Module: Spreadsheet::Excel::Writer::Biff8

Includes:
Spreadsheet::Encodings
Included in:
Workbook, Worksheet
Defined in:
lib/spreadsheet/excel/writer/biff8.rb

Overview

of Excel grows and methods get moved here for disambiguation.

Constant Summary collapse

@@bytesize = 
RUBY_VERSION >= '1.9' ? :bytesize : :size

Instance Method Summary collapse

Instance Method Details

#_unicode_string(string, count_length = 1) ⇒ Object

Encode string into a Biff8 Unicode String Header and Body.



42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
 
# File 'lib/spreadsheet/excel/writer/biff8.rb', line 42

def _unicode_string string, count_length=1
  data = internal string
  size = data.send(@@bytesize) / 2
  fmt = count_length == 1 ? 'C2' : 'vC'
  data, wide = compress_unicode_string data
  opts = wide
  header = [
    size, # Length of the string (character count, ln)
    opts, # Option flags:
          # Bit  Mask  Contents
          #   0  0x01  Character compression (ccompr):
          #            0 = Compressed (8-bit characters)
          #            1 = Uncompressed (16-bit characters)
          #   2  0x04  Asian phonetic settings (phonetic):
          #            0 = Does not contain Asian phonetic settings
          #            1 = Contains Asian phonetic settings
          #   3  0x08  Rich-Text settings (richtext):
          #            0 = Does not contain Rich-Text settings
          #            1 = Contains Rich-Text settings
    #0x00,# (optional, only if richtext=1) Number of Rich-Text
          #                                formatting runs (rt)
    #0x00,# (optional, only if phonetic=1) Size of Asian phonetic
          #                                settings block (in bytes, sz)
  ].pack fmt
  data << '' # (optional, only if richtext=1)
             # List of rt formatting runs (➜ 3.2)
  data << '' # (optional, only if phonetic=1)
             # Asian Phonetic Settings Block (➜ 3.4.2)
  [header, data, wide]
end

#compress_unicode_string(data) ⇒ Object

Check whether the string data can be compressed (i.e. every second byte is a Null-byte) and perform compression. Returns the data and compression_status (0/1)



16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
 
# File 'lib/spreadsheet/excel/writer/biff8.rb', line 16

def compress_unicode_string data
  compressed = ''
  expect_null = false
  data.each_byte do |byte|
    if expect_null
      if byte != 0
        return [data, 1] # 1 => Data consists of wide Chars
      end
      expect_null = false
    else
      compressed << byte
      expect_null = true
    end
  end
  [compressed, 0] # 0 => Data consists of compressed Chars
end

#unicode_string(string, count_length = 1) ⇒ Object

Encode string into a Biff8 Unicode String. Header and body are encoded separately by #_unicode_string. This method simply combines the two.



35
36
37
38
 
# File 'lib/spreadsheet/excel/writer/biff8.rb', line 35

def unicode_string string, count_length=1
  header, data, _ = _unicode_string string, count_length
  header << data
end