docs: story page to check color contrasts

.eslintrc.cjs

@@ -48,7 +48,7 @@ module.exports = {
     // NX
     '@nx/enforce-module-boundaries': 2,
     // Prettier
-    "prettier/prettier": [1, { "endOfLine": "auto" }],
+    'prettier/prettier': [1, { endOfLine: 'auto' }],
     // Typescript
     '@typescript-eslint/consistent-type-definitions': [1, 'interface'],
     '@typescript-eslint/array-type': [2, { default: 'array', readonly: 'array' }],

packages/utils/theme/src/contrastCheck.doc.mdx

@@ -0,0 +1,73 @@
+import { Canvas, Meta } from '@storybook/addon-docs'
+import * as ContrastCheck from './contrastCheck.stories'
+
+<Meta of={ContrastCheck} />
+
+# Contrast check
+
+## Usage
+
+```typescript
+import { getThemeContrastReport, checkColorContrast } from '@spark-ui/theme-utils'
+```
+
+### getThemeContrastReport
+
+Use `getThemeContrastReport(theme)` to get a detailed report of the contrast ratio for each pair of colors in the theme.
+
+For exemple `main` colored background is supposed to have `onMain` colored text. The pair `main/onMain` must provide sufficient contrast ratio to pass [SC 1.4.3 - Contrast (Minimum) (Level AA)](https://www.w3.org/WAI/WCAG21/Understanding/contrast-minimum.html).
+Same goes for every other color pair in a Spark theme.
+
+Each pair is tested for normal text size and larger text size, as they both have different contrast requirements.
+
+Score can be: `Failed`, `AA` or `AAA`.
+
+```typescript
+import { checkColorContrast } from '@spark-ui/theme-utils'
+
+const report = getThemeContrastReport(theme)
+```
+
+Report looks like this:
+
+```json
+// Exemple for the main color
+{
+  "main": {
+    "previewStyles": "bg-main text-on-main",
+    "small": {
+      "contrastRatio": "3.48",
+      "score": "Failed",
+      "textSize": "Small",
+      "colors": ["#EC5A13", "#FFFFFF"]
+    },
+    "large": {
+      "contrastRatio": "3.48",
+      "score": "Failed",
+      "textSize": "Small",
+      "colors": ["#EC5A13", "#FFFFFF"]
+    }
+  }
+  // other colors...
+}
+```
+
+### checkColorContrast
+
+Use `checkColorContrast` to compare two colors given a font-size.
+
+```typescript
+import { checkColorContrast } from '@spark-ui/theme-utils'
+
+const LARGE_FONT_SIZE = 24
+
+checkColorContrast('#EC5A13', '#FFFFFF', LARGE_FONT_SIZE) // { "contrastRatio": "3.48", "score": "Failed", "textSize": "Large", "colors": ["#EC5A13", "#FFFFFF"] }
+```
+
+## Spark theme contrasts
+
+This section displays card with all color schemes offered by Spark themes (default and dark).
+
+It can be used by Axe dev tools or Playwright for an a11y color check.
+
+<Canvas of={ContrastCheck.Default} />

packages/utils/theme/src/contrastCheck.stories.tsx

@@ -0,0 +1,94 @@
+import { Icon } from '@spark-ui/icon'
+import { Block } from '@spark-ui/icons/dist/icons/Block'
+import { Check } from '@spark-ui/icons/dist/icons/Check'
+import { Tabs } from '@spark-ui/tabs'
+import { Tag } from '@spark-ui/tag'
+import { Meta, StoryFn } from '@storybook/react'
+import { cx } from 'class-variance-authority'
+import { ReactNode } from 'react'
+
+import { getThemeContrastReport } from './contrastCheck'
+import { defaultTheme } from './defaultTheme'
+import { defaultThemeDark } from './defaultThemeDark'
+import { type Theme } from './types'
+
+const meta: Meta = {
+  title: 'Utils/theme-utils/contrast check',
+}
+
+export default meta
+
+const ScoreTag = ({ score }: { score: string }) => {
+  const isSuccess = score.includes('AA')
+
+  return (
+    <Tag design="tinted" intent={isSuccess ? 'success' : 'danger'}>
+      {score}
+      <Icon>{isSuccess ? <Check /> : <Block />}</Icon>
+    </Tag>
+  )
+}
+
+const Cell = ({ className, children }: { className?: string; children: ReactNode }) => {
+  return <td className={cx('border-sm border-outline p-md', className)}>{children}</td>
+}
+
+const ThemeReport = ({ theme, ...rest }: { theme: Theme }) => {
+  const report = getThemeContrastReport(theme)
+
+  return (
+    <table className="table-auto bg-surface text-on-surface" {...rest}>
+      <thead className="sticky">
+        <tr>
+          <th className="p-sm text-left">Color</th>
+          <th className="p-sm text-left">Preview</th>
+          <th className="p-sm text-left">Ratio</th>
+          <th className="p-sm text-left">Score (small text)</th>
+          <th className="p-sm text-left">Score (large text)</th>
+        </tr>
+      </thead>
+      <tbody>
+        {Object.entries(report).map(([color, result]) => {
+          return (
+            <tr>
+              <Cell>{color}</Cell>
+              <Cell className={cx('border-current px-lg', result.previewStyles)}>
+                <span className="text-body-1">small, </span>
+                <span className="text-headline-1">large</span>
+              </Cell>
+              <Cell>{result.small.contrastRatio}</Cell>
+              <Cell>
+                <ScoreTag score={result.small.score} />
+              </Cell>
+              <Cell>
+                <ScoreTag score={result.large.score} />
+              </Cell>
+            </tr>
+          )
+        })}
+      </tbody>
+    </table>
+  )
+}
+
+export const Default: StoryFn = _args => (
+  <div className="flex">
+    <Tabs defaultValue="tab1">
+      <Tabs.List>
+        <Tabs.Trigger value="tab1">
+          <span>Default theme</span>
+        </Tabs.Trigger>
+        <Tabs.Trigger value="tab2">
+          <span>Dark theme</span>
+        </Tabs.Trigger>
+      </Tabs.List>
+
+      <Tabs.Content value="tab1" data-theme="default">
+        <ThemeReport theme={defaultTheme} />
+      </Tabs.Content>
+      <Tabs.Content value="tab2" data-theme="dark" className="bg-surface">
+        <ThemeReport theme={defaultThemeDark} />
+      </Tabs.Content>
+    </Tabs>
+  </div>
+)