Fix precision rounding issues in LineWrapper

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Unreleased
 
 - Fix null values in table cells rendering as `[object Object]`
+- Fix further LineWrapper precision issues
 
 ### [v0.17.0] - 2025-04-12
 

lib/line_wrapper.js

@@ -85,10 +85,10 @@ class LineWrapper extends EventEmitter {
   }
 
   wordWidth(word) {
-    return (
+    return PDFNumber(
       this.document.widthOfString(word, this) +
-      this.characterSpacing +
-      this.wordSpacing
+        this.characterSpacing +
+        this.wordSpacing,
     );
   }
 

lib/utils.js

@@ -1,8 +1,27 @@
-export function PDFNumber(n) {
+const fArray = new Float32Array(1);
+const uArray = new Uint32Array(fArray.buffer);
+
+export function PDFNumber(n, roundUp = false) {
   // PDF numbers are strictly 32bit
-  // so convert this number to the nearest 32bit number
+  // so convert this number to a 32bit number
   // @see ISO 32000-1 Annex C.2 (real numbers)
-  return Math.fround(n);
+  const rounded = Math.fround(n);
+  if (roundUp) {
+    if (rounded >= n) return rounded;
+  } else if (rounded <= n) return rounded;
+
+  // Will have to perform 32bit float truncation
+  fArray[0] = n;
+
+  // Get the 32-bit representation as integer and shift bits
+  if (!(roundUp ^ (n > 0))) {
+    uArray[0] += 1;
+  } else {
+    uArray[0] -= 1;
+  }
+
+  // Return the float value
+  return fArray[0];
 }
 
 /**

tests/unit/utils.spec.js

@@ -1,4 +1,4 @@
-import { normalizeSides } from '../../lib/utils';
+import { normalizeSides, PDFNumber } from '../../lib/utils';
 
 describe('normalizeSides', () => {
   test.each([
@@ -54,3 +54,31 @@ describe('normalizeSides', () => {
     });
   });
 });
+
+describe('PDFNumber', () => {
+  test.each([
+    [0, 0],
+    [0.04999999701976776], //float32 rounded down
+    [0.05],
+    [0.05000000074505806], //float32 rounded up
+    [1],
+    [-1],
+    [-5.05],
+    [5.05],
+  ])('PDFNumber(%f) -> %f', (n) => {
+    expect(PDFNumber(n)).toBeLessThanOrEqual(n);
+    expect(PDFNumber(n, false)).toBeLessThanOrEqual(n);
+  });
+  test.each([
+    [0],
+    [0.04999999701976776], //float32 rounded down
+    [0.05],
+    [0.05000000074505806], //float32 rounded up
+    [1],
+    [-1],
+    [-5.05],
+    [5.05],
+  ])('PDFNumber(%f, true) -> %f', (n) => {
+    expect(PDFNumber(n, true)).toBeGreaterThanOrEqual(n);
+  });
+});