions.freeCompilerArgs += "-Xcontext-receivers"
+}
+
+dependencies {
+    implementation("io.github.shawxingkwok:kt-util:1.0.2")
+    implementation project(":api") // 'io.github.shawxingkwok:android-util-view:[latest]'
+}
+//endregion

stopwatch/proguard-rules.pro

@@ -0,0 +1,21 @@
+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

stopwatch/src/androidTest/java/pers/shawxingkwok/stopwatch/ExampleInstrumentedTest.kt

@@ -0,0 +1,24 @@
+package pers.shawxingkwok.stopwatch
+
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.ext.junit.runners.AndroidJUnit4
+
+import org.junit.Test
+import org.junit.runner.RunWith
+
+import org.junit.Assert.*
+
+/**
+ * Instrumented test, which will execute on an Android device.
+ *
+ * See [testing documentation](http://d.android.com/tools/testing).
+ */
+@RunWith(AndroidJUnit4::class)
+class ExampleInstrumentedTest {
+    @Test
+    fun useAppContext() {
+        // Context of the app under test.
+        val appContext = InstrumentationRegistry.getInstrumentation().targetContext
+        assertEquals("pers.shawxingkwok.stopwatch", appContext.packageName)
+    }
+}

stopwatch/src/main/AndroidManifest.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+
+    <application
+            android:allowBackup="true"
+            android:icon="@mipmap/ic_launcher"
+            android:label="@string/app_name"
+            android:roundIcon="@mipmap/ic_launcher_round"
+            android:supportsRtl="true"
+            android:name=".App"
+            android:theme="@style/Theme.AndroidUtilView">
+        <activity
+                android:name=".MainActivity"
+                android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

stopwatch/src/main/java/pers/shawxingkwok/stopwatch/App.kt

@@ -0,0 +1,18 @@
+package pers.shawxingkwok.stopwatch
+
+import android.annotation.SuppressLint
+import android.app.Application
+import android.content.Context
+
+class App : Application() {
+    companion object{
+        @SuppressLint("StaticFieldLeak")
+        lateinit var context: Context
+            private set
+    }
+
+    override fun onCreate() {
+        super.onCreate()
+        context = applicationContext
+    }
+}

stopwatch/src/main/java/pers/shawxingkwok/stopwatch/MainActivity.kt

@@ -0,0 +1,121 @@
+package pers.shawxingkwok.stopwatch
+
+import android.annotation.SuppressLint
+import android.os.Bundle
+import androidx.activity.viewModels
+import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.lifecycleScope
+import androidx.recyclerview.widget.LinearLayoutManager
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
+import pers.shawxingkwok.androidutil.view.onClick
+import pers.shawxingkwok.ktutil.updateIf
+import pers.shawxingkwok.stopwatch.databinding.ActivityMainBinding
+import java.util.*
+import kotlin.concurrent.timer
+
+class MainActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityMainBinding
+    private val vm: MainViewModel by viewModels()
+    private val adapter = StopwatchAdapter()
+
+    @SuppressLint("SetTextI18n")
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        binding = ActivityMainBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        binding.rv.adapter = adapter
+        binding.rv.layoutManager = LinearLayoutManager(this)
+
+        // the way of collecting flow is different in Fragment.
+        vm.duration.onEach {
+            binding.tvDuration.text = StopwatchUtil.formatDuration(it)
+        }
+        .launchIn(lifecycleScope)
+
+        vm.intervals.onEach {
+            val sizeChanged = it.size != adapter.intervals.size
+            adapter.intervals = it
+            adapter.update(sizeChanged)
+        }
+        .launchIn(lifecycleScope)
+
+        var timer: Timer? = null
+
+        vm.isRunning.onEach { isRunning ->
+            when{
+                !isRunning -> {
+                    timer?.cancel()
+                    timer = null
+                }
+                timer == null ->
+                    timer = timer(period = 10) {
+                        vm.addDuration()
+                        vm.updateTopIntervals()
+                    }
+                // else -> do nothing if recovered after onStop
+            }
+
+            // switch button stop/start
+            val tv = binding.tvRight
+
+            if (isRunning) {
+                tv.text = "Stop"
+                tv.setBackgroundResource(R.drawable.circle_dark_red)
+                tv.setTextColor(StopwatchUtil.lightRed)
+            } else {
+                tv.text = "Start"
+                tv.setBackgroundResource(R.drawable.circle_dark_green)
+                tv.setTextColor(StopwatchUtil.lightGreen)
+            }
+        }
+        .launchIn(lifecycleScope)
+
+        vm.tvLeftState.onEach {(duration, isRunning) ->
+            val tv = binding.tvLeft
+            when{
+                // disabled
+                duration == 0 -> {
+                    tv.setBackgroundResource(R.drawable.circle_dark_grey)
+                    tv.text = "Lap"
+                    tv.setTextColor(StopwatchUtil.whiteGrey)
+                    tv.isClickable = false
+                }
+                // lap
+                isRunning -> {
+                    tv.setBackgroundResource(R.drawable.circle_light_grey)
+                    tv.text = "Lap"
+                    tv.setTextColor(StopwatchUtil.white)
+                    tv.isClickable = true
+                    // This OnClickListener is variable, which also explains why there is a
+                    // function `setFixedListeners` at last.
+                    tv.onClick { _ ->
+                        vm.insertIntervals()
+
+                        val layoutManager = binding.rv.layoutManager as LinearLayoutManager
+                        val topVisiblePosition = layoutManager.findFirstVisibleItemPosition()
+                            .updateIf({ it == -1 }) { 0 }
+                        binding.rv.scrollToPosition(topVisiblePosition)
+                    }
+                }
+                // reset
+                else ->{
+                    tv.setBackgroundResource(R.drawable.circle_light_grey)
+                    tv.text = "Reset"
+                    tv.setTextColor(StopwatchUtil.white)
+                    tv.isClickable = true
+                    tv.onClick {
+                        vm.resetDuration()
+                        vm.clearIntervals()
+                    }
+                }
+            }
+        }
+        .launchIn(lifecycleScope)
+
+        binding.tvRight.onClick {
+            vm.switchIsRunning()
+        }
+    }
+}

stopwatch/src/main/java/pers/shawxingkwok/stopwatch/MainViewModel.kt

@@ -0,0 +1,46 @@
+package pers.shawxingkwok.stopwatch
+
+import androidx.lifecycle.ViewModel
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.update
+
+class MainViewModel : ViewModel() {
+    private val _duration = MutableStateFlow(0)
+    private val _intervals = MutableStateFlow(intArrayOf())
+    private val _isRunning = MutableStateFlow(false)
+
+    val duration: StateFlow<Int> = _duration
+    val intervals: StateFlow<IntArray> = _intervals
+    val isRunning: StateFlow<Boolean> = _isRunning
+    val tvLeftState = combine(duration, isRunning){ a, b -> a to b }
+
+    fun addDuration(){
+        _duration.value++
+    }
+
+    fun resetDuration(){
+        _duration.value = 0
+    }
+
+    fun insertIntervals(){
+        _intervals.update { intArrayOf(0) + it }
+    }
+
+    fun updateTopIntervals(){
+        _intervals.value =
+            if (_intervals.value.none())
+                intArrayOf(1)
+            else
+                _intervals.value.clone().also { it[0]++ }
+    }
+
+    fun clearIntervals(){
+        _intervals.value = intArrayOf()
+    }
+
+    fun switchIsRunning(){
+        _isRunning.update { !it }
+    }
+}