jetc.dev Newsletter Issue #113
Published: 2022-04-26
This week, we look at 1.2.0-alpha08
, custom modifiers, and composable sizing.
We explore writing Compose tests, both for their own merits and for collecting
screenshots. We peek at a tree widget and an event queue implementation. And I point
out that “oh, just copy the composable and change it to meet your needs!” does
not always work out.
Alpha Analysis
Reviewing the release notes for the latest Jetpack Compose update!
1.2.0-alpha08
came out, with support for Kotlin 1.6.20! 🎉
In addition, the new alpha:
-
Makes some adjustments to the tracing APIs, including restricting them to apps that opt into them
-
Adds supports for more font weights when using
FontFamily.SansSerif
, even on older Android versions -
Tweaks the
PointerInputChange
API -
Adds
LazyLayout()
for your own lazy composables
Also, we got 1.0.0-alpha21
of Wear Compose, with a bunch of new options for
curved content, a new SwipeDismissableNavHostState
, changes to autoCenter
,
and a lot more!
One Off the Stack, One Off the Slack
You’ve got questions. That’s understandable!
How Can You Create a Reusable Modifier in Compose?
If you find yourself repeating the same Modifier
chain, you might want to create
a custom Modifier
that represents that chain. See a few techniques for doing this
in this week’s highlighted Stack Overflow question.
How Big Should a Composable Be?
Should a composable function be capped at 50 lines? 100? 500? A few developers debated
this, in this week’s highlighted Kotlinlang #compose
Slack thread!
Composable Commentary
Posts, videos, and other new information related to Jetpack Compose!
Twitter going all in on Jetpack Compose for feature development
This is an official “puff piece” from Google on the use of Compose UI by Twitter, explaining what development process improvements Twitter is seeing from making this change.
Medium: Alternatives to Idling Resources in Compose tests
A much more useful official post from Google comes by way of Jose Alcérreca. Jose
reviews waitUntil()
on ComposeTestRule
to block test execution until some
state is achieved. This can be used in lieu of Espresso-style idling or the
never-reliable delay()
approach to wait for some work to complete before proceeding
to test the UI.
Medium: Automating Beautiful Screenshots Using Jetpack Compose
Medium user sinasamaki examines how to grab screenshots from instrumented tests, then how to automate collecting those screenshots using Fastlane.
Medium: Jetpack Compose: Runtime Permissions
Erselan Khan looks at Accompanist’s tools for requesting runtime permissions,
centered around the rememberPermissionState()
and rememberMultiplePermissionsState()
functions.
Medium: Exploring Google Map Compose Library For Android
Stephen Vinouze returns, examining the official composable wrapper for Google Maps. Stephen specifically looks at how to add markers and how to address those markers as the user pans and zooms the map.
Other Interesting Links
- Medium: Integrating ExoPlayer in Jetpack Compose Android
- Jetpack Compose Ticket ZigZag View
- How to Create a Collapsing Toolbar in Android using Jetpack Compose?
- Nested Scrolling in Android using Jetpack Compose
- Android Custom Dialog using jetpack compose
- Medium: Jetpack Compose Basics
- Jetpack Compose Basics - Preview and it’s parameters
- Slides: Jetpack Compose - The Future of Android Development (Extended)
Resource Roundup
100% pure code!
GitHub: adrielcafe / bonsai
Adriel Café planted a Bonsai()
tree widget composable, supporting both Compose UI
for Android and Compose for Desktop. You can create your tree structure through a DSL
or via filesystem or JSON integration.
GitHub: patrykandpatryk / vico
GitHub user patrykandpatryk created a chart library for Compose UI and the classic
View
system, though not by the traditional interop approaches (e.g., using AndroidView()
to wrap the View
in a composable). The library supports bar and line charts,
including a combined “composed” chart.
GitHub: JustinGuedes / redactable-android
Justin Guedes brings us a LoadableView()
wrapper composable that will render
your UI with “redacted” content, showing a shimmer effect, while you load the
actual content.
Gist: okmanideep / EventQueue.kt
Manideep Polireddi created an EventQueue
implementation, designed for composables
to be able to react to events coming from a viewmodel. See this Twitter thread
for usage notes.
Other Interesting Links
- GitHub: re-ovo / md3compat (backward compatible Material You implementation)
- GitHub: copper-leaf / ballast (KMP state management framework)
- GitHub: timbrueggenthies / compose-video-player (Compose-first video player)
…And One More Thing
When we ask why certain official composables do not offer Feature X, we are often
told “it’s all open source, just copy and modify the composable to do what you want”.
While true, this approach has a variety of problems. One of those problems: some
official composables cannot be copied, because they rely on internal
APIs.
For example, as part of an upcoming blog post series, I wanted to create a Presentation()
composable. In the Android SDK, Presentation
is a key way to get content onto
external displays. For reasons I have never really understood, Presentation
is a subclass of Dialog
. But, since Compose UI has a Dialog()
composable,
I figured that I could copy it and tweak the implementation to use a Presentation
instead of a Dialog
.
That… did not work. A fair bit of the Dialog()
implementation relies on internal
APIs. Most notably, the content of the dialog is handled by a DialogLayout
class that extends AbstractComposeView
and overrides some internal
functions.
It is not out of the question that I could hack away at things and eventually
get rid of those internal
references. For the purposes of a demonstration in a blog
post, I elected to go a different route.
Most of the composables that we are suggested to clone and modify will be farther
away from low-level Compose UI plumbing. For example, wanting a Compose Material
widget that goes against Material Design in one area is likely to be relatively
easy to address. However, the closer you get to the Android SDK, the more likely it is
that you will run into places where the code that you are copying depends on being
part of Compose UI itself, as Dialog()
does.
Or, you can subscribe to the Atom feed or follow Mark Murphy in the Fediverse.
Recent Issues:
- 2024-10-29: Relay! Paparazzi! droidcon Lisbon 2024! Server-defined UI! And... desktop OS trays?!?
- 2024-10-22: Compose patch! Compose alpha! Compose Multiplatform stable! droidcon NYC! Adaptive UIs! MVI! HTML conversions! Math rendering! And... are we now Fluent in Compose?!?
- 2024-10-15: Alpha and beta BOMs! Compose Multiplatform UI testing! Compose Multiplatform camera apps! Passing data between screens in Navigation for Compose! JSON rendering!