Blog

Insights on Jetpack Compose hot reload, Android, Compose UI development, and Compose HotSwan engineering.

Compose Preview Screenshots in CI: A Real Device Catalog on Every Commit

Your @Preview functions live in one editor, behind a recompile, on a renderer that does not match a phone. This walks through rendering a preview on a real device, capturing every preview into a browsable HTML catalog with captureAllPreviews, tuning the per preview render delay so slow screens still come out clean, running it all in GitHub Actions on a managed Android device, and publishing the catalog to GitHub Pages on every commit. With a working Pokedex Compose example, plus where Paparazzi and Roborazzi fit alongside it.

Jaewoong Eum (skydoves)·May 13, 2026·11 min read

From ViewModel to Pixels: Hot Reloading Compose Side Effects in One Loop

Side effects in Jetpack Compose are where the build-restart-navigate loop hurts most. A LaunchedEffect only fires when its key changes, so testing one means rebuilding, relaunching, and recreating the exact state that triggers it. With hot reload, you change the key or the body, save, and the effect re-runs immediately on the same screen. Walked through with two examples from Pokedex Compose.

Jaewoong Eum (skydoves)·May 10, 2026·8 min read

Hot Reloading AGSL Shaders Without a Rebuild: A Compose Walkthrough

Editing an AGSL shader source string at runtime usually means a full rebuild. With remember(SHADER_SRC) and HotSwan literal patching, every constant inside the shader and every Kotlin side knob becomes tunable on a running device. Walked through with a thin film soap bubble physics demo, originally by Kyriakos Georgiopoulos.

Jaewoong Eum (skydoves)·May 8, 2026·9 min read

Tuning Compose Themes Live: A Visual Feedback Loop for UI Design

Choosing a Compose UI theme usually means editing colors in source, rebuilding for thirty seconds, judging by gut, and repeating. With HotSwan Palette, an AI agent fans out several theme variants live on your running app, captures a screenshot of each, and serves a side by side grid you pick from in the browser. See every option before you commit, no rebuilds. Walked through with Now in Android.

Jaewoong Eum (skydoves)·May 7, 2026·10 min read

Tuning Compose Animations Without Rebuilding: Hot Reload for Dynamic Design

Animation development in Jetpack Compose means rebuilding your app for every tiny change to a duration, easing curve, or color value. With hot reload, you can tune animations by eye on a real device and see every change reflected in under a second.

Jaewoong Eum (skydoves)·May 2, 2026·9 min read

Why Your Android Build Takes So Long for a One Line Change

Trace the full path from a one line code change to running pixels on an Android device. Explore Gradle task graphs, Kotlin incremental compilation, KAPT vs KSP, dexing, and where the time actually goes.

Jaewoong Eum (skydoves)·April 16, 2026·12 min read

Compose Preview Renders Differently Than Your Real Device. Here's Why.

Android Studio's Compose Preview does not render the same pixels as a real device. Explore the layoutlib rendering engine, font divergence, image loading boundaries, system UI simulation, dynamic theming, and how to get pixel accurate previews on device.

Jaewoong Eum (skydoves)·April 14, 2026·14 min read

Compose Preview Driven Development with Instant Feedback

A practical guide to preview driven development with Jetpack Compose. Learn how to structure previews that stay maintainable, avoid common pitfalls, and extend previews into on device rendering and automated screenshot catalogs with zero rebuild time.

Jaewoong Eum (skydoves)·April 11, 2026·10 min read

Compose Hot Reload: Real-Time UI Updates on Running Android Devices

Android developers spend more time waiting for builds than looking at their changes. HotSwan eliminates the build-wait-navigate loop by hot reloading Compose UI changes on a running device in under a second. No restart, no state loss, no navigation reset. This article covers how it works, what you can hot reload, and why it changes day to day Compose UI development.

Jaewoong Eum (skydoves)·April 10, 2026·8 min read