Class: ImageSize

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

Overview

This is an adapted version of the image_size library to support some extra information from the JPEG file format. Additions have a comment with the word ‘koan’.

Defined Under Namespace

Modules: Type

Constant Summary collapse

JpegCodeCheck = 
[
	"\xc0", "\xc1", "\xc2", "\xc3",
	"\xc5", "\xc6", "\xc7",
	"\xc9", "\xca", "\xcb",
	"\xcd", "\xce", "\xcf",
]

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(img_data, img_type = nil) ⇒ ImageSize

receive image & make size argument is image String or IO



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# File 'lib/image_size.rb', line 42

def initialize(img_data, img_type = nil)
	@img_data = img_data.dup
	@img_wedth = nil
	@img_height = nil

	if @img_data.is_a?(IO)
		@img_top = @img_data.read(128)
		@img_data.seek(0, 0)
# define Singleton-method definition to IO (byte, offset)
		def @img_data.read_o(length = 1, offset = nil)
			self.seek(offset, 0) if offset
			ret = self.read(length)
			raise "cannot read!!" unless ret
			ret
		end
	elsif @img_data.is_a?(String)
		@img_top = @img_data[0, 128]
# define Singleton-method definition to String (byte, offset)
		def @img_data.read_o(length = 1, offset = nil)
			@img_offset = 0 if !(defined?(@img_offset))
			@img_offset = offset if offset
			ret = self[@img_offset, length]
			@img_offset += length
			ret
		end
	else
		raise "argument class error!! #{img_data.type}"
	end

	if img_type.nil?
		@img_type = check_type()
	else
		match = false
		Type.constants.each do |t|
			match = true if img_type == t
		end
		raise("img_type is failed. #{img_type}\n") if match == false
		@img_type = img_type
	end

	eval("@img_width, @img_height = measure_" + @img_type + "()") if @img_type != Type::OTHER
end

Class Method Details

.type_list ⇒ Object

image type list



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# File 'lib/image_size.rb', line 36

def ImageSize.type_list
	Type.constants 
end

Instance Method Details

#get_bpc ⇒ Object

koan: additions to get the precision and number of components of a JPEG file



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# File 'lib/image_size.rb', line 95

def get_bpc
	if @img_type == Type::JPEG then @img_bpc else nil end
end

#get_components ⇒ Object 



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# File 'lib/image_size.rb', line 98

def get_components
	if @img_type == Type::JPEG then @img_components else nil end
end

#get_height ⇒ Object 



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# File 'lib/image_size.rb', line 87

def get_height
	if @img_type == Type::OTHER then nil else @img_height end
end

#get_type ⇒ Object

get parameter



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# File 'lib/image_size.rb', line 86

def get_type; @img_type; end

#get_width ⇒ Object 



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# File 'lib/image_size.rb', line 90

def get_width
	if @img_type == Type::OTHER then nil else @img_width end
end

#measure_SWF ⇒ Object 



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# File 'lib/image_size.rb', line 256

def measure_SWF()
	header = @img_data.read_o(9)
	raise("This file is not SWF.") unless header.unpack('a3')[0] == 'FWS'

	bit_length = Integer("0b#{header.unpack('@8B5')}")
	header << @img_data.read_o(bit_length*4/8+1)
	str = header.unpack("@8B#{5+bit_length*4}")[0]
	last = 5
	x_min = Integer("0b#{str[last,bit_length]}")
	x_max = Integer("0b#{str[(last += bit_length),bit_length]}")
	y_min = Integer("0b#{str[(last += bit_length),bit_length]}")
	y_max = Integer("0b#{str[(last += bit_length),bit_length]}")
	width = (x_max - x_min)/20
	height = (y_max - y_min)/20
	[width, height]
end