Logarithmic strategy (compose.logarithmic / code.logarithmic)

August 30, 2026 · View on GitHub

Artifact: io.github.bodenberg:appdimens-kmp-logarithmic:3.2.0 (:library-logarithmic) See MODULES.md · README installation

Same API surface as scaled with prefixes logsdp / loghdp / logwdp / logssp / … — see COMPOSE-API-CONVENTIONS.md §3.

What it is

Logarithmic shapes the multiplier with the natural log around 300 dp on the effective axis: above 300 dp it grows with ln(dim/300); below it shrinks with ln(300/dim). Internal sensitivity 0.4 in the current implementation. Smooths extremes without rigid plateaus like fluid.

Calculation used

Mathematically (effective axis dim in dp):

  • inv = 1/300
  • If dim > 300: scale = 1 + 0.4 × ln(dim × inv)
  • If dim ≤ 300: scale = 1 − 0.4 × ln(300 / dim)
  • out = base × scale

Implementation note: For smallest-width + default inverter, scale is derived from the immutable per-window snapshot (DimenCache.currentMetrics) at resolution time — no process-global pre-computation. Other qualifiers still evaluate the piecewise ln formula above inline.

  • With a: multiply by the pre-computed aspect-ratio factor (DimenCache.currentAspectRatioMul); custom sensitivity uses 1+k×logNormalizedAr1 + \text{k} \times \text{logNormalizedAr}.

Implementation: calculateLogarithmicDpCompose in DimenLogarithmicDp.kt.

How to use

import com.appdimens.kmp.compose.logarithmic.logsdp

Modifier.height(56.logsdp)

Prefixes: logsdp, loghdp, logwdp (+ Sp, px, variants).

Code: com.appdimens.kmp.code.logarithmic.

Why use it

Damped growth across very wide size ranges, useful when linear jumps between compact phones and tablets hurt hierarchy.

When to use it

  • Very wide sw ranges with the same token.
  • When power still grows too fast at the top end.

Advantages and trade-offs

  • Pros: smooth, monotonic curve; anchor at 300 dp.
  • Cons: less intuitive for non-technical stakeholders; document logarithmic tokens in the design system.

Apply locally (accent type, nav icons) and keep scaled for the base grid; compare side by side with interpolated in mocks before locking in.

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