coroutines.Flow support, restoring subscriptions after component reat…

…tach
ArTemmey · Feb 11, 2021 · d979d27 · d979d27
1 parent 8b36933
commit d979d27
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Showing 7 changed files with 146 additions and 64 deletions.
diff --git a/app/src/main/java/ru/impression/ui_generator_example/Ext.kt b/app/src/main/java/ru/impression/ui_generator_example/Ext.kt
@@ -1,14 +1,28 @@
 package ru.impression.ui_generator_example
 
 import android.view.View
+import androidx.core.view.isGone
 import androidx.core.view.isInvisible
+import androidx.core.view.isVisible
 import androidx.databinding.BindingAdapter
 
 object DataBindingExt {
 
     @JvmStatic
     @BindingAdapter("isInvisible")
-    fun setIsVisible(view: View, value: Boolean) {
+    fun setIsInvisible(view: View, value: Boolean) {
         view.isInvisible = value
     }
+
+    @JvmStatic
+    @BindingAdapter("isVisible")
+    fun setIsVisible(view: View, value: Boolean) {
+        view.isVisible = value
+    }
+
+    @JvmStatic
+    @BindingAdapter("isGone")
+    fun setIsGone(view: View, value: Boolean) {
+        view.isGone = value
+    }
 }
diff --git a/app/src/main/java/ru/impression/ui_generator_example/MainFragment.kt b/app/src/main/java/ru/impression/ui_generator_example/MainFragment.kt
@@ -2,6 +2,7 @@ package ru.impression.ui_generator_example
 
 import androidx.fragment.app.Fragment
 import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.flow
 import kotlinx.coroutines.launch
 import ru.impression.ui_generator_annotations.MakeComponent
 import ru.impression.ui_generator_annotations.Prop
@@ -17,6 +18,20 @@ class MainFragment :
 
 class MainFragmentViewModel : CoroutineViewModel() {
 
+    var countDown by state(flow {
+        delay(1000)
+        emit(3)
+        delay(1000)
+        emit(2)
+        delay(1000)
+        emit(1)
+        delay(1000)
+        emit(0)
+    })
+
+    val countDownIsLoading get() = ::countDown.isLoading
+
+
     @Prop
     var welcomeText by state<String?>(null)
 
@@ -34,9 +49,6 @@ class MainFragmentViewModel : CoroutineViewModel() {
     val currentTimeIsLoading get() = ::currentTime.isLoading
 
     fun reloadCurrentTime() {
-        launch {
-            ::currentTime.reload().join()
-            toastMessage = "Current time reloaded"
-        }
+        ::currentTime.reload()
     }
 }
diff --git a/app/src/main/res/layout/main_fragment.xml b/app/src/main/res/layout/main_fragment.xml
@@ -10,85 +10,108 @@
 
     </data>
 
-    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        android:gravity="center"
-        android:orientation="vertical">
+        android:layout_height="match_parent">
 
         <ru.impression.ui_generator_example.ToastShowerComponent
             message="@={viewModel.toastMessage}"
             android:layout_width="0dp"
             android:layout_height="0dp" />
 
-        <androidx.appcompat.widget.AppCompatTextView
+        <ProgressBar
+            isVisible="@{viewModel.countDownIsLoading}"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:text="@{viewModel.welcomeText}"
-            android:textSize="24sp"
-            android:textStyle="bold" />
+            android:layout_gravity="center" />
 
-        <LinearLayout
+        <TextView
+            isVisible="@{!viewModel.countDownIsLoading &amp;&amp; viewModel.countDown > 0}"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:layout_marginTop="32dp"
-            android:orientation="horizontal">
+            android:layout_gravity="center"
+            android:text="@{String.valueOf(viewModel.countDown)}"
+            android:textSize="24sp"
+            android:textStyle="bold"
+            tools:text="3..2..1" />
 
-            <ru.impression.ui_generator_example.TitledPictureComponent
+        <LinearLayout
+            isVisible="@{!viewModel.countDownIsLoading &amp;&amp; viewModel.countDown == 0}"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:gravity="center"
+            android:orientation="vertical">
+
+            <androidx.appcompat.widget.AppCompatTextView
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                app:picture="@drawable/sample_image_1"
-                app:title="Apples" />
+                android:text="@{viewModel.welcomeText}"
+                android:textSize="24sp"
+                android:textStyle="bold" />
 
-            <ru.impression.ui_generator_example.TitledPictureComponent
+            <LinearLayout
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:layout_marginStart="16dp"
-                app:picture="@drawable/sample_image_2"
-                app:title="Flower" />
-
-        </LinearLayout>
-
-        <ru.impression.ui_generator_example.CounterComponent
-            count="@={viewModel.count}"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="32dp" />
-
-        <TextView
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="32dp"
-            android:text="Current time is:"
-            android:textStyle="bold" />
-
-        <FrameLayout
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="8dp">
+                android:layout_marginTop="32dp"
+                android:orientation="horizontal">
+
+                <ru.impression.ui_generator_example.TitledPictureComponent
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    app:picture="@drawable/sample_image_1"
+                    app:title="Apples" />
+
+                <ru.impression.ui_generator_example.TitledPictureComponent
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_marginStart="16dp"
+                    app:picture="@drawable/sample_image_2"
+                    app:title="Flower" />
+
+            </LinearLayout>
+
+            <ru.impression.ui_generator_example.CounterComponent
+                count="@={viewModel.count}"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="32dp" />
 
             <TextView
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:layout_gravity="center"
-                android:text="@{viewModel.currentTime}"
-                tools:text="12345" />
+                android:layout_marginTop="32dp"
+                android:text="Current time is:"
+                android:textStyle="bold" />
 
-            <ProgressBar
-                isInvisible="@{!viewModel.currentTimeIsLoading}"
+            <FrameLayout
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:layout_gravity="center" />
+                android:layout_marginTop="8dp">
 
-        </FrameLayout>
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="center"
+                    android:text="@{viewModel.currentTime}"
+                    tools:text="12345" />
 
-        <Button
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content"
-            android:layout_marginTop="8dp"
-            android:onClick="@{() -> viewModel.reloadCurrentTime()}"
-            android:text="reload" />
+                <ProgressBar
+                    isInvisible="@{!viewModel.currentTimeIsLoading}"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_gravity="center" />
+
+            </FrameLayout>
+
+            <Button
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:onClick="@{() -> viewModel.reloadCurrentTime()}"
+                android:text="reload" />
+
+        </LinearLayout>
 
-    </LinearLayout>
+    </FrameLayout>
 
 </layout>
diff --git a/ui-generator-base/src/main/java/ru/impression/ui_generator_base/ComponentViewModel.kt b/ui-generator-base/src/main/java/ru/impression/ui_generator_base/ComponentViewModel.kt
@@ -21,8 +21,10 @@ abstract class ComponentViewModel(val attrs: IntArray? = null) : ViewModel(), St
 
     private val stateObserversNotifier = Runnable { notifyStateObservers(true) }
 
+    private val subscriptionsInitializers = ArrayList<(() -> Unit)>()
+
     protected fun <T> state(initialValue: T, attr: Int? = null, onChanged: ((T) -> Unit)? = null) =
-        StateDelegate(this, initialValue, null, onChanged)
+        StateDelegate(this, initialValue, onChanged)
             .also { delegate -> attr?.let { delegateToAttrs[delegate] = it } }
 
     @CallSuper
@@ -44,6 +46,15 @@ abstract class ComponentViewModel(val attrs: IntArray? = null) : ViewModel(), St
         component = null
     }
 
+    fun initSubscriptions(block: () -> Unit) {
+        block()
+        subscriptionsInitializers.add(block)
+    }
+
+    fun restoreSubscriptions() {
+        subscriptionsInitializers.forEach { it() }
+    }
+
     fun addStateObserver(lifecycleOwner: LifecycleOwner, observer: () -> Unit) {
         fun addActual() {
             val set = stateObservers[lifecycleOwner]

diff --git a/ui-generator-base/src/main/java/ru/impression/ui_generator_base/CoroutineViewModel.kt b/ui-generator-base/src/main/java/ru/impression/ui_generator_base/CoroutineViewModel.kt
@@ -2,12 +2,16 @@ package ru.impression.ui_generator_base
 
 import androidx.annotation.CallSuper
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.Flow
 
 abstract class CoroutineViewModel(attrs: IntArray? = null) : ComponentViewModel(attrs),
     ClearableCoroutineScope by ClearableCoroutineScopeImpl(Dispatchers.IO) {
 
-    protected fun <T> state(getInitialValue: suspend () -> T, onChanged: ((T?) -> Unit)? = null) =
-        StateDelegate(this, null, getInitialValue, onChanged)
+    protected fun <T> state(loadValue: suspend () -> T, onChanged: ((T?) -> Unit)? = null) =
+        StateDelegate(this, null, onChanged, loadValue = loadValue)
+
+    protected fun <T> state(valueFlow: Flow<T>, onChanged: ((T?) -> Unit)? = null) =
+        StateDelegate(this, null, onChanged, valueFlow = valueFlow)
 
     @CallSuper
     override fun onCleared() {

diff --git a/ui-generator-base/src/main/java/ru/impression/ui_generator_base/StateDelegate.kt b/ui-generator-base/src/main/java/ru/impression/ui_generator_base/StateDelegate.kt
@@ -2,6 +2,8 @@ package ru.impression.ui_generator_base
 
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Job
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.launch
 import ru.impression.ui_generator_annotations.Prop
 import kotlin.properties.ReadWriteProperty
@@ -11,8 +13,9 @@ import kotlin.reflect.full.findAnnotation
 open class StateDelegate<R : StateOwner, T>(
     val parent: R,
     initialValue: T,
-    val getInitialValue: (suspend () -> T)?,
-    val onChanged: ((T) -> Unit)?
+    val onChanged: ((T) -> Unit)?,
+    val loadValue: (suspend () -> T)? = null,
+    val valueFlow: Flow<T>? = null
 ) : ReadWriteProperty<R, T> {
 
     @Volatile
@@ -27,7 +30,10 @@ open class StateDelegate<R : StateOwner, T>(
     private var loadJob: Job? = null
 
     init {
-        if (getInitialValue != null) load(false)
+        when {
+            loadValue != null -> load(false)
+            valueFlow != null -> collectValueFlow()
+        }
     }
 
     @Synchronized
@@ -36,13 +42,24 @@ open class StateDelegate<R : StateOwner, T>(
         isLoading = true
         if (notifyStateChangedBeforeLoading) parent.onStateChanged()
         return (parent as CoroutineScope).launch {
-            val result = getInitialValue!!.invoke()
+            val result = loadValue!!.invoke()
             isLoading = false
             setValueToProperty(result)
             loadJob = null
         }.also { loadJob = it }
     }
 
+    private fun collectValueFlow() {
+        isLoading = true
+        fun collect() = (parent as CoroutineScope).launch {
+            valueFlow!!.collect {
+                isLoading = false
+                setValueToProperty(it)
+            }
+        }
+        (parent as? ComponentViewModel)?.initSubscriptions(::collect) ?: collect()
+    }
+
     @Synchronized
     override fun getValue(thisRef: R, property: KProperty<*>) = value
 

diff --git a/...processor/src/main/java/ru/impression/ui_generator_processor/ViewComponentClassBuilder.kt b/...processor/src/main/java/ru/impression/ui_generator_processor/ViewComponentClassBuilder.kt
@@ -167,6 +167,7 @@ class ViewComponentClassBuilder(
                 if (isDetachedFromWindow) {
                   isDetachedFromWindow = false
                   viewModel.setComponent(this)
+                  viewModel.restoreSubscriptions()
                 }
                 lifecycle.handleLifecycleEvent(%T.Event.ON_CREATE)
                 """.trimIndent(),