PyMuPDF Ignores Right-Alignment in Comb Text Fields - Bug?

PyMuPDF
1

Issue: PyMuPDF (fitz) fills right-aligned comb text fields as left-aligned, ignoring PDF alignment attributes.

Expected: LastName “Doe” right-aligned in comb field.

Actual: “Doe” left-filled, alignment ignored.
I also notice both Off Gender radio buttons are filled.

Can anyone suggest a workaround other than left padding with spaces?

Sample Files:

test_filled.pdf (27.3 KB)

test.fdf

%FDF-1.4
1 0 obj
<< /FDF << /F (test.pdf) /UF (test.pdf) /Fields [
<< /T (Awesomeness) /V (Off) >>
<< /T (FirstName) /V () >>
<< /T (Gender) /V (Off) >>
<< /T (LastName) /V (Doe) >>
<< /T (MiddleName) /V () >>
] /ID [<ECB52F8A018ABD74B7CBCDFED9C3FB73> <3EF278CFEF2D81C0A157F92C3E37D336>] >> /Type /Catalog >>
endobj
trailer
<< /Root 1 0 R >>
%%EOF

PyMuPdf_Fdf_Loader.py

import fitz  # PyMuPDF
import re

# Step 1: Parse FDF to dict
def fdf_to_dict(fdf_path):
    with open(fdf_path, 'r') as f:
        fdf = f.read()
    pattern = r'<<\s*/T\s*\(\s*([^)]+)\s*\)\s*/V\s*\(\s*(.*?)\s*\)\s*>>'
    fields = {}
    for match in re.finditer(pattern, fdf, re.DOTALL):
        name = match.group(1).strip()
        value = match.group(2).strip()
        fields[name] = value
    print("FDF fields:", fields)
    return fields

# Step 2: Load PDF, fill forms
doc = fitz.open("test.pdf")
form_data = fdf_to_dict("test.fdf")

# Debug: PDF fields match FDF perfectly
pdf_fields = [w.field_name for page in doc for w in page.widgets()]
print("PDF fields:", set(pdf_fields))

filled = 0
for page in doc:
    for field in page.widgets():
        name = field.field_name
        if name in form_data:
            field.field_value = form_data[name]  # Correct: direct assignment
            field.update()  # Commit to PDF
            print(f"Filled {name}: {form_data[name]}")
            filled += 1

print(f"Filled {filled} fields")
doc.save("test_filled.pdf", garbage=4, deflate=True)
doc.close()
print("Saved test_filled.pdf")

Windows commands:

echo Y | copy "sample_template_with_comb_text_field_right_aligned.pdf" test.pdf
python PyMuPdf_Fdf_Loader.py

PyMuPDF Code (line 30 fills correctly but alignment broken):

field.field_value = form_data[name]  # Works, but ignores right-alignment
field.update()

PDF Field Properties (template has):

  • Comb: Yes (n chars)
  • Alignment: Right (explicit)
  • PyMuPDF respects comb separation but drops alignment.

Version: PyMuPDF 1.24.10, Python 3.11, Windows 11

2

This is not a bug! Alignments other than the implicit default “left” are against the “COMB” intention and thus make no sense: all popular PDF viewers ignore it.

3

???

I use Brave, a chromium browser.

Open the file, delete Last name entry, put your cursor in Middle name field (or any other) The enter a new Last Name. The alignment setting is honoured.

Adobe Acrobat Reader Version 2026.001.21411 - same
PDF-XChange Editor - same
Microsoft Edge Version 146.0.3856.109 - same

For example?

btw, right aligned is important when entering amounts.