Fluid strategy (compose.fluid / code.fluid)

April 4, 2026 · View on GitHub

Same API surface as scaled with prefixes fsdp / fhdp / fwdp / fssp / … — see COMPOSE-API-CONVENTIONS.md §3.

What it is

Fluid clamps variation to a narrow band around the base in the mid phone range: the effective size interpolates between 80% and 120% of the base while the axis (in dp) runs from 320 to 768; below 320 it stays at 80%; above 768 it caps at 120%.

Calculation used

With dim the effective axis in dp:

  • minV = base × 0.8, maxV = base × 1.2
  • If dim ≤ 320 → v = minV
  • If dim ≥ 768 → v = maxV
  • Else → linear interpolation of minV to maxV between 320 and 768
  • With a: multiply by the pre-computed aspect-ratio factor (DimenCache.currentAspectRatioMul); custom sensitivity uses 1+k×logNormalizedAr1 + \text{k} \times \text{logNormalizedAr}.

Implementation: calculateFluidDpCompose in DimenFluidDp.kt.

How to use

import com.appdimens.dynamic.compose.fluid.fsdp
import com.appdimens.dynamic.compose.fluid.fssp

Modifier.padding(16.fsdp)
Text("Title", fontSize = 20.fssp)

Compose prefixes: fsdp, fhdp, fwdp (and Sp, px, inverter, a/i variants).

Code: com.appdimens.dynamic.code.fluid.

Why use it

For typography and spacing that should not swing much across typical phones, avoiding visible jumps on small width changes.

When to use it

  • Dense UI in the 320–768 dp band.
  • When scaled feels too sensitive between two phone sizes.

Advantages and trade-offs

  • Pros: stable behavior for most devices; clear plateaus outside the band.
  • Cons: above 768 dp size stops growing (120% cap) — may or may not be desired; large tablets may need another strategy or larger tokens.

Use fluid on specific components (e.g. card body text) alongside scaled elsewhere; test at 320 and 768 and on tablets to validate the upper plateau.

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