Class: WizRtf::Image

Inherits:
Object
  • Object
show all
Defined in:
lib/wiz_rtf/image.rb

Overview

Represents an image

This class represents an image within a RTF document. Currently only the PNG, JPEG, GIF and Windows Bitmap formats are supported.

Constant Summary collapse

JPEG_SOF_BLOCKS = 
[0xC0, 0xC1, 0xC2, 0xC3, 0xC5, 0xC6, 0xC7, 0xC9, 0xCA, 0xCB, 0xCD, 0xCE, 0xCF]
PIC_TYPE = 
{png: :pngblip, jpg: :jpegblip, bmp: :pngblip, gif: :pngblip}

Instance Method Summary collapse

Constructor Details

#initialize(file) ⇒ Image

This is the constructor for the Image class.

  • file - image file path and filename.

Example:

WizRtf::Image.new(‘h:eahey.png’)



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# File 'lib/wiz_rtf/image.rb', line 22

def initialize(file)
  begin
    @img = IO.binread(file)
    @width, @height = self.size
  rescue  Exception => e
    STDERR.puts "** error parsing #{file}: #{e.inspect}"
  end
end

Instance Method Details

#render(io) ⇒ Object

Outputs the Partial Rtf Document to a Generic Stream as a Rich Text Format (RTF).

  • io - The Generic IO to Output the RTF Document.



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# File 'lib/wiz_rtf/image.rb', line 83

def render(io)
  io.group do
    io.cmd '*'
    io.cmd 'shppict'
    io.group do
      io.cmd :pict
      io.cmd PIC_TYPE[@type]
      io.cmd :picscalex, 99
      io.cmd :picscaley, 99
      io.cmd :picw, @width
      io.cmd :pich, @height
      io.write "\n"
      @img.each_byte do |b|
        hex_str = b.to_s(16)
        hex_str.insert(0,'0') if hex_str.length == 1
        io.write hex_str
      end
      io.write "\n"
    end
  end if @img
end

#size ⇒ Object

Returns an array containing the width and height of the image. It will return nil if the image could not be fetched, or if the image type was not recognised.



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# File 'lib/wiz_rtf/image.rb', line 56

def size
  case self.type
    when :gif
      @img[6..10].unpack('SS')
    when :png
      @img[16..24].unpack('NN')
    when :bmp
      d = @img[14..28]
      d.unpack('C')[0] == 40 ? d[4..-1].unpack('LL') : d[4..8].unpack('SS')
    when :jpg
      d = StringIO.new(@img)
      section_marker = 0xff # Section marker.

      d.seek(2) # Skip the first two bytes of JPEG identifier.

      loop do
        marker, code, length = d.read(4).unpack('CCn')
        fail "JPEG marker not found!" if marker != section_marker
        if JPEG_SOF_BLOCKS.include?(code)
          #@bits, @height, @width, @channels = d.read(6).unpack("CnnC")

          return d.read(6).unpack('CnnC')[1..2].reverse
        end
        d.seek(length - 2, IO::SEEK_CUR)
      end
  end
end

#type ⇒ Object

Returns an symbol indicating the image type fetched from a image file. It will return nil if the image could not be fetched, or if the image type was not recognised.



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# File 'lib/wiz_rtf/image.rb', line 33

def type
  png = Regexp.new("\x89PNG".force_encoding("binary"))
  jpg = Regexp.new("\xff\xd8\xff\xe0\x00\x10JFIF".force_encoding("binary"))
  jpg2 = Regexp.new("\xff\xd8\xff\xe1(.*){2}Exif".force_encoding("binary"))

  @type = case @img
            when /^GIF8/
              :gif
            when /^#{png}/
              :png
            when /^#{jpg}/
              :jpg
            when /^#{jpg2}/
              :jpg
            when /^BM/
              :bmp
            else
              nil
          end
end