header and footer in Prawn PDF

Question

I have read through all relevant posts on Prawn but found no mentioning (even in Prawn's own documentation) of headers and footers.

However, I did see a demo on Prawnto's own website about headers and footers. I copied the entire source of that demo just to see if it works but an error of undefined method "header" is complained about. Am I to understand that Prawn took out header and footer recently in the gem or is there something else I need to do first to use header and footer?

The demo page: http://cracklabs.com/prawnto/code/prawn_demos/source/text/flowing_text_with_header_and_footer

the part of code of concern:

Prawn::Document.generate("flow_with_headers_and_footers.pdf")  do

  header margin_box.top_left do 
      text "Here's My Fancy Header", :size => 25, :align => :center   
  end   

  text "hello world!"
end

And by header, just in case, I mean the snippets of words that appear usually at a corner of every page of a document. Like your account number in your bills pages.

thanks!

Answer 1

The only way I've found to get a repeating item on a page is to use the Prawn::Document::LazyBoundingBox method. Basically this allows you to define a bounding box that is only rendered once you call it. So the usual pseudo-code steps are

1. Define lazy bounding box element assign to somevar
2. One each new page call the element.

The example from the source shows how

file = "lazy_bounding_boxes.pdf"
Prawn::Document.generate(file, :skip_page_creation => true) do
  point = [bounds.right-50, bounds.bottom + 25]
  page_counter = lazy_bounding_box(point, :width => 50) do
  text "Page: #{page_count}"
end 

10.times do
  start_new_page
  text "Some filler text for the page"  
  page_counter.draw
end

end

This gives you a Page-count text output on each new page. What would be ideal is if this could be applied in the setup of a page template that is reused without the manual call to render the element. The combined with text flow it would give the traditional solution of headers and footers.

Answer 2

START EDIT

This works in prawn >= 0.12

END EDIT

Here is my solution using repeat, canvas and cell. Essentially I'm drawing my bounding boxes at the absolute top and bottom of every page. I'm using cell to have better styling control over it. Hope this is going to be helpful to someone. ( I used slightly annoying colors to better illustrate how you can control styling of header and footer)

 Prawn::Document.generate("headers_and_footers_with_background.pdf") do
  repeat :all do
    # header
    canvas do
      bounding_box([bounds.left, bounds.top], :width => bounds.width) do
        cell :content => 'Header',
             :background_color => 'EEEEEE',
             :width => bounds.width,
             :height => 50,
             :align => :center,
             :text_color => "001B76",
             :borders => [:bottom],
             :border_width => 2,
             :border_color => '00FF00',
             :padding => 12
      end
    end
    # footer
    canvas do
      bounding_box [bounds.left, bounds.bottom + 50], :width  => bounds.width do
        cell :content => 'Footer',
             :background_color => '333333',
             :width => bounds.width,
             :height => 50,
             :align => :center,
             :text_color => "FFFFFF",
             :borders => [:top],
             :border_width => 2,
             :border_color => 'FF0000',
             :padding => 12
      end
    end
  end
  # body
  bounding_box([bounds.left, bounds.top - 25], :width  => bounds.width, :height => bounds.height - 50) do
    100.times do
      text "Some filler text for the page"
    end
  end
end

Answer 3

here's the problem when using the bounding_box for creating the custom footer contents... it is still rendering within the bounds of a margin.

I was looking for something that will write the contents in the margin area together with number_pages.(because a footer usually is set in the bottom margin area)... and it seems that there were none.

so instead, I used text_box and place the coordinates outside my main bounding box like so:

repeat :all do
      text_box "My custom footer", size: 7, align: :center, :at => [bounds.left, bounds.bottom], :height => 100, :width => bounds.width
end

take note that the repeat :all , will render this footer text to every page.

Answer 4

It's little bit different with latest version of Prawn you must passe an hash

Prawn::Document.generate("page_with_numbering.pdf") do
  text "Hai"
  start_new_page
  text "bai"
  start_new_page
  text "-- Hai again"
  number_pages "<page> in a total of <total>", { :start_count_at => 0, :page_filter => :all, :at => [bounds.right - 50, 0], :align => :right, :size => 14 }
end

Answer 5

@GrantSayer thx for the example, but this will only let you show the current page number, not the total number of pages.

You can also use the number_pages function for the footer:

Prawn::Document.generate("page_with_numbering.pdf") do
  text "Hai"
  start_new_page
  text "bai"
  start_new_page
  text "-- Hai again"
  number_pages "<page> in a total of <total>", [bounds.right - 50, 0]
end

However, in my case I also need to format/style and right align the page numbers to match company style guides. I used go_to_page(k) to create my own header and footer functions, which add the header and footer to each page after all the pages are created. This gives me both styling options and the total number of pages:

Prawn::Document.generate("footer_example.pdf", :skip_page_creation => true) do
  10.times do
    start_new_page
    text "Some filler text for the page"
  end

  # footer
  page_count.times do |i|
    go_to_page(i+1)
    lazy_bounding_box([bounds.right-50, bounds.bottom + 25], :width => 50) {
      text "#{i+1} / #{page_count}"
    }.draw
  end
end

Answer 6

If you want a footer that do not write stuff over your text, you have to create the bounding_box below the margin of the document using bounds.bottom.

require 'prawn'

file_name = 'hello.pdf'
random_table = (0..50).map{|i|[*('a'..'z')]} # generate a 2D array for example (~2 pages)

Prawn::Document::generate(file_name) do |pdf|
    pdf.table random_table
    pdf.page_count.times do |i|
        pdf.bounding_box([pdf.bounds.left, pdf.bounds.bottom], :width => pdf.bounds.width, :height => 30) {
        # for each page, count the page number and write it
        pdf.go_to_page i+1
             pdf.move_down 5 # move below the document margin
             pdf.text "#{i+1}/#{pdf.page_count}", :align => :center # write the page number and the total page count
        }
    end
end

It should look like that, you can see that the footer is outside the margin bottom :

Hope it help someone