Accessible Theme Builder
Component Detail
Description
Assembles the final Flutter ThemeData by composing the contrast-safe color scheme, the accessible text theme, and token-driven component themes (input decorations, button themes, card themes). Acts as the integration point between the token layer and the Flutter widget tree, ensuring all theme values trace back to validated tokens.
theme-builder
Summaries
The Accessible Theme Builder ensures every visual element of the mobile application meets accessibility standards while maintaining brand consistency. By centralizing color, typography, and component styling into a single validated layer, it reduces the risk of accessibility violations that could expose the organization to legal liability under ADA and WCAG compliance requirements. It supports both light and dark mode variants, directly improving usability for users with visual impairments and expanding the addressable user base. Consistent, validated theming also accelerates design iteration and reduces costly rework cycles across the product.
The Theme Builder is a medium-complexity shared component sitting at the intersection of design and engineering, with three upstream dependencies — design-token-provider, contrast-safe-color-palette, and accessible-text-style-system — that must be stable before this component can be finalized. Plan for a dedicated integration sprint after token and color work completes. Testing must cover both light and dark theme variants across device sizes, and compliance validation should be automated in CI to catch regressions early. Any upstream token change triggers regression testing across all themed UI surfaces, making change-control discipline on upstream components a key scheduling risk.
The Theme Builder composes Flutter's ThemeData by integrating outputs from design-token-provider, contrast-safe-color-palette, accessible-text-style-system, and token-accessibility-enforcer. It exposes buildLightTheme() and buildDarkTheme() as primary entry points, each invoking applyComponentThemes() to layer ButtonTheme, InputDecorationTheme, CardTheme, and other component-level overrides onto the base theme. The validateThemeCompliance() method runs token assertion checks in debug mode, surfacing violations early in development. The registerThemeExtension() API supports custom ThemeExtension subclasses without breaking the core theme contract.
As a shared component, changes here propagate across the entire widget tree and require full UI regression coverage.
Responsibilities
- Compose ThemeData from color scheme, text theme, and component themes
- Apply token-enforced component themes (ButtonTheme, InputDecorationTheme, etc.)
- Provide both light and dark ThemeData variants
- Assert token compliance during theme construction in debug mode
Interfaces
buildLightTheme() → ThemeData
buildDarkTheme() → ThemeData
applyComponentThemes(ThemeData base) → ThemeData
validateThemeCompliance(ThemeData theme) → bool
registerThemeExtension(ThemeExtension ext) → ThemeData
Relationships
Dependencies (4)
Components this component depends on