Class: EXIFR::TIFF::Field
- Inherits:
-
Object
- Object
- EXIFR::TIFF::Field
- Defined in:
- lib/exifr/tiff.rb
Overview
:nodoc:
Instance Attribute Summary collapse
-
#offset ⇒ Object
readonly
Returns the value of attribute offset.
-
#tag ⇒ Object
readonly
Returns the value of attribute tag.
-
#value ⇒ Object
readonly
Returns the value of attribute value.
Instance Method Summary collapse
-
#initialize(data, pos) ⇒ Field
constructor
A new instance of Field.
Constructor Details
#initialize(data, pos) ⇒ Field
Returns a new instance of Field.
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# File 'lib/exifr/tiff.rb', line 532 def initialize(data, pos) @tag, count, @offset = data.readshort(pos), data.readlong(pos + 4), data.readlong(pos + 8) @type = data.readshort(pos + 2) case @type when 1 # byte len, pack = count, proc { |d| d } when 6 # signed byte len, pack = count, proc { |d| sign_byte(d) } when 2 # ascii len, pack = count, proc { |d| d.unpack('Z*') } when 3 # short len, pack = count * 2, proc { |d| d.unpack(data.short + '*') } when 8 # signed short len, pack = count * 2, proc { |d| d.unpack(data.short + '*').map{|n| sign_short(n)} } when 4 # long len, pack = count * 4, proc { |d| d.unpack(data.long + '*') } when 9 # signed long len, pack = count * 4, proc { |d| d.unpack(data.long + '*').map{|n| sign_long(n)} } when 7 # undefined # UserComment if @tag == 0x9286 len, pack = count, proc { |d| d.strip } len -= 8 # reduce to account for first 8 bytes start = len > 4 ? @offset + 8 : (pos + 8) # UserComment first 8-bytes is char code @value = [pack[data[start..(start + len - 1)]]].flatten end when 5 # unsigned rational len, pack = count * 8, proc do |d| rationals = [] d.unpack(data.long + '*').each_slice(2) do |f| rationals << rational(*f) end rationals end when 10 # signed rational len, pack = count * 8, proc do |d| rationals = [] d.unpack(data.long + '*').map{|n| sign_long(n)}.each_slice(2) do |f| rationals << rational(*f) end rationals end end if len && pack && @type != 7 start = len > 4 ? @offset : (pos + 8) d = data[start..(start + len - 1)] @value = d && [pack[d]].flatten end end |
Instance Attribute Details
#offset ⇒ Object (readonly)
Returns the value of attribute offset.
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# File 'lib/exifr/tiff.rb', line 530 def offset @offset end |
#tag ⇒ Object (readonly)
Returns the value of attribute tag.
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# File 'lib/exifr/tiff.rb', line 530 def tag @tag end |
#value ⇒ Object (readonly)
Returns the value of attribute value.
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# File 'lib/exifr/tiff.rb', line 530 def value @value end |