data/images/16bit.alpha data/images/16bit.dat @@ -185,19 +185,17 @@ module Prawn raise Errors::UnsupportedImageType, 'PNG uses unsupported interlace method' end - if png.bits > 8 - raise Errors::UnsupportedImageType, 'PNG uses more than 8 bits' - end - # some PNG types store the colour and alpha channel data together, # which the PDF spec doesn't like, so split it out. png.split_alpha_channel! - case png.pixel_bytes + case png.colors when 1 color = :DeviceGray when 3 color = :DeviceRGB + else + raise Errors::UnsupportedImageType, "PNG uses an unsupported number of colors (#{png.colors})" end # build the image dict @@ -212,7 +210,7 @@ module Prawn unless png.alpha_channel obj.data[:DecodeParms] = {:Predictor => 15, - :Colors => png.pixel_bytes, + :Colors => png.colors, :BitsPerComponent => png.bits, :Columns => png.width} end @@ -269,7 +267,7 @@ module Prawn :Subtype => :Image, :Height => png.height, :Width => png.width, - :BitsPerComponent => 8, + :BitsPerComponent => png.bits, :Length => png.alpha_channel.size, :Filter => :FlateDecode, :ColorSpace => :DeviceGray, lib/prawn/images.rb @@ -14,13 +14,13 @@ module Prawn module Images # A convenience class that wraps the logic for extracting the parts # of a PNG image that we need to embed them in a PDF - class PNG + class PNG attr_reader :palette, :img_data, :transparency attr_reader :width, :height, :bits attr_reader :color_type, :compression_method, :filter_method attr_reader :interlace_method, :alpha_channel attr_accessor :scaled_width, :scaled_height - + # Process a new PNG image # # <tt>data</tt>:: A string containing a full PNG file @@ -88,13 +88,30 @@ module Prawn end end - def pixel_bytes - @pixel_bytes ||= case @color_type - when 0, 3, 4 then 1 - when 1, 2, 6 then 3 + # number of color components to each pixel + # + def colors + case self.color_type + when 0, 3, 4 + return 1 + when 2, 6 + return 3 + end + end + + # number of bits used per pixel + # + def pixel_bitlength + if alpha_channel? + self.bits * (self.colors + 1) + else + self.bits * self.colors end end + # split the alpha channel data from the raw image data in images + # where it's required. + # def split_alpha_channel! unfilter_image_data if alpha_channel? end @@ -110,11 +127,10 @@ module Prawn @img_data = "" @alpha_channel = "" - # each pixel has the color bytes, plus a byte of alpha channel - pixel_length = pixel_bytes + 1 - scanline_length = pixel_length * @width + 1 # for filter + pixel_bytes = pixel_bitlength / 8 + scanline_length = pixel_bytes * self.width + 1 row = 0 - pixels = [] + pixels = [] paeth, pa, pb, pc = nil until data.empty? do row_data = data.slice! 0, scanline_length @@ -123,42 +139,42 @@ module Prawn when 0 # None when 1 # Sub row_data.each_with_index do |byte, index| - left = index < pixel_length ? 0 : row_data[index - pixel_length] + left = index < pixel_bytes ? 0 : row_data[index - pixel_bytes] row_data[index] = (byte + left) % 256 #p [byte, left, row_data[index]] end when 2 # Up row_data.each_with_index do |byte, index| - col = index / pixel_length - upper = row == 0 ? 0 : pixels[row-1][col][index % pixel_length] + col = index / pixel_bytes + upper = row == 0 ? 0 : pixels[row-1][col][index % pixel_bytes] row_data[index] = (upper + byte) % 256 end when 3 # Average row_data.each_with_index do |byte, index| - col = index / pixel_length - upper = row == 0 ? 0 : pixels[row-1][col][index % pixel_length] - left = index < pixel_length ? 0 : row_data[index - pixel_length] + col = index / pixel_bytes + upper = row == 0 ? 0 : pixels[row-1][col][index % pixel_bytes] + left = index < pixel_bytes ? 0 : row_data[index - pixel_bytes] row_data[index] = (byte + ((left + upper)/2).floor) % 256 end when 4 # Paeth left = upper = upper_left = nil row_data.each_with_index do |byte, index| - col = index / pixel_length + col = index / pixel_bytes - left = index < pixel_length ? 0 : row_data[index - pixel_length] + left = index < pixel_bytes ? 0 : row_data[index - pixel_bytes] if row.zero? upper = upper_left = 0 else - upper = pixels[row-1][col][index % pixel_length] + upper = pixels[row-1][col][index % pixel_bytes] upper_left = col.zero? ? 0 : - pixels[row-1][col-1][index % pixel_length] + pixels[row-1][col-1][index % pixel_bytes] end p = left + upper - upper_left pa = (p - left).abs pb = (p - upper).abs - pc = (p - upper_left).abs + pc = (p - upper_left).abs paeth = if pa <= pb && pa <= pc left @@ -167,16 +183,15 @@ module Prawn else upper_left end - + row_data[index] = (byte + paeth) % 256 - #p [byte, paeth, row_data[index]] end else raise ArgumentError, "Invalid filter algorithm #{filter}" end s = [] - row_data.each_slice pixel_length do |slice| + row_data.each_slice pixel_bytes do |slice| s << slice end pixels << s @@ -184,10 +199,12 @@ module Prawn end # convert the pixel data to seperate strings for colours and alpha + color_byte_size = self.colors * self.bits / 8 + alpha_byte_size = self.bits / 8 pixels.each do |row| row.each do |pixel| - @img_data << pixel[0,pixel_bytes].pack("C*") - @alpha_channel << pixel.last + @img_data << pixel[0, color_byte_size].pack("C*") + @alpha_channel << pixel[color_byte_size, alpha_byte_size].pack("C*") end end lib/prawn/images/png.rb @@ -45,11 +45,6 @@ describe "the image() function" do filename = "#{Prawn::BASEDIR}/data/images/dice_interlaced.png" lambda { @pdf.image filename, :at => [100,100] }.should.raise(Prawn::Errors::UnsupportedImageType) end - - it "should raise an UnsupportedImageType if passed a 16 bit PNG" do - filename = "#{Prawn::BASEDIR}/data/images/16bit.png" - lambda { @pdf.image filename, :at => [100,100] }.should.raise(Prawn::Errors::UnsupportedImageType) - end describe ":fit option" do it "should fit inside the defined constraints" do spec/images_spec.rb @@ -14,7 +14,7 @@ describe "When reading a greyscale PNG file (color type 0)" do before(:each) do @filename = "#{Prawn::BASEDIR}/data/images/web-links.png" @data_filename = "#{Prawn::BASEDIR}/data/images/web-links.dat" - @img_data = File.binread(@filename) + @img_data = File.binread(@filename) end it "should read the attributes from the header chunk correctly" do @@ -105,7 +105,7 @@ describe "When reading an indexed color PNG file (color type 3)" do before(:each) do @filename = "#{Prawn::BASEDIR}/data/images/rails.png" @data_filename = "#{Prawn::BASEDIR}/data/images/rails.dat" - @img_data = File.binread(@filename) + @img_data = File.binread(@filename) end it "should read the attributes from the header chunk correctly" do @@ -158,7 +158,7 @@ describe "When reading a greyscale+alpha PNG file (color type 4)" do it "should correctly extract the alpha channel data from the image data chunk" do png = Prawn::Images::PNG.new(@img_data) png.split_alpha_channel! - data = File.binread(@alpha_data_filename) + data = File.binread(@alpha_data_filename) png.alpha_channel.should == data end end @@ -169,7 +169,7 @@ describe "When reading an RGB+alpha PNG file (color type 6)" do @filename = "#{Prawn::BASEDIR}/data/images/dice.png" @data_filename = "#{Prawn::BASEDIR}/data/images/dice.dat" @alpha_data_filename = "#{Prawn::BASEDIR}/data/images/dice.alpha" - @img_data = File.binread(@filename) + @img_data = File.binread(@filename) end it "should read the attributes from the header chunk correctly" do @@ -187,7 +187,43 @@ describe "When reading an RGB+alpha PNG file (color type 6)" do it "should correctly return the raw image data (with no alpha channel) from the image data chunk" do png = Prawn::Images::PNG.new(@img_data) png.split_alpha_channel! - data = File.binread(@data_filename) + data = File.binread(@data_filename) + png.img_data.should == data + end + + it "should correctly extract the alpha channel data from the image data chunk" do + png = Prawn::Images::PNG.new(@img_data) + png.split_alpha_channel! + data = File.binread(@alpha_data_filename) + png.alpha_channel.should == data + end +end + +describe "When reading a 16bit RGB+alpha PNG file (color type 6)" do + + before(:each) do + @filename = "#{Prawn::BASEDIR}/data/images/16bit.png" + @data_filename = "#{Prawn::BASEDIR}/data/images/16bit.dat" + @alpha_data_filename = "#{Prawn::BASEDIR}/data/images/16bit.alpha" + @img_data = File.binread(@filename) + end + + it "should read the attributes from the header chunk correctly" do + png = Prawn::Images::PNG.new(@img_data) + + png.width.should == 32 + png.height.should == 32 + png.bits.should == 16 + png.color_type.should == 6 + png.compression_method.should == 0 + png.filter_method.should == 0 + png.interlace_method.should == 0 + end + + it "should correctly return the raw image data (with no alpha channel) from the image data chunk" do + png = Prawn::Images::PNG.new(@img_data) + png.split_alpha_channel! + data = File.binread(@data_filename) png.img_data.should == data end spec/png_spec.rb 09f19fab7b46cfdf7037f4c4fd0cdeeb90eac6a2 James Healy jimmy@deefa.com http://github.com/sandal/prawn/commit/a1c0c2874d84c13157e6aa6326603d7c5299f5cc a1c0c2874d84c13157e6aa6326603d7c5299f5cc 2009-05-25T10:41:07-07:00 2009-05-25T10:26:42-07:00 add support for 16bit PNGs, types 4 and 6 904d42b13f76111fc6f7bbfacc772eede98c7bdb James Healy jimmy@deefa.com