Work around astefanutti/decktape#220 in CI

slides/makepdf.rb

@@ -1,5 +1,19 @@
 #!/usr/bin/env ruby
 
+# Configuration options
+website_address = 'http://localhost:1313/Course-Laboratory-of-Software-Systems/' # always add the trailing slash
+decktape_options = '-s 1440x900 -p 20'
+
+# Workaround for decktape bug
+puts 'Working around bug: https://github.com/astefanutti/decktape/issues/220'
+puts 'By replacing max vieport relative sizes 95/80 with 120/140'
+
+shortcode_path = 'layouts/shortcodes/image.html'
+custom_image_shortcode = File.read(shortcode_path)
+replace_width = custom_image_shortcode.gsub(/}}\s*95\s*{{/, '}}120{{')
+replace_both = replace_width.gsub(/}}\s*80\s*{{/, '}}140{{')
+File.open(shortcode_path, 'w') { | file | file.puts replace_both }
+
 log_file_name = "hugo.log"
 `touch #{log_file_name}`
 log_file = File.open(log_file_name, "r")
@@ -20,18 +34,19 @@
 end
 puts "Generation complete!"
 
-def generate_slides(target)
+def generate_slides(decktape_command, target)
     proposed_name = target&.gsub('/', '-') || ""
     pdf_name = proposed_name&.empty? ? "00-introduction" : proposed_name
     puts "Using decktape to generate #{pdf_name}.pdf from /#{target}"
-    `decktape -s 1440x900 http://localhost:1313/Course-Laboratory-of-Software-Systems/#{target} #{pdf_name}.pdf`
+    `#{decktape_command}#{target} #{pdf_name}.pdf`
 end
 
+decktape_command_base = "decktape #{decktape_options} #{website_address}"
 for pack in contents
-    generate_slides pack
+    generate_slides(decktape_command_base, pack)
 end
 # Site has been generated and is being served. Launch decktape
-`decktape http://localhost:1313/Course-Laboratory-of-Software-Systems/ slides.pdf`
+puts `#{decktape_command_base} slides.pdf`
 # Terminate the server
 Process.kill("TERM", server)
 begin
@@ -40,3 +55,8 @@ def generate_slides(target)
     puts "The server terminated before I could wait for it."
 end
 File.delete(log_file)
+
+# Undo the bug workaround
+puts 'Undoing the bug workaround'
+File.open(shortcode_path, 'w') { | file | file.puts custom_image_shortcode }
+puts 'Done.'