[Fragment] Replace bind with setOutput function. (#319)

* [Fragment] Replace bind with setOutput function.

* Remove extra line.

formula-android-compose/src/main/java/com/instacart/formula/android/compose/ComposeViewFactory.kt

@@ -1,45 +1,29 @@
 package com.instacart.formula.android.compose
 
-import android.os.SystemClock
 import android.view.LayoutInflater
 import android.view.ViewGroup
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.rxjava3.subscribeAsState
 import androidx.compose.ui.platform.ComposeView
 import com.instacart.formula.android.FeatureView
 import com.instacart.formula.android.ViewFactory
+import com.jakewharton.rxrelay3.BehaviorRelay
 
 
 abstract class ComposeViewFactory<RenderModel> : ViewFactory<RenderModel> {
 
     override fun create(inflater: LayoutInflater, container: ViewGroup?): FeatureView<RenderModel> {
         val view = ComposeView(inflater.context)
-        var firstRender = true
+        val outputRelay = BehaviorRelay.create<RenderModel>()
+        view.setContent {
+            val model = outputRelay.subscribeAsState(null).value
+            if (model != null) {
+                Content(model)
+            }
+        }
         return FeatureView(
             view = view,
-            bind = { state ->
-                view.setContent {
-                    val model = state.observable.subscribeAsState(null).value
-                    if (model != null) {
-                        val start = SystemClock.uptimeMillis()
-                        Content(model)
-                        val end = SystemClock.uptimeMillis()
-                        state.environment.eventListener?.onRendered(
-                            fragmentId = state.fragmentId,
-                            durationInMillis = end - start,
-                        )
-
-                        if (firstRender) {
-                            firstRender = false
-                            state.environment.eventListener?.onFirstModelRendered(
-                                fragmentId = state.fragmentId,
-                                durationInMillis = end - state.initializedAtMillis,
-                            )
-                        }
-                    }
-                }
-                null
-            }
+            setOutput = outputRelay::accept,
         )
     }
 

formula-android/src/main/java/com/instacart/formula/android/FeatureView.kt

@@ -13,18 +13,11 @@ import io.reactivex.rxjava3.core.Observable
  * [FeatureView].
  *
  * @param view The root Android view.
- * @param bind A bind function connects state observable to the view rendering.
+ * @param setOutput A function called to apply [RenderModel] to the view.
  * @param lifecycleCallbacks Optional lifecycle callbacks if you need to know the Fragment state.
  */
 class FeatureView<RenderModel>(
     val view: View,
-    val bind: (State<RenderModel>) -> Cancelable?,
+    val setOutput: (RenderModel) -> Unit,
     val lifecycleCallbacks: FragmentLifecycleCallback? = null,
-) {
-    class State<RenderModel>(
-        val initializedAtMillis: Long,
-        val fragmentId: FragmentId,
-        val environment: FragmentEnvironment,
-        val observable: Observable<RenderModel>,
-    )
-}
+)

formula-android/src/main/java/com/instacart/formula/android/FormulaFragment.kt

@@ -7,10 +7,9 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.fragment.app.Fragment
-import com.instacart.formula.Cancelable
 import com.instacart.formula.android.internal.FormulaFragmentDelegate
 import com.instacart.formula.android.internal.getFormulaFragmentId
-import com.jakewharton.rxrelay3.BehaviorRelay
+import java.lang.Exception
 
 class FormulaFragment : Fragment(), BaseFormulaFragment<Any> {
     companion object {
@@ -31,13 +30,14 @@ class FormulaFragment : Fragment(), BaseFormulaFragment<Any> {
         requireArguments().getParcelable<FragmentKey>(ARG_CONTRACT)!!
     }
 
-    private var initializedAtMillis: Long? = SystemClock.uptimeMillis()
-
     private var featureView: FeatureView<Any>? = null
-    private val stateRelay: BehaviorRelay<Any> = BehaviorRelay.create()
-    private var cancelable: Cancelable? = null
+    private var output: Any? = null
 
-    private var lifecycleCallback: FragmentLifecycleCallback? = null
+    private var initializedAtMillis: Long? = SystemClock.uptimeMillis()
+    private var firstRender = true
+
+    private val lifecycleCallback: FragmentLifecycleCallback?
+        get() = featureView?.lifecycleCallbacks
 
     override fun onAttach(context: Context) {
         super.onAttach(context)
@@ -47,6 +47,8 @@ class FormulaFragment : Fragment(), BaseFormulaFragment<Any> {
     }
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
+        firstRender = true
+
         val viewFactory = FormulaFragmentDelegate.viewFactory(this) ?: run {
             // No view factory, no view
             return null
@@ -59,17 +61,9 @@ class FormulaFragment : Fragment(), BaseFormulaFragment<Any> {
 
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
-        featureView?.let { value ->
-            val state = FeatureView.State(
-                initializedAtMillis = initializedAtMillis ?: SystemClock.uptimeMillis(),
-                fragmentId = getFormulaFragmentId(),
-                environment = FormulaFragmentDelegate.fragmentEnvironment(),
-                observable = stateRelay,
-            )
-            cancelable = value.bind(state)
-            this.lifecycleCallback = value.lifecycleCallbacks
-            lifecycleCallback?.onViewCreated(view, savedInstanceState)
-        }
+        tryToSetState()
+
+        lifecycleCallback?.onViewCreated(view, savedInstanceState)
     }
 
     override fun onActivityCreated(savedInstanceState: Bundle?) {
@@ -110,21 +104,18 @@ class FormulaFragment : Fragment(), BaseFormulaFragment<Any> {
     override fun onDestroyView() {
         initializedAtMillis = null
 
-        cancelable?.cancel()
-        cancelable = null
-
         lifecycleCallback?.onDestroyView()
-        lifecycleCallback = null
         super.onDestroyView()
         featureView = null
     }
 
     override fun setState(state: Any) {
-        stateRelay.accept(state)
+        output = state
+        tryToSetState()
     }
 
     override fun currentState(): Any? {
-        return stateRelay.value
+        return output
     }
 
     override fun getFragmentKey(): FragmentKey {
@@ -134,4 +125,33 @@ class FormulaFragment : Fragment(), BaseFormulaFragment<Any> {
     override fun toString(): String {
         return "${key.tag} -> $key"
     }
+
+    private fun tryToSetState() {
+        val output = output ?: return
+        val view = featureView ?: return
+
+        val fragmentId = getFormulaFragmentId()
+        val environment = FormulaFragmentDelegate.fragmentEnvironment()
+
+        try {
+            val start = SystemClock.uptimeMillis()
+            view.setOutput(output)
+            val end = SystemClock.uptimeMillis()
+
+            environment.eventListener?.onRendered(
+                fragmentId = fragmentId,
+                durationInMillis = end - start,
+            )
+
+            if (firstRender) {
+                firstRender = false
+                environment.eventListener?.onFirstModelRendered(
+                    fragmentId = fragmentId,
+                    durationInMillis = end - (initializedAtMillis ?: SystemClock.uptimeMillis()),
+                )
+            }
+        } catch (exception: Exception) {
+            environment.onScreenError(key, exception)
+        }
+    }
 }

formula-android/src/main/java/com/instacart/formula/android/ViewInstance.kt

@@ -3,7 +3,6 @@ package com.instacart.formula.android
 import android.view.View
 import com.instacart.formula.RenderView
 import com.instacart.formula.Renderer
-import com.instacart.formula.android.views.FeatureViewBindFunction
 
 /**
  * View instance contains an initialized Android [view] and provides factory
@@ -37,7 +36,7 @@ abstract class ViewInstance {
     ): FeatureView<RenderModel> {
         return FeatureView(
             view = view,
-            bind = FeatureViewBindFunction(renderer),
+            setOutput = renderer,
             lifecycleCallbacks = lifecycleCallbacks
         )
     }