Class: Writexlsx::ImageProperty

Inherits:
Object
  • Object
show all
Includes:
Utility::Common
Defined in:
lib/write_xlsx/image_property.rb

Constant Summary

Constants included from Utility::Common

Utility::Common::PERL_TRUE_VALUES

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Utility::Common

#absolute_char, #check_parameter, #float_to_str, #ptrue?, #put_deprecate_message

Constructor Details

#initialize(filename, options = {}) ⇒ ImageProperty

Returns a new instance of ImageProperty.



15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
 
# File 'lib/write_xlsx/image_property.rb', line 15

def initialize(filename, options = {})
  @filename    = filename
  @description = options[:description]
  @decorative  = options[:decorative]
  @position    = options[:position]
  @name        = File.basename(filename)

  # Open the image file and import the data.
  data = File.binread(filename)
  @md5  = Digest::MD5.hexdigest(data)
  if data.unpack1('x A3') == 'PNG'
    process_png(data)
  elsif data.unpack1('n') == 0xFFD8
    process_jpg(data)
  elsif data.unpack1('A4') == 'GIF8'
    process_gif(data)
  elsif data.unpack1('A2') == 'BM'
    process_bmp(data)
  else
    # TODO. Add Image::Size to support other types.
    raise "Unsupported image format for file: #{filename}\n"
  end

  # Set a default dpi for images with 0 dpi.
  @x_dpi = 96 if @x_dpi == 0
  @y_dpi = 96 if @y_dpi == 0
end

Instance Attribute Details

#body ⇒ Object

Returns the value of attribute body.



13
14
15
 
# File 'lib/write_xlsx/image_property.rb', line 13

def body
  @body
end

#decorative ⇒ Object (readonly)

Returns the value of attribute decorative.



12
13
14
 
# File 'lib/write_xlsx/image_property.rb', line 12

def decorative
  @decorative
end

#description ⇒ Object (readonly)

Returns the value of attribute description.



12
13
14
 
# File 'lib/write_xlsx/image_property.rb', line 12

def description
  @description
end

#filename ⇒ Object (readonly)

Returns the value of attribute filename.



12
13
14
 
# File 'lib/write_xlsx/image_property.rb', line 12

def filename
  @filename
end

#height ⇒ Object (readonly)

Returns the value of attribute height.



11
12
13
 
# File 'lib/write_xlsx/image_property.rb', line 11

def height
  @height
end

#md5 ⇒ Object (readonly)

Returns the value of attribute md5.



11
12
13
 
# File 'lib/write_xlsx/image_property.rb', line 11

def md5
  @md5
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



11
12
13
 
# File 'lib/write_xlsx/image_property.rb', line 11

def name
  @name
end

#position ⇒ Object

Returns the value of attribute position.



13
14
15
 
# File 'lib/write_xlsx/image_property.rb', line 13

def position
  @position
end

#ref_id ⇒ Object

Returns the value of attribute ref_id.



13
14
15
 
# File 'lib/write_xlsx/image_property.rb', line 13

def ref_id
  @ref_id
end

#type ⇒ Object (readonly)

Returns the value of attribute type.



11
12
13
 
# File 'lib/write_xlsx/image_property.rb', line 11

def type
  @type
end

#width ⇒ Object (readonly)

Returns the value of attribute width.



11
12
13
 
# File 'lib/write_xlsx/image_property.rb', line 11

def width
  @width
end

#x_dpi ⇒ Object (readonly)

Returns the value of attribute x_dpi.



11
12
13
 
# File 'lib/write_xlsx/image_property.rb', line 11

def x_dpi
  @x_dpi
end

#y_dpi ⇒ Object (readonly)

Returns the value of attribute y_dpi.



11
12
13
 
# File 'lib/write_xlsx/image_property.rb', line 11

def y_dpi
  @y_dpi
end

Instance Method Details

#process_bmp(data) ⇒ Object

Extract width and height information from a BMP file.



143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
 
# File 'lib/write_xlsx/image_property.rb', line 143

def process_bmp(data)       # :nodoc:
  @type = 'bmp'

  # Check that the file is big enough to be a bitmap.
  raise "#{@filename} doesn't contain enough data." if data.bytesize <= 0x36

  # Read the bitmap width and height. Verify the sizes.
  @width, @height = data.unpack("x18 V2")
  raise "#{@filename}: largest image width #{width} supported is 65k." if width > 0xFFFF
  raise "#{@filename}: largest image height supported is 65k." if @height > 0xFFFF

  # Read the bitmap planes and bpp data. Verify them.
  planes, bitcount = data.unpack("x26 v2")
  raise "#{@filename} isn't a 24bit true color bitmap." unless bitcount == 24
  raise "#{@filename}: only 1 plane supported in bitmap image." unless planes == 1

  # Read the bitmap compression. Verify compression.
  compression = data.unpack1("x30 V")
  raise "#{@filename}: compression not supported in bitmap image." unless compression == 0

  @x_dpi = @y_dpi = 96
end

#process_gif(data) ⇒ Object

Extract width and height information from a GIF file.



131
132
133
134
135
136
137
138
139
140
 
# File 'lib/write_xlsx/image_property.rb', line 131

def process_gif(data)
  @type  = 'gif'
  @x_dpi = 96
  @y_dpi = 96

  @width  = data[6, 2].unpack1("v")
  @height = data[8, 2].unpack1("v")

  raise "#{@filename}: no size data found in gif image.\n" if @height.nil?
end

#process_jpg(data) ⇒ Object 



85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
 
# File 'lib/write_xlsx/image_property.rb', line 85

def process_jpg(data)
  @type  = 'jpeg'
  @x_dpi = 96
  @y_dpi = 96

  offset = 2
  data_length = data.bytesize

  # Search through the image data to read the JPEG markers.
  while offset < data_length
    marker  = data[offset + 0, 2].unpack1("n")
    length  = data[offset + 2, 2].unpack1("n")

    # Read the height and width in the 0xFFCn elements
    # (Except C4, C8 and CC which aren't SOF markers).
    if (marker & 0xFFF0) == 0xFFC0 &&
       marker != 0xFFC4 && marker != 0xFFCC
      @height = data[offset + 5, 2].unpack1("n")
      @width  = data[offset + 7, 2].unpack1("n")
    end

    # Read the DPI in the 0xFFE0 element.
    if marker == 0xFFE0
      units     = data[offset + 11, 1].unpack1("C")
      x_density = data[offset + 12, 2].unpack1("n")
      y_density = data[offset + 14, 2].unpack1("n")

      if units == 1
        @x_dpi = x_density
        @y_dpi = y_density
      elsif units == 2
        @x_dpi = x_density * 2.54
        @y_dpi = y_density * 2.54
      end
    end

    offset += length + 2
    break if marker == 0xFFDA
  end

  raise "#{@filename}: no size data found in jpeg image.\n" unless @height
end

#process_png(data) ⇒ Object

Extract width and height information from a PNG file.



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
72
73
74
75
76
77
78
79
80
81
82
83
 
# File 'lib/write_xlsx/image_property.rb', line 46

def process_png(data)
  @type   = 'png'
  @width  = 0
  @height = 0
  @x_dpi  = 96
  @y_dpi  = 96

  offset = 8
  data_length = data.size

  # Search through the image data to read the height and width in th the
  # IHDR element. Also read the DPI in the pHYs element.
  while offset < data_length

    length = data[offset + 0, 4].unpack1("N")
    png_type   = data[offset + 4, 4].unpack1("A4")

    case png_type
    when "IHDR"
      @width  = data[offset + 8, 4].unpack1("N")
      @height = data[offset + 12, 4].unpack1("N")
    when "pHYs"
      x_ppu = data[offset + 8,  4].unpack1("N")
      y_ppu = data[offset + 12, 4].unpack1("N")
      units = data[offset + 16, 1].unpack1("C")

      if units == 1 && ptrue?(x_ppu) && ptrue?(y_ppu)
        @x_dpi = x_ppu * 0.0254
        @y_dpi = y_ppu * 0.0254
      end
    end

    offset = offset + length + 12

    break if png_type == "IEND"
  end
  raise "#{@filename}: no size data found in png image.\n" unless @height
end