android-ux

Android UX

This reference covers the non-obvious platform facts and reviewing an existing screen for M3 compliance, not the basics of building M3-correct UI.

Non-obvious platform facts

Foldable postures

Foldables introduce postures beyond window size classes. Detect them with WindowInfoTracker + FoldingFeature (Jetpack WindowManager), and never place interactive content or critical information across the hinge.

Posture	Detection	Layout behavior
Flat (unfolded)	no folding feature	Treat as Medium/Expanded by width
Half-opened, horizontal fold (tabletop)	HALF_OPENED + Orientation.HORIZONTAL	Content top half, controls bottom half
Half-opened, vertical fold (book)	HALF_OPENED + Orientation.VERTICAL	List left, detail right
Folded (cover screen)	—	Treat as Compact

@Composable
fun FoldAwareLayout() {
    val context = LocalContext.current
    val layoutInfo by WindowInfoTracker.getOrCreate(context)
        .windowLayoutInfo(context)  // accepts @UiContext — Activity, InputMethodService, or createWindowContext()
        .collectAsStateWithLifecycle(initialValue = WindowLayoutInfo(emptyList()))

    val fold = layoutInfo.displayFeatures.filterIsInstance<FoldingFeature>().firstOrNull()
    when {
        fold?.state == FoldingFeature.State.HALF_OPENED ->
            if (fold.orientation == FoldingFeature.Orientation.HORIZONTAL) TabletopLayout() else BookLayout()
        else -> StandardAdaptiveLayout()  // by window size class
    }
}

M3 contrast levels (user-controlled contrast)

Compose's dynamicLightColorScheme / dynamicDarkColorScheme read the system contrast setting automatically (SDK 34+) and expose no contrast parameter. To offer in-app contrast control (Standard 0.0 / Medium 0.5 / High 1.0 tonal distance), build the scheme from Hct + SchemeContent:

// com.google.android.material:material (MDC-Android), package com.google.android.material.color.utilities
// Marked @RestrictTo(LIBRARY_GROUP) — internal API, may change between versions; re-check on version bumps.
val hct = Hct.fromInt(0xFF6750A4.toInt())
val scheme = SchemeContent(hct, /* isDark = */ false, /* contrastLevel = */ 1.0)
val colorScheme = lightColorScheme(
    primary = Color(scheme.primary),
    onPrimary = Color(scheme.onPrimary),
    // ... map remaining roles
)