Write two hex digits for standard font character codes below 0x10

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ### Unreleased
 
+- Fix text in a standard font garbling or dropping the characters after a tab, a carriage return or any other character code below `0x10`, which was written into the hex string of the text as a single digit, so the following digits paired up wrongly: a `\r` before a line break showed as `Ð`, and `Tab\there` was read back as `Tab–†W&P`. Fixes #1425, #606
 - Reuse the glyph width and kerning tables of a standard font across documents instead of building them again for every document that uses it, which made a short document using two standard fonts more than twice as slow to create
 - Fix `doc.table()` parsing a font passed as binary data (e.g. registered with `registerFont(name, uint8Array)`) again for every cell, when it restores the font after measuring and drawing the cell, which made tables with such fonts slower. A font loaded from the same `Uint8Array` is now reused without parsing it again
 - Add `lineBreak: 'whitespace'` to `doc.text()`, which breaks a line only at whitespace, a soft hyphen or a zero-width space. The Unicode line breaking rules the wrapper follows also allow a break after a hyphen or a slash, so `design-system` or `https://github.com/foliojs/pdfkit` could be cut at a line end, and a text extractor that joins the lines, such as a résumé parser, reads two words

lib/font/afm.js

@@ -148,7 +148,7 @@ class AFMFont {
     for (let i = 0, len = text.length; i < len; i++) {
       let char = text.charCodeAt(i);
       char = WIN_ANSI_MAP[char] || char;
-      res.push(char.toString(16));
+      res.push(char.toString(16).padStart(2, '0'));
     }
 
     return res;

tests/unit/afm.spec.js

@@ -230,6 +230,18 @@ describe('AFMFont', () => {
     expect(font.getKernPair('A', '.notdef')).toBe(0);
   });
 
+  test('encodes character codes below 0x10 as two hex digits', () => {
+    const font = new AFMFont(Helvetica);
+
+    expect(font.encodeText('a\tb\r\x01')).toEqual([
+      '61',
+      '09',
+      '62',
+      '0d',
+      '01',
+    ]);
+  });
+
   test('does not mutate generated data while decoding it', () => {
     const originalData = JSON.stringify(Helvetica);
     const font = new AFMFont(Helvetica);

tests/unit/text.spec.js

@@ -21,6 +21,15 @@ describe('Text', () => {
       expect(docData).toContainText({ text: 'simple text' });
     });
 
+    test('with a tab or carriage return keeps the following characters', () => {
+      const docData = logData(document);
+
+      document.text('a\tb\rc', { lineBreak: false });
+      document.end();
+
+      expect(docData).toContainText({ text: 'a\tb\rc' });
+    });
+
     test('with destination', () => {
       // just check that there is no exception
       document.text('simple text', { destination: 'anchor' });