fix(theming): Adjust dark high contrast to fulfill WCAG 2.1 AAA contrast

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

apps/theming/lib/Themes/CommonThemeTrait.php

@@ -38,9 +38,9 @@ trait CommonThemeTrait {
 	 * This is shared between multiple themes because colorMainBackground and colorMainText
 	 * will change in between.
 	 */
-	protected function generatePrimaryVariables(string $colorMainBackground, string $colorMainText): array {
+	protected function generatePrimaryVariables(string $colorMainBackground, string $colorMainText, bool $highContrast = false): array {
 		$isBrightColor = $this->util->isBrightColor($colorMainBackground);
-		$colorPrimaryElement = $this->util->elementColor($this->primaryColor, $isBrightColor, $colorMainBackground);
+		$colorPrimaryElement = $this->util->elementColor($this->primaryColor, $isBrightColor, $colorMainBackground, $highContrast);
 		$colorPrimaryLight = $this->util->mix($colorPrimaryElement, $colorMainBackground, -80);
 		$colorPrimaryElementLight = $this->util->mix($colorPrimaryElement, $colorMainBackground, -80);
 		$invertPrimaryTextColor = $this->util->invertTextColor($colorPrimaryElement);

apps/theming/lib/Themes/DarkHighContrastTheme.php

@@ -59,17 +59,22 @@ class DarkHighContrastTheme extends DarkTheme implements ITheme {
 		$colorMainBackground = '#000000';
 		$colorMainBackgroundRGB = join(',', $this->util->hexToRGB($colorMainBackground));
 
+		$colorError = '#ff5252';
+		$colorWarning = '#ffcc00';
+		$colorSuccess = '#42a942';
+		$colorInfo = '#38c0ff';
+
 		return array_merge(
 			$defaultVariables,
-			$this->generatePrimaryVariables($colorMainBackground, $colorMainText),
+			$this->generatePrimaryVariables($colorMainBackground, $colorMainText, true),
 			[
 				'--color-main-background' => $colorMainBackground,
 				'--color-main-background-rgb' => $colorMainBackgroundRGB,
 				'--color-main-background-translucent' => 'rgba(var(--color-main-background-rgb), 1)',
 				'--color-main-text' => $colorMainText,
 
-				'--color-background-dark' => $this->util->lighten($colorMainBackground, 30),
-				'--color-background-darker' => $this->util->lighten($colorMainBackground, 30),
+				'--color-background-dark' => $this->util->lighten($colorMainBackground, 25),
+				'--color-background-darker' => $this->util->lighten($colorMainBackground, 25),
 
 				'--color-main-background-blur' => $colorMainBackground,
 				'--filter-background-blur' => 'none',
@@ -82,6 +87,26 @@ class DarkHighContrastTheme extends DarkTheme implements ITheme {
 				'--color-text-light' => $colorMainText,
 				'--color-text-lighter' => $colorMainText,
 
+				'--color-error' => $colorError,
+				'--color-error-rgb' => join(',', $this->util->hexToRGB($colorError)),
+				'--color-error-hover' => $this->util->lighten($colorError, 10),
+				'--color-error-text' => $this->util->lighten($colorError, 25),
+
+				'--color-warning' => $colorWarning,
+				'--color-warning-rgb' => join(',', $this->util->hexToRGB($colorWarning)),
+				'--color-warning-hover' => $this->util->lighten($colorWarning, 10),
+				'--color-warning-text' => $this->util->lighten($colorWarning, 10),
+
+				'--color-success' => $colorSuccess,
+				'--color-success-rgb' => join(',', $this->util->hexToRGB($colorSuccess)),
+				'--color-success-hover' => $this->util->lighten($colorSuccess, 10),
+				'--color-success-text' => $this->util->lighten($colorSuccess, 35),
+
+				'--color-info' => $colorInfo,
+				'--color-info-rgb' => join(',', $this->util->hexToRGB($colorInfo)),
+				'--color-info-hover' => $this->util->lighten($colorInfo, 10),
+				'--color-info-text' => $this->util->lighten($colorInfo, 20),
+
 				'--color-scrollbar' => $this->util->lighten($colorMainBackground, 35),
 
 				// used for the icon loading animation

apps/theming/lib/Util.php

@@ -81,7 +81,7 @@ class Util {
 	 * @param ?bool $brightBackground
 	 * @return string
 	 */
-	public function elementColor($color, ?bool $brightBackground = null, ?string $backgroundColor = null) {
+	public function elementColor($color, ?bool $brightBackground = null, ?string $backgroundColor = null, bool $highContrast = false) {
 		if ($backgroundColor !== null) {
 			$brightBackground = $brightBackground ?? $this->isBrightColor($backgroundColor);
 			// Minimal amount that is possible to change the luminance
@@ -93,7 +93,9 @@ class Util {
 			$contrast = $this->colorContrast($color, $blurredBackground);
 
 			// Min. element contrast is 3:1 but we need to keep hover states in mind -> min 3.2:1
-			while ($contrast < 3.2 && $iteration++ < 100) {
+			$minContrast = $highContrast ? 5.5 : 3.2;
+
+			while ($contrast < $minContrast && $iteration++ < 100) {
 				$hsl = Color::hexToHsl($color);
 				$hsl['L'] = max(0, min(1, $hsl['L'] + ($brightBackground ? -$epsilon : $epsilon)));
 				$color = '#' . Color::hslToHex($hsl);

apps/theming/tests/Themes/AccessibleThemeTestCase.php

@@ -30,7 +30,15 @@ class AccessibleThemeTestCase extends TestCase {
 	protected ITheme $theme;
 	protected Util $util;
 
+	/**
+	 * Set to true to check for WCAG AAA level accessibility
+	 */
+	protected bool $WCAGaaa = false;
+
 	public function dataAccessibilityPairs() {
+		$textContrast = $this->WCAGaaa ? 7.0 : 4.5;
+		$elementContrast = 3.0;
+
 		return [
 			'primary-element on background' => [
 				[
@@ -44,7 +52,7 @@ class AccessibleThemeTestCase extends TestCase {
 					'--color-background-darker',
 					'--color-main-background-blur',
 				],
-				3.0,
+				$elementContrast,
 			],
 			'status color elements on background' => [
 				[
@@ -64,7 +72,18 @@ class AccessibleThemeTestCase extends TestCase {
 					'--color-background-darker',
 					'--color-main-background-blur',
 				],
-				3.0,
+				$elementContrast,
+			],
+			// Those two colors are used for borders which will be `color-main-text` on focussed state, thus need 3:1 contrast to it
+			'success-error-border-colors' => [
+				[
+					'--color-error',
+					'--color-success',
+				],
+				[
+					'--color-main-text',
+				],
+				$elementContrast,
 			],
 			'primary-element-text' => [
 				[
@@ -75,7 +94,7 @@ class AccessibleThemeTestCase extends TestCase {
 					'--color-primary-element',
 					'--color-primary-element-hover',
 				],
-				4.5,
+				$textContrast,
 			],
 			'primary-element-light-text' => [
 				['--color-primary-element-light-text'],
@@ -83,7 +102,7 @@ class AccessibleThemeTestCase extends TestCase {
 					'--color-primary-element-light',
 					'--color-primary-element-light-hover',
 				],
-				4.5,
+				$textContrast,
 			],
 			'main-text' => [
 				['--color-main-text'],
@@ -94,7 +113,7 @@ class AccessibleThemeTestCase extends TestCase {
 					'--color-background-darker',
 					'--color-main-background-blur',
 				],
-				4.5,
+				$textContrast,
 			],
 			'max-contrast-text' => [
 				['--color-text-maxcontrast'],
@@ -103,14 +122,14 @@ class AccessibleThemeTestCase extends TestCase {
 					'--color-background-hover',
 					'--color-background-dark',
 				],
-				4.5,
+				$textContrast,
 			],
 			'max-contrast text-on blur' => [
 				['--color-text-maxcontrast-background-blur'],
 				[
 					'--color-main-background-blur',
 				],
-				4.5,
+				$textContrast,
 			],
 			'status-text' => [
 				[
@@ -125,7 +144,7 @@ class AccessibleThemeTestCase extends TestCase {
 					'--color-background-dark',
 					'--color-main-background-blur',
 				],
-				4.5,
+				$textContrast,
 			],
 		];
 	}

apps/theming/tests/Themes/DarkHighContrastThemeTest.php

@@ -0,0 +1,142 @@
+<?php
+/**
+ * @copyright Copyright (c) 2022 John Molakvoæ <skjnldsv@protonmail.com>
+ *
+ * @author John Molakvoæ <skjnldsv@protonmail.com>
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+namespace OCA\Theming\Tests\Themes;
+
+use OCA\Theming\AppInfo\Application;
+use OCA\Theming\ImageManager;
+use OCA\Theming\ITheme;
+use OCA\Theming\Service\BackgroundService;
+use OCA\Theming\Themes\DarkHighContrastTheme;
+use OCA\Theming\ThemingDefaults;
+use OCA\Theming\Util;
+use OCP\App\IAppManager;
+use OCP\Files\IAppData;
+use OCP\IConfig;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use OCP\IUserSession;
+use PHPUnit\Framework\MockObject\MockObject;
+
+class DarkHighContrastThemeTest extends AccessibleThemeTestCase {
+	/** @var ThemingDefaults|MockObject */
+	private $themingDefaults;
+	/** @var IUserSession|MockObject */
+	private $userSession;
+	/** @var IURLGenerator|MockObject */
+	private $urlGenerator;
+	/** @var ImageManager|MockObject */
+	private $imageManager;
+	/** @var IConfig|MockObject */
+	private $config;
+	/** @var IL10N|MockObject */
+	private $l10n;
+	/** @var IAppManager|MockObject */
+	private $appManager;
+
+	// !! important: Enable WCAG AAA tests
+	protected bool $WCAGaaa = true;
+
+	protected function setUp(): void {
+		$this->themingDefaults = $this->createMock(ThemingDefaults::class);
+		$this->userSession = $this->createMock(IUserSession::class);
+		$this->urlGenerator = $this->createMock(IURLGenerator::class);
+		$this->imageManager = $this->createMock(ImageManager::class);
+		$this->config = $this->createMock(IConfig::class);
+		$this->l10n = $this->createMock(IL10N::class);
+		$this->appManager = $this->createMock(IAppManager::class);
+
+		$this->util = new Util(
+			$this->config,
+			$this->appManager,
+			$this->createMock(IAppData::class),
+			$this->imageManager
+		);
+
+		$this->themingDefaults
+			->expects($this->any())
+			->method('getColorPrimary')
+			->willReturn('#0082c9');
+
+		$this->themingDefaults
+			->expects($this->any())
+			->method('getDefaultColorPrimary')
+			->willReturn('#0082c9');
+
+		$this->themingDefaults
+			->expects($this->any())
+			->method('getBackground')
+			->willReturn('/apps/' . Application::APP_ID . '/img/background/' . BackgroundService::DEFAULT_BACKGROUND_IMAGE);
+
+		$this->l10n
+			->expects($this->any())
+			->method('t')
+			->willReturnCallback(function ($text, $parameters = []) {
+				return vsprintf($text, $parameters);
+			});
+
+		$this->urlGenerator
+			->expects($this->any())
+			->method('imagePath')
+			->willReturnCallback(function ($app = 'core', $filename = '') {
+				return "/$app/img/$filename";
+			});
+
+		$this->theme = new DarkHighContrastTheme(
+			$this->util,
+			$this->themingDefaults,
+			$this->userSession,
+			$this->urlGenerator,
+			$this->imageManager,
+			$this->config,
+			$this->l10n,
+			$this->appManager,
+		);
+
+		parent::setUp();
+	}
+
+
+	public function testGetId() {
+		$this->assertEquals('dark-highcontrast', $this->theme->getId());
+	}
+
+	public function testGetType() {
+		$this->assertEquals(ITheme::TYPE_THEME, $this->theme->getType());
+	}
+
+	public function testGetTitle() {
+		$this->assertEquals('Dark theme with high contrast mode', $this->theme->getTitle());
+	}
+
+	public function testGetEnableLabel() {
+		$this->assertEquals('Enable dark high contrast mode', $this->theme->getEnableLabel());
+	}
+
+	public function testGetDescription() {
+		$this->assertEquals('Similar to the high contrast mode, but with dark colours.', $this->theme->getDescription());
+	}
+
+	public function testGetMediaQuery() {
+		$this->assertEquals('(prefers-color-scheme: dark) and (prefers-contrast: more)', $this->theme->getMediaQuery());
+	}
+}