fix(textkit): fix glyphIndexAt regression

.changeset/wise-clocks-drop.md

@@ -0,0 +1,5 @@
+---
+"@react-pdf/textkit": minor
+---
+
+fix(textkit): advanceWidthBetween regression with glyphIndices

packages/renderer/tests/text.test.jsx

@@ -11,6 +11,11 @@ import {
 } from '@react-pdf/renderer';
 import renderToImage from './renderComponent';
 
+Font.register({
+  family: 'NotoSansJP',
+  src: 'https://fonts.gstatic.com/s/notosansjp/v52/-F6jfjtqLzI2JPCgQBnw7HFyzSD-AsregP8VFBEj75s.ttf',
+});
+
 const styles = StyleSheet.create({
   title: {
     margin: 20,
@@ -155,4 +160,36 @@ describe('text', () => {
 
     expect(image).toMatchImageSnapshot();
   });
+
+  test('should wrap CJK text at character boundaries', async () => {
+    const image = await renderToImage(
+      <Document>
+        <Page size={[200, 120]} style={{ padding: 10 }}>
+          <View style={{ width: 80, padding: 5, border: '1px solid #ccc' }}>
+            <Text style={{ fontFamily: 'NotoSansJP', fontSize: 12 }}>
+              本当に長いテキスト
+            </Text>
+          </View>
+        </Page>
+      </Document>,
+    );
+
+    expect(image).toMatchImageSnapshot();
+  });
+
+  test('should wrap mixed CJK and Latin text', async () => {
+    const image = await renderToImage(
+      <Document>
+        <Page size={[200, 120]} style={{ padding: 10 }}>
+          <View style={{ width: 100, padding: 5, border: '1px solid #ccc' }}>
+            <Text style={{ fontFamily: 'NotoSansJP', fontSize: 12 }}>
+              Hello世界！これはテストです。
+            </Text>
+          </View>
+        </Page>
+      </Document>,
+    );
+
+    expect(image).toMatchImageSnapshot();
+  });
 });

packages/textkit/src/run/glyphIndexAt.ts

@@ -15,6 +15,14 @@ const glyphIndexAt = (index: number, run: Run) => {
   const glyphIndices = run?.glyphIndices;
   if (!glyphIndices) return index;
 
+  // If index is past all glyph mappings, return length (one past end)
+  if (
+    glyphIndices.length > 0 &&
+    index > glyphIndices[glyphIndices.length - 1]
+  ) {
+    return glyphIndices.length;
+  }
+
   let result = index;
 
   for (let i = glyphIndices.length - 1; i >= 0; i -= 1) {

packages/textkit/tests/attributedString/advanceWidthBetween.test.ts

@@ -228,4 +228,55 @@ describe('attributeString advanceWidthBetween operator', () => {
 
     expect(advanceWidthBetween(1, 2, string)).toBe(10);
   });
+
+  test('should return correct per-character width for CJK runs split by script', () => {
+    // Simulates scriptItemizer splitting "本当にテキスト" into:
+    //   run 0: "本当" (Han)
+    //   run 1: "に"   (Hiragana)
+    //   run 2: "テキスト" (Katakana)
+    const pos = (w: number) => ({
+      xAdvance: w,
+      yAdvance: 0,
+      xOffset: 0,
+      yOffset: 0,
+    });
+    const string = {
+      string: '本当にテキスト',
+      runs: [
+        {
+          start: 0,
+          end: 2,
+          attributes: {},
+          glyphIndices: [0, 1],
+          positions: [pos(12), pos(12)],
+        },
+        {
+          start: 2,
+          end: 3,
+          attributes: {},
+          glyphIndices: [0],
+          positions: [pos(12)],
+        },
+        {
+          start: 3,
+          end: 7,
+          attributes: {},
+          glyphIndices: [0, 1, 2, 3],
+          positions: [pos(12), pos(11), pos(12), pos(12)],
+        },
+      ],
+    };
+
+    // Each character should return its own width, not 0
+    expect(advanceWidthBetween(0, 1, string)).toBe(12); // 本
+    expect(advanceWidthBetween(1, 2, string)).toBe(12); // 当
+    expect(advanceWidthBetween(2, 3, string)).toBe(12); // に
+    expect(advanceWidthBetween(3, 4, string)).toBe(12); // テ
+    expect(advanceWidthBetween(4, 5, string)).toBe(11); // キ
+    expect(advanceWidthBetween(5, 6, string)).toBe(12); // ス
+    expect(advanceWidthBetween(6, 7, string)).toBe(12); // ト
+
+    // Cross-run range
+    expect(advanceWidthBetween(0, 7, string)).toBe(83);
+  });
 });

packages/textkit/tests/run/advanceWidthBetween.test.ts

@@ -129,4 +129,43 @@ describe('run advanceWidthBetween operator', () => {
 
     expect(advanceWidthBetween(7, 9, run)).toBe(32);
   });
+
+  test('should return correct width for each character with glyphIndices', () => {
+    // Simulates a CJK run where scriptItemizer splits by script
+    // e.g., "本当" as a Han run with 1:1 glyph mapping
+    const run = {
+      start: 0,
+      end: 2,
+      attributes: {},
+      glyphIndices: [0, 1],
+      positions: [
+        { xAdvance: 12, yAdvance: 0, xOffset: 0, yOffset: 0 },
+        { xAdvance: 12, yAdvance: 0, xOffset: 0, yOffset: 0 },
+      ],
+    };
+
+    expect(advanceWidthBetween(0, 1, run)).toBe(12);
+    expect(advanceWidthBetween(1, 2, run)).toBe(12);
+    expect(advanceWidthBetween(0, 2, run)).toBe(24);
+  });
+
+  test('should return correct width for last character with glyphIndices and offset start', () => {
+    // Run starting at offset, like a Katakana run after Han+Hiragana runs
+    const run = {
+      start: 3,
+      end: 7,
+      attributes: {},
+      glyphIndices: [0, 1, 2, 3],
+      positions: [
+        { xAdvance: 12, yAdvance: 0, xOffset: 0, yOffset: 0 },
+        { xAdvance: 11, yAdvance: 0, xOffset: 0, yOffset: 0 },
+        { xAdvance: 12, yAdvance: 0, xOffset: 0, yOffset: 0 },
+        { xAdvance: 12, yAdvance: 0, xOffset: 0, yOffset: 0 },
+      ],
+    };
+
+    expect(advanceWidthBetween(3, 4, run)).toBe(12);
+    expect(advanceWidthBetween(6, 7, run)).toBe(12);
+    expect(advanceWidthBetween(3, 7, run)).toBe(47);
+  });
 });

packages/textkit/tests/run/glyphIndexAt.test.ts

@@ -81,4 +81,28 @@ describe('run glyphIndexAt operator', () => {
     expect(glyphIndexAt(0, run)).toBe(0);
     expect(glyphIndexAt(1, run)).toBe(2);
   });
+
+  test('should return length for index past all glyph mappings', () => {
+    const run = {
+      start: 0,
+      end: 2,
+      attributes: {},
+      glyphIndices: [0, 1],
+    };
+
+    expect(glyphIndexAt(2, run)).toBe(2);
+    expect(glyphIndexAt(5, run)).toBe(2);
+  });
+
+  test('should return length for index past ligature mappings', () => {
+    const run = {
+      start: 0,
+      end: 5,
+      attributes: {},
+      glyphIndices: [0, 1, 2, 4],
+    };
+
+    expect(glyphIndexAt(5, run)).toBe(4);
+    expect(glyphIndexAt(10, run)).toBe(4);
+  });
 });