Class: Fontisan::Tables::Vvar

Inherits:
Binary::BaseRecord show all
Defined in:
lib/fontisan/tables/vvar.rb

Overview

Parser for the 'VVAR' (Vertical Metrics Variations) table

The VVAR table provides variation data for vertical metrics including:

  • Advance height variations
  • Top side bearing (TSB) variations

This table uses the ItemVariationStore structure to efficiently store delta values for different regions in the design space.

Reference: OpenType specification, VVAR table

Examples:

Reading a VVAR table

data = font.table_data("VVAR")
vvar = Fontisan::Tables::Vvar.read(data)
advance_deltas = vvar.advance_height_deltas(glyph_id, coordinates)

Instance Method Summary collapse

Methods inherited from Binary::BaseRecord

#raw_data, read

Instance Method Details

#advance_height_delta_set(glyph_id) ⇒ Array<Integer>?

Get advance height delta set for a glyph

Parameters:

  • glyph_id (Integer) —

    Glyph ID

Returns:

  • (Array<Integer>, nil) —

    Delta values or nil



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# File 'lib/fontisan/tables/vvar.rb', line 135

def advance_height_delta_set(glyph_id)
  return nil unless item_variation_store

  # If no mapping, use glyph_id directly
  if advance_height_mapping.nil?
    return item_variation_store.delta_set(0, glyph_id)
  end

  # Use mapping to get delta set indices
  map_data = advance_height_mapping.map_data
  return nil if glyph_id >= map_data.length

  delta_index = map_data[glyph_id]
  outer_index = (delta_index >> 16) & 0xFFFF
  inner_index = delta_index & 0xFFFF

  item_variation_store.delta_set(outer_index, inner_index)
end

#advance_height_mapping ⇒ VariationCommon::DeltaSetIndexMap?

Parse advance height mapping

Returns:



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# File 'lib/fontisan/tables/vvar.rb', line 58

def advance_height_mapping
  return @advance_height_mapping if defined?(@advance_height_mapping)
  return @advance_height_mapping = nil if advance_height_mapping_offset.zero?

  data = raw_data
  offset = advance_height_mapping_offset

  return @advance_height_mapping = nil if offset >= data.bytesize

  map_data = data.byteslice(offset..-1)
  @advance_height_mapping = VariationCommon::DeltaSetIndexMap.read(map_data)
rescue StandardError => e
  warn "Failed to parse VVAR advance height mapping: #{e.message}"
  @advance_height_mapping = nil
end

#bsb_delta_set(glyph_id) ⇒ Array<Integer>?

Get BSB delta set for a glyph

Parameters:

  • glyph_id (Integer) —

    Glyph ID

Returns:

  • (Array<Integer>, nil) —

    Delta values or nil



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# File 'lib/fontisan/tables/vvar.rb', line 181

def bsb_delta_set(glyph_id)
  return nil unless item_variation_store

  # If no mapping, use glyph_id directly
  if bsb_mapping.nil?
    return item_variation_store.delta_set(0, glyph_id)
  end

  # Use mapping to get delta set indices
  map_data = bsb_mapping.map_data
  return nil if glyph_id >= map_data.length

  delta_index = map_data[glyph_id]
  outer_index = (delta_index >> 16) & 0xFFFF
  inner_index = delta_index & 0xFFFF

  item_variation_store.delta_set(outer_index, inner_index)
end

#bsb_mapping ⇒ VariationCommon::DeltaSetIndexMap?

Parse BSB (bottom side bearing) mapping

Returns:



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# File 'lib/fontisan/tables/vvar.rb', line 96

def bsb_mapping
  return @bsb_mapping if defined?(@bsb_mapping)
  return @bsb_mapping = nil if bsb_mapping_offset.zero?

  data = raw_data
  offset = bsb_mapping_offset

  return @bsb_mapping = nil if offset >= data.bytesize

  map_data = data.byteslice(offset..-1)
  @bsb_mapping = VariationCommon::DeltaSetIndexMap.read(map_data)
rescue StandardError => e
  warn "Failed to parse VVAR BSB mapping: #{e.message}"
  @bsb_mapping = nil
end

#item_variation_store ⇒ VariationCommon::ItemVariationStore?

Parse the item variation store

Returns:



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# File 'lib/fontisan/tables/vvar.rb', line 39

def item_variation_store
  return @item_variation_store if defined?(@item_variation_store)
  return @item_variation_store = nil if item_variation_store_offset.zero?

  data = raw_data
  offset = item_variation_store_offset

  return @item_variation_store = nil if offset >= data.bytesize

  store_data = data.byteslice(offset..-1)
  @item_variation_store = VariationCommon::ItemVariationStore.read(store_data)
rescue StandardError => e
  warn "Failed to parse VVAR item variation store: #{e.message}"
  @item_variation_store = nil
end

#tsb_delta_set(glyph_id) ⇒ Array<Integer>?

Get TSB delta set for a glyph

Parameters:

  • glyph_id (Integer) —

    Glyph ID

Returns:

  • (Array<Integer>, nil) —

    Delta values or nil



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# File 'lib/fontisan/tables/vvar.rb', line 158

def tsb_delta_set(glyph_id)
  return nil unless item_variation_store

  # If no mapping, use glyph_id directly
  if tsb_mapping.nil?
    return item_variation_store.delta_set(0, glyph_id)
  end

  # Use mapping to get delta set indices
  map_data = tsb_mapping.map_data
  return nil if glyph_id >= map_data.length

  delta_index = map_data[glyph_id]
  outer_index = (delta_index >> 16) & 0xFFFF
  inner_index = delta_index & 0xFFFF

  item_variation_store.delta_set(outer_index, inner_index)
end

#tsb_mapping ⇒ VariationCommon::DeltaSetIndexMap?

Parse TSB (top side bearing) mapping

Returns:



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# File 'lib/fontisan/tables/vvar.rb', line 77

def tsb_mapping
  return @tsb_mapping if defined?(@tsb_mapping)
  return @tsb_mapping = nil if tsb_mapping_offset.zero?

  data = raw_data
  offset = tsb_mapping_offset

  return @tsb_mapping = nil if offset >= data.bytesize

  map_data = data.byteslice(offset..-1)
  @tsb_mapping = VariationCommon::DeltaSetIndexMap.read(map_data)
rescue StandardError => e
  warn "Failed to parse VVAR TSB mapping: #{e.message}"
  @tsb_mapping = nil
end

#v_org_delta_set(glyph_id) ⇒ Array<Integer>?

Get vertical origin delta set for a glyph

Parameters:

  • glyph_id (Integer) —

    Glyph ID

Returns:

  • (Array<Integer>, nil) —

    Delta values or nil



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# File 'lib/fontisan/tables/vvar.rb', line 204

def v_org_delta_set(glyph_id)
  return nil unless item_variation_store

  # If no mapping, use glyph_id directly
  if v_org_mapping.nil?
    return item_variation_store.delta_set(0, glyph_id)
  end

  # Use mapping to get delta set indices
  map_data = v_org_mapping.map_data
  return nil if glyph_id >= map_data.length

  delta_index = map_data[glyph_id]
  outer_index = (delta_index >> 16) & 0xFFFF
  inner_index = delta_index & 0xFFFF

  item_variation_store.delta_set(outer_index, inner_index)
end

#v_org_mapping ⇒ VariationCommon::DeltaSetIndexMap?

Parse vertical origin mapping

Returns:



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# File 'lib/fontisan/tables/vvar.rb', line 115

def v_org_mapping
  return @v_org_mapping if defined?(@v_org_mapping)
  return @v_org_mapping = nil if v_org_mapping_offset.zero?

  data = raw_data
  offset = v_org_mapping_offset

  return @v_org_mapping = nil if offset >= data.bytesize

  map_data = data.byteslice(offset..-1)
  @v_org_mapping = VariationCommon::DeltaSetIndexMap.read(map_data)
rescue StandardError => e
  warn "Failed to parse VVAR vertical origin mapping: #{e.message}"
  @v_org_mapping = nil
end

#valid? ⇒ Boolean

Check if table is valid

Returns:

  • (Boolean) —

    True if valid



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# File 'lib/fontisan/tables/vvar.rb', line 226

def valid?
  major_version == 1 && minor_version.zero?
end

#version ⇒ Float

Get version as a float

Returns:

  • (Float) —

    Version number (e.g., 1.0)



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# File 'lib/fontisan/tables/vvar.rb', line 32

def version
  major_version + (minor_version / 10.0)
end