Merge pull request #8 from Akylas/fix/font-clone-typeface

fix(android): don't copy cached typeface when cloning a Font

Author: farfromrefug

packages/core/ui/styling/font-common.ts

@@ -20,9 +20,10 @@ export abstract class FontBase implements Font {
 			Object.assign(clone, this);
 		} else {
 			clone.isDirty = true;
-			// clear android cached typeface. need to find a better way
-			clone['_typeface'] = null;
 		}
+		// clear android cached typeface (Object.assign copies it to clones too)
+		// so it is recreated from the updated font properties
+		clone['_typeface'] = null;
 		return clone;
 	}
 

packages/core/ui/styling/font.spec.ts

@@ -0,0 +1,39 @@
+import { Font } from './font';
+
+describe('Font', () => {
+	describe('cloneOrDirty', () => {
+		// simulate the android cached typeface set by Font.getAndroidTypeface()
+		const fontWithCachedTypeface = () => {
+			const font = new Font('serif', 12, 'normal', 'normal');
+			font['_typeface'] = { cached: true };
+			return font;
+		};
+
+		it('clones do not carry the cached typeface', () => {
+			const font = fontWithCachedTypeface();
+			const clones = [font.withFontWeight('700'), font.withFontFamily('monospace'), font.withFontStyle('italic'), font.withFontSize(20), font.withFontScale(2), font.withFontVariationSettings([{ axis: 'wght', value: 700 }])];
+			for (const clone of clones) {
+				expect(clone).not.toBe(font);
+				expect(clone['_typeface']).toBeNull();
+			}
+			// source font keeps its own cache
+			expect(font['_typeface']).toEqual({ cached: true });
+		});
+
+		it('clones keep the font descriptor and apply the new property', () => {
+			const clone = fontWithCachedTypeface().withFontWeight('700');
+			expect(clone.fontFamily).toBe('serif');
+			expect(clone.fontSize).toBe(12);
+			expect(clone.fontStyle).toBe('normal');
+			expect(clone.fontWeight).toBe('700');
+		});
+
+		it('dirtied (non cloned) font clears the cached typeface', () => {
+			const font = fontWithCachedTypeface();
+			const result = font.withFontWeight('700', false);
+			expect(result).toBe(font);
+			expect(result.isDirty).toBe(true);
+			expect(result['_typeface']).toBeNull();
+		});
+	});
+});