comunes/tane
1
0
Fork 0
Code Issues Pull requests Projects Releases 7 Packages Wiki Activity Actions

fix(ui): darken seedMuted and app-bar green to meet WCAG AA contrast

Browse source 
seedMuted (hints, card subtitles, search placeholder) was #8A9880 —
2.62:1 on the canvas and 3.05:1 on white, failing AA for the 13px text
it colours. Darkened to #617057: 5.30:1 on white, 4.56:1 on canvas,
4.88:1 on the field fill, same muted green-grey hue.

The new contrast test also caught the app-bar green: white titles on
#3E8C38 were 4.19:1, so it is nudged to #3A8434 (4.64:1) — a barely
visible change.

test/ui/theme_contrast_test.dart pins the WCAG relative-luminance math
and asserts every text/background pair the palette actually uses.
This commit is contained in:
vjrj 2026-07-09 12:50:26 +02:00
parent 2812c99280
commit 21072633b5
3 changed files with 60 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

52
apps/app_seeds/test/ui/theme_contrast_test.dart Normal file
View file

@ -0,0 +1,52 @@
import 'dart:math';
import 'dart:ui';
import 'package:flutter/material.dart' show Colors;
import 'package:flutter_test/flutter_test.dart';
import 'package:tane/ui/theme.dart';
/// WCAG 2.x relative luminance of a color (sRGB).
double _luminance(Color c) {
double channel(double v) =>
v <= 0.03928 ? v / 12.92 : pow((v + 0.055) / 1.055, 2.4).toDouble();
return 0.2126 * channel(c.r) + 0.7152 * channel(c.g) + 0.0722 * channel(c.b);
}
/// WCAG contrast ratio between two colors (order-independent, 1..21).
double _contrast(Color a, Color b) {
final la = _luminance(a);
final lb = _luminance(b);
final lighter = max(la, lb);
final darker = min(la, lb);
return (lighter + 0.05) / (darker + 0.05);
}
void main() {
void expectAa(Color foreground, Color background, String label) {
expect(
_contrast(foreground, background),
greaterThanOrEqualTo(4.5),
reason: '$label must meet WCAG AA (4.5:1) for normal text',
);
}
group('palette meets WCAG AA (4.5:1) for text', () {
test('seedMuted (hints, subtitles) on every background it sits on', () {
// White: search-field fill and home cards. Canvas/field: M3 surfaces.
expectAa(seedMuted, Colors.white, 'seedMuted on white');
expectAa(seedMuted, seedCanvas, 'seedMuted on canvas');
expectAa(seedMuted, seedField, 'seedMuted on field fill');
});
test('body and secondary text on the canvas', () {
expectAa(seedOnSurface, seedCanvas, 'onSurface on canvas');
expectAa(seedTitle, seedCanvas, 'titles on canvas');
expectAa(seedOnSurfaceVariant, seedCanvas, 'onSurfaceVariant on canvas');
});
test('white text on the green action colours', () {
expectAa(Colors.white, seedGreen, 'white on primary green');
expectAa(Colors.white, seedAppBar, 'white on app-bar green');
});
});
}