AppDimens Flutter

August 22, 2026 · View on GitHub

Responsive dimensions for Android · iOS · Web · Windows · macOS · Linux — modular strategy library with fast-lane resolution

Write values like 16.sdp and the library scales them from the live window snapshot (size, density, font scale) — on every platform Flutter runs on, with the same math, the same API grammar and the same performance architecture as AppDimens Dynamic and AppDimens KMP.

This is a faithful Flutter port of the AppDimens family: same formulas (bit-parity constants), same suffix grammar (sdp, sdpa, sdpPh…), same facilitators, builders, inverters, cache design and fast lane.

✨ Highlights (3.2.0)


🧮 14 scaling modes	Scaled (default), Percent, Power, Fluid, Auto, Logarithmic, Interpolated, Diagonal, Perimeter, Fill, Fit, Density + Resize fitting + physical units
⚡ Fast lane	`16.sdp` = one static snapshot read + one multiply (~6.6–8.7 ns on a modern JIT — every audited stem sits on the harness noise floor; the Kotlin engine measures 6–30 ns on device)
🪟 Per-window snapshots	Immutable `DimenMetrics` published by `AppDimensProvider`; rotation, split-screen and font-scale changes self-heal — no stale values
🧊 Snapshot-partitioned cache	Max 4 partitions × 512 entries; dominant families bypass the hash entirely (one multiply beats a lookup)
🔤 One grammar everywhere	Suffixes `a` · `i` · `ia`, inverters `Ph/Lh/Pw/Lw`, facilitators `Rotate/Mode/Qualifier/Screen` (+ logic-only `Plain`) on every strategy
🧩 Modular	Principal artifact `appdimens_flutter` plus one opt-in package per strategy (`appdimens_percent`, `appdimens_power`, …) and an all-in-one `appdimens_bom`
♾️ Multiplatform	Android · iOS · Web · Windows · macOS · Linux — pure Dart engine, zero platform channels

🚀 Quick start

Installation

All 15 packages are published on pub.dev. Add the principal artifact with:

flutter pub add appdimens_flutter      # Flutter apps
dart pub add appdimens_flutter         # pure-Dart packages

Optional strategy satellites — install only what you use:

flutter pub add appdimens_percent        # literal % of screen axes (spaceW/spaceH)
flutter pub add appdimens_power          # sub-linear growth for large screens
flutter pub add appdimens_fluid          # clamped band ±20%
flutter pub add appdimens_auto           # phone/tablet knee at 480 dp
flutter pub add appdimens_logarithmic    # strong ±0.4·ln damping
flutter pub add appdimens_interpolated   # fixed 50% blend
flutter pub add appdimens_diagonal       # orientation-stable diagonal ratio
flutter pub add appdimens_perimeter      # half-perimeter ratio
flutter pub add appdimens_density        # dpi/160 physical alignment
flutter pub add appdimens_fill           # cover-like growth
flutter pub add appdimens_fit            # contain-like growth
flutter pub add appdimens_resize         # constraint auto-fit widgets
flutter pub add appdimens_units          # mm/cm/inch helpers

# or everything at once:
flutter pub add appdimens_bom

Equivalent pubspec.yaml:

dependencies:
  appdimens_flutter: ^3.2.0            # principal artifact (core + scaled)
  # optional strategies, exactly like the Kotlin satellite modules:
  appdimens_percent: ^3.2.0
  appdimens_auto: ^3.2.0
  # …or everything at once:
  appdimens_bom: ^3.2.0

Packages on pub.dev

Package	Purpose
appdimens_flutter	Principal artifact: core engine, cache, Scaled (`sdp/hdp/wdp/ssp`)
appdimens_bom	All-in-one meta-package (whole family, one version)
appdimens_percent · appdimens_power · appdimens_fluid · appdimens_auto	Percent · Power · Fluid · Auto
appdimens_logarithmic · appdimens_interpolated · appdimens_diagonal · appdimens_perimeter	Logarithmic · Interpolated · Diagonal · Perimeter
appdimens_density · appdimens_fill · appdimens_fit	Density · Fill · Fit
appdimens_resize · appdimens_units	Constraint auto-fit · mm/cm/inch units

The principal artifact is appdimens_flutter — the bare name appdimens was blocked by the pub.dev naming-similarity policy (app_dimen).

Wrap your app once

import 'package:appdimens_flutter/appdimens.dart';

void main() => runApp(
      AppDimensApp(                       // publishes the window snapshot
        child: MaterialApp(home: const MyPage()),
      ),
    );

Use it

import 'package:appdimens_flutter/appdimens.dart';

Box(
  width: 100.wdp,
  height: 48.hdp,
).padding(EdgeInsets.all(16.sdp))
 .child(Text('Hello', fontSize: 16.ssp));

That exact code scales correctly on phones, tablets, foldables, desktop windows and the browser.

Extension	Based on	Typical use
`sdp`	Smallest window width	Padding, margins
`hdp`	Window height	Row height
`wdp`	Window width	Column width
`ssp`	Same idea as `sdp`, for text	`fontSize`
`sem`	Same, ignoring the system font scale	`fontSize`

Suffixes

Suffix	Meaning
(none)	Default curve
`a`	Aspect-ratio aware curve
`i`	Ignore multi-window heuristic (returns the raw base inside split-screen)
`ia`	Both

16.sdpa       // + aspect ratio
32.hdpi       // height axis + ignore multi-window
16.sspa       // scalable sp + aspect ratio

Orientation inverters

32.sdpPh   // SW-based; in portrait uses height
32.sdpLw   // SW-based; in landscape uses width
50.hdpLw   // Height-based; in landscape uses width
50.wdpLh   // Width-based; in landscape uses height

Facilitators

80.sdpRotate(50)                                   // landscape → 50 scaled instead
30.sdpMode(200, UiModeType.television)             // TV → 200 scaled
60.sdpQualifier(120, DpQualifier.smallWidth, 600)  // sw ≥ 600 → 120 scaled
16.sdpRotatePlain(24)                              // logic-only pick (no double scaling)

Builder chain

final pad = 100.scaledDp
    .screen(UiModeType.television, DpQualifier.smallWidth, 600, 250)
    .screenMode(UiModeType.television, 500)
    .screenQualifier(DpQualifier.smallWidth, 600, 150)
    .screenOrientation(OrientationRequest.landscape, 120);
// resolved.sdp → scaled value under the current window

Auto-resize widgets

AutoResizeText('Headline that must fit', minSp: 10, maxSp: 28),
AutoResizeSquare(min: 40, max: 120, child: Icon(Icons.aspect_ratio)),

Explicit context (no provider needed)

final pad = 16.sdpOf(context);          // any AppDimensContext
final px  = AppDimens.getDimensionInPx(context, DpQualifier.smallWidth, 16);

📦 Modules

Package	Contents
`appdimens_flutter`	`common`, `core` (engine/cache/metrics), scaled families, provider
`appdimens_percent` … `appdimens_units`	One package per strategy — mirrors `appdimens-kmp-` / `appdimens-dynamic-`
`appdimens_bom`	Meta-package re-exporting everything at a coherent version
`apps/sample`	Converted sample app (strategy routing demo + benchmark dashboard)
`apps/benchlab`	BenchLab competitor benchmark (A/B methodology, parity tables, reports)

Full graph and dependency rules: DOCUMENTATION/MODULES.md.

📚 Documentation

Resource	Use for
DOCUMENTATION/README.md	Per-strategy explanations (14 guides)
DOCUMENTATION/API-CONVENTIONS.md	Every extension property & facilitator catalog
DOCUMENTATION/MATHEMATICS-AND-CALCULUS.md	Formal math, constants, precision policy
DOCUMENTATION/MODULES.md	Package graph
GUIDE-FOR-BEGINNERS.md	Plain-language walkthrough
PERFORMANCE.md / PERFORMANCE-COMPARATIVE.md	Measured numbers and competitor comparison
MIGRATION.md	Replacing the deprecated 2.x Flutter API
LLMS.txt · skills/	AI-agent resources (LLM index + agent workflow skill)

Recommendation order for most apps: Scaled (with or without a) → then percent → then auto; explore the rest when you have a clear need (fluid, fit, diagonal…).

🖥️ Example apps

apps/sample — every section of the demo (core extensions, inverters, facilitators, builder chains, auto-resize) plus a benchmark dashboard.
apps/benchlab — the BenchLab pipeline (UI probe, isolate engine probe, legacy T1/T2/T3 passes, resolution-parity tables, report export).

flutter run --device <id> -t lib/main.dart   # inside apps/sample or apps/benchlab

🤝 Contributing & community

CONTRIBUTING.md · CODE_OF_CONDUCT.md · SECURITY.md
Strategy packages are generated from scripts/generate_satellites.py (single source of truth for the shared grammar).
⭐ Star the repository to follow updates!

Apache License 2.0 — responsive layout utilities for Flutter (Android · iOS · Web · Windows · macOS · Linux). Part of the AppDimens family: Android/Dynamic · KMP · Flutter.