Class: OLEWriter

Inherits:
Object
  • Object
show all
Defined in:
lib/spreadsheet/olewriter.rb

Constant Summary collapse

MaxSize =

Not meant for public consumption

7087104
BlockSize = 
4096
BlockDiv = 
512
ListBlocks = 
127

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(arg) ⇒ OLEWriter

Accept an IO or IO-like object or a filename (as a String)



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# File 'lib/spreadsheet/olewriter.rb', line 20

def initialize(arg)
   if arg.kind_of?(String)
     @io = File.open(arg, "w")
   else
     @io = arg
   end
   @io.binmode

   @biff_only     = false
   @size_allowed  = true
   @biff_size     = 0
   @book_size     = 0
   @big_blocks    = 0
   @list_blocks   = 0
   @root_start    = 0
   @block_count   = 4
end

Instance Attribute Details

#biff_size ⇒ Object (readonly)

Returns the value of attribute biff_size.



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# File 'lib/spreadsheet/olewriter.rb', line 16

def biff_size
  @biff_size
end

#big_blocks ⇒ Object (readonly)

Returns the value of attribute big_blocks.



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# File 'lib/spreadsheet/olewriter.rb', line 16

def big_blocks
  @big_blocks
end

#book_size ⇒ Object (readonly)

Returns the value of attribute book_size.



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# File 'lib/spreadsheet/olewriter.rb', line 16

def book_size
  @book_size
end

#list_blocks ⇒ Object (readonly)

Returns the value of attribute list_blocks.



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# File 'lib/spreadsheet/olewriter.rb', line 16

def list_blocks
  @list_blocks
end

#root_start ⇒ Object (readonly)

Returns the value of attribute root_start.



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# File 'lib/spreadsheet/olewriter.rb', line 17

def root_start
  @root_start
end

#size_allowed ⇒ Object (readonly)

Returns the value of attribute size_allowed.



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# File 'lib/spreadsheet/olewriter.rb', line 17

def size_allowed
  @size_allowed
end

Class Method Details

.open(arg) ⇒ Object

Imitate IO.open behavior



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# File 'lib/spreadsheet/olewriter.rb', line 39

def self.open(arg)
  if block_given?
    ole = self.new(arg)
    result = yield(ole)
    ole.close
    result
  else
    self.new(arg)
  end
end

Instance Method Details

#calculate_sizes ⇒ Object

Calculate various sizes needed for the OLE stream



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# File 'lib/spreadsheet/olewriter.rb', line 79

def calculate_sizes
   @big_blocks  = (@book_size.to_f/BlockDiv.to_f).ceil
   @list_blocks = (@big_blocks / ListBlocks) + 1
   @root_start  = @big_blocks
end

#close ⇒ Object

Write root entry, big block list and close the filehandle.



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# File 'lib/spreadsheet/olewriter.rb', line 86

def close
   if @size_allowed == true
      write_padding
      write_property_storage
      write_big_block_depot
   end
   @io.close
end

#print(*args, &block) ⇒ Object 



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# File 'lib/spreadsheet/olewriter.rb', line 54

def print(*args, &block)
  @io.print(*args, &block)
end

#set_size(size = BlockSize) ⇒ Object

Set the size of the data to be written to the OLE stream

  • (1 x end words)) = 13842

MaxSize = @big_blocks * 512 bytes = 7087104

Raises:



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# File 'lib/spreadsheet/olewriter.rb', line 64

def set_size(size = BlockSize)
   raise MaxSizeError if size > MaxSize

   @biff_size = size

   if biff_size > BlockSize
      @book_size = size
   else
      @book_size = BlockSize
   end

   @size_allowed = true
end

#write(*args, &block) ⇒ Object

Delegate ‘write’ and ‘print’ to the internal IO object.



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# File 'lib/spreadsheet/olewriter.rb', line 51

def write(*args, &block)
  @io.write(*args, &block)
end

#write_big_block_depot ⇒ Object

Write a big block depot



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# File 'lib/spreadsheet/olewriter.rb', line 122

def write_big_block_depot
   total_blocks = @list_blocks * 128
   used_blocks  = @big_blocks + @list_blocks + 2
   
   marker = [-3].pack("V")
   eoc    = [-2].pack("V")
   unused = [-1].pack("V")

   num_blocks = @big_blocks - 1

   1.upto(num_blocks){|n|
      write([n].pack("V"))
   }

   write eoc
   write eoc

   1.upto(@list_blocks){ write(marker) }

   used_blocks.upto(total_blocks){ write(unused) }
   
end

#write_header ⇒ Object

Write the OLE header block



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# File 'lib/spreadsheet/olewriter.rb', line 96

def write_header
   return if @biff_only == true
   calculate_sizes
   root_start = @root_start

   write([0xD0CF11E0, 0xA1B11AE1].pack("NN"))
   write([0x00, 0x00, 0x00, 0x00].pack("VVVV"))
   write([0x3E, 0x03, -2, 0x09].pack("vvvv"))
   write([0x06, 0x00, 0x00].pack("VVV"))
   write([@list_blocks, root_start].pack("VV"))
   write([0x00, 0x1000,-2].pack("VVV"))
   write([0x00, -2 ,0x00].pack("VVV"))

   unused = [-1].pack("V")

   1.upto(@list_blocks){
      root_start += 1
      write([root_start].pack("V"))
   }

   @list_blocks.upto(108){
      write(unused)
   }
end

#write_padding ⇒ Object

Pad the end of the file



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# File 'lib/spreadsheet/olewriter.rb', line 187

def write_padding
   min_size = 512
   min_size = BlockSize if @biff_size < BlockSize

   if @biff_size % min_size != 0
      padding = min_size - (@biff_size % min_size)
      write("\0" * padding)
   end
end

#write_pps(name, type, dir, start, size) ⇒ Object

Write property sheet in property storage



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# File 'lib/spreadsheet/olewriter.rb', line 154

def write_pps(name, type, dir, start, size)
   length = 0
   ord_name = []
   unless name.empty? 
      name += "\0"
      ord_name = name.unpack("c*")
      length = name.length * 2
   end

   zero = [0].pack("C")
   unknown = [0].pack("V")
   
   write(ord_name.pack("v*"))

   for n in 1..64-length
      write(zero)
   end

   write([length,type,-1,-1,dir].pack("vvVVV"))

   for n in 1..5
      write(unknown)
   end
   
   for n in 1..4
      write([0].pack("V"))
   end

   write([start,size].pack("VV"))
   write(unknown)
end

#write_property_storage ⇒ Object

Write property storage



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# File 'lib/spreadsheet/olewriter.rb', line 146

def write_property_storage
   write_pps('Root Entry', 0x05,  1,   -2, 0x00)
   write_pps('Book',       0x02, -1, 0x00, @book_size)
   write_pps("",           0x00, -1, 0x00, 0x0000)
   write_pps("",           0x00, -1, 0x00, 0x0000)
end