feat(core): first class a11y support (#8909)

packages/core/accessibility/font-scale.ios.ts

@@ -0,0 +1,109 @@
+import * as Application from '../application';
+import { FontScaleCategory, getClosestValidFontScale } from './font-scale-common';
+export * from './font-scale-common';
+
+let currentFontScale: number = null;
+function fontScaleChanged(origFontScale: number) {
+	const oldValue = currentFontScale;
+	currentFontScale = getClosestValidFontScale(origFontScale);
+
+	if (oldValue !== currentFontScale) {
+		Application.notify({
+			eventName: Application.fontScaleChangedEvent,
+			object: Application,
+		});
+	}
+}
+
+export function getCurrentFontScale(): number {
+	setupConfigListener();
+
+	return currentFontScale;
+}
+
+export function getFontScaleCategory(): FontScaleCategory {
+	if (currentFontScale < 0.85) {
+		return FontScaleCategory.ExtraSmall;
+	}
+
+	if (currentFontScale > 1.5) {
+		return FontScaleCategory.ExtraLarge;
+	}
+
+	return FontScaleCategory.Medium;
+}
+
+const sizeMap = new Map<string, number>([
+	[UIContentSizeCategoryExtraSmall, 0.5],
+	[UIContentSizeCategorySmall, 0.7],
+	[UIContentSizeCategoryMedium, 0.85],
+	[UIContentSizeCategoryLarge, 1],
+	[UIContentSizeCategoryExtraLarge, 1.15],
+	[UIContentSizeCategoryExtraExtraLarge, 1.3],
+	[UIContentSizeCategoryExtraExtraExtraLarge, 1.5],
+	[UIContentSizeCategoryAccessibilityMedium, 2],
+	[UIContentSizeCategoryAccessibilityLarge, 2.5],
+	[UIContentSizeCategoryAccessibilityExtraLarge, 3],
+	[UIContentSizeCategoryAccessibilityExtraExtraLarge, 3.5],
+	[UIContentSizeCategoryAccessibilityExtraExtraExtraLarge, 4],
+]);
+
+function contentSizeUpdated(fontSize: string) {
+	if (sizeMap.has(fontSize)) {
+		fontScaleChanged(sizeMap.get(fontSize));
+
+		return;
+	}
+
+	fontScaleChanged(1);
+}
+
+function useIOSFontScale() {
+	if (Application.ios.nativeApp) {
+		contentSizeUpdated(Application.ios.nativeApp.preferredContentSizeCategory);
+	} else {
+		fontScaleChanged(1);
+	}
+}
+
+let fontSizeObserver;
+function setupConfigListener(attempt = 0) {
+	if (fontSizeObserver) {
+		return;
+	}
+
+	if (!Application.ios.nativeApp) {
+		if (attempt > 100) {
+			fontScaleChanged(1);
+
+			return;
+		}
+
+		// Couldn't get launchEvent to trigger.
+		setTimeout(() => setupConfigListener(attempt + 1), 1);
+
+		return;
+	}
+
+	fontSizeObserver = Application.ios.addNotificationObserver(UIContentSizeCategoryDidChangeNotification, (args) => {
+		const fontSize = args.userInfo.valueForKey(UIContentSizeCategoryNewValueKey);
+		contentSizeUpdated(fontSize);
+	});
+
+	Application.on(Application.exitEvent, () => {
+		if (fontSizeObserver) {
+			Application.ios.removeNotificationObserver(fontSizeObserver, UIContentSizeCategoryDidChangeNotification);
+			fontSizeObserver = null;
+		}
+
+		Application.off(Application.resumeEvent, useIOSFontScale);
+	});
+
+	Application.on(Application.resumeEvent, useIOSFontScale);
+
+	useIOSFontScale();
+}
+
+export function initAccessibilityFontScale(): void {
+	setupConfigListener();
+}