mileszs · unixmonkey · Mar 16, 2019 · Oct 31, 2013 · Dec 23, 2013 · Dec 23, 2013
diff --git a/README.md b/README.md
@@ -235,7 +235,8 @@ class ThingsController < ApplicationController
                             disable_links:     true,
                             disable_toc_links: true,
                             disable_back_links:true,
-                            xsl_style_sheet:   'file.xsl'} # optional XSLT stylesheet to use for styling table of contents
+                            xsl_style_sheet:   'file.xsl'}, # optional XSLT stylesheet to use for styling table of contents
+               progress: proc { |output| puts output } # proc called when console output changes
       end
     end
   end
@@ -297,6 +298,22 @@ save_path = Rails.root.join('pdfs','filename.pdf')
 File.open(save_path, 'wb') do |file|
   file << pdf
 end
+
+# you can also track progress on your PDF generation, such as when using it from within a Resque job
+class PdfJob
+  def perform
+    blk = proc { |output|
+      match = output.match(/\[.+\] Page (?<current_page>\d+) of (?<total_pages>\d+)/)
+      if match
+        current_page = match[:current_page].to_i
+        total_pages = match[:total_pages].to_i
+        message = "Generated #{current_page} of #{total_pages} pages"
+        at current_page, total_pages, message
+      end
+    }
+    WickedPdf.new.pdf_from_string(html, progress: blk)
+  end
+end
 ```
 If you need to display utf encoded characters, add this to your pdf views or layouts:
 ```html

diff --git a/lib/wicked_pdf.rb b/lib/wicked_pdf.rb
@@ -27,6 +27,7 @@
 require 'wicked_pdf/railtie'
 require 'wicked_pdf/tempfile'
 require 'wicked_pdf/middleware'
+require 'wicked_pdf/progress'
 
 class WickedPdf
   DEFAULT_BINARY_VERSION = Gem::Version.new('0.9.9')
@@ -36,6 +37,8 @@ class WickedPdf
   cattr_accessor :config
   attr_accessor :binary_version
 
+  include Progress
+
   def initialize(wkhtmltopdf_binary_path = nil)
     @exe_path = wkhtmltopdf_binary_path || find_wkhtmltopdf_binary_path
     raise "Location of #{EXE_NAME} unknown" if @exe_path.empty?
@@ -68,15 +71,18 @@ def pdf_from_url(url, options = {})
     options.merge!(WickedPdf.config) { |_key, option, _config| option }
     generated_pdf_file = WickedPdfTempfile.new('wicked_pdf_generated_file.pdf', options[:temp_path])
     command = [@exe_path]
-    command << '-q' unless on_windows? # suppress errors on stdout
     command += parse_options(options)
     command << url
     command << generated_pdf_file.path.to_s
 
     print_command(command.inspect) if in_development_mode?
 
-    err = Open3.popen3(*command) do |_stdin, _stdout, stderr|
-      stderr.read
+    if track_progress?(options)
+      invoke_with_progress(command, options)
+    else
+      err = Open3.popen3(*command) do |_stdin, _stdout, stderr|
+        stderr.read
+      end
     end
     if options[:return_file]
       return_file = options.delete(:return_file)

diff --git a/lib/wicked_pdf/progress.rb b/lib/wicked_pdf/progress.rb
@@ -0,0 +1,33 @@
+class WickedPdf
+  module Progress
+    require 'pty' # no support for windows
+    require 'English'
+
+    def track_progress?(options)
+      options[:progress] && !on_windows?
+    end
+
+    def invoke_with_progress(command, options)
+      output = []
+      begin
+        PTY.spawn(command.join(' ')) do |stdout, _stdin, pid|
+          begin
+            stdout.sync
+            stdout.each_line("\r") do |line|
+              output << line.chomp
+              options[:progress].call(line) if options[:progress]
+            end
+          rescue Errno::EIO # rubocop:disable Lint/HandleExceptions
+            # child process is terminated, this is expected behaviour
+          ensure
+            ::Process.wait pid
+          end
+        end
+      rescue PTY::ChildExited
+        puts 'The child process exited!'
+      end
+      err = output.join('\n')
+      raise "#{command} failed (exitstatus 0). Output was: #{err}" unless $CHILD_STATUS && $CHILD_STATUS.exitstatus.zero?
+    end
+  end
+end
diff --git a/test/unit/wicked_pdf_test.rb b/test/unit/wicked_pdf_test.rb
@@ -1,5 +1,4 @@
 require 'test_helper'
-
 WickedPdf.config = { :exe_path => ENV['WKHTMLTOPDF_BIN'] || '/usr/local/bin/wkhtmltopdf' }
 HTML_DOCUMENT = '<html><body>Hello World</body></html>'.freeze
 
@@ -226,4 +225,16 @@ def setup
     cover_option = @wp.get_valid_option('cover')
     assert_equal @wp.get_parsed_options(options), "--disable-javascript --header-center 3 #{cover_option} http://example.org"
   end
+
+  test 'should output progress when creating pdfs on compatible hosts' do
+    wp = WickedPdf.new
+    output = []
+    options = { :progress => proc { |o| output << o } }
+    wp.pdf_from_string HTML_DOCUMENT, options
+    if RbConfig::CONFIG['target_os'] =~ /mswin|mingw/
+      assert_empty output
+    else
+      assert(output.collect { |l| !l.match(/Loading/).nil? }.include?(true)) # should output something like "Loading pages (1/5)"
+    end
+  end
 end