Flutter Color & Theme Document Studio

Convert Hex/RGB inputs into valid Flutter Color(0xAARRGGBB) expressions or generate typed Material 3 theme documents with contrast validation.

Flutter Color & Theme Document Studio

Convert ARGB colors and generate typed Flutter Material 3 ThemeData documents with WCAG contrast validation.

Colour Swatch

Alpha: 100%

Palette Presets

Hex Input (#RRGGBB or #AARRGGBB)

Red (R)45

Green (G)212

Blue (B)191

Alpha (A)255 (1.00)

Copyable Flutter Code

Flutter Color (ARGB)

const Color(0xFF2DD4BF)

Notice: Flutter uses ARGB format where the first two hex digits represent Alpha opacity.

Hex (RGB)

#2DD4BF

Hex with Alpha (#AARRGGBB)

#FF2DD4BF

CSS rgba()

rgba(45, 212, 191, 1.00)

Tool Specification: Tasks, Realistic Inputs, Outputs & Local Data Handling

Comprehensive operational parameters, validation rules, input/output behaviors, and data privacy guarantees for the Flutter Color & Theme Document Studio.

1. Task It Solves & Why It Matters

In Flutter and Skia/Impeller graphics engines, colors are represented as 32-bit unsigned integers in 0xAARRGGBB byte order, whereas web CSS uses #RRGGBB or #RRGGBBAA. Passing a 6-digit hex code directly to Flutter (Color(0x2DD4BF)) results in an invisible transparent color because bits 24–31 (Alpha) evaluate to 0.

This tool converts RGB channels and Web Hex into compile-time const Color(0xAARRGGBB) constants, computes WCAG 2.2 AA/AAA contrast ratios against light and dark surfaces, and generates complete Material 3 ThemeData dart files.

2. Realistic Example Inputs & Outputs

Input (6-char Hex): #2DD4BF → Output: const Color(0xFF2DD4BF), CSS rgba(45, 212, 191, 1.00).
Input (8-char ARGB Hex): #802DD4BF → Output: const Color(0x802DD4BF) (Alpha: 128 / 50% opacity).
Channel Sliders: Red: 45, Green: 212, Blue: 191, Alpha: 255. All channels synchronize bi-directionally with the visual swatch and text fields.
Theme Generator Output: Complete app_theme.dart with ColorScheme roles, custom ThemeExtension<AppSpacingTheme>, and typography scales.

3. Input Validation & Error Handling

The hex parser validates input strings on every keystroke. It expects 6 or 8 hexadecimal digits with or without a leading #.

Invalid Length or Characters: Typing invalid strings (e.g. #GGZZ or 123) displays an inline error message and preserves existing channel values.
Reset Action: Clicking Reset immediately clears errors and restores the default teal baseline (#2DD4BF).
Download Action: Clicking Download outputs a standalone flutter_color.dart or app_theme.dart file via local DOM Blob creation.

4. Limitations & Data Handling

Limitations: The converter does not parse arbitrary CSS color names (e.g., rebeccapurple) or CSS variables (var(--primary)). WCAG 2.2 calculations evaluate mathematical luminance between solid flat colors under standard illumination; gradients and blurred overlay surfaces require manual visual evaluation.

Data Handling: All color math, bit shifting, and Dart code generation runs strictly in local browser memory. The tool itself never sends your colors to a server. Like every page on this site, it loads Google AdSense, which uses cookies as described in our privacy policy. State persistence is isolated to client-side IndexedDB storage.

Flutter Color Architecture: ARGB Math & Material 3 Roles

Understanding how Flutter represents colors in memory and how Material Design 3 derives harmonious tonal palettes is essential for building accessible, visually consistent cross-platform applications.

1. Why Flutter Uses 0xAARRGGBB Integers

In standard web CSS, 8-digit hexadecimal colors follow the #RRGGBBAA format where alpha is at the end. In Flutter and Skia/Impeller graphics engines, colors are represented as 32-bit unsigned integers in 0xAARRGGBB byte order.

A common developer pitfall is passing a 6-digit hex code directly: Color(0x2563EB). Because bits 24–31 represent alpha, omitting them evaluates to 0x002563EB — creating a completely transparent color that renders invisibly. Always prefix solid hex colors with 0xFF.

2. Relative Luminance & WCAG 2.1 Contrast

Web Content Accessibility Guidelines (WCAG) 2.1 require a minimum contrast ratio of 4.5:1 for normal body text and 3.0:1 for large headings (18pt+ or 14pt bold).

Contrast is calculated by converting sRGB channels to linear light space and computing relative luminance L = 0.2126*R + 0.7152*G + 0.0722*B. The contrast ratio between foreground and background is (L1 + 0.05) / (L2 + 0.05). Testing your theme ensures readability for users with low vision or varying ambient lighting.

3. Material 3 Tonal Palettes & Dynamic Seed Extraction

Material 3 shifts away from arbitrary color picking to algorithmic tonal palettes. When you define ColorScheme.fromSeed(seedColor: Color(0xFF6750A4)), Flutter extracts the key hue and Chroma to construct tonal swatches from tone 0 (pure black) to tone 100 (pure white).

Primary & onPrimary: Tone 40 in light mode with tone 100 text; tone 80 in dark mode with tone 20 text.
Container Pairs: Subtle container fills (tone 90 light, tone 30 dark) paired with accessible text roles.
Surface & Outline: Neutral tonal palettes that automatically adapt to light/dark system settings.

4. Idiomatic Flutter Color Construction Patterns

Flutter provides multiple constructors for distinct use cases:

const Color(0xFF1E293B) — Compile-time constant hex integer.
Color.fromARGB(255, 30, 41, 59) — Explicit integer channel assignment [0..255].
Color.fromRGBO(30, 41, 59, 1.0) — Floating-point opacity [0.0..1.0] matching CSS syntax.
color.withValues(alpha: 0.8) — Flutter 3.27+ non-deprecated opacity replacement.