Adds port of pdfinvert to Ruby, including improvements and new features.

 * $DEBUG controls amount of files left for inspection.
 * Arbitrarily large embedded images are now supported.
 * User can specify which embedded images to convert.
 * Code is cleaner and more robust than old one.
 * Supports embedded image types other than PNG.

pdfinvert.rb

@@ -0,0 +1,351 @@
+#!/usr/bin/ruby
+
+# Copyright 2013, Raphael Reitzig
+# <code@verrech.net>
+#
+# pdfinvert is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# pdfinvert is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with pdfinvert. If not, see <http://www.gnu.org/licenses/>.
+
+# Inverts colors in a PDF, including embedded images. Can use replacement 
+# tables instead of inverting all colors. Can transform all embedded images
+# or use rules to determine which remain unchanged. Can add page numbers (`-pn`).
+#
+# Color files have one rule per line. Each line has the format
+#
+#   dd #xxxxxx #xxxxxx
+#
+# where
+#
+#  * dd is an integer used for fuzzy color matching in embedded binary
+#       images (see imagemagick documentation). Higher numbers mean colors
+#       "farther away" from the specified source color are replaced.
+#  * xxxxxx is an RGC color in hex. The first color is the source color, the
+#           second the replacement color.
+#
+#  So, for instance, the line
+#
+#   30 #ffffff #000000
+#
+#  will replace white with black, and in embedded images also colors "30-close"
+#  to white.
+#  Note that rules are applied in sequence, from top to bottom.
+#
+# Image rule files have one line per page. Every line contains whitespace-separated
+# zeros and ones; if the i-th digit is zero, the i-th embedded image on that
+# page is not converted, otherwise it is. Illegal entries and missing numbers are 
+# considered to be one.
+#
+# For example, the file
+#
+#   1 0 0
+#   
+#   1 1 0
+#
+# Means that images two and three on page one as well as image three on page three
+# remain unchanged; all other images will be converted.
+#
+# Requirements:
+#  * ruby
+#  * inkscape
+#  * imagemagick
+#  * pdftk
+#  * gs
+
+require 'fileutils'
+
+$DEBUG = false
+
+# # # # # # # # # # # # # # # 
+# Init
+# # # # # # # # # # # # # # # 
+
+if ( ARGV.size == 0 )
+  puts "Usage: pdfinvert [-pn] [-c <color file>] [-i <image rule file>] <input file> [output file]"
+  Process.exit
+end
+
+$pagenumbers = false
+$colors = ""
+$images = ""
+$input = ""
+
+# Read in command line parameters
+skip = 0
+(0..ARGV.size - 1).each { |i|
+  if ( skip > 0 )
+    skip -= 1
+    next
+  end
+
+  if ( ARGV[i] == "-pn" )
+    $pagenumbers = true
+  elsif ( ARGV[i] == "-c" )
+    $colors = ARGV[i+1]
+    skip = 1
+  elsif ( ARGV[i] == "-i" )
+    $images = ARGV[i+1]
+    skip = 1
+  elsif ( $input == "" )
+    $input = ARGV[i]
+    $filename = File.basename($input, ".pdf")
+    $output = "#{$filename}_inverted.pdf"
+  else
+    $output = ARGV[i];
+  end
+}
+
+# Verify that input file exists
+if ( $input == "" )
+  puts "Please provide an input file."
+  Process.exit
+elsif ( !File.exists?($input) )
+  puts "File '#{$input}' does not exist.";
+  Process.exit;
+end
+
+$tmp = "/tmp/pdfinvert_#{$filename}"
+$dir = Dir.pwd
+
+# Ensure that temporary directory exists and is empty
+if ( !Dir.exists?($tmp) )
+  Dir.mkdir($tmp)
+else
+  Dir["#{$tmp}/*"].each { |f| File.delete(f) }
+end
+
+# Preprocess replacement colors file
+$colorrules = {}
+$colororder = []
+if ( $colors != "" )
+  if ( File.exists?($colors) )
+    File.open($colors, "r") { |f|
+      f.readlines.each { |line|
+        entry = line.strip.split(/\s+/)
+        entry[0] = Integer(entry[0])
+        entry[1] = entry[1][1..6]
+        entry[2] = entry[2][1..6]
+        $colorrules[entry[1]] = [entry[0], entry[2]]
+        $colororder.push(entry[1])
+      }    
+    }
+  else
+    puts "Color specification file '#{$colors}' does not exist. Inverting now."
+    $colors = ""
+  end
+end
+
+def replacecolor(color)
+  if ( $colors != "" )
+    if ( $colorrules.include?(color) )
+      $colorrules[color][1]
+    else
+      color
+    end
+  else
+    sprintf("%06x", 0xFFFFFF - Integer("0x#{color}", 16))
+  end
+end
+
+# Preprocess image rule file
+$imagerules = [[]]
+if ( $images != "" )
+  if ( File.exists?($images) )
+    File.open($images, "r") { |f|
+      ctr = 1
+      f.readlines.each { |line|
+        $imagerules[ctr] = line.strip.split(/\s+/).map { |b| Integer(b) rescue 1 }
+        ctr += 1
+      }    
+    }
+  else
+    puts "Image rule file '#{$images}' does not exist. Converting all images now."
+    $images = ""
+  end
+end
+
+def convertimage?(page, image)
+  if ( $imagerules.size > page && $imagerules[page].size > image )
+    $imagerules[page][image] != 0
+  else
+    true
+  end
+end
+
+# Function that returns page number inset for SVG
+def pagenumber(nr, x, y) 
+  return "  <g id=\"pagenumberg\">\n" + 
+         "    <text xml:space=\"preserve\" style=\"font-size:25px;font-style:normal;font-weight:normal;line-height:125%;letter-spacing:0px;word-spacing:0px;fill:#888888;fill-opacity:1;stroke:none;font-family:Sans;\" " +
+             "x=\"#{x}\" y=\"#{y}\" id=\"pagenumbert\" >\n" +
+         "      <tspan  id=\"pagenumberts\" x=\"#{x}\" y=\"#{y}\" style=\"font-weight:1;font-style:normal;font-stretch:normal;font-variant:normal;font-size:25px;font-family:Sans;\">\n" +
+         "        #{nr}\n" +
+         "      </tspan>\n" +
+         "    </text>\n" +
+         "  </g>";
+end
+
+# This function processes the given file
+def invert(file) 
+  log = "Inverting #{file}...\n"
+  basename = File.basename(file, ".pdf")
+
+  p = IO::popen("inkscape -l #{basename}.svg #{file} 2>&1")
+  log += p.readlines.join
+  FileUtils.rm(file) if !$DEBUG
+
+  # Change size form US Letter to A4 (may want to generalise?):
+  #sed -e 's/width="765"/width="210mm"/;s/height="990"/height="297mm"/' ${1%.pdf}.svg \
+  #  > ${1%.pdf}a4.svg;
+  #mv ${1%.pdf}a4.svg ${1%.pdf}.svg;
+  # This does not rescale/fit!
+
+  svg = []
+  File.open("#{basename}.svg", "r") { |f|
+    svg = f.readlines
+  }
+  FileUtils.rm("#{basename}.svg") if !$DEBUG
+
+  pnr = file.gsub(/[^0-9]/, "").to_i
+  pny = nil
+  pnx = nil
+  imgctr = -1
+  svg.map! { |line|
+    # Replace colors of SVG elements as specified
+    line.gsub!(/#([0-9a-f]{6})/) { |match|      
+      "##{replacecolor($~[1])}"
+    }
+
+    # Replace colors in binary images as specified
+    line.gsub!(/"data:image\/(\w+?);base64,(.*)"/) { |match|
+      imgctr += 1
+      if ( convertimage?(pnr, imgctr) )
+        imgtype = $~[1]
+        File.open("#{basename}_#{imgctr}.b64", "w") { |f| f.write($~[2]) }
+
+        # Convert base 64 string to image
+        p = IO::popen("base64 -d #{basename}_#{imgctr}.b64 > #{basename}_#{imgctr}.#{imgtype} 2>&1")
+        log += p.readlines.join
+
+        # Invert/replace colors
+        if ( $colors == "" )
+          p = IO::popen("convert #{basename}_#{imgctr}.#{imgtype} -negate #{basename}_#{imgctr}.#{imgtype} 2>&1")
+          log += p.readlines.join
+        else
+          $colororder.each { |color|
+            fuzz = $colorrules[color][0]
+            p = IO::popen("convert #{basename}_#{imgctr}.#{imgtype} -fuzz #{fuzz}% " + 
+                            "-fill \"##{replacecolor(color)}\" -opaque \"##{color}\" " + 
+                            "#{basename}_#{imgctr}.#{imgtype} 2>&1")
+            log += p.readlines.join
+          }
+        end
+
+        # Convert back to base 64
+        p = IO::popen("base64 #{basename}_#{imgctr}.#{imgtype} > #{basename}_#{imgctr}.b64 2>&1")
+        log += p.readlines.join
+
+        result = "\"data:image/#{imgtype};base64,#{File.open("#{basename}_#{imgctr}.b64", "r") { |f| result = f.readlines.join}}\""
+
+        # Cleanup
+        FileUtils.rm("#{basename}_#{imgctr}.b64") if !$DEBUG
+        FileUtils.rm("#{basename}_#{imgctr}.#{imgtype}") if !$DEBUG
+
+        result
+      else
+        # Leave old image in place
+        "\"data:image/#{$~[1]};base64,#{$~[2]}\""
+      end
+    }
+
+    # Add page number (if requested)
+    if ( $pagenumbers )    
+      # Find out (--> page number position) and change document height.
+      # Need room for page number! No worry, we resize later, anyway.
+      if ( pny == nil )
+        line.gsub!(/height="(\d+)"/) { |match|
+          newheight = Integer($~[1]) + 30
+          pny = newheight.to_s
+          "height=\"#{newheight}\""
+        }
+      end
+
+      # Find out document width (--> page number position)
+      if ( pnx == nil && /width="(\d+)"/ =~ line.strip )
+        pnx = (Integer($~[1]) / 2).to_s
+      end
+
+      line.gsub!("</svg>", "\n#{pagenumber(pnr, pnx, pny)}\n</svg>")
+    end
+    line
+  }
+
+  File.open("#{basename}_inv.svg", "w") { |f|
+    f.write(svg.join)
+  }
+
+  p = IO::popen("inkscape -A #{file} #{basename}_inv.svg 2>&1")
+  log += p.readlines.join
+  FileUtils.rm("#{basename}_inv.svg") if !$DEBUG
+
+  # Change PDF size to A4. Nasty workaround.
+  p = IO::popen("gs -sOutputFile=#{basename}a4.pdf -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sPAPERSIZE=a4 " +
+                   "-dFIXEDMEDIA -dPDFFitPage -q -f #{file} 2>&1")
+  log += p.readlines.join
+  FileUtils.mv("#{basename}a4.pdf", file)
+
+  log += "Done inverting #{file}.\n";
+  return log
+end
+
+# # # # # # # # # # # # # # # 
+# Actual Work
+# # # # # # # # # # # # # # # 
+
+FileUtils.cp($input, $tmp)
+Dir.chdir($tmp)
+$input = File.basename($input)
+
+`pdftk #{$input} burst output #{$tmp}/input_%04d.pdf`
+FileUtils.rm($input) if !$DEBUG
+
+$log = ""
+
+# Invert all pages
+begin
+  gem "parallel"
+  require 'parallel'
+
+  $log += Parallel.map(Dir["input_*"]) { |f|
+    invert(f)
+  }.join("\n")
+rescue Gem::LoadError
+  # Fall back to sequential processing if gem is not available
+  $log += "Hint:  install gem 'parallel' to speed up jobs with many pages!\n\n"
+  Dir["input_*"].each { |f|
+    $log += invert(f)
+  }
+end
+
+# Write log (for debugging)
+File.open("log", "w") { |f|
+  f.write($log)
+}  if $DEBUG
+
+# Join pages together again
+`pdftk input_*.pdf cat output output.pdf allow AllFeatures` 
+
+# # # # # # # # # # # # # # # 
+# Wrap-up
+# # # # # # # # # # # # # # # 
+
+Dir.chdir($dir)
+FileUtils.cp("#{$tmp}/output.pdf", $output)