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 perfectly out-of-the-box in 95% of cases without manual configuration
• 📱 Universal Platform Support: Seamlessly handles mobile phones, tablets, desktop, and web with platform-specific optimizations
• 🔄 Orientation-Aware: Automatically adjusts scaling factors when device rotates between portrait and landscape
• 🎯 Design Fidelity: Keeps your UI proportional to design mockups while adapting to any screen size
• ⚡ High Performance: Cached calculations and threshold-based updates minimize overhead
• 🛠️ Developer-Friendly: Simple API similar to flutter_screenutil with powerful customization when needed

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! 🙏

Screenshots #

Desktop #

Autoscale and Enable/Disable Examples #

📑 Table of Contents #

Jump to any section:

🚀 Quick Start #

• 🧠 Intelligent Auto-Configuration
• ✨ Key Features
• 📦 Installation
• ⚡ Quick Start Guide

📖 Core Concepts #

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

🎨 Usage & Widgets #

• Extension Methods (.w, .h, .sp, .r)
• SKit Helper Class
• Comprehensive Text Widgets (textFull, textStyleFull)
• Size System Configuration
• SKitTheme - Centralized Design System
• Context Extensions

🔧 Advanced Features #

• ScaleManager Direct API
• Responsive Builder & Columns
• ThemeData Integration
• Orientation Autoscale (Landscape vs Portrait)
• Enable/Disable Scaling (Runtime Toggle)
• Device Preview Integration
• Font Configuration (Automatic Font Selection)

📚 Reference #

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

🤝 Community #

• Contributing
• Support
• License

🧠 Intelligent Auto-Configuration #

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

🚀 Zero Configuration Required #

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  // That's it! Everything else is automatic ✨
  child: MaterialApp(home: HomePage()),
)

No need to set minScale, maxScale, or orientation boosts — the package intelligently handles everything based on your device and screen!

💡 When to manually configure? Only if you have specific requirements like strict design compliance (±5%) or need different values than the intelligent defaults. See Manual Override Examples below.

Features #

• 🎯 Easy Scaling: Simple API similar to flutter_screenutil (.w, .sw, .sh, .r, .sp, .h)
• 🧠 Intelligent Auto-Configuration: Zero-config setup with smart device/orientation detection (95% use cases)
• 📱 Responsive Design: Automatic scaling based on screen dimensions and aspect ratios
• ⚡ High Performance: Intelligent caching system prevents recalculation on every rebuild
• 🔧 Const Widgets: Generate const-compatible widgets for better performance
• 🚀 Extension Methods: Use context extensions for cleaner code
• 📐 Size System: Predefined size enums (xs, sm, md, lg, xl, xxl) for consistent design
• 🎨 Theme Support: Centralized theme configuration with SKitTheme
• 📱 Device Detection: Built-in tablet, mobile, and desktop detection
• 🔄 Smart Caching: Flyweight pattern with automatic cache invalidation on size/orientation change
• 🎨 ThemeData Integration: Use responsive scaling in Flutter's theme system
• 🔤 Font Configuration: Automatic font selection per language with Google Fonts support
• 🧭 Orientation Autoscale: Configurable autoscale behavior for landscape vs portrait
• 🔁 Runtime Toggle: Enable/disable scaling globally to compare with raw Flutter sizes

Installation #

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

dependencies:
  flutter_scale_kit: ^1.0.12

Then run:

flutter pub get

Quick Start #

1. Configure Size Values (Optional but Recommended) #

Set up your size configurations at app startup. This is where you define what values SKSize.md, SKSize.lg, etc. represent for padding, margin, radius, and spacing:

void main() {
  // Configure size values 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));

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

  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).

2. Wrap Your App #

Wrap your MaterialApp with ScaleKitBuilder at the top level:

import 'package:flutter/material.dart';
import 'package:flutter_scale_kit/flutter_scale_kit.dart';

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

  @override
  Widget build(BuildContext context) {
    return ScaleKitBuilder(
      designWidth: 375,
      designHeight: 812,
      designType: DeviceType.mobile,
      // That's it! Scale limits are automatically configured ✨
      // minScale & maxScale are optional - only set if you need custom behavior
      child: MaterialApp(
        title: 'My App',
        home: HomePage(),
      ),
    );
  }
}

🎯 Intelligent Auto-Configuration

Scale Kit automatically determines optimal scale limits based on your device, screen size, orientation, and design dimensions. In 95% of cases, you don't need to set minScale or maxScale manually — the package intelligently adapts:

• 📱 Mobile phones (Portrait: 0.85-1.15x, Landscape: 0.85-1.25x)

  • Tight bounds keep UI consistent across iPhone SE to iPhone Pro Max
  • Detects extreme aspect ratios (foldables, notched screens) and adjusts automatically

• 📲 Tablets (Portrait: 0.8-1.3x, Landscape: 0.75-1.4x)

  • Comfortable scaling for iPad Mini to iPad Pro
  • Increases range if your mobile design runs on large tablets

• 💻 Desktop & Web (Landscape: 0.6-2.0x, Portrait: 0.7-1.8x)

  • Widest range for resizable windows (800px to ultrawide 3440px monitors)
  • Detects small windows vs ultrawide displays and adjusts limits
  • Caps upscaling when mobile designs run on large desktop screens

The algorithm considers orientation changes, aspect ratios (narrow/standard/wide), and the relationship between your design dimensions and actual screen size — so your app looks great everywhere without configuration.

Understanding Scale Limits (minScale & maxScale)

⚙️ When to Manually Configure

Only override the auto-detected limits if you have specific requirements:

Scale limits control how much your UI can grow or shrink relative to your design dimensions. They're applied after the base scale calculation but before orientation boosts.

How it works:

Scale Kit first calculates raw scale factors:

• scaleWidth = screenWidth / designWidth
• scaleHeight = screenHeight / designHeight

Then it clamps them:

• finalScaleWidth = clamp(scaleWidth, minScale, maxScale)
• finalScaleHeight = clamp(scaleHeight, minScale, maxScale)

Real-world example:

Suppose your design is 375×812 (iPhone 13 mini) and the user opens your app on an iPad Pro (1024×1366 portrait):

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

With minScale: 0.8, maxScale: 1.2:
  scaleWidth = clamp(2.73, 0.8, 1.2) = 1.2x  →  A 100px button becomes 120px ✓
  scaleHeight = clamp(1.68, 0.8, 1.2) = 1.2x

Manual Override Examples (Optional):

These settings are only needed if you want different behavior than the intelligent defaults:

💡 Remember: The package already auto-detects optimal values for mobile/tablet/desktop in both portrait and landscape. These manual overrides are for edge cases only!

How limits interact with .w / .h extensions:

// Design: 375×812, Screen: 1024×1366, maxScale: 1.2
200.w  // = 200 * 1.2 = 240  (clamped from 2.73)
100.h  // = 100 * 1.2 = 120  (clamped from 1.68)
16.sp  // Font: 16 * 1.2 * orientationBoost (e.g. 1.2 landscape) * textScaleFactor

Pro Tip:
Set minScale close to 1.0 (e.g., 0.9) if your design already uses small phones as a baseline—this prevents UI from shrinking too much on even smaller screens. Use a higher maxScale (e.g., 1.5) if you want tablets to feel spacious without creating separate tablet layouts.

Understanding Orientation Boosts (Advanced)

Orientation boosts are multipliers applied AFTER scale clamping to make UI elements more readable/usable when devices rotate. The intelligent defaults work great for most apps, but understanding the math helps with custom tuning.

📐 The Complete Scaling Formula:

For sizing (width, height, padding, margin):

finalSize = designValue × clampedScale × orientationSizeBoost

For fonts (text):

finalFontSize = designFontSize × clampedScale × orientationFontBoost × systemTextScale

🔄 Default Orientation Boosts (Smart Defaults):

📊 Real-World Math Example:

Design specs: 375×812 (mobile portrait)
Scenario: iPhone 14 rotated to landscape (852×390)

Step 1: Calculate raw scales

scaleWidth = 852 / 375 = 2.27x
scaleHeight = 390 / 812 = 0.48x

Step 2: Apply intelligent scale limits (mobile landscape: 0.85-1.25x)

clampedWidth = clamp(2.27, 0.85, 1.25) = 1.25x
clampedHeight = clamp(0.48, 0.85, 1.25) = 0.85x

Step 3: Apply orientation boost (mobile landscape: 1.2x)

// For a 16px font:
16.sp = 16 × 1.25 (clamped) × 1.2 (landscape boost) = 24px ✓ More readable!

// For a 100px wide container:
100.w = 100 × 1.25 (clamped) × 1.2 (landscape boost) = 150px ✓ Proportionally larger!

// For a 50px tall element:
50.h = 50 × 0.85 (clamped) × 1.2 (landscape boost) = 51px ✓ Adjusted for short screen!

Without boost:

16.sp = 16 × 1.25 = 20px (too small in landscape)
100.w = 100 × 1.25 = 125px (cramped)

🎯 When to Customize Boosts:

Use Case 1: Dense Information Display

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  // Reduce landscape boost for data-heavy apps (dashboards, spreadsheets)
  mobileLandscapeFontBoost: 1.0,  // No font boost
  mobileLandscapeSizeBoost: 1.0,  // No size boost
  tabletLandscapeFontBoost: 1.0,
  tabletLandscapeSizeBoost: 1.0,
  child: MaterialApp(...),
)

Use Case 2: Extra Readable Text

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  // Boost fonts more than sizes for reading apps (books, articles)
  mobileLandscapeFontBoost: 1.4,   // 40% bigger text
  mobileLandscapeSizeBoost: 1.1,   // 10% bigger containers
  child: MaterialApp(...),
)

Use Case 3: Portrait-Optimized Tablet

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,
  // Boost portrait mode for tablets used vertically (POS systems, kiosks)
  tabletPortraitFontBoost: 1.3,
  tabletPortraitSizeBoost: 1.3,
  child: MaterialApp(...),
)

📱 Complete Example with All Parameters:

// Design: 375×812
// Device: iPad landscape (1024×768)
// Custom: slight boost for readability

ScaleKitBuilder(
  designWidth: 375,
  designHeight: 812,

  // Let intelligent limits auto-detect (recommended)
  // minScale: null, maxScale: null,

  // Custom orientation boosts
  tabletLandscapeFontBoost: 1.15,  // 15% bigger text
  tabletLandscapeSizeBoost: 1.1,   // 10% bigger UI elements

  child: MaterialApp(
    home: Scaffold(
      body: Column(
        children: [
          // Math breakdown:
          // Raw scale: 1024/375 = 2.73x, clamped to 1.4x (tablet max)
          // With boost: 1.4 × 1.1 = 1.54x for sizes, 1.4 × 1.15 = 1.61x for fonts

          Text(
            'Title',
            style: TextStyle(
              fontSize: 24.sp,  // 24 × 1.61 = 38.64px (readable on large tablet)
            ),
          ),

          Container(
            width: 200.w,   // 200 × 1.54 = 308px (well-proportioned)
            height: 100.h,  // 100 × 1.54 = 154px
            padding: EdgeInsets.all(16.w),  // 16 × 1.54 = 24.64px
          ),
        ],
      ),
    ),
  ),
)

💡 Key Takeaways:

1. Orientation boosts multiply AFTER scale clamping — they fine-tune the final result
2. Separate font & size boosts — text can scale differently from UI elements
3. Per-device configuration — mobile, tablet, and desktop can have different boosts
4. Smart defaults work for 95% of cases — only customize for specialized UIs
5. Portrait vs Landscape — landscape typically gets boosts, portrait stays 1.0x
6. System text scaling respected — .sp also multiplies by user's accessibility settings

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.r),
  ),
  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.

Usage #

Extension Methods #

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            // Scaled radius

// 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

SKit Helper Class #

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,
)

// 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!
)

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!

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

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 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)

SKitTheme - Centralized Design System #

Define all your design tokens in one place:

// Define theme
const theme = SKitTheme(
  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 = theme.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 SKitTheme.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 theme = SKitTheme(
  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 = theme.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 SKitTheme.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;

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(),
  ),
)

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.

Comparison with flutter_screenutil

Enable/Disable Scaling (Runtime Toggle) #

You can turn scaling off entirely to compare against raw Flutter sizes.

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:

• When disabled, .w/.h/.sp and ScaleManager methods return the input value (no scaling).
• Re-enable to restore responsive scaling.

Tip: Use the example app’s settings (tune icon) to live-test autoscale flags and boosts, then Save to apply. You can Reset to defaults from the sheet.

When resizing windows (desktop/web) or changing device sizes, flutter_screenutil often scales cards and paddings more aggressively, which can make components look oversized. Scale Kit clamps scale factors and applies orientation-aware boosts, keeping practical sizes and better visual balance during resizes and rotations.

Device Preview Integration (Optional) #

If you use device_preview during development, share its simulated platform with Scale Kit so that device detection remains 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.

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,
  textTheme: ThemeData.light().textTheme,  // ✅ All styles get font automatically
)

Custom Font Family:

You can also use custom font families (fonts loaded in pubspec.yaml):

FontConfig.instance.setLanguageFont(
  LanguageFontConfig(
    languageCode: 'ar',
    customFontFamily: 'CustomArabicFont',  // From pubspec.yaml
  ),
);

Note: If no font is configured, Flutter's default font (Roboto on Android, San Francisco on iOS) will be used. The font configuration is completely optional.

Package Size #

Important: When you add this package as a dependency using flutter pub get, you will NOT download the example folder. Pub.dev automatically excludes the example folder from the package distribution. The example folder is only available on the pub.dev website for documentation purposes.

The package size is optimized and only includes the necessary library code (lib/ folder).

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)
• .r - Scaled radius/border radius (e.g., 12.r)
• .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

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.