vjrj
21072633b5
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.
52 lines
1.8 KiB
Dart
52 lines
1.8 KiB
Dart
import 'dart:math';
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import 'dart:ui';
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import 'package:flutter/material.dart' show Colors;
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import 'package:flutter_test/flutter_test.dart';
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import 'package:tane/ui/theme.dart';
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/// WCAG 2.x relative luminance of a color (sRGB).
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double _luminance(Color c) {
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double channel(double v) =>
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v <= 0.03928 ? v / 12.92 : pow((v + 0.055) / 1.055, 2.4).toDouble();
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return 0.2126 * channel(c.r) + 0.7152 * channel(c.g) + 0.0722 * channel(c.b);
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}
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/// WCAG contrast ratio between two colors (order-independent, 1..21).
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double _contrast(Color a, Color b) {
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final la = _luminance(a);
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final lb = _luminance(b);
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final lighter = max(la, lb);
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final darker = min(la, lb);
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return (lighter + 0.05) / (darker + 0.05);
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}
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void main() {
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void expectAa(Color foreground, Color background, String label) {
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expect(
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_contrast(foreground, background),
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greaterThanOrEqualTo(4.5),
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reason: '$label must meet WCAG AA (4.5:1) for normal text',
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);
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}
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group('palette meets WCAG AA (4.5:1) for text', () {
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test('seedMuted (hints, subtitles) on every background it sits on', () {
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// White: search-field fill and home cards. Canvas/field: M3 surfaces.
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expectAa(seedMuted, Colors.white, 'seedMuted on white');
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expectAa(seedMuted, seedCanvas, 'seedMuted on canvas');
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expectAa(seedMuted, seedField, 'seedMuted on field fill');
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});
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test('body and secondary text on the canvas', () {
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expectAa(seedOnSurface, seedCanvas, 'onSurface on canvas');
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expectAa(seedTitle, seedCanvas, 'titles on canvas');
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expectAa(seedOnSurfaceVariant, seedCanvas, 'onSurfaceVariant on canvas');
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});
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test('white text on the green action colours', () {
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expectAa(Colors.white, seedGreen, 'white on primary green');
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expectAa(Colors.white, seedAppBar, 'white on app-bar green');
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});
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});
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}
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