Web Font Formats

Fontisan supports conversion to web-optimized formats (WOFF and WOFF2) for optimal web delivery.

Overview

Format	Compression	Browser Support	Use Case
WOFF	zlib	All modern browsers (IE 9+)	Wide compatibility
WOFF2	Brotli	Modern browsers	Smallest size

The format you pick is the algorithm choice — WOFF 1.0 mandates zlib, WOFF2 mandates Brotli. There is no separate --compression flag. Each format exposes its algorithm's tunable parameters instead (level, quality, threshold, transform).

WOFF2

WOFF2 provides 30-50% smaller files than TTF/OTF.

Conversion

# Basic WOFF2 conversion
fontisan convert font.ttf --to woff2 --output font.woff2

# From any format
fontisan convert font.otf --to woff2 --output font.woff2
fontisan convert font.pfb --to woff2 --output font.woff2

Recommended Options

Fontisan::ConversionOptions.from_preset(:web_optimized)
# From: :otf, To: :woff2
# opening: {}
# generating: { brotli_quality: 11, transform_tables: true,
#              optimize_tables: true, preserve_metadata: true }

WOFF2 Benefits

• 30-50% smaller than TTF/OTF
• Broader browser support
• Preprocessing transforms for better compression

WOFF

WOFF provides wider compatibility with older browsers.

Conversion

# Basic WOFF conversion
fontisan convert font.ttf --to woff --output font.woff

Options

options = Fontisan::ConversionOptions.new(
  to: :woff,
  generating: {
    zlib_level: 9,           # max zlib compression
    preserve_metadata: true
  }
)

For maximum legacy reach use the :legacy_web preset:

Fontisan::ConversionOptions.from_preset(:legacy_web)
# From: :otf, To: :woff
# generating: { zlib_level: 9, optimize_tables: true, preserve_metadata: true }

web_optimized Preset

Optimize fonts for web delivery:

Fontisan::ConversionOptions.from_preset(:web_optimized)
# From: :otf, To: :woff2
# opening: {}
# generating: { brotli_quality: 11, transform_tables: true,
#              optimize_tables: true, preserve_metadata: true }

Use Cases

• Web font delivery
• Reducing page load time
• Bandwidth optimization

Type 1 → Web Fonts

Convert legacy Type 1 fonts to web formats.

Workflow

Type 1 → OTF → WOFF2

CLI

# Direct conversion
fontisan convert font.pfb --to woff2 --output font.woff2 --preset type1_to_modern

# Step by step
fontisan convert font.pfb --to otf --output font.otf --generate-unicode
fontisan convert font.otf --to woff2 --output font.woff2

Options

# Via OTF intermediate
options = Fontisan::ConversionOptions.new(
  opening: { decompose_composites: false, generate_unicode: true },
  generating: {
    brotli_quality: 11     # WOFF2
    # For WOFF instead, use: zlib_level: 9
  }
)

Compression Knobs

Each web format exposes its algorithm's parameters. Knobs that don't apply to the requested target are rejected up-front with a clear error.

WOFF (zlib)

Option	CLI	Range	Default	Notes
zlib_level	--zlib-level=N	0–9	6	0 = no compression, 9 = smallest
uncompressed	--uncompressed	bool	false	Store tables uncompressed (legal per WOFF 1.0 §5.1; compLength == origLength)
compression_threshold	--compression-threshold=N	bytes	100	Skip compression for tables smaller than N

# Max zlib compression
options = Fontisan::ConversionOptions.new(
  to: :woff,
  generating: { zlib_level: 9 }
)

# No compression (legal per spec; useful for tooling pipelines)
options = Fontisan::ConversionOptions.new(
  to: :woff,
  generating: { uncompressed: true }
)

WOFF2 (Brotli)

Option	CLI	Range	Default	Notes
brotli_quality	--brotli-quality=N	0–11	11	0 = fastest, 11 = smallest
transform_tables	--[no-]transform-tables	bool	false	Apply glyf/loca and hmtx transformations

# Smallest possible WOFF2
options = Fontisan::ConversionOptions.new(
  to: :woff2,
  generating: { brotli_quality: 11, transform_tables: true }
)

Cross-format validation

Passing a WOFF knob to a WOFF2 target (or vice versa) is rejected at conversion time by FormatConverter.validate_options_for_target!:

# Rejected at convert time: brotli_quality does not apply to woff
Fontisan.convert('font.ttf', to: :woff, output: 'font.woff',
                 brotli_quality: 11)
# => Fontisan::Error: ... Option(s) :brotli_quality do not apply to --to woff.
#    Accepted for woff: zlib_level, uncompressed, compression_threshold,
#                       metadata_xml, private_data

The CLI equivalent exits 1 with the same message.

Table Transforms (WOFF2)

WOFF2 supports table transformations for better compression:

Table	Transform
glyf	Combined with loca, bbox deltas
hmtx	Combined with hhea
CFF	De-subroutinization

options = Fontisan::ConversionOptions.new(
  to: :woff2,
  generating: { transform_tables: true }
)

CLI equivalent:

fontisan convert font.ttf --to woff2 --output font.woff2 --transform-tables

Metadata Handling

Preserve Metadata

fontisan convert font.ttf --to woff2 --preserve-metadata

Keeps copyright, license, and other metadata intact.

Strip Metadata

fontisan convert font.ttf --to woff2 --strip-metadata

Removes metadata for smaller file size (check license first).

Examples

Complete Web Font Workflow

require 'fontisan'

# Load source
font = Fontisan::FontLoader.load('source.ttf')

# Create WOFF2
woff2_options = Fontisan::ConversionOptions.from_preset(:web_optimized)
Fontisan::FontWriter.write(font, 'font.woff2', options: woff2_options)

# Create WOFF for older browsers (max zlib)
woff_options = Fontisan::ConversionOptions.from_preset(:legacy_web)
Fontisan::FontWriter.write(font, 'font.woff', options: woff_options)

Top-level Fontisan.convert

# WOFF2 with max Brotli
Fontisan.convert('font.ttf', to: :woff2, output: 'font.woff2',
                 brotli_quality: 11, transform_tables: true)

# WOFF with max zlib (for IE / older browsers)
Fontisan.convert('font.ttf', to: :woff, output: 'font.woff', zlib_level: 9)

# WOFF stored uncompressed (legal per WOFF 1.0 §5.1)
Fontisan.convert('font.ttf', to: :woff, output: 'font.woff', uncompressed: true)

Batch Web Conversion

# Convert all TTF files to WOFF2 with max Brotli
for f in fonts/*.ttf; do
  fontisan convert "$f" --to woff2 --output "web/$(basename "${f%.ttf}.woff2")" \
    --brotli-quality 11 --transform-tables
done

Compare File Sizes

# Check file sizes
ls -la font.ttf font.woff font.woff2

# Example output:
# -rw-r--r--  font.ttf    124,500 bytes
# -rw-r--r--  font.woff    98,200 bytes   (21% smaller)
# -rw-r--r--  font.woff2   62,300 bytes   (50% smaller)

Browser Support

Browser	WOFF	WOFF2
Chrome	5+	36+
Firefox	3.6+	35+
Safari	5.1+	12+
Edge	All	14+
IE	9+	—

For maximum compatibility, provide both WOFF and WOFF2.