How to avoid recomposition in jetpack compose

Android Studio Profiler - CPU timeline. Memory Consumption: When Composable functions are recomposed, Jetpack Compose utilizes memory. Jul 28, 2021 · Well, I've found working solution myself, still not sure if this "boilerplate code" is needed :( But this works as intended, means "page" is dismissed once navigated from it. Jul 19, 2023 · Finally, I have found the answer : Nested Collections and Recomposition. var test = remember { mutableStateOf(0) } Canvas(modifier = Modifier. Compose assumes that whenever you read a state, you don’t update its value in composable immediately. startDestinationRoute?. This Aug 18, 2021 · Compose can optimize recomposition by running composable functions in parallel. On this page. You can refer this question and answer as well. LaunchedEffect: run suspend functions in the scope of a composable. Feb 18, 2024 · key(key) {. ComposableForType1() } Jul 11, 2022 · 2. State and effect use cases. observe(lifeCycleOwner) value = it. For example : A->B->A->B. when (type) {. 1. Oct 26, 2021 · State in ViewModel is a really good tutorial that explains on how to manage lists. The gotchas discussed here break performance optimizations built into Compose and trigger unnecessary work, which have the potential to slow down an Jun 18, 2024 · Layout Inspector. As a first task when trying to optimize performance of your app, you should seek any heavy composables or a long-running task on the main thread. route) { // Pop up to the start destination of the graph to // avoid building up a large stack of destinations // on the back stack as users select items navController. Recomposition: re-running composables to update the Composition when data changes. internal fun AppointmentScreen(. Jun 18, 2024 · To take a system trace and see the new recomposition tracing in action, follow these steps: Open the profiler: Figure 2. I am quite new to Jetpack compose and have an issue that my list is not recomposing when a property of an object in the list changes. LoginScreen. Oct 6, 2023 · By managing state appropriately and recognizing how changes in one composable can affect others, you can create robust and dynamic user interfaces with Jetpack Compose. For example, you can store it in a mutable state list, as shown here: val counters = remember { names. Architecting your Compose UI In Compose, the only way to update the UI is by changing the state of the app. Jul 12, 2023 · However, the @Stable annotation is not intended to enforce immutability or stability on properties; rather, it serves as an indication to Compose about the stability of the class as a whole. navController: NavHostController. You can use the content slot, which uses a ColumnScope to layout sheet content composables in a column: Programmatically expanding and collapsing the sheet is done using SheetState. On bottom right corner u can find layout inspector option. Sep 12, 2022 · Next recomposition on TimedLayout() will enforce new key in the compose and therefore new value. getAllProducts() in your MainViewModel init instead of having the LaunchedEffect. Builder(LocalContext. Move lambdas out of a recompose scope to a variable for reuse or use method reference instead, so they don’t get recreated every time a scope is called ( source of the tip with a case study). fillMaxSize()) {. In this article, we will dive into Jetpack Compose’s Stability. By enabling this u can easily see recomposition count. Sep 11, 2022 · This is indeed the expected behavior. bottomBar = { BottomBar(navController = navController) }, content = {. Note: If you scroll a lazy list, all invisible items will be destroyed. Optimizing Lazy List in Jetpack Compose. Composition: The core of Jetpack Compose is composition. Type1 -> {. Defer reads as long as possible. Thanks, that's very useful. 2. setDataSlow(data1) }, update = {. Jul 13, 2023 · The remember API's automatic recomposition, state retention across recompositions, performance optimizations, and integration with other Jetpack Compose APIs make it a valuable tool for building Feb 2, 2024 · Common Use Cases: The use of remember helps manage state efficiently and ensures that the state persists even when the Composable function is recomposed due to external changes or user Jul 10, 2022 · Here you should use the SideEffects to make sure data is only loaded once and not on recompositions (if the data does not change). What you can control is your UI state. Apr 9, 2021 · For this, I had used 'invalidate ()' while using Custom view. You can use the Layout Inspector to check how often a composable is recomposed or skipped, which can help identify issues with your app. Copy the item you're about to mutate, remove Jun 24, 2022 · I am trying to call a composable which has a parameter. Edit: while working on the fix I experienced some Gradle dependencies caching problems. navController. toMutableStateList() } LazyColumn( modifier = modifier ){. Click CPU timeline. onClick = {number = Random. Understanding the LaunchedEffect function is essential for harnessing the full potential of Jetpack Compose. Mar 27, 2022 · This is the expected behavior of state and jetpack compose. Here are a couple of common “gotchas” and how you fix them. Jan 3, 2024 · 3. animateContentSize(). This is the composable I want to call onClick @Composable fun ShowCustomChromeTab(articleUrl: String){ . During navigation from Navhost, I found out that the composable screens are getting recomposition multiple times. // AppointmentsScreen. Not sure about your question. You can see in the usage that we are using collectAsState() for StateFlow . This could save time and increase performance if the recompositions are expensive and or numerous. By defining sub-trees of Aug 30, 2022 · Please try restoreState = true:. This behavior is bothers me. We are Nov 27, 2020 · Jetpack Compose is the newest thing in town. In second case, with derivedStateOf the behavior is the same, except we do not trigger any recomposition for CounterButton. Here's a gif showing how both behaves when I change its value: Here's the code: class MainActivity : ComponentActivity() {. The con is that depending on your list implementation this might not be O(1). Initial composition: creation of a Composition by running composables the first time. This is the expected behavior. Jan 26, 2023 · Workaround. Nov 7, 2022 · 1. Jetpack compose only recomposes if the value of the state changes. Follow best practices to optimize your app on Compose. These mistakes might give you code that seems to run well enough, but can hurt your UI performance. Jun 21, 2024 · Lifecycle of a composable in the Composition. I don't know why in my code the text where I type "hi" is always recomposed. rememberCoroutineScope: obtain a composition-aware scope to launch a coroutine outside a composable. then inside SideEffect I can use lastTicker value ( to compare last ticker and current ticker in my case) before assign it to new value to use for next composition. The fact that it uses scrollState won't make it recompose, only reading state value will trigger recomposition. navigate(Screen. route) { inclusive = true } Jun 1, 2022 · Official article about Jetpack Compose phases and this article about deferring reads for performance suggests moving any state reads from Composition phase to Layout or Draw phases such as. fun MainScreen(context: Context) {. Apr 20, 2021 · 11. When recomposition is canceled, Compose discards the UI tree from the recomposition. value) Button(onClick = { countState. It goes against the very concept of encapsulation. Declarative Programming is the name. Apr 16, 2022 · The easiest way to debug recompositions is to use good ol' log statements to see which composables functions are being called and the frequency with which they are being called. I'm using recomposeHighlighter to show recompositions. The problem is that you can’t directly cause a normal back press action in the same click event. */. navigate() it will automatically recompose the targeted route. In the legacy Android View system, we use invalidate() to do the same. Also, you have to give Compose a message that the dummy variable is being read in the Text, so it would trigger recompostions. map { 0 }. The method converts StateFlow to State. var count by remember { mutableStateOf(0) } // Causes recomposition on click. You can store state in a view model in a variety of ways - compose mutable state, the Flow or LiveData - anything that will cause recomposition when the value changes. fun <T> mutableStateOf(. foundation dependency: Jun 21, 2024 · If you want to implement a bottom sheet, you can use the ModalBottomSheet composable. Mar 24, 2023 · Jetpack Compose Debugging Recomposition: This article explains the Compose phases and how to debug recomposition to optimize app performance. You can't use a Composable function on the onClick lambda, but you can just rewrite your code with: Text("CountState is: " + countState. Lambda memoization is done automatically by the compiler by generating a remember call implicitly based on the stable values captured by the lambda. Mar 6, 2023 · Here we can avoid the problem by replacing Duration with State<Duration>, but this approach will not always work. Jan 13, 2023 · 2. popUpTo(Screen. May 18, 2021 · With this solution, i could prevent recomposition and the "re-navigation". The comparison uses the equals method. Second and Third Text have number to their right, not in the same position as the first Text. Oct 5, 2023 · Recomposition is when Jetpack Compose re-executes the composables that may have changed in response to state changes, and then updates the Composition to reflect any changes. Aug 17, 2022 · This problem is characteristic of declarative UI frameworks, and for instance in React it is known as Property Drilling. val scaffoldState = rememberScaffoldState(rememberDrawerState(DrawerValue. So both can be used. val timestamp by viewModel. And most of this answer uses article as reference and quoted most from it. Let’s delve into four key points to remember when using @Stable: 1. This Oct 5, 2022 · 9. I found a workaround solution in this post where you use this: MainScaffold(. You can use rememberSheetState to create an instance of SheetState that should Feb 16, 2024 · The basic idea is to use auto-resizing (which is the default behavior) if we don’t have a height remembered, for example when first initialized, and use the height remembered if there is one. Lazy loading, through components like LazyRow or LazyColumn in Jetpack Compose, can significantly boost your app’s speed. However, we have to watch Aug 13, 2022 · Deep diving into Jetpack Compose’s Stability. You need to use a MutableStateList<T>. It is basically designed based on position memoization, and the stability of composable also has a big impact. Reusable lambdas or use method reference. Layout Inspector -> View option component tree -> Show Recomposition count. It is still in Alpha, but it shows promising signs. A scope is non-inline Composable function that returns Unit. I don't know if we need to be aware and build composables thinking of this recomposition after navigation or it should be library's responsibility. Text("Count up") When you click the button: the countState MutableState value is changed. If you create a scope that scope is recomposed when the value it reads changes. Oct 29, 2021 · From the docs, you can see that compose supports Flow, LiveData and RxJava. graph. This section in the compose's doc explains what are stable types and how to skip recomposition. When passing items: List<Int> as parameter, compose always recomposes, regardless of List is immutable and cannot be changed. content() This approach uses the key composable function to help Compose track and optimize the recompositions of NotChangableAndroidView and ChangableAndroidView based on their keys. Android Studio - Start Profiling. Figure 4. Closed)) val scope = rememberCoroutineScope() val navController Sep 10, 2021 · 14. Sep 10, 2021 · 4. Dec 3, 2023 · First Text i. Mar 10, 2022 · The setDataFast() method needs to be called frequently, and is very fast. Layout Inspector lets you inspect a Compose layout inside a running app in an emulator or physical device. setDataFast(data2) The problem is, the factory lambda gets only called once, even when data1 changes. Jul 21, 2022 · modifier = Modifier. Nov 7, 2022 at 10:04. I understand this is by design. This will cause recomposition as youre writing to snapshot state. It is quite difficult to answer this question briefly, in a simplified form - Compose uses the Snapshot System to detect changes. navigate(item. Sep 14, 2021 · NavHost is a composable, So naturally it can be composed and recomposed several times! If you want to do a one-time action in a composable lifecycle, use LaunchedEffect. As the name suggests, this enables us to move around content without the need for recomposition. Since a list operation changes only the contents of the object, but not the object reference itself, the composition will not be recomposed. Jun 2, 2021 · by using remember { mutableStateOf(ticker)}, I can persist value of ticker throught recomposition. It uses an observer pattern to observe changes to state. Modifier. So, the natural code in Compose would be something like this: val v = CustomView(it) v. Use Flow if the layers beyond ViewModel (like repo) are the data sources and they use Flow data type. Compose tracks these and runs all composables in the Composition that read that particular State<T>, and any composables that they call that Feb 21, 2022 · Using this knowledge, you can easily prevent a view from being recomposed: you need to move part, which doesn't depends on the state, into a separate composable. Even if variable is not change, it triggers a recomposition while scrolling Lazy Column. Sep 1, 2022 · You just need to cache your products somehow so that reload and reset isn't happening, there are many ways to do that with increasing complexity and architecture but the simplest fix would be just to call viewModel. If you found the article Aug 9, 2022 · Recomposition is the process of calling composable again and again on input changes. g. fillMaxWidth() for some Boxes in the composable layout, infinite recomposition in LazyColumn stopped. While the addition of an unstable property might violate the contract, Compose still allows you to mark the class as @Stable. Jun 21, 2024 · This is due to how composition and recomposition work in Compose. route) {. Nov 27, 2020 · Edit March 2022. Avoid backwards writes. A fundamental difference between View-based UI and Jetpack Compose is that Compose doesn't rely on Dec 19, 2020 · To learn how composition and recomposition works you can check out Under the hood of Jetpack Compose article by Leland Richardson, which describes inner works very well, also youtube video here. LaunchedEffect(key){ // relaunched every time its parameter changes. Every time the state of the UI changes, Compose recreates the parts of the UI tree that changed. But to my confusion, the following class is also treated as Stable Aug 4, 2021 · In New Android Studio Hedgehog you can directly check what is causing a composable to recompose with the help of Layout Inspector. You can use coil's setParameter method on the builder which will reload whenever the parameter changes. In your question when you add a new item to SnapshotStateList whole Column is composed because Column doesn't create a composition scope due to inline keyword. On a… Sep 27, 2022 · Recomposition is optimistic, which means Compose expects to finish recomposition before the parameters change again. It enters the Composition, gets recomposed 0 or more times, and leaves the Composition. Jetpack compose always needs a state object to be modified before recomposition can occur. Gotchas in Jetpack Compose Recomposition. rememberSaveable: remember only save state across recompositions and doesn't handle configuration changes and process death, so to survive configuration changes and process death you should May 16, 2023 · Therefore, developers need to use Recomposition carefully and avoid unnecessary recomputations. But now I'm using Jetpack Compose and unable to find a way to recompose 'Canvas'. This question is a perfect example on how different layout structuring, wrapping / scoping can prevent unnecessary recompositions. Figure 3. timestamp. The green one is constrained to the top, and the blue one is constrained between the green one and the bottom of the screen. To fix this, use a List instead of MutableList. : adding a new parameter) results in changes to all its parents. Because of it, my ViewModel is calling API data source multiple times too. If a parameter does change before recomposition finishes, Compose might cancel the recomposition and restart it with the new parameter. Every time you enter any screen/fragment, you refresh data model which eventually recomposes your composable. background() to Modifier. However, you can use an option to save the current state of the screen that you leave and restore the state of the screen that you target. In the case where you want to animate some state between different views, you can use the Crossfade animation: Crossfade(targetState = type) { type ->. Jan 18, 2024 · Jetpack Compose Scoped/Smart Recomposition. @Composable. To prevent redundant recompositions, in such cases derivedStateOf should be used: it'll trigger recomposition only when produced result, based on other state variables, like scrollState, is changed: Feb 13, 2022 · Smart recomposition in Jetpack Compose works by so called donut-hole skipping, which leads to only those scopes being recomposed, that need to be (since something might have changed in it). User clicks on button1: Its state variable updates, triggering a recomposition within the first button’s scope. Key Term: Composition: a description of the UI built by Jetpack Compose when it executes composables. kt. let { route -> popUpTo(route) { saveState = true } } // Avoid multiple copies of the same destination when // reselecting the same item Aug 3, 2021 · I have two squares. Check out my question and linked other questions observing draw phases of unrelated Composables being called but scoping also works for this one too. The parts of the code that depend on the state register change listeners, when the value changes, all registered listeners are notified. Even if uiState. var model by remember{ mutableStateOf(Register())} because by default mutableStateOf uses SnapshotMutationPolicy that checks if two instances are equal. You're calling navigate on each recomposition. Apr 9, 2021 · 0. val (showDialog, setShowDialog) = remember { mutableStateOf(false) } var setDialogTitle : String = "" //Update this variable. This new number are skipped numbers. There are 2 built-in ways for persisting state in Compose: remember: exists to save state in Composable functions between recompositions. AccountsScreen. 0-alpha03. It provides a structured Nov 9, 2021 · 2. Aug 8, 2021 · Hence, all you need to do is just add a 'dummy' variable of type MutableState, and then modify it from the onClick s of the buttons in concern. //It's a good idea to pass the user ID as an argument and use it as the key. e Notification1 is recomposed with new data. The long-running work might mean different things depending on how complicated your UI is and how much time there is to compose the UI. User clicks on button2: Its state variable updates separately from button1, leading to recomposition within the Sep 12, 2021 · In Jetpack Compose, you can use BackHandler to execute custom behavior when a user clicks the back button. If a composable function calls a function on a Apr 1, 2022 · 12. itemsIndexed(items = names) { i, name ->. It is different from XML based user interface programming. 6 days ago · Tools for Compose. – Jeel Vankhede. Your problem lays in these lines: navController. You only need remember explicitly if one or more of the captured values is not considered stable by the compiler. Anyway, when the problem approached for the 2nd time - the solution was to upgrade compose. Mar 8, 2021 · A Jetpack Compose Tutorial for Beginners – How To Understand Composables & Recomposition. One way of handling this issue is by updating your data model from view model, so that your state changes upon subscription inside your composable function. Nov 28, 2021 · So, in first case, with remember with the key on every button click we trigger recomposition of the Button and for some reason for the CounterButton. This lets Compose take advantage of multiple cores, and run composable functions not on the screen at a lower priority. or using derivedStateOf to watch ticker change only, avoid recomposition Mar 10, 2023 · 1. I Jan 9, 2024 · Here are the fundamental concepts and stages in the Jetpack Compose lifecycle: 1. Compose recomposes only the "nearest" scope. Jetpack Compose deferring reads in phases for performance Mar 31, 2022 · 2. Based on the articles i created 2 separate samples. You need to move the state one level up or in the caller site. Let’s see this code: @Composable. Jetpack Compose Smart Recomposition. Jetpack compose no longer uses LazyColumnFor so I've updated the answer to reflect the current state of compose. Android Studio brings a lot of new features specifically for Jetpack Compose. Oct 8, 2021 · 20. While this is a beginner's guide to Compose, it will not be a beginner's guide to Android – so you should have Jun 19, 2022 · Android Jetpack Compose - Composable Function get recomposed each time Text-field value changes 1 Unexpected re-composition when using Java classes (even if not being read/observed) Jul 29, 2023 · Composition works in the following way: Initial State: The entire composable gets composed with the initial values. fun BadComposable() {. To all folks coming here looking for an alternative to android View 's animateLayoutChanges or its programmatical counterpart, LayoutTransition(), to use with Jetpack Compose and Composable Layouts, there are two main approaches that I have explained below: First approach is to use Modifier. drawBehind{} to defer read to Draw phase. . // content. Recomposition is typically triggered by a change to a State<T> object. This optimization means a composable function might execute within a pool of background threads. value: T, Mar 14, 2022 · Jetpack Compose recently introduced a new function named movableContentOf in version 1. May 14, 2023 · 1. Jul 21, 2023 · Sometimes, simple animations can cause composables to recompose way more times then they should be. Use with Data Aug 11, 2021 · So I want to have only one function that have all details regarding the dialog than each button will update the variable and pass it into the dialog Function. Mar 8, 2022 · Using official docs approach is fine only until you just need to navigate clicking on the items of the BottomBar. Here is my Jetpack compose code for 'gradual growing line': @Composable. The goal to avoid a recomposition is to avoid reading the state updates each time any update happens. In my composable I get a list of available appointments from my view model and it is collected as a state. Composite navigation recomposes both disappearing and appearing views during transition. Additional Resources. The text was fixed to "hi", and onClick also maintained the instance using uiEvent remember. Nov 8, 2022 · The difference between the 2 components is basically that I read the value through a lambda and also added the Slider component inside a Scoped composable. Ryan Michael Kay. value += "Lorem Ipsum". collectAsState() ImageRequest. State holders like MutableStateFlow, and MutableState only send change notifications when the old and new state values are not equal. @Composable functions are recomposed. When you are using navController. This is really obvious but there's some nuance to it - we want to trigger these log statements only when recompositions are happening. Accelerate heavy composables. Dec 10, 2022 · Avoid backward writes. If you do this, you do a backward write. You might encounter common Compose pitfalls. value++ }) {. To get rid Jun 21, 2024 · Use derivedStateOf to limit recompositions. nextInt(0,99)} ){. 2. Apr 20, 2023 · 7. To accomplish this, Compose will rerun a composable function whenever its inputs change. Oct 25, 2021 · You can either remove the item and re-add it with the new value, this will cause recomposition to the list as the change is structural. current) Apr 29, 2022 · SHORT ANSWER: You use remember in Android Compose when you want to remember the value. Navigate your app to the UI you want to trace and then select System Trace and Record. Composables can accept state and expose events. It involves defining the structure and appearance of a Feb 2, 2022 · @Jerome animation will start if targetState value passed to AnimatedContent is changed since the last recomposition. – Jan 18, 2024 · It helps prevent unnecessary work and resource consumption. And when recomposition happens or not draw phase of every Composable is called as far as i recall. Share . Jetpack compose does smart recomposition, which means it skips the composition if the input hasn't changed unlike invalidate() which redraws everything even if it’s not changed. Nov 25, 2022 · We could also avoid recomposition without derivedStateOf. Jetpack Compose: Debugging May 5, 2023 · Compose Recomposition is a powerful feature of Jetpack Compose that allows developers to update parts of the UI dynamically without recomposing the entire UI hierarchy. fun SplashUI() {. val labels = MutableStateFlow(listOf<String>()) To add an element to it: label. You can use AnimatedVisibility to show/hide one specific view. First of all, a little bit of Jun 26, 2024 · Side-effects in Compose. Jetpack Compose Guidelines : This guide from Stream provides valuable insights into the best practices for using Jetpack Compose, including how to write skippable and restartable composable functions to Aug 5, 2022 · Recomposition in Jetpack Compose is the mechanism in which state changes are reflected within an app’s UI. getData(). LONG ANSWER: The mechanism works as follows when a state variable changes then recomposition is triggered, and you see the updated screen on your mobile. You can use timestamp of last change as a parameter or something like that. For example, some coding errors might force your UI to recompose excessively, which Oct 15, 2021 · You don't need to keep it in the activity, you just need to move it out of the LazyColumn. @Compose. Dec 23, 2023 · Understanding the @Stable annotation in Jetpack Compose is crucial for writing efficient and performant UI code. It embraces a code-first approach while improving the developer productivity without having to choose between using design interface or code editor. val scrollState = rememberScrollState() Box() {. One way to do this is to use produceState: val myData by produceState(initialValue = empty) viewModel. For Compose to trigger recomposition you need to change value of. Jun 12, 2023 · I'm working on a Jetpack Compose application and I've encountered an issue with unnecessary recomposition when using a variable reference inside a lambda. isLoading is changed, it is not related to Text, so I expected that recomposition would be skipped, but recomposition always occurs when Text is changed. //it has a parameter } Jul 10, 2021 · Compose skips the recomposition of a composable if all the inputs are stable and haven't changed. I thought it just increment by small number on every recomposition. May 18, 2021 · 1. This tutorial will teach you a few fundamental concepts and terms related to the Jetpack Compose UI Library on Android. fun CardSell(modifier: Modifier = Modifier){. Here is the preview of inspector: mutableStateOf(10) Button(. 5. 6. On every 5th click we trigger a recomposition for a Text as well. ( List is interface without @Stable annotation ). Wrap List parameters. So any Composable function which accepts List<T> as parameter always gets recomposed, no intelligent recomposition. You can use Compose State to hold and mutate this state. You can read answers about this in the links below. Sep 4, 2020 · Updated answer. Jun 20, 2021 · var id:Int=1, var name:String="Anonymous") However, the following class is treated as stable and favors smart recomposition when we pass the same instance again. A solution is to coordinate these two actions within your custom behavior. rememberUpdatedState: reference a value in an effect that shouldn't restart if the value changes. The following snippet is from the tutorial: There are two ways to fix this: Change our data class WellnessTask so that checkedState becomes MutableState instead of Boolean, which causes Compose to track an item change. ContentType. it. Jun 1, 2022 · 1. If the composables are identical in structure and only their data or state changes, Compose can optimize the recomposition process more effectively. val id:Int=1, val name:String="Anonymous") So, I can understand that all the public properties should be immutable. I am new in Jetpack Compose and try to using the layout inspector to see recomposition count. It produces complex and unmaintenable code, as any change in the children (e. For example: Case 1. Jetpack Compose has smart-recomposition, a system that helps do recomposition efficiently. Dec 13, 2021 · In Compose you should react on state changes instead of looking for or creating listeners. I saw the large number when button is clicked. But first, let’s remember why our code without derivatedStateOf recomposed: The reason is that the counterState changes its value and we read its value inside the composable. The problem is that your MutableList does not change when you modify its contents (the reference still remains the same). . In this applicaiton i am using Rafael Costa's Compose Destination library. nx do bf bi jf ng yb wl kv ex