lib/chunky_png.rb in chunky_png-0.0.2 vs lib/chunky_png.rb in chunky_png-0.0.3

@@ -8,11 +8,38 @@
 require 'chunky_png/pixel_matrix/encoding'
 require 'chunky_png/pixel_matrix/decoding'
 require 'chunky_png/pixel_matrix'
 require 'chunky_png/image'
 
+# ChunkyPNG
+#
+# The ChunkyPNG module defines some constants that are used in the
+# PNG specification.
 module ChunkyPNG
   extend self
+
+  ###################################################
+  # PNG international standard defined constants
+  ###################################################
+
+  COLOR_GRAYSCALE       = 0
+  COLOR_TRUECOLOR       = 2
+  COLOR_INDEXED         = 3
+  COLOR_GRAYSCALE_ALPHA = 4
+  COLOR_TRUECOLOR_ALPHA = 6
+
+  FILTERING_DEFAULT     = 0
+
+  COMPRESSION_DEFAULT   = 0
+
+  INTERLACING_NONE      = 0
+  INTERLACING_ADAM7     = 1
+
+  FILTER_NONE           = 0
+  FILTER_SUB            = 1
+  FILTER_UP             = 2
+  FILTER_AVERAGE        = 3
+  FILTER_PAETH          = 4
 
   def load_from_io(io)
     ChunkyPNG::Datastream.read(io)
   end