What about a desktop app?

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A guide to Compose on desktop for the curious Android dev Sebastiano Poggi What about... a desktop app? @seebrock3r

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Setting expectations

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Different mindset Desktop-only APIs may differ Same idea

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Different mindset Desktop-only APIs may differ Same idea

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Notable differences • Lifecycle is much easier • Window chrome, menu bars, tray icons • Less restrictions • E.g., full filesystem access, no permissions system • Some things require "going down" • Swing and/or P/Invoke via JNI

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https://www.jetbrains.com/toolbox-app/ https://github.com/theapache64/stackzy

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it's beta Some stuff may be missing or broken Builds upon Jetpack Compose stable

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Getting started

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GOTO: https:!"github.com/JetBrains/compose-jb/ Compose for Desktop sources repo

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Hold on! Only one link to write down: https:!"go.sebastiano.dev/desktop-app-2021 Look out for the symbol

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IDE support • Compose Multiplatform plugin • Also supports web • Android Studio and IntelliJ IDEA • Tooling is lagging behind Jetpack Compose's • No interactive preview and animation inspector • Missing many quality-of-life tweaks

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Familiar faces • Core Compose libraries: runtime foundation ui material • Same packages and API names as Jetpack Compose • Compose compiler plugin • Requires Kotlin (duh)

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What's different

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Android-only APIs • No access to anything outside: • androidx.compose.* • java.* • kotlin.* • No permissions • No Android-only dependencies • Architecture Components • Other Jetpack libraries • Firebase • etc What's different Old-school UI Resources a11y UI testing

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What's different • No Android Views • MapView, etc • No WebView equivalent • Interop with "classic" Java UI • Swing hosts Compose • Compose can wrap Swing • No activities and fragments • Different (easier) lifecycle • Swing windows Android-only APIs Old-school UI Resources a11y UI testing

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What's different • Java resources system • No buckets • No concept of configuration • No orientation, display size, etc • I18n support is not built in • No RTL support yet • No animated GIFs • No animated vector drawables • Non-animated are supported • Resource refs not resolved • Lottie not supported yet • Maybe Skottie in the future? Android-only APIs Old-school UI Resources a11y UI testing

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What's different • APIs are there, but not hooked up • semantics() • Work in progress • Should be there for 1.0.0 • Current state: • Mostly works on macOS • Other OSes done next • No clue about ETAs, sorry Android-only APIs Old-school UI Resources a11y UI testing

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What's different • Not entirely true, it's mostly the same • UI testing is the same as on Android • Except, of course, (much) faster • Use createComposeRule() • Additional API (e.g., mouse scroll) • Fun idea: run your UI tests on CfD • Screenshot testing is different • TestComposeWindow • WIP: APIs for animations Android-only APIs Old-school UI Resources a11y UI testing

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Unique features

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Unique features • Desktop is different from mobile • Unique needs == unique features • Windowing • Multiple windows at the same time • Compose handles JFrames for you

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Unique features • Enhanced keyboard support • Keyboard shortcuts • Tooltips • Menus, tray icons, desktop notifications • Native installers (msi/exe, dmg/pkg, deb/rpm) • Output size saving tips • Notarization for macOS

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Unique features • Scrollbars • Yes, Jetpack Compose still doesn't have those • Works with scroll modifiers and LazyColumn/LazyRow • Mouse events • Pointer movement (hover) • Modifier keys and mouse buttons

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Unique features • Desktop-only components & integrations • Split panel • Video player • CEF-based WebView (outdated) • LWJGL integration

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Unique features • Desktop-only components & integrations • Split panel • Video player • CEF-based WebView (outdated) • LWJGL integration EXPERIMENTAL

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Libraries

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Libraries • A lot of JVM-only libraries out there • Some direct replacements • Some Android libs make no sense on desktop • Well, most don't • Some Accompanist libs work on desktop • Pager, Placeholder, FlowLayout, Swipe-to-Refresh (?)

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Libraries • No Play Services • No Firebase • Java or REST APIs for some • No Architecture Components • No ViewModel, Navigation, Room, Hilt, etc

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Library alternatives Navigation Decompose Room SqlDelight Hilt Dagger Timber Arbor Coil/Glide/Picasso/... Hand-rolled ! ViewModel Essenty's InstanceKeeper (but it's not really the same)

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Theming

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Theming • Material theme is fully supported • Material You will, as well • Material is not great on desktop • Huge touch targets for use with mouse • There is no "official" desktop-oriented UI framework

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Kirill Aurora Grouchnikov's

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Distribute your app

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Distribute your app • Gradle tasks to build installers • OS-specific outputs • macOS is different • Requires notarisation • Signing to make Gatekeeper happy • Only required to distribute, not to run locally

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Life outside app stores • No Play Store, Amazon Appstore, Samsung App Gallery • No auto-updates, built-in licensing and IAB • Some Java libs may help to compensate (e.g., update4j) • You may be able to publish on OS stores... • But mileage may vary • May be harder on macOS App Store

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Closing remarks

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Closing remarks • Kotlin Multiplatform support • Share business logic • Share some degree of UI code (Android and Desktop) • Web is totally different, hard to share • Check out Jake Wharton's Mosaic