AppDimens Flutter — Smart Responsive Dimensioning

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

       

        

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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.

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✨ 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

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🚀 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);

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📦 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.

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📚 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…).

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🖥️ 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

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🤝 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!

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