jpg.rb in prawn-2.4.0

- old
+ new

@@ -14,10 +14,12 @@
   module Images
     # A convenience class that wraps the logic for extracting the parts
     # of a JPG image that we need to embed them in a PDF
     #
     class JPG < Image
+      class FormatError < StandardError; end
+
       # @group Extension API
 
       attr_reader :width, :height, :bits, :channels
       attr_accessor :scaled_width, :scaled_height
 
@@ -33,18 +35,19 @@
       # Process a new JPG image
       #
       # <tt>:data</tt>:: A binary string of JPEG data
       #
       def initialize(data)
+        super()
         @data = data
         d = StringIO.new(@data)
         d.binmode
 
         c_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')
-          raise 'JPEG marker not found!' if marker != c_marker
+          raise FormatError, 'JPEG marker not found!' if marker != c_marker
 
           if JPEG_SOF_BLOCKS.include?(code)
             @bits, @height, @width, @channels = d.read(6).unpack('CnnC')
             break
           end