Conversion Overview

Fontisan's conversion system is based on the TypeTool 3 manual's recommended options for different font format conversions. The system provides:

• Type-safe option validation — Catch errors before conversion
• Format-specific defaults — Recommended options per conversion type
• Named presets — Common workflows pre-configured
• Fine-grained control — Override any option when needed

Quick Start

Using the CLI

# Basic conversion
fontisan convert input.ttf --to otf --output output.otf

# Show recommended options
fontisan convert input.ttf --to otf --show-options

# Use a preset
fontisan convert font.pfb --to otf --preset type1_to_modern --output output.otf

# Custom options
fontisan convert input.ttf --to otf --autohint --hinting-mode auto --output output.otf

Using the API

require 'fontisan'

# Get recommended options
options = Fontisan::ConversionOptions.recommended(from: :ttf, to: :otf)

# Use a preset
options = Fontisan::ConversionOptions.from_preset(:web_optimized)

# Build custom options
options = Fontisan::ConversionOptions.new(
  from: :ttf,
  to: :otf,
  opening: { autohint: true, convert_curves: true },
  generating: { hinting_mode: "auto" }
)

# Convert with options
converter = Fontisan::Converters::OutlineConverter.new
tables = converter.convert(font, options: options)

Supported Formats

Input Formats

Format	Description	Extensions
TTF	TrueType Font	.ttf
OTF	OpenType/CFF Font	.otf
Type 1	Adobe Type 1 Font	.pfb, .pfa
TTC	TrueType Collection	.ttc
OTC	OpenType Collection	.otc
dfont	Apple Data Fork Font	.dfont
WOFF	Web Open Font Format	.woff
WOFF2	Web Open Font Format 2	.woff2
SVG	SVG Font	.svg

Output Formats

All input formats can be converted to: TTF, OTF, WOFF, WOFF2

Collections (TTC, OTC, dfont) can be converted between each other.

Conversion Guides

• TTF ↔ OTF — TrueType and OpenType conversion
• Type 1 → Modern — Converting legacy Type 1 fonts
• Web Formats — WOFF and WOFF2 optimization
• Collections — TTC, OTC, and dfont handling
• Curve Conversion — Quadratic ↔ Cubic curves
• Options Reference — Complete option documentation

Presets

Fontisan includes presets for common workflows:

Preset	Description
type1_to_modern	Type 1 → OpenType for modern use
modern_to_type1	OpenType → Type 1 for legacy systems
web_optimized	Any → WOFF2 for web delivery
archive_to_modern	Collection → Individual OTF files

# Using presets
options = Fontisan::ConversionOptions.from_preset(:web_optimized)

Hinting Modes

Control hinting behavior with --hinting-mode:

Mode	Description	Use Case
preserve	Keep original hints	Same-format conversions
auto	Apply automatic hinting	Cross-format conversions
none	Remove all hints	Maximum file size reduction
full	Full hint conversion	Print applications

Best Practices

1. Use presets when possible — Presets are optimized for common workflows
2. Show options first — Use --show-options to understand what will be applied
3. Test conversions — Always verify output fonts in target applications
4. Preserve metadata — Keep copyright and license information intact

Troubleshooting

Conversion Fails

# Check if source file is valid
fontisan info font.ttf

# Validate source font
fontisan validate font.ttf

# Try with verbose flag
fontisan convert font.ttf --to otf --verbose

Output Font Too Large

# Enable optimization
fontisan convert font.ttf --to otf --optimize-tables

# Remove hinting
fontisan convert font.ttf --to otf --hinting-mode none

# Use web font format
fontisan convert font.ttf --to woff2

Poor Rendering Quality

# Use autohinting
fontisan convert font.ttf --to otf --autohint --hinting-mode auto

# Preserve original hints
fontisan convert font.ttf --to otf --hinting-mode preserve