Flutter Scale Kit #

A high-performance responsive design package for Flutter that helps you create adaptive UIs across different screen sizes with easy-to-use scaling utilities.

✨ Key Features #

• 🧠 Intelligent Auto-Configuration: Automatically detects optimal scale limits based on device type, screen size, orientation, and aspect ratio—works out of the box in 95% of cases
• 📱 Universal Platform Support: Handles phones, tablets, desktop, and web with platform-specific optimizations and built-in device detection helpers
• 🔄 Orientation-Aware Scaling: Adjusts scaling factors on rotation with per-orientation boosts and optional overrides
• 🎯 Design Fidelity: Keeps UI proportional to design mockups via size enums (SKSize), design tokens, and centralized ScaleKitDesignValues
• ⚡ High Performance: Cached calculations, flyweight factories, and threshold-based updates minimize rebuild overhead
• 🛠️ Developer-Friendly API: Familiar .w, .h, .sp, .rSafe extensions plus SKit helpers, responsive builders, and ThemeData integration
• 🔤 Font Intelligence: Language-aware font configuration with Google Fonts/custom families applied automatically across Text and themes
• 🧪 Runtime Controls & Tooling: Enable/disable scaling at runtime, integrate with device_preview, and compare raw Flutter vs scaled behavior instantly
• 📚 Comprehensive Docs & Examples: Live web demo, screenshots, and step-by-step guides covering quick start through advanced tuning

If this package helps you, please click "Like" on the pub.dev page — it improves discoverability and ranking.

💝 Support this project: If you find Flutter Scale Kit useful, consider buying me a coffee to help me continue developing and maintaining open-source packages. Your support means a lot! 🙏

📑 Table of Contents #

Jump to any section:

• 📸 Screenshots

🚀 Quick Start #

• 🧠 Intelligent Auto-Configuration
• ✨ Key Features
• 📦 Installation
• ⚡ Quick Start Guide
• 💡 Recommended Building Blocks

📖 Core Concepts #

• Understanding Scale Limits (minScale & maxScale)
• Understanding Orientation Boosts (Advanced)

🎨 Usage & Widgets #

• Layout & Container Helpers (SKit)
• Extension Methods (.w, .h, .sp, .rSafe)
• Typography & Theme
• Size System Configuration
• ScaleKitDesignValues - Centralized Design System
• Context Extensions

🔧 Advanced Features #

• ScaleManager Direct API
• Responsive Builder & Columns
• ThemeData Integration
• Orientation Autoscale (Landscape vs Portrait)
• Font Configuration (Automatic Font Selection)

🧪 Optional Tools #

• Enable/Disable Scaling (Runtime Toggle)
• Device Preview Integration (Optional)

📚 Reference #

• API Reference
• Performance
• Architecture
• Advanced Tuning Reference
• Device-Specific Scaling
• FAQ

🤝 Community #

• Contributing
• Support
• License

Screenshots #

Desktop #

Autoscale and Enable/Disable Examples #

🧠 Intelligent Auto-Configuration #

Scale Kit is SMART — it automatically detects and configures optimal scaling for your app:

That’s all—no minScale, maxScale, or boost knobs required. The limits and boosts you saw above activate automatically so 95% of projects ship with zero manual tuning.

💡 When to tweak manually? Only when you need tighter compliance (e.g., ±5% variance for brand-critical screens) or a custom scaling feel. Jump to Manual Override Examples for recipes, and follow the Quick Start Guide for the full setup flow.

Installation #

Add this to your package's pubspec.yaml file:

dependencies:
  flutter_scale_kit: ^1.1.2

Then run:

flutter pub get

⚡ Quick Start Guide #

1. Configure Size Values & Fonts (Optional but Recommended) #

Set up your size configurations and optional font setup at app startup. This defines what values SKSize.md, SKSize.lg, etc. represent for padding, margin, radius, and spacing. FontConfig is optional but recommended for a full design system.

void main() {
  // Configure sizes at app startup (before runApp)
  setPaddingSizes(SizeValues.custom(xs: 4, sm: 8, md: 16, lg: 24, xl: 32, xxl: 48));
  setMarginSizes(SizeValues.custom(xs: 2, sm: 4, md: 8, lg: 12, xl: 16, xxl: 24));
  setRadiusSizes(SizeValues.custom(xs: 2, sm: 4, md: 8, lg: 12, xl: 16, xxl: 24));
  setSpacingSizes(SizeValues.custom(xs: 4, sm: 8, md: 12, lg: 16, xl: 20, xxl: 24));
  setTextSizes(TextSizeValues.custom(s14: 15, s16: 17, s18: 20, s24: 26));

  // Set default values for methods without parameters
  setDefaultPadding(16);
  setDefaultMargin(8);
  setDefaultRadius(12);
  setDefaultSpacing(8);
  setDefaultTextSize(14);

  // Optional: apply FontConfig during app bootstrap
  FontConfig.instance
    ..setDefaultFont(googleFont: GoogleFonts.inter)
    ..setLanguageFont(
      const LanguageFontConfig(
        languageCode: 'ja',
        googleFont: GoogleFonts.notoSansJp,
      ),
    )
    ..setLanguageGroupFont(
      const LanguageGroupFontConfig(
        languageCodes: ['ar', 'fa', 'ur'],
        googleFont: GoogleFonts.almarai,
      ),
    );

  // Optionally cache the defaults for reuse (e.g., wrap in your own widget)
  final defaults = SKitValues.defaults(); // returns padding/margin/radius/spacing with current config
  debugPrint('Default padding: ${defaults.padding}');

  runApp(const MyApp());
}

Note: If you don't configure sizes, default values will be used (xs=2, sm=4, md=8, lg=12, xl=16, xxl=24). FontConfig is optional—see Typography & Theme for details.

2. Wrap Your App #

Drop ScaleKitBuilder above your root app and pass the design size you targeted in Figma/Sketch. Everything else rides on the smart defaults described in Intelligent Auto-Configuration: per-device min/max clamps, landscape boosts, font selection, and responsive caches.

import 'package:flutter/material.dart';
import 'package:flutter_scale_kit/flutter_scale_kit.dart';
import 'package:google_fonts/google_fonts.dart'; // Import for FontConfig example

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    // 👇 Wrap your app so every route inherits responsive scaling
    return ScaleKitBuilder(
      designWidth: 375,
      designHeight: 812,
      designType: DeviceType.mobile,
      child: MaterialApp(
        title: 'My App',
        // Optional: create a responsive theme once ScaleKitBuilder is in place
        theme: ResponsiveThemeData.create(
          context: context,
          colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
          useMaterial3: true,
        ),
        home: HomePage(),
      ),
    );
  }
}

• Phones hold between 0.85–1.25×, even on foldables.
• Tablets expand comfortably without blowing out typography.
• Desktop & web respect tiny windows and ultrawide monitors.

📝 FontConfig & responsive theme are optional: if you never call FontConfig or ResponsiveThemeData, everything renders with Flutter’s defaults. Configure them later for a complete design system (see Typography & Theme)—all SKit text helpers and cached styles will pick up your fonts automatically.

Need a different feel? Head to Manual Override Examples for tighter or looser ranges.

Understanding Scale Limits (minScale & maxScale)

Scale limits are the guard rails that keep responsive layouts feeling familiar as screens grow or shrink. In nearly every project you can leave them unset and let Scale Kit pick the right range for each device type and orientation.

• Auto first: the defaults protect small phones from feeling cramped and keep large monitors from blowing up every pixel.
• Optional overrides: add limits only when you need a tighter (or looser) experience than the defaults provide.

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  minScale: 0.9, // Optional override
  maxScale: 1.2, // Optional override
  child: MaterialApp(home: HomePage()),
);

Need the exact formulas or override recipes? Jump to the Advanced Tuning Reference.

Understanding Orientation Boosts (Advanced)

Orientation boosts are gentle multipliers that run after scale limits to keep content readable when a device rotates. Smart defaults already cover the common cases, so you only tweak them for specialized layouts.

• Boosts are split for fonts and sizes so text can scale differently from containers.
• System text scaling (.sp) is respected on top of these multipliers.

Curious about the math, per-device parameters, or real-world scenarios? See the Advanced Tuning Reference.

3. Use Extension Methods #

Use extension methods for quick scaling:

Container(
  width: 200.w,      // Scaled width
  height: 100.h,     // Scaled height
  padding: EdgeInsets.all(16.w),
  decoration: BoxDecoration(
    borderRadius: BorderRadius.circular(12.rSafe),
  ),
  child: Text(
    'Hello World',
    style: TextStyle(fontSize: 16.sp),
  ),
)

4. Use SKit Helper Methods #

Use SKit helper methods for convenient widget creation:

SKit.padding(
  all: 16,
  child: SKit.roundedContainer(
    all: 12,
    color: Colors.blue.shade50,
    borderColor: Colors.blue,
    borderWidth: 2,
    child: Text('Hello'),
  ),
)

Note: Most containers need both borderRadius and border. Use borderColor and borderWidth parameters to add borders to your rounded containers. You can also specify borders on individual sides (top, bottom, left, right) with different colors and widths. All border widths are automatically scaled based on screen size. You can further enhance the decoration with gradient, backgroundImage, boxShadow, elevation, shadowColor, and shape for Material-like cards or image-backed surfaces.

5. Recommended Building Blocks #

Kick-start your layouts with the helpers teams reach for most. Each snippet keeps things simple up front and links to the deep-dive section when you’re ready.

ScaleKitBuilder + .w/.h/.sp #

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  child: MaterialApp(
    home: Scaffold(
      body: Padding(
        padding: EdgeInsets.all(20.w),
        child: Text(
          'Welcome!',
          style: TextStyle(fontSize: 20.sp),
        ),
      ),
    ),
  ),
);

• Place ScaleKitBuilder directly above your MaterialApp (or CupertinoApp) so every route inherits scaling.
• .w, .h, and .sp keep spacing, components, and fonts proportional to the screen.
  ➜ Learn more in Extension Methods.

SKit helper widgets #

SKit.roundedContainer(
  all: 16,
  color: Colors.white,
  padding: EdgeInsets.symmetric(horizontal: 20.w, vertical: 16.h),
  borderColor: Colors.black12,
  borderWidth: 1,
  radiusMode: SKRadiusMode.safe, // uses rSafe clamp internally
  child: Column(
    crossAxisAlignment: CrossAxisAlignment.start,
    children: [
      SKit.text(
        'Dashboard',
        textSize: SKTextSize.s20,
        fontWeight: FontWeight.w600,
      ),
      SizedBox(height: 12.h),
      SKit.text(
        'All metrics auto-scale with the screen.',
        textSize: SKTextSize.s16,
        color: Colors.grey.shade600,
      ),
    ],
  ),
);

• One-liners for padding/margin: SKit.padding(horizontal: 24, vertical: 12); use enums for presets (SKit.paddingSize(horizontal: SKSize.lg)).
• Containers respect .rSafe by default via SKRadiusMode.safe, so borders stay natural on large screens.
  ➜ Explore the full API in SKit Helper Class.

textFull / textStyleFull #

textFull(
  'Headline',
  fontSize: 24,
  fontWeight: FontWeight.w600,
  maxLines: 2,
  textAlign: TextAlign.center,
);

• One call sets typography, layout, and accessibility options—fonts auto-scale.
• Ideal for marketing screens, dashboards, or anywhere text configuration repeats.
  ➜ Details in Comprehensive Text Widgets.

ScaleKitDesignValues design system #

const design = ScaleKitDesignValues(
  textMd: 16,
  paddingMd: 16,
  radiusMd: 12,
  spacingMd: 16,
);

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  child: MaterialApp(
    home: Builder(
      builder: (context) {
        final values = design.compute();
        return SKPadding(
          padding: values.paddingMd!,
          child: SKContainer(
            margin: values.marginMd,
            decoration: BoxDecoration(
              borderRadius: values.borderRadiusMd,
            ),
            child: Text('Hello', style: values.textMd),
          ),
        );
      },
    ),
  ),
);

• Define tokens once, compute per screen, and reuse responsive values everywhere.
• Works great with const widgets and reduces repetitive size/spacing code.
  ➜ Deep dive at ScaleKitDesignValues - Centralized Design System.

Need device-aware layouts? SKResponsiveBuilder chooses the right builder for mobile, tablet, desktop, and landscape variants automatically. See Responsive Builder & Columns.

SKResponsiveBuilder layout switcher #

SKResponsiveBuilder(
  mobile: (_) => _CardsGrid(columns: 1),
  tablet: (_) => _CardsGrid(columns: 2),
  desktop: (_) => _CardsGrid(columns: 4),
  mobileLandscape: (_) => _CardsGrid(columns: 2),
);

• Supplies dedicated builders per device/orientation and falls back intelligently when one is missing.
• Perfect for dashboards, catalog pages, or any layout that needs different density on phones vs tablets vs desktop.
  ➜ Details in Responsive Builder & Columns.

Usage #

Flutter Scale Kit provides multiple ways to create responsive UIs. Whether you prefer extension methods like .w and .sp, helper widgets like SKit.roundedContainer(), or comprehensive text styling with SKit.textFull(), there's an API that fits your workflow.

All text-related APIs (extensions, SKit.text*, responsive themes) automatically apply your FontConfig when one is registered—otherwise they fall back to Flutter's default fonts so you can adopt the system gradually.

Quick Examples #

// Extension methods - Simple and familiar
Container(
  width: 200.w,      // Scaled width
  height: 100.h,     // Scaled height
  child: Text(
    'Hello World',
    style: TextStyle(fontSize: 16.sp),  // Scaled font size
  ),
)

// SKit helpers - Pre-built responsive widgets
SKit.roundedContainer(
  all: 16,           // Responsive padding
  color: Colors.blue.shade50,
  child: Text('Content'),
)

// Comprehensive text widgets - All attributes in one place
SKit.textFull(
  'Styled Text',
  fontSize: 18,      // Automatically scaled
  fontWeight: FontWeight.bold,
  color: Colors.blue,
  textAlign: TextAlign.center,
)

Layout & Container Helpers (SKit) #

The SKit class provides convenient methods for creating widgets:

Extension Methods (.w, .h, .sp, .rSafe) #

All extension methods work similar to flutter_screenutil:

// Width scaling
200.w           // Scaled width

// Height scaling
100.h           // Scaled height

// Font size scaling
16.sp           // Scaled font size

// Border radius scaling
12.r            // Full responsive radius (great for circles/avatars)
12.rSafe        // Stable radius (clamped, default for corners)
12.rFixed       // Constant radius (no scaling)

// Screen percentage
0.5.sw          // 50% of screen width
0.25.sh         // 25% of screen height

// Font size with system factor
16.spf          // Scaled font size with system text scale factor

Layout & Container Helpers (SKit) #

The SKit class provides convenient methods for creating widgets:

// Padding
SKit.padding(all: 16, child: widget)
SKit.paddingSize(all: SKSize.md, child: widget)
final insets = SKit.paddingEdgeInsets(all: 16); // Scaled EdgeInsets

// Margin
SKit.margin(12, child: widget)
SKit.marginSize(all: SKSize.md, child: widget)
final marginInsets = SKit.marginEdgeInsetsSize(all: SKSize.md);

// Rounded container with border on all sides
SKit.roundedContainer(
  all: 12,
  color: Colors.blue.shade50,
  borderColor: Colors.blue,
  borderWidth: 2,
)

// Lock the radius to design value (no scaling)
SKit.roundedContainer(
  all: 12,
  radiusMode: SKRadiusMode.fixed,
  color: Colors.orange.shade50,
)

// Force fully responsive radius (useful for pills/avatars)
SKit.roundedContainer(
  all: 50,
  radiusMode: SKRadiusMode.scaled,
  color: Colors.purple.shade50,
)

> By default, all `SKit.rounded*` helpers use `SKRadiusMode.safe`, which gently clamps the radius to keep corners natural on large displays.

// Rounded container with border on specific sides
SKit.roundedContainer(
  all: 12,
  color: Colors.green.shade50,
  borderTop: true,
  borderBottom: true,
  borderColor: Colors.green,
  borderWidth: 2,
)

// Rounded container with different colors per side
SKit.roundedContainer(
  all: 12,
  color: Colors.pink.shade50,
  borderTop: true,
  borderTopColor: Colors.red,
  borderTopWidth: 3,
  borderBottom: true,
  borderBottomColor: Colors.blue,
  borderBottomWidth: 2,
)

// Rounded container with gradient, elevation, and image overlay
SKit.roundedContainer(
  all: 16,
  gradient: const LinearGradient(
    colors: [Color(0xFF7F7FD5), Color(0xFF86A8E7), Color(0xFF91EAE4)],
  ),
  elevation: 8,
  shadowColor: Colors.black54,
  backgroundImage: const DecorationImage(
    image: AssetImage('assets/images/rounded_bg.png'),
    fit: BoxFit.cover,
    colorFilter: ColorFilter.mode(Colors.black26, BlendMode.darken),
  ),
  padding: EdgeInsets.all(20),
  child: Text(
    'Gradient + shadow + background image',
    style: TextStyle(color: Colors.white),
  ),
)

SKit.roundedContainerSize(
  all: SKSize.md,
  color: Colors.blue.shade50,
  borderColor: Colors.blue,
  borderWidth: 2,
)

// Fetch scaled EdgeInsets directly (great for custom widgets/layouts)
final padding = SKit.paddingEdgeInsetsSize(horizontal: SKSize.md, vertical: SKSize.sm);
final rawPadding = SKit.paddingEdgeInsets(all: 12); // accepts doubles when you skip enums

// Spacing
SKit.hSpace(8)           // Horizontal spacing
SKit.vSpace(8)           // Vertical spacing
SKit.sSpace(8)           // Square spacing

// Text - Simple version (common use)
SKit.text('Hello', textSize: SKTextSize.s16)
SKit.text('Hello', fontSize: 16, fontWeight: FontWeight.bold)

// Text - Full version (ALL attributes available)
SKit.textFull(
  'Hello World',
  fontSize: 18,
  fontWeight: FontWeight.w600,
  color: Colors.blue,
  letterSpacing: 0.5,
  textAlign: TextAlign.center,
  maxLines: 2,
  overflow: TextOverflow.ellipsis,
  shadows: [Shadow(color: Colors.black26, offset: Offset(1, 1))],
  // + 20 more attributes available!
)

// TextStyle - Full version (ALL attributes)
final style = SKit.textStyleFull(
  fontSize: 16,
  fontWeight: FontWeight.bold,
  color: Colors.white,
  backgroundColor: Colors.blue,
  letterSpacing: 1.0,
  height: 1.5,
  decoration: TextDecoration.underline,
  shadows: [Shadow(...)],
  // + more attributes!
)

Typography & Theme #

Comprehensive Text Widgets (New in v1.0.11)

Problem: Manually creating Text widgets with all attributes is verbose and repetitive.

Solution: Use SKit.textFull() and SKit.textStyleFull() with ALL Flutter Text/TextStyle attributes pre-configured!

✅ These helpers respect your FontConfig automatically (or default platform fonts when none is configured), so typography stays consistent across languages without extra work.

SKit.textFull() - Complete Text Widget

Instead of writing this:

Text(
  'Hello World',
  style: TextStyle(
    fontSize: 18.sp,
    fontWeight: FontWeight.w600,
    color: Colors.blue,
    letterSpacing: 0.5,
    decoration: TextDecoration.underline,
    shadows: [Shadow(color: Colors.black26, offset: Offset(1, 1))],
  ),
  textAlign: TextAlign.center,
  maxLines: 2,
  overflow: TextOverflow.ellipsis,
  softWrap: true,
  textDirection: TextDirection.ltr,
)

Simply write this:

SKit.textFull(
  'Hello World',
  fontSize: 18,  // Automatically scaled!
  fontWeight: FontWeight.w600,
  color: Colors.blue,
  letterSpacing: 0.5,
  decoration: TextDecoration.underline,
  shadows: [Shadow(color: Colors.black26, offset: Offset(1, 1))],
  textAlign: TextAlign.center,
  maxLines: 2,
  overflow: TextOverflow.ellipsis,
  softWrap: true,
  textDirection: TextDirection.ltr,
)

Available Parameters (30+ attributes):

• Style: fontSize, fontWeight, fontStyle, color, backgroundColor, fontFamily, fontFamilyFallback
• Spacing: letterSpacing, wordSpacing, height
• Decoration: decoration, decorationColor, decorationStyle, decorationThickness
• Effects: shadows, foreground, background
• Layout: textAlign, textDirection, textBaseline, leadingDistribution
• Behavior: softWrap, overflow, maxLines, textScaler
• Accessibility: semanticsLabel, textWidthBasis, textHeightBehavior, selectionColor
• Advanced: locale, fontFeatures, fontVariations

SKit.textStyleFull() - Complete TextStyle

Create comprehensive TextStyles with all Flutter attributes:

final headerStyle = SKit.textStyleFull(
  fontSize: 24,
  fontWeight: FontWeight.bold,
  color: Colors.white,
  backgroundColor: Colors.blue,
  letterSpacing: 1.2,
  wordSpacing: 2.0,
  height: 1.5,
  decoration: TextDecoration.none,
  shadows: [
    Shadow(color: Colors.black38, offset: Offset(2, 2), blurRadius: 4),
  ],
  textBaseline: TextBaseline.alphabetic,
  leadingDistribution: TextLeadingDistribution.even,
);

Text('Header', style: headerStyle)

Why use these? ✅ All attributes in one place - no need to remember which parameters go where
✅ Automatic scaling - fontSize automatically scaled with .sp
✅ Type-safe - all Flutter Text/TextStyle parameters available with autocomplete
✅ Less boilerplate - write less code, get more functionality
✅ Consistent styling - reuse styles easily across your app

When to use:

• Use SKit.text() for simple text (basic styling)
• Use SKit.textFull() when you need advanced Text widget features
• Use SKit.textStyleFull() when you need reusable comprehensive styles

ThemeData Integration

Use responsive scaling in your theme:

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  designType: DeviceType.mobile,
  child: MaterialApp(
    theme: ResponsiveThemeData.create(
      context: context,
      colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
      useMaterial3: true,
    ),
    home: HomePage(),
  ),
)

Font Configuration (Automatic Font Selection)

Configure fonts for different languages. All TextStyles automatically use the configured font for the current language:

import 'package:google_fonts/google_fonts.dart';

void main() {
  // Configure font for specific language (optional)
  // If not configured, Flutter's default font will be used
  FontConfig.instance.setLanguageFont(
    LanguageFontConfig(
      languageCode: 'ar',
      googleFont: GoogleFonts.almarai,  // Pass GoogleFonts function
    ),
  );

  FontConfig.instance.setLanguageFont(
    LanguageFontConfig(
      languageCode: 'en',
      googleFont: GoogleFonts.inter,
    ),
  );

  // Configure font for language group
  FontConfig.instance.setLanguageGroupFont(
    LanguageGroupFontConfig(
      languageCodes: ['ar', 'fa', 'ur'],
      googleFont: GoogleFonts.almarai,
    ),
  );

  // Set default font (used when no specific language config exists)
  FontConfig.instance.setDefaultFont(
    googleFont: GoogleFonts.inter,
  );

  runApp(const MyApp());
}

Usage:

Once configured, all TextStyles automatically use the configured font:

// Automatic font application - no manual configuration needed
Text('Hello', style: TextStyle(fontSize: 16.sp))  // ✅ Uses FontConfig automatically

// Or via theme - all theme text styles get the font automatically
ResponsiveThemeData.create(
  context: context,
  colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
  useMaterial3: true,
)

Size System Configuration #

Important: Configure your size values at the start of your app (typically in main() or app initialization) before using size enums. This ensures consistent sizing throughout your application.

Where to Configure

Set up your size configurations in your app's initialization:

void main() {
  // Configure sizes at app startup (before runApp)
  setPaddingSizes(SizeValues.custom(xs: 4, sm: 8, md: 16, lg: 24, xl: 32, xxl: 48));
  setMarginSizes(SizeValues.custom(xs: 2, sm: 4, md: 8, lg: 12, xl: 16, xxl: 24));
  setRadiusSizes(SizeValues.custom(xs: 2, sm: 4, md: 8, lg: 12, xl: 16, xxl: 24));
  setSpacingSizes(SizeValues.custom(xs: 4, sm: 8, md: 12, lg: 16, xl: 20, xxl: 24));
  setTextSizes(TextSizeValues.custom(s14: 15, s16: 17, s18: 20, s24: 26));

  // Set default values for methods without parameters
  setDefaultPadding(16);
  setDefaultMargin(8);
  setDefaultRadius(12);
  setDefaultSpacing(8);
  setDefaultTextSize(14);

  runApp(const MyApp());
}

Using Size Enums

After configuration, use size enums throughout your app:

// Padding with size enum
SKit.paddingSize(all: SKSize.md, child: widget)
SKit.paddingSize(horizontal: SKSize.lg, vertical: SKSize.sm, child: widget)

// Margin with size enum
SKit.marginSize(all: SKSize.md, child: widget)

// Radius with size enum
SKit.roundedContainerSize(all: SKSize.lg, color: Colors.blue)

// Spacing with size enum
SKit.hSpaceSize(SKSize.md)  // Horizontal spacing
SKit.vSpaceSize(SKSize.sm)  // Vertical spacing

Using Default Values

When you've set default values, you can use methods without parameters:

SKit.pad()              // Uses default padding (16)
SKit.margin()           // Uses default margin (8)
SKit.rounded()         // Uses default safe radius (12)
SKit.h()                // Uses default spacing (8)
SKit.v()                // Uses default spacing (8)

Rounded Container with Border

Most containers need both border radius and border. Use borderColor and borderWidth parameters:

// Container with radius and border on all sides
SKit.roundedContainer(
  all: 12,
  color: Colors.blue.shade50,
  borderColor: Colors.blue,
  borderWidth: 2,  // Border thickness (automatically scaled)
  child: Text('Content'),
)

// Border on specific sides only
SKit.roundedContainer(
  all: 12,
  color: Colors.green.shade50,
  borderTop: true,      // Border on top
  borderBottom: true,    // Border on bottom
  borderColor: Colors.green,
  borderWidth: 2,
  child: Text('Content'),
)

// Different colors and widths for different sides
SKit.roundedContainer(
  all: 12,
  color: Colors.pink.shade50,
  borderTop: true,
  borderTopColor: Colors.red,
  borderTopWidth: 3,
  borderBottom: true,
  borderBottomColor: Colors.blue,
  borderBottomWidth: 2,
  borderLeft: true,
  borderLeftColor: Colors.green,
  borderLeftWidth: 1,
  child: Text('Content'),
)

// Using size enum
SKit.roundedContainerSize(
  all: SKSize.md,
  color: Colors.blue.shade50,
  borderColor: Colors.blue,
  borderWidth: 2,
  child: Text('Content'),
)

// Using default radius with border
SKit.rounded(
  null,
  const Text('Content'),
  Colors.blue.shade50,
  Colors.blue,  // borderColor
  2,            // borderWidth
)

Border Parameters:

• borderColor - Border color for all sides (if individual sides not specified)
• borderWidth - Border width for all sides (automatically scaled)
• borderTop, borderBottom, borderLeft, borderRight - Show border on specific sides (boolean)
• borderTopColor, borderBottomColor, borderLeftColor, borderRightColor - Individual side colors
• borderTopWidth, borderBottomWidth, borderLeftWidth, borderRightWidth - Individual side widths (automatically scaled)

ScaleKitDesignValues - Centralized Design System #

Define all your design tokens in one place:

// Define theme
const design = ScaleKitDesignValues(
  textXs: 10,
  textSm: 12,
  textMd: 14,
  textLg: 16,
  textXl: 18,
  textXxl: 24,
  paddingXs: 4,
  paddingSm: 8,
  paddingMd: 16,
  paddingLg: 24,
  paddingXl: 32,
  radiusSm: 4,
  radiusMd: 8,
  radiusLg: 12,
  spacingXs: 4,
  spacingSm: 8,
  spacingMd: 16,
  spacingLg: 24,
);

// Compute once
final values = design.compute();

// Use everywhere with const widgets
SKPadding(
  padding: values.paddingMd!,
  child: SKContainer(
    decoration: BoxDecoration(
      borderRadius: values.borderRadiusMd,
    ),
    child: Text('Hello', style: values.textMd),
  ),
)

Compute once, use everywhere (performance best practice) #

The compute pattern lets you pre-scale all your design tokens once per build and reuse them across your widget tree. This minimizes repeated calculations, enables more const-friendly widgets, and improves frame-time stability.

When to use compute:

• Use ScaleKitDesignValues.compute() in a widget's build method (or builder) when you need many scaled values together (text styles, paddings, margins, radii, spacing, sizes).
• Prefer it for list/grid items and complex screens to avoid recalculating the same values per child.

Benefits:

• All values are scaled together with one factory access.
• Fewer object allocations and repeated calculations.
• Cleaner code: one place defines your tokens, one object provides them.

Example: precompute many values and build with them

// Define your design tokens once (can be const)
const design = ScaleKitDesignValues(
  textSm: 12,
  textMd: 14,
  textLg: 16,
  paddingSm: 8,
  paddingMd: 16,
  paddingLg: 24,
  spacingSm: 8,
  spacingMd: 16,
  spacingLg: 24,
  radiusSm: 6,
  radiusMd: 12,
);

@override
Widget build(BuildContext context) {
  // Compute once per build
  final values = design.compute();

  return ListView.separated(
    padding: values.paddingHorizontal,
    itemCount: 20,
    separatorBuilder: (_, __) => SizedBox(height: values.spacingMd!),
    itemBuilder: (context, index) {
      return SKContainer(
        margin: values.marginHorizontal,
        decoration: BoxDecoration(
          color: Colors.white,
          borderRadius: values.borderRadiusMd,
        ),
        padding: values.paddingMd,
        child: Row(
          children: [
            Container(
              width: values.widthSm ?? 40,
              height: values.heightSm ?? 40,
              decoration: BoxDecoration(
                color: Colors.blue.shade50,
                borderRadius: values.borderRadiusSm,
              ),
            ),
            SizedBox(width: values.spacingMd!),
            Expanded(
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text('Title', style: values.textLg?.copyWith(fontWeight: FontWeight.bold)),
                  SizedBox(height: values.spacingSm!),
                  Text('Subtitle text', style: values.textSm),
                ],
              ),
            ),
          ],
        ),
      );
    },
  );
}

Legacy compute helper (simple one-off values)

If you only need a few values in places where defining a full theme is overkill, you can use the legacy SKitValues.compute factory. This is maintained for convenience but ScaleKitDesignValues.compute() is recommended for larger UIs.

final v = SKitValues.compute(
  padding: 16,
  margin: 8,
  borderRadius: 12,
  width: 120,
  height: 48,
  fontSize: 16,
);

return SKPadding(
  padding: v.padding,
  child: SKContainer(
    margin: v.margin,
    decoration: BoxDecoration(borderRadius: v.borderRadius),
    width: v.width,
    height: v.height,
    child: Text('Button', style: TextStyle(fontSize: v.fontSize)),
  ),
);

Tips:

• Compute close to where values are used to respect current device metrics and orientation.
• Recompute automatically when MediaQuery or locale changes (ScaleKitBuilder handles this); do not store across frames.
• Pair with FontConfig: precomputed TextStyles automatically apply the selected font per language.

Context Extensions #

Use context extensions for responsive scaling:

Container(
  padding: context.scalePadding(horizontal: 20, vertical: 16),
  margin: context.scaleMargin(all: 8),
  decoration: BoxDecoration(
    borderRadius: context.scaleBorderRadius(all: 12),
  ),
  child: const Text('Content'),
)

// Device detection
if (context.isMobile) {
  // Mobile layout
} else if (context.isTablet) {
  // Tablet layout
}

ScaleManager Direct API #

Responsive Builder & Columns #

Build different widgets per device/orientation with sensible fallbacks, and resolve responsive integers (e.g., Grid columns) quickly.

SKResponsive Widget

Use when you have separate builders for each device/orientation:

// Widget builder with separate builders
SKResponsive(
  mobile: (_) => Text('Mobile portrait'),
  mobileLandscape: (_) => Text('Mobile landscape'), // Falls back to mobile if null
  tablet: (_) => Text('Tablet portrait'),
  tabletLandscape: (_) => Text('Tablet landscape'), // Falls back to tablet -> mobileLandscape -> mobile
  desktop: (_) => Text('Desktop'),
)

Fallback rules:

• mobileLandscape → falls back to mobile if null
• tabletLandscape → falls back to tablet → mobileLandscape → mobile if null
• Device: desktop → tablet → mobile; tablet → mobile

SKResponsiveBuilder Widget

Supports two usage patterns:

Pattern 1: Builder with device/orientation info Use when you need access to device and orientation in your builder function:

SKResponsiveBuilder(
  builder: (context, device, orientation) {
    if (device == DeviceType.mobile && orientation == Orientation.landscape) {
      return Text('Mobile Landscape');
    }
    if (device == DeviceType.tablet) {
      return Text('Tablet');
    }
    return Text('Desktop or other');
  },
  desktopAs: DesktopAs.tablet, // Optional: make desktop behave like tablet
)

Pattern 2: Separate builders (like SKResponsive) Use when you prefer separate builders for each device/orientation:

SKResponsiveBuilder(
  mobile: (_) => Text('Mobile'),
  tablet: (_) => Text('Tablet'),
  desktop: (_) => Text('Desktop'),
  mobileLandscape: (_) => Text('Mobile Landscape'), // Falls back to mobile if null
  tabletLandscape: (_) => Text('Tablet Landscape'), // Falls back to tablet -> mobileLandscape -> mobile
)

Priority: If both patterns are provided, device-specific builders take priority over the main builder.

// Responsive integer with fallback rules (alias for columns)
final cols = SKit.responsiveInt(
  mobile: 2, // required base
  tablet: 4, // optional (falls back to mobile if null)
  desktop: 8, // optional (falls back to tablet->mobile if null)
  mobileLandscape: 4, // optional override for mobile landscape
  // tabletLandscape falls back to mobileLandscape, then tablet, then mobile
);
GridView.count(crossAxisCount: cols)

Both widgets support the same fallback rules:

• Device: desktop → tablet → mobile; tablet → mobile
• Orientation: landscape → device portrait; for tablet.landscape → mobile.landscape → mobile.portrait

Desktop behavior (CSS-like):

• On Android/iOS, devices are classified only as mobile or tablet by width; desktop logic doesn’t apply.
• On desktop (width ≥ 1200), desktop values are used by default. You can opt to reuse tablet/mobile values to mimic CSS breakpoints.
• This lets you build grids like in CSS (e.g., 2/4/8 columns) while forcing desktop to act like tablet/mobile if that’s desired.

Examples:

// Make desktop behave like tablet for layout decisions
SKResponsive(
  mobile: (_) => MobileView(),
  tablet: (_) => TabletView(),
  desktop: (_) => DesktopView(),
  desktopAs: DesktopAs.tablet, // 👈 map desktop to tablet behavior
)

// Resolve an integer (e.g., Grid crossAxisCount) with desktop mapped to tablet
final cols = SKit.responsiveInt(
  mobile: 2,
  tablet: 4,
  desktop: 8,
  desktopAs: DesktopAs.tablet, // 👈 desktop will use tablet values unless explicitly provided
);
GridView.count(crossAxisCount: cols)

Access scale values directly:

final scale = ScaleManager.instance;

Container(
  width: scale.getWidth(200),
  height: scale.getHeight(100),
  decoration: BoxDecoration(
    borderRadius: BorderRadius.circular(scale.getRadius(12)),
  ),
  child: Text(
    'Hello',
    style: TextStyle(fontSize: scale.getFontSize(16)),
  ),
)

Helper Properties #

Access device properties similar to flutter_screenutil:

final scaleKit = ScaleManager.instance;

// Device properties
double screenWidth = scaleKit.screenWidth;
double screenHeight = scaleKit.screenHeight;
double pixelRatio = scaleKit.pixelRatio;
double statusBarHeight = scaleKit.statusBarHeight;
double bottomBarHeight = scaleKit.bottomBarHeight;
double textScaleFactor = scaleKit.textScaleFactor;
double scaleWidth = scaleKit.scaleWidth;
double scaleHeight = scaleKit.scaleHeight;
Orientation orientation = scaleKit.orientation;

Orientation Autoscale (Landscape vs Portrait) #

Scale Kit lets you control autoscale behavior per orientation. Defaults are tuned for comfort: landscape boosts are enabled, portrait boosts are disabled.

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  // Orientation-specific flags
  autoScaleLandscape: true,  // default
  autoScalePortrait: false,  // default
  // Optional landscape boosts
  mobileLandscapeFontBoost: 1.2,
  mobileLandscapeSizeBoost: 1.2,
)

Notes:

• Landscape: readability boosts (e.g., +20% fonts on mobile) can apply.
• Portrait: stable sizes by default; set autoScalePortrait: true if you want portrait boosts.
• Size boosts only apply in landscape by default; portrait preserves your design intent.

API Reference #

Extension Methods (on num) #

• .w - Scaled width (e.g., 200.w)
• .sw - Screen width percentage (e.g., 0.5.sw = 50% width)
• .sh - Screen height percentage (e.g., 0.25.sh = 25% height)
• .rSafe - Stable radius with gentle clamping (e.g., 12.rSafe)
• .r - Fully responsive radius/border radius (e.g., 12.r)
• .rFixed - Constant radius (no scaling, e.g., 12.rFixed)
• .sp - Scaled font size (e.g., 16.sp)
• .h - Scaled height (e.g., 100.h)
• .spf - Font size with system text scale factor (e.g., 16.spf)

Context Extensions #

• context.scaleWidth(double width) - Get scaled width
• context.scaleHeight(double height) - Get scaled height
• context.scaleFontSize(double fontSize) - Get scaled font size
• context.scaleSize(double size) - Get scaled size
• context.scalePadding(...) - Get responsive padding
• context.scaleMargin(...) - Get responsive margin
• context.scaleBorderRadius(...) - Get responsive border radius
• context.isMobile - Check if device is mobile
• context.isTablet - Check if device is tablet
• context.isDesktop - Check if device is desktop

ScaleManager Properties #

• pixelRatio - Device pixel density
• screenWidth - Device width in logical pixels
• screenHeight - Device height in logical pixels
• bottomBarHeight - Bottom safe zone distance
• statusBarHeight - Status bar height (includes notch)
• textScaleFactor - System font scaling factor
• scaleWidth - Ratio of actual width to UI design width
• scaleHeight - Ratio of actual height to UI design height
• orientation - Screen orientation (portrait/landscape)
• devicePixelRatio - Physical pixels per logical pixel
• topSafeHeight - Top safe area height
• bottomSafeHeight - Bottom safe area height
• safeAreaHeight - Total safe area height
• safeAreaWidth - Safe area width

ScaleManager Methods #

• getWidth(double width) - Get scaled width
• getHeight(double height) - Get scaled height
• getFontSize(double fontSize) - Get scaled font size
• getFontSizeWithFactor(double fontSize) - Get scaled font size with system factor
• getRadius(double radius) - Get scaled radius
• getScreenWidth(double percentage) - Get screen width percentage
• getScreenHeight(double percentage) - Get screen height percentage

FontConfig API #

• FontConfig.instance - Singleton instance for font configuration
• setLanguageFont(LanguageFontConfig) - Configure font for specific language
• setLanguageGroupFont(LanguageGroupFontConfig) - Configure font for language group
• setDefaultFont({googleFont?, customFontFamily?}) - Set default font
• setLanguagesFonts(List<LanguageFontConfig>) - Configure multiple languages at once
• setLanguageGroupsFonts(List<LanguageGroupFontConfig>) - Configure multiple language groups
• getTextStyle({languageCode?, baseTextStyle}) - Get TextStyle with configured font
• currentLanguageCode - Get current language code
• clear() - Clear all font configurations

Performance #

Flutter Scale Kit uses intelligent caching to minimize recalculations:

• Flyweight Pattern: Reuses cached calculated values
• Cache Invalidation: Automatically clears cache on size/orientation change
• Const Widgets: Pre-calculated values for const-compatible widgets
• Singleton Pattern: Single instance manages all scaling operations
• Threshold-Based Updates: Only recalculates on significant size changes (>5%)

Architecture #

The package uses design patterns for optimal performance:

• Singleton: ScaleManager - Global scale configuration
• Factory: ScaleValueFactory - Creates cached scaled values
• Flyweight: ScaleValueCache - Reuses cached values

🛠️ Advanced Tuning Reference #

Ready to go beyond the defaults? These notes expand on the core concepts above so you always know what will happen before you flip a switch.

Manual Scale Limit Overrides #

Scale limits clamp the raw width/height ratios that Flutter Scale Kit calculates:

• scaleWidth = screenWidth / designWidth
• scaleHeight = screenHeight / designHeight
• finalScaleWidth = clamp(scaleWidth, minScale, maxScale)
• finalScaleHeight = clamp(scaleHeight, minScale, maxScale)

Real-world example

Design: 375×812 (iPhone 13 mini) → Displayed on an iPad Pro portrait (1024×1366)

Without limits:
  scaleWidth = 1024 / 375 = 2.73x  →  100px button → 273px (too huge)
  scaleHeight = 1366 / 812 = 1.68x

With minScale: 0.8, maxScale: 1.2:
  clampedWidth = clamp(2.73, 0.8, 1.2) = 1.2x  →  100px button → 120px ✓
  clampedHeight = clamp(1.68, 0.8, 1.2) = 1.2x

Override recipes

Quick check

// Design: 375×812, Screen: 1024×1366, maxScale: 1.2
200.w; // 200 × 1.2 = 240  (instead of 546 without clamping)
16.sp; // 16 × 1.2 × orientationBoost × systemTextScale

Pro tip: Start with minScale ≈ 0.9 and maxScale ≈ 1.4 if you just want a gentle clamp for tablets while keeping phones untouched.

Orientation Boost Deep Dive #

Orientation boosts multiply after clamping to adapt layouts when a device rotates:

finalSize      = designValue × clampedScale × orientationSizeBoost
finalFontSize  = designFontSize × clampedScale × orientationFontBoost × systemTextScale

Smart defaults

Math in action

Design: 375×812 (mobile portrait) → iPhone 14 landscape (852×390)

Raw scales:
  width  = 852 / 375 = 2.27x
  height = 390 / 812 = 0.48x

Auto limits applied (0.85 - 1.25):
  width  = clamp(2.27, 0.85, 1.25) = 1.25x
  height = clamp(0.48, 0.85, 1.25) = 0.85x

Orientation boost (1.2× landscape):
  16.sp = 16 × 1.25 × 1.2 = 24.0px
 100.w = 100 × 1.25 × 1.2 = 150.0px
  50.h = 50 × 0.85 × 1.2 = 51.0px

Customization patterns

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  // Dashboards—stay dense in landscape
  mobileLandscapeFontBoost: 1.0,
  mobileLandscapeSizeBoost: 1.0,
);

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  // Reading experience—text gets extra lift
  mobileLandscapeFontBoost: 1.4,
  mobileLandscapeSizeBoost: 1.1,
);

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  // Portrait-first tablet (POS/kiosk)
  tabletPortraitFontBoost: 1.3,
  tabletPortraitSizeBoost: 1.3,
);

Key takeaways

1. Boosts run after clamping, so limits always win first.
2. Fonts and sizes use separate multipliers—tune readability independently.
3. System text scaling stacks on top of everything else.

🧪 Optional Tools #

Enable/Disable Scaling (Runtime Toggle) #

Keep a runtime switch handy when you want to compare Scale Kit against vanilla Flutter sizing.

final enabled = ValueNotifier<bool>(true);

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  enabledListenable: enabled, // runtime toggle
  enabled: enabled.value,      // initial
  child: MaterialApp(...),
);

// Toggle anywhere
enabled.value = false; // disables scaling (values returned unmodified)

Notes:

• .w/.h/.sp and ScaleManager methods return raw values while disabled.
• Reactivate to restore responsive scaling immediately.
• The example app's settings sheet (tune icon) exposes the same toggle for quick experiments.

Device Preview Integration (Optional) #

If you use device_preview during development, share its simulated platform with Scale Kit so detection stays accurate inside the preview surface:

import 'package:device_preview/device_preview.dart';

void main() {
  ScaleManager.setDevicePreviewPlatformGetter((context) {
    try {
      return DevicePreview.platformOf(context);
    } catch (_) {
      return null; // Fall back to default detection when preview is disabled
    }
  });

  runApp(const MyApp());
}

Wrap your app with DevicePreview as normal (e.g., DevicePreview(builder: (_) => app)). Returning null keeps the default logic when preview mode is turned off. Skip this helper if you prefer—the package works fine without it; this just keeps platform detection perfect when you hop between simulated devices.

Device-Specific Scaling #

The package automatically adapts scaling strategies based on:

• Device Type: Mobile, Tablet, Desktop, Web
• Aspect Ratio: Narrow, Wide, Standard
• Orientation: Portrait, Landscape
• Foldable Devices: Detects fold/unfold transitions

Contributing #

Contributions are welcome! Please feel free to submit a Pull Request.

License #

This project is licensed under the MIT License - see the LICENSE file for details.

Support #

If you find this package useful, please consider:

• ⭐ Giving it a star on GitHub - it helps others discover the package
• 💝 Buy me a coffee - Support my open-source work and help me continue developing and maintaining packages
• 🐛 Report bugs - Help improve the package by reporting issues
• 💡 Suggest features - Share your ideas for improvements
• 📖 Share with others - Let other developers know about Flutter Scale Kit

Your support, whether through donations, stars, or feedback, helps me dedicate more time to:

• ✨ Maintaining and improving Flutter Scale Kit
• 🚀 Building new features and projects
• 📚 Creating better documentation and examples
• 🐛 Fixing bugs and responding to issues faster
• 💡 Exploring new ideas and innovations

Thank you for being part of this journey! Every contribution, no matter how small, makes a difference. 💙

Acknowledgements #

Huge thanks to the authors and contributors of flutter_screenutil and similar responsive design packages. We used them extensively, learned from their great ideas, and built Flutter Scale Kit as an alternative optimized for our apps' performance and developer experience. flutter_screenutil is a solid package; this project simply explores a different set of trade‑offs (compute-once patterns, caching, language-aware fonts, and orientation-aware scaling) that matched our needs.

FAQ #

Q: Why choose Flutter Scale Kit over flutter_screenutil?

A: If you want compute-once patterns, automatic font selection by language, orientation-aware scaling controls, and an optional runtime toggle to compare raw Flutter vs scaled values, Scale Kit might fit better. If you’re happy with your current setup, flutter_screenutil remains an excellent choice.

Q: How do I disable scaling to compare with raw Flutter sizes?

A: Use ScaleKitBuilder(enabled: false) or provide enabledListenable for a runtime switch. In the example, tap the tune icon to toggle and Save.

Q: Can I control autoscale separately for portrait and landscape?

A: Yes. autoScaleLandscape (default true) and autoScalePortrait (default false) let you enable/disable boosts per orientation. You can also set device-specific font/size boosts.

Q: Do all TextStyles get my configured font automatically?

A: Yes. Fonts apply automatically via FontConfig integration in theme creation and text style scaling. If no configuration is provided, Flutter’s default font is used.

Q: Why is borderRadius removed when using different border colors per side?

A: It’s a Flutter limitation. When individual sides have different colors, BoxDecoration can’t combine non-uniform borders with borderRadius. We avoid the rendering error by omitting borderRadius in those cases.

Q: Will this increase my package size?

A: The package only ships the lib/ code. The example and screenshots are not included in the pub.dev download. Use Google Fonts conditionally as needed.