fix: render unicode characters in typed signatures (#2728)

packages/lib/constants/pdf.test.ts

@@ -0,0 +1,44 @@
+import { describe, expect, it } from 'vitest';
+
+import { getSignatureFontFamily } from './pdf';
+
+describe('getSignatureFontFamily', () => {
+  const expectCaveat = (family: string) => expect(family).toBe('Caveat');
+  const expectNotoChain = (family: string) => {
+    expect(family).toContain('"Noto Sans"');
+    expect(family).toContain('"Noto Sans Chinese"');
+    expect(family).toContain('"Noto Sans Japanese"');
+    expect(family).toContain('"Noto Sans Korean"');
+    expect(family).toContain('sans-serif');
+    expect(family).not.toContain('Caveat');
+  };
+
+  it('returns Caveat for ASCII-only text', () => {
+    expectCaveat(getSignatureFontFamily('John Doe'));
+    expectCaveat(getSignatureFontFamily(''));
+  });
+
+  it('returns the Noto chain for any non-ASCII character', () => {
+    expectNotoChain(getSignatureFontFamily('François'));
+    expectNotoChain(getSignatureFontFamily('Müller'));
+    expectNotoChain(getSignatureFontFamily('Søren'));
+    expectNotoChain(getSignatureFontFamily('Иванов'));
+    expectNotoChain(getSignatureFontFamily('Ελληνικά'));
+    expectNotoChain(getSignatureFontFamily('عربي'));
+    expectNotoChain(getSignatureFontFamily('עברית'));
+    expectNotoChain(getSignatureFontFamily('도큐멘소'));
+    expectNotoChain(getSignatureFontFamily('中文签名'));
+    expectNotoChain(getSignatureFontFamily('こんにちは'));
+  });
+
+  it('returns the Noto chain for mixed ASCII + non-ASCII input', () => {
+    expectNotoChain(getSignatureFontFamily('Hello 안녕'));
+    expectNotoChain(getSignatureFontFamily('Ivan Ωmega'));
+  });
+
+  it('returns the Noto chain for scripts not covered by a dedicated Noto file', () => {
+    expectNotoChain(getSignatureFontFamily('ሰላም')); // Ethiopic
+    expectNotoChain(getSignatureFontFamily('សួស្ដី')); // Khmer
+    expectNotoChain(getSignatureFontFamily('ᠮᠣᠩᠭᠣᠯ')); // Mongolian
+  });
+});

packages/lib/constants/pdf.ts

@@ -9,6 +9,20 @@ export const MIN_HANDWRITING_FONT_SIZE = 20;
 
 export const CAVEAT_FONT_PATH = () => `${NEXT_PUBLIC_WEBAPP_URL()}/fonts/caveat.ttf`;
 
+const SIGNATURE_FONT_FAMILY_CAVEAT = 'Caveat';
+
+// CN-before-JP: the JP Noto file's Han glyphs use JP shapes, so pure-CN
+// text would otherwise render with JP forms. Family names sync with
+// apps/remix/app/app.css and packages/lib/server-only/pdf/helpers.ts.
+const SIGNATURE_FONT_FAMILY_NOTO =
+  '"Noto Sans", "Noto Sans Chinese", "Noto Sans Japanese", "Noto Sans Korean", sans-serif';
+
+const isASCII = (str: string) => /^\p{ASCII}*$/u.test(str);
+
+// Deliberately never mix handwriting + sans-serif within one signature.
+export const getSignatureFontFamily = (typedSignatureText: string): string =>
+  isASCII(typedSignatureText) ? SIGNATURE_FONT_FAMILY_CAVEAT : SIGNATURE_FONT_FAMILY_NOTO;
+
 export const PDF_SIZE_A4_72PPI = {
   width: 595,
   height: 842,

packages/lib/server-only/pdf/render-certificate.ts

@@ -14,6 +14,7 @@ import { renderSVG } from 'uqr';
 
 import { NEXT_PUBLIC_WEBAPP_URL } from '../../constants/app';
 import { APP_I18N_OPTIONS } from '../../constants/i18n';
+import { getSignatureFontFamily } from '../../constants/pdf';
 import { RECIPIENT_ROLE_SIGNING_REASONS, RECIPIENT_ROLES_DESCRIPTION } from '../../constants/recipient-roles';
 import type { TDocumentAuditLogBaseSchema } from '../../types/document-audit-logs';
 import { svgToPng } from '../../utils/images/svg-to-png';
@@ -302,7 +303,7 @@ const renderColumnTwo = (options: RenderColumnOptions) => {
         x: 2,
         text: recipient.signatureField?.signature?.typedSignature,
         padding: 4,
-        fontFamily: 'Caveat',
+        fontFamily: getSignatureFontFamily(recipient.signatureField?.signature?.typedSignature),
         fontSize: 16,
         align: 'center',
         verticalAlign: 'middle',

packages/lib/universal/field-renderer/render-signature-field.ts

@@ -1,6 +1,6 @@
 import Konva from 'konva';
 
-import { DEFAULT_SIGNATURE_TEXT_FONT_SIZE } from '../../constants/pdf';
+import { DEFAULT_SIGNATURE_TEXT_FONT_SIZE, getSignatureFontFamily } from '../../constants/pdf';
 import { AppError } from '../../errors/app-error';
 import type { TSignatureFieldMeta } from '../../types/field-meta';
 import { resolveFieldOverflowMode } from '../../types/field-meta';
@@ -187,7 +187,7 @@ const createFieldSignature = (field: FieldToRender, options: RenderFieldElementO
     isLabel,
     textToRender,
     fontSize,
-    fontFamily: 'Caveat, sans-serif',
+    fontFamily: getSignatureFontFamily(textToRender),
     lineHeight: 1,
     letterSpacing: 0,
     textAlign: 'center',
@@ -209,7 +209,7 @@ const createFieldSignature = (field: FieldToRender, options: RenderFieldElementO
     wrap: overflowLayout.wrap,
     text: textToRender,
     fontSize,
-    fontFamily: 'Caveat, sans-serif',
+    fontFamily: getSignatureFontFamily(textToRender),
     align: overflowLayout.textAlign,
     width: overflowLayout.width,
     height: overflowLayout.height,
@@ -280,7 +280,7 @@ export const renderSignatureFieldElement = (field: FieldToRender, options: Rende
         isLabel,
         textToRender: fieldSignature.text(),
         fontSize: fieldSignature.fontSize(),
-        fontFamily: 'Caveat, sans-serif',
+        fontFamily: getSignatureFontFamily(fieldSignature.text()),
         lineHeight: 1,
         letterSpacing: 0,
         textAlign: 'center',