Class: Fontisan::Type1::PFMGenerator

Inherits:
Object
  • Object
show all
Defined in:
lib/fontisan/type1/pfm_generator.rb

Overview

PFM (Printer Font Metrics) file generator

[‘PFMGenerator`](lib/fontisan/type1/pfm_generator.rb) generates Printer Font Metrics files from TTF/OTF fonts.

PFM files are binary files used by Windows for printer font metrics. They include:

  • Character widths

  • Kerning pairs

  • Font metadata (name, version, copyright, etc.)

  • Extended text metrics

Examples:

Generate PFM from TTF

font = Fontisan::FontLoader.load("font.ttf")
pfm_data = Fontisan::Type1::PFMGenerator.generate(font)
File.binwrite("font.pfm", pfm_data)

Generate PFM with 1000 UPM scaling

pfm_data = Fontisan::Type1::PFMGenerator.generate(font, upm_scale: 1000)

See Also:

Constant Summary collapse

PFM_VERSION =

PFM constants

0x0100
PFM_HEADER_SIZE = 
256
DRIVER_INFO_SIZE =

Driver info structure

118
EXT_METRICS_SIZE =

Extended metrics size

48
ANSI_CHARSET =

Windows charset constants

0
DEFAULT_CHARSET = 
1
SYMBOL_CHARSET = 
2
FIXED_PITCH =

Font pitch and family bits

1
VARIABLE_PITCH = 
0
FAMILY_DONTCARE =

Family bits (shift left 4)

0 << 4
FAMILY_ROMAN = 
1 << 4
FAMILY_SWISS = 
2 << 4
FAMILY_MODERN = 
3 << 4
FAMILY_SCRIPT = 
4 << 4
FAMILY_DECORATIVE = 
5 << 4
FAMILY_MODERN_LOWERCASE = 
6 << 4

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(font, options = {}) ⇒ PFMGenerator

Initialize a new PFMGenerator

Parameters:



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# File 'lib/fontisan/type1/pfm_generator.rb', line 86

def initialize(font, options = {})
  @font = font
  @metrics = MetricsCalculator.new(font)

  # Set up scaler
  upm_scale = options[:upm_scale] || 1000
  @scaler = if upm_scale == :native
              UPMScaler.native(font)
            else
              UPMScaler.new(font, target_upm: upm_scale)
            end
end

Class Method Details

.generate(font, options = {}) ⇒ String

Generate PFM binary data from a font

Parameters:

Options Hash (options):

  • :upm_scale (Integer, :native) —

    Target UPM (1000 for Type 1, :native for no scaling)

Returns:

  • (String) —

    PFM file binary data



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# File 'lib/fontisan/type1/pfm_generator.rb', line 66

def generate(font, options = {})
  new(font, options).generate_pfm
end

.generate_to_file(font, path, options = {}) ⇒ void

This method returns an undefined value.

Generate PFM file from a font and write to file

Parameters:



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# File 'lib/fontisan/type1/pfm_generator.rb', line 76

def generate_to_file(font, path, options = {})
  pfm_data = generate(font, options)
  File.binwrite(path, pfm_data)
end

Instance Method Details

#generate_pfm ⇒ String

Generate PFM binary data

Returns:

  • (String) —

    PFM file binary data



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# File 'lib/fontisan/type1/pfm_generator.rb', line 102

def generate_pfm
  # Collect font data
  char_widths = collect_character_widths
  return "" if char_widths.empty?

  # Build sections
  header_data = build_header(char_widths)
  face_name_data = build_face_name
  driver_info_data = build_driver_info
  ext_metrics_data = build_extended_metrics
  width_table_data = build_width_table(char_widths)
  kerning_data = build_kerning_table

  # Calculate offsets
  dfFace_offset = PFM_HEADER_SIZE
  dfExtMetrics_offset = dfFace_offset + face_name_data.length + driver_info_data.length
  dfExtentTable_offset = dfExtMetrics_offset + ext_metrics_data.length
  dfPairKernTable_offset = if kerning_data.empty?
                             0
                           else
                             dfExtentTable_offset + width_table_data.length
                           end
  dfDriverInfo_offset = if dfPairKernTable_offset.positive?
                          dfPairKernTable_offset + kerning_data.length
                        else
                          dfExtentTable_offset + width_table_data.length
                        end

  # Update offsets in header
  update_header_offsets(header_data, dfFace_offset, dfExtMetrics_offset,
                        dfExtentTable_offset, dfPairKernTable_offset,
                        dfDriverInfo_offset)

  # Combine all sections: Header + Face Name + Driver Info + Ext Metrics + Width Table + Kerning
  header_data + face_name_data + driver_info_data + ext_metrics_data +
    width_table_data + kerning_data
end