Scaled

Strategy module: appdimens_flutter · part of the AppDimens Flutter family

What it is

Linear scaling against the design baseline: values grow proportionally with the chosen window axis. It is the most widely used strategy in real apps and the recommended default of the whole family.

Calculation used

out = b × (d × ι)          ι = 1/300
out = b × (1 + (d − 300) × (0.10/30 + k × ln(AR/1.78)))   // with the a suffix

d is the axis selected by the qualifier (sw, height or width). The aspect-ratio variant adjusts growth for very tall/very wide screens.

How to use

import 'package:appdimens_flutter/appdimens.dart';
final pad    = 16.sdp;        // smallest-width curve
final height = 48.hdp;         // height curve
final width  = 100.wdp;        // width curve
final text   = 16.ssp;         // text (framework applies font scale)
final fixed  = 16.sem;         // text ignoring the font scale
final ar     = 16.sdpa;        // + aspect-ratio aware curve
final px     = 16.sdpPx;       // physical pixels

Why use it

One multiply on the hot path (the snapshot pre-computes scale), zero allocations, and a mental model everyone understands: 300 dp of design width maps 1:1.

When to use it

Default for padding, margins, icons, buttons, cards — anything without a special constraint.

Advantages & trade-offs

✅ Advantages	⚠️ Trade-offs
Fastest path in the library · predictable · identical semantics to SDP/SSP ecosystems
---	---

Recommended usage strategy

Use plain sdp when one curve is enough; add a when your layouts must stay balanced on extreme aspect ratios (foldables, tall phones, desktop windows).

---

AppDimens Flutter 3.2.0 — see MATHEMATICS-AND-CALCULUS.md for the formal derivation.