Dispatch Issue # 10

🥂 Tipsy Tip

Smooth Animations with keyframesWithSpline

Looking to add buttery smooth animations to your Jetpack Compose app? Introducing keyframesWithSpline! Unlike the standard keyframes animation spec, keyframesWithSpline produces a natural, smooth curve—perfect for animating predefined X, Y coordinates.

What's the Big Deal?

When animating movements along a path, especially with non-linear motions, smoothness is key. Traditional keyframes can produce abrupt transitions between points. With keyframesWithSpline, you get a Monotone Cubic Hermite Spline interpolation, resulting in seamless animations 😵‍💫

But what the hell is Monotone Cubic Hermite Spline interpolation?

Here's a simpler way to think about it:

When you have a bunch of points (like X and Y coordinates) and you want to connect them with a smooth curve (instead of jagged straight lines), Monotone Cubic Hermite Spline interpolation is basically a “draw a smooth curve through all these points without any weird wiggles or overshoots” technique.

1. "Monotone" means no dramatic, unintended dips or peaks. Think of a gentle hill rather than a roller coaster.
2. "Cubic Hermite Spline" is just math-speak for a formula that guarantees the curve gently passes through each point in a smooth, continuous way.

Here's how one can use it:

val pathAnimation = keyframesWithSpline<Offset> {
    durationMillis = 2000
    Offset(0f, 0f) at 0  // Starting point
    Offset(100f, 200f) at 500
    Offset(200f, 100f) at 1000
    Offset(300f, 300f) at 1500
    Offset(400f, 0f) at 2000  // Ending point
}

val position by animateValueAsState(
    targetValue = ...,
    animationSpec = pathAnimation
)

🔦 Community Spotlight

Have you ever wrestled with the order of Modifiers in Jetpack Compose? You’re not alone! Modifier ordering can sometimes lead to unexpected UI results.

Marcin Moskala has crafted a fun game called Modifier Order Guesser to help you sharpen your intuition about Modifiers.

Here’s how it works - you're presented with a snippet of code that leverages Modifiers and are also presented two components that potentially represent the output of the code snippet. Your job is to pick the right option out of the two. Great way to pass some time and wrap your heads around Modifier ordering.

💡 If your team meets regularly to talk Android, this game could be a fun segment in one of those meetings!

🥷 Featured Developer

I’d like to amplify a really talented Android community member, Rivu Chakraborty, who’s looking for his next role. He’s India’s very first GDE and has worked at companies like Viacom18, Meesho, Gojek, Paytm, BYJU’s, etc. He’s trying to relocate his family so if you or your company are hiring in Europe, kindly reach out to him directly 🙏🏻

Rivu Chakraborty

@rivuchakraborty

I am looking for opportunities in Europe. If you're hiring for senior Android/KMP roles, let's get in touch.I have been in industry for over 13 years (mostly in Android), have been working with KMP for ~6 years, led KMP in my current org with 200+ millions of users (on prod with KMP). Will need Visa and relocation support. Reason: can't find good schooling options for my autistic son in India, so decided as a family to relocate.

🍾 Pop Quiz: Solution

// Compiles successfully
fun puzzle() {
    return run { 42 }
}

// Doesn't compile
fun puzzle() {
    return 42 // Error: return type mismatch
}

// Why??

In Kotlin, if a function doesn't explicitly declare a return type, it defaults to returning Unit. When you use run, its return type is inferred from the context. Since puzzle() is expected to return Unit, run is inferred as run<Unit> { 42 }.

Moreover, for Unit-returning lambdas, the last expression isn't treated as the return value. So, run { 42 } effectively does nothing significant and returns Unit, satisfying the function's expected return type.

It is a crucial feature of the Kotlin language which makes its easy to work with lambdas in practical cases. This feature is actually called "Coercion to Unit" in the Kotlin language specification.

🦄 How you can help?

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On that note, here’s hoping that your bugs are minor and your compilations are error free.