How to Work with WOFF Fonts in Python

WOFF (Web Open Font Format) is the standard for delivering fonts on the web. WOFF 1 uses zlib compression and WOFF 2 uses Brotli compression, both wrapping an underlying TrueType or CFF font. Aspose.Font FOSS for Python loads both formats and exposes the inner font data through a clean API.

Step-by-Step Guide

Step 1: Install the Package

pip install "aspose-font>=1.0.0"

Step 2: Import Required Classes

from aspose_font.loader import FontLoader
from aspose_font.converter import FontConverter
from aspose_font import FontType

Step 3: Load and Inspect a WOFF Font

from aspose_font.loader import FontLoader

woff_font = FontLoader.open("MyFont.woff")
print(f"Name: {woff_font.font_name}")
print(f"Family: {woff_font.font_family}")
print(f"Glyphs: {woff_font.num_glyphs}")
print(f"Type: {woff_font.font_type}")

Step 4: Read WOFF Metadata

WOFF files may contain an XML metadata block with licensing, credits, and description. Access it through the metadata_xml property.

from aspose_font.loader import FontLoader

font = FontLoader.open("MyFont.woff")
# WOFF fonts may include an XML metadata block
xml = getattr(font, "metadata_xml", None)
if xml:
    print(xml)
else:
    print("No metadata in this WOFF file")

Step 5: Access Inner TTF Tables

Both WoffFont and Woff2Font expose an inner_font property that gives you the underlying TtfFont. Through it you can access all standard OpenType tables.

from aspose_font.loader import FontLoader

font = FontLoader.open("MyFont.woff")
# WOFF wraps a TrueType font; access its tables via inner_font
inner = getattr(font, "inner_font")
tables = inner.ttf_tables

print(f"Units/em: {tables.head.units_per_em}")
print(f"Family name: {tables.name.best_name(1)}")

Step 6: Convert TTF to WOFF

from aspose_font.loader import FontLoader
from aspose_font.converter import FontConverter
from aspose_font import FontType

ttf_font = FontLoader.open("MyFont.ttf")
woff_font = FontConverter.convert(ttf_font, FontType.WOFF)
woff_bytes = woff_font.to_bytes()

from pathlib import Path
Path("MyFont.woff").write_bytes(woff_bytes)

Step 7: Convert TTF to WOFF2

from aspose_font.loader import FontLoader
from aspose_font.converter import FontConverter
from aspose_font import FontType

ttf_font = FontLoader.open("MyFont.ttf")
woff2_font = FontConverter.convert(ttf_font, FontType.WOFF2)
woff2_bytes = woff2_font.to_bytes()

from pathlib import Path
Path("MyFont.woff2").write_bytes(woff2_bytes)

Step 8: Convert Between WOFF and WOFF2

from aspose_font.loader import FontLoader
from aspose_font.converter import FontConverter
from aspose_font import FontType

# WOFF -> WOFF2
woff_font = FontLoader.open("MyFont.woff")
woff2_font = FontConverter.convert(woff_font, FontType.WOFF2)

# WOFF2 -> WOFF
woff2_font = FontLoader.open("MyFont.woff2")
woff_font = FontConverter.convert(woff2_font, FontType.WOFF)

Common Issues and Fixes

FontParseException: Invalid WOFF signature — The file is not a valid WOFF font. Verify the file is not corrupted and starts with the WOFF magic bytes.

FontParseException: WOFF table decompression failed — A compressed table inside the WOFF file is corrupted. Try re-downloading the font file.

Large WOFF2 output — WOFF2 uses Brotli compression which produces smaller files than WOFF 1 (zlib). If your WOFF2 output is unexpectedly large, ensure you are starting from an optimized TTF source.

Frequently Asked Questions

What is the difference between WOFF and WOFF2?

WOFF 1 uses zlib compression and WOFF 2 uses Brotli compression. WOFF2 typically achieves 20-30% better compression than WOFF 1. Both wrap the same underlying TrueType or CFF font data.

Can I access font tables from a WOFF file?

Yes. Use the inner_font property to get the underlying TtfFont, then access tables via inner_font.ttf_tables.

Does the library support WOFF metadata?

Yes. Both WoffFont and Woff2Font expose a metadata_xml property containing the optional XML metadata block.