compose-preview

Jetpack Compose Preview

A plugin for CodeOnTheGo that renders Jetpack Compose @Preview composables on-device — it compiles and runs the previews inside the IDE, without a full app build-and-run.

Surfaces as a preview action in the editor toolbar, shown only when a Kotlin file containing @Preview is open (on those files it also hides the built-in XML layout-preview action, so there's a single preview entry point). Tapping it opens a Jetpack Compose Preview screen that renders every @Preview in the file, honoring light/dark, @PreviewParameter, and per-preview background and size.

Building

cd compose-preview
./gradlew assemblePlugin

The .cgp lands in build/plugin/. Install it from inside CodeOnTheGo via the Plugin Manager.

How it works

• Toolbar integration — contributes an EDITOR_TOOLBAR action via UIExtension.getToolbarActions(), gated to Compose files by an isVisibleProvider. getHiddenToolbarActionIds() hides the host's XML preview action while a Compose file is open.
• Render pipeline — parses the file's @Preview functions, compiles the current editor buffer with the bundled Compose toolchain, dexes it, loads it through a child DexClassLoader, and invokes each composable into a host-Activity-backed ComposeView. Supports All (labelled cards) and Single display modes, @PreviewParameter value expansion, and per-@Preview showBackground / widthDp / heightDp / uiMode.
• Project context — resolves the module's classpaths through the official IdeProjectService (getModuleContext). When compiled intermediates are missing it shows a Build required screen whose button triggers a Gradle build via IdeBuildService, then re-renders.
• Bundled toolchain — src/main/assets/compose/compose-jars.zip carries the Compose compiler + runtime jars used to compile and run previews on-device (the host no longer ships them after extraction). Kept uncompressed in the .cgp (noCompress += "zip").
• Docs & tooltips — implements DocumentationExtension to register tiered tooltip entries; Tier-3 HTML is served from src/main/assets/docs/.
• UI — Views + ViewBinding (fragment_compose_preview.xml), MVVM (ComposePreviewViewModel).

Dependencies from libs/

• ../libs/plugin-api.jar — the plugin API surface (compile-only; provided by the IDE at runtime).
• ../libs/gradle-plugin.jar — the com.itsaky.androidide.plugins.build Gradle plugin that packages the .cgp.

Unlike most example plugins, this one bundles Jetpack Compose itself (compose-bom as implementation) into the .cgp and ships the on-device compile toolchain under assets/.

Note: this plugin requires the extended plugin-api — IdeProjectService.getModuleContext, UIExtension.getHiddenToolbarActionIds, ToolbarAction.isVisibleProvider, and IdeBuildService.executeTasks. If assemblePlugin fails with unresolved references to those, the shared libs/ jars are older than the API this plugin needs; refresh them from a CodeOnTheGo build that includes the extensions (../scripts/update-libs.sh --local <path-to-CodeOnTheGo>).