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# encoding: utf-8
# prawn/font/afm.rb : Implements AFM font support for Prawn
#
# Copyright May 2008, Gregory Brown / James Healy. All Rights Reserved.
#
# This is free software. Please see the LICENSE and COPYING files for details.
require 'prawn/encoding'
module Prawn
class Font
class AFM < Font
BUILT_INS = %w[ Courier Helvetica Times-Roman Symbol ZapfDingbats
Courier-Bold Courier-Oblique Courier-BoldOblique
Times-Bold Times-Italic Times-BoldItalic
Helvetica-Bold Helvetica-Oblique Helvetica-BoldOblique ]
def unicode?
false
end
def self.metrics_path
if m = ENV['METRICS']
@metrics_path ||= m.split(':')
else
@metrics_path ||= [
# use Prawn's font directories (Debian patch)
Prawn::DATADIR+'/fonts/']
end
end
attr_reader :attributes #:nodoc:
def initialize(document, name, options={}) #:nodoc:
unless BUILT_INS.include?(name)
raise Prawn::Errors::UnknownFont, "#{name} is not a known font."
end
super
@attributes = {}
@glyph_widths = {}
@bounding_boxes = {}
@kern_pairs = {}
file_name = @name.dup
file_name << ".afm" unless file_name =~ /\.afm$/
file_name = file_name[0] == ?/ ? file_name : find_font(file_name)
parse_afm(file_name)
@ascender = @attributes["ascender"].to_i
@descender = @attributes["descender"].to_i
@line_gap = Float(bbox[3] - bbox[1]) - (@ascender - @descender)
end
# The font bbox, as an array of integers
#
def bbox
@bbox ||= @attributes['fontbbox'].split(/\s+/).map { |e| Integer(e) }
end
# NOTE: String *must* be encoded as WinAnsi
def compute_width_of(string, options={}) #:nodoc:
scale = (options[:size] || size) / 1000.0
if options[:kerning]
strings, numbers = kern(string).partition { |e| e.is_a?(String) }
total_kerning_offset = numbers.inject(0.0) { |s,r| s + r }
(unscaled_width_of(strings.join) - total_kerning_offset) * scale
else
unscaled_width_of(string) * scale
end
end
# Returns true if the font has kerning data, false otherwise
#
def has_kerning_data?
@kern_pairs.any?
end
# built-in fonts only work with winansi encoding, so translate the
# string. Changes the encoding in-place, so the argument itself
# is replaced with a string in WinAnsi encoding.
#
def normalize_encoding(text)
enc = Prawn::Encoding::WinAnsi.new
text.unpack("U*").collect { |i| enc[i] }.pack("C*")
rescue ArgumentError
raise Prawn::Errors::IncompatibleStringEncoding,
"Arguments to text methods must be UTF-8 encoded"
end
# Returns the number of characters in +str+ (a WinAnsi-encoded string).
#
def character_count(str)
str.length
end
# Perform any changes to the string that need to happen
# before it is rendered to the canvas. Returns an array of
# subset "chunks", where each chunk is an array of two elements.
# The first element is the font subset number, and the second
# is either a string or an array (for kerned text).
#
# For Adobe fonts, there is only ever a single subset, so
# the first element of the array is "0", and the second is
# the string itself (or an array, if kerning is performed).
#
# The +text+ parameter must be in WinAnsi encoding (cp1252).
#
def encode_text(text, options={})
[[0, options[:kerning] ? kern(text) : text]]
end
def glyph_present?(char)
if char == "_"
true
else
normalize_encoding(char) != "_"
end
end
private
def register(subset)
font_dict = {:Type => :Font,
:Subtype => :Type1,
:BaseFont => name.to_sym}
# Symbolic AFM fonts (Symbol, ZapfDingbats) have their own encodings
font_dict.merge!(:Encoding => :WinAnsiEncoding) unless symbolic?
@document.ref!(font_dict)
end
def symbolic?
attributes["characterset"] == "Special"
end
def find_font(file)
self.class.metrics_path.find { |f| File.exist? "#{f}/#{file}" } + "/#{file}"
rescue NoMethodError
raise Prawn::Errors::UnknownFont,
"Couldn't find the font: #{file} in any of:\n" +
self.class.metrics_path.join("\n")
end
def parse_afm(file_name)
section = []
File.foreach(file_name) do |line|
case line
when /^Start(\w+)/
section.push $1
next
when /^End(\w+)/
section.pop
next
end
case section
when ["FontMetrics", "CharMetrics"]
next unless line =~ /^CH?\s/
name = line[/\bN\s+(\.?\w+)\s*;/, 1]
@glyph_widths[name] = line[/\bWX\s+(\d+)\s*;/, 1].to_i
@bounding_boxes[name] = line[/\bB\s+([^;]+);/, 1].to_s.rstrip
when ["FontMetrics", "KernData", "KernPairs"]
next unless line =~ /^KPX\s+(\.?\w+)\s+(\.?\w+)\s+(-?\d+)/
@kern_pairs[[$1, $2]] = $3.to_i
when ["FontMetrics", "KernData", "TrackKern"],
["FontMetrics", "Composites"]
next
else
parse_generic_afm_attribute(line)
end
end
end
def parse_generic_afm_attribute(line)
line =~ /(^\w+)\s+(.*)/
key, value = $1.to_s.downcase, $2
@attributes[key] = @attributes[key] ?
Array(@attributes[key]) << value : value
end
# converts a string into an array with spacing offsets
# bewteen characters that need to be kerned
#
# String *must* be encoded as WinAnsi
#
def kern(string)
kerned = [[]]
last_byte = nil
kern_pairs = latin_kern_pairs_table
string.unpack("C*").each do |byte|
if k = last_byte && kern_pairs[[last_byte, byte]]
kerned << -k << [byte]
else
kerned.last << byte
end
last_byte = byte
end
kerned.map { |e|
e = (Array === e ? e.pack("C*") : e)
e.respond_to?(:force_encoding) ? e.force_encoding("Windows-1252") : e
}
end
def latin_kern_pairs_table
return @kern_pairs_table if defined?(@kern_pairs_table)
character_hash = Hash[Encoding::WinAnsi::CHARACTERS.zip((0..Encoding::WinAnsi::CHARACTERS.size).to_a)]
@kern_pairs_table = @kern_pairs.inject({}) do |h,p|
h[p[0].map { |n| character_hash[n] }] = p[1]
h
end
end
def latin_glyphs_table
@glyphs_table ||= (0..255).map do |i|
@glyph_widths[Encoding::WinAnsi::CHARACTERS[i]].to_i
end
end
private
def unscaled_width_of(string)
glyph_table = latin_glyphs_table
string.unpack("C*").inject(0) do |s,r|
s + glyph_table[r]
end
end
end
end
end
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