Module: Imghdr

Defined in:
lib/imghdr.rb,
lib/imghdr/version.rb

Defined Under Namespace

Classes: Error

Constant Summary collapse

VERSION = 
"0.1.0"

Class Method Summary collapse

Class Method Details

.what(file) ⇒ Object

Raises:



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# File 'lib/imghdr.rb', line 7

def self.what(file)
  raise Error, "Path is only allowed to be a String" unless file.is_a?(String)
  raise Error, "File is not readable: #{file}" unless File.readable?(file)
  raise Error, "File not found: #{file}" unless File.exist?(file)
  raise Error, "File is not a file: #{file}" unless File.file?(file)
  raise Error, "File is empty: #{file}" if File.zero?(file)

  File.open(file, "rb") do |f|
    f = f.read(32)
    if f[6..9].include? "JFIF" or f[6..9].include? "Exif"
      return "jpeg"
    elsif f.include? "PNG"
      return "png"
    elsif f[0..7].include? "GIF89" or f[0..7].include? "GIF87"
      return "gif"
    elsif f[0..1].include? "BM" or f[0..1].include? "CI"
      return "bmp"
    elsif f[0..3].include? "RIFF" and f[8..11].include? "WEBP"
      return "webp"
    elsif f[0..3].include? "II" or f[0..3].include? "MM"
      return "tiff"
    elsif f[0..3].include? "P1" or f[0..3].include? "P4"
      return "pbm"
    elsif f[0..3].include? "P2" or f[0..3].include? "P5"
      return "pgm"
    elsif f[0..3].include? "P3" or f[0..3].include? "P6"
      return "ppm"
    elsif f[0..10].include? "#define "
      return "xbm"
      # UNDERLINES ARE HAVE ASCII-8BIT ENCODING
    else
      f.force_encoding("UTF-8")
      if f[0..1] == "\u0001\xDA"        # ASCII-8BIT: "\x01\xda"
        return "rgb"
      elsif f[0..3] == "Y\xA6j\x95"     # ASCII-8BIT: "\x59\xA6\x6A\x95"
        return "rast"
      elsif f[0..3] == "v/1\u0001"      # ASCII-8BIT: "\x76\x2F\x31\x01"
        return "exr"
      else
        return nil                      # unknown type
      end
    end
  end
end