Document and Callbacks - shairontoledo/rghost GitHub Wiki

The document is a big facade with two other PsFacade and DocumentCallbackFacade

Creating document with 80 rows per page and custom paper

 doc=RGhost::Document.new :rows_per_page => 80, paper => [30,5]

Document A4 with row height 0.5 and font encoding CodePage1252

 doc=RGhost::Document.new :row_height => 0.5, :font_encoding => 'CodePage1252'

Defining all margins

 doc=RGhost::Document.new :margin => 0.5

Parameters

• :paper – Facade to paper defined on the construction of Paper class
• :margin, :duplex and :tuble – Facade to options defined on the construction of Paper class
• :rows_per_page – Specifies count of rows per pages.
• :landscape – Whether true invert de size(width per height)
• :count_pages – Defines postscript internal variable to display with class TextIn. Example:

Sample

  doc=RGhost::Document.new :count_pages => 10
     doc.before_page_create :except => 1 do
     text_in :x => 15, :y => 5, :write => "Page %current_page% of %count_pages%"
  end

it’ll improve way as the things works inside of RGhost

  doc=RGhost::Document.new :count_pages => 10
     doc.before_page_create :except => 1 do |chunk|
     chunk.text_in :x => 15, :y => 5, :write => "Page %current_page% of %count_pages%"
  end

The value above count_pages will be evaluated inside of document for all pages except page one.

• :fontsize – Defines the size of tag :default_font.
• :row_height and row_padding – Its names say by itself :)
• :font_encoding – Specifies encoding of data input. You can look for supported encoding using the method RGhost::Config.encode_test

Callbacks are custom code blocks defined inside Document. All callbacks implicitly receive an instance of PsFacade to create any PsObject. The callbacks‘ execution depends on the algorithms predefined in Postscript core library. There are two kinds of callbacks, Static and Dynamic callbacks.

In a Static callback there aren‘t parameters to control the inclusion and exception in the current scope, which is usually applied to events which happen one time, for example after_document_create: “after document create” will always execute once for each document. Otherwise, with Dynamic callbacks there is control of scope using conditional :only or :except; this is the only difference in relation to static callbacks. The parameters of a Dynamic callback must be one integer or one array of integers.

Example: For all pages except page 3

doc.before_page_create :except => 3 do 
     # do something 
 end 

For just 2 and 4 pages

doc.before_page_create :only => [2,4] do 
     # do something 
 end 

Most callbacks are defined in facades such as DocumentCallbackFacade and Grid::CallbackFacade
This module is included inside Document class. It will create methods to make it easier to use.

Example for a document with 4 pages; looking at the picture you can see the order in which the callbacks are executed.

You can combine the callback before_page_create and text_in for product page numbering using internal variables. Example:

doc=RGhost::Document.new :count_pages => 3
doc.before_page_create :except => 1 do |chunk|
  chunk.text_in :x=> 3, :y=> 5.5, :text => "%current_page% of %count_pages%"
end

doc.next_page
doc.next_page
doc.next_page

Starts and Ends internal benchmark will write at bottom of page.
Example

 doc=RGhost::Document.new
  doc.benchmark :start
  doc.... #do something
  doc.benchmarck :stop
  doc.render ...

Facade to RGhost::Engine#render converts a document to an output format, such as :pdf, :png, :ps, :jpeg, :tiff etc The parameter device can be found at RGhost::Constants::Devices or at Details of Ghostscript output devices

Method render has the following options available.

• :filename – File path.
• :logfile – Writes the converter‘s process into a file.
• :multipage – if true the output will be one page per file posfixed by 0001.ext, for example, one file name ‘test.png’ with two pages will create test_001.png and test002.png
• :resolution – Integer value for output resolution.
• :size – Crops a single page using a string of dimensions, example, ‘200x180’, ‘140x90’.
• :range – Specifies range of pages (PDF only)
• :quality – PDF Quality

Arrays of Hashes for Ghostscript interpreter. Look at Parameter switch for more details. You can use two parameter :s and :d, examples

  :s => [{:GenericResourceDir => /dir, :DEFAULTPAPERSIZE=> "a3"}]
  :d => [ {:TextAlphaBits => 2}  ]

Or one string using the parameter :raw, as below

  :raw => "-sGenericResourceDir=/test -dTextAlphaBits=2"

Examples

 doc=RGhost::Document.new
  #do something
 doc.render :pdf,  :filename => 'foo.pdf   # PDF output
 doc.render :jpeg, :filename => 'foo.jpg'  # JPEG output
 doc.render :png,  :filename => 'foo.png',  :multipage => true # PNG output one page per file
 doc.render :tiff, :filename => 'foo.tiff', :resolution => 300      # TIFF with 300dpi
 doc.render :ps, :raw => '-sFONTMAP=/var/myoptional/font/map', :filename => 'test.ps'

 doc=Document.new
 doc.raw "hahahah!" #it produced an error in ps stack
 doc.render :jpeg, :filename => 'with_error.jpg'
 puts r.errors  if r.error? 
 #=> GPL Ghostscript 8.61: Unrecoverable error, exit code 1.\ Error: /undefined in hahahah!