Parent

Included Modules

PDF::Reader::Page

high level representation of a single PDF page. Ties together the various low level classes in PDF::Reader and provides access to the various components of the page (text, images, fonts, etc) in convenient formats.

If you require access to the raw PDF objects for this page, you can access the Page dictionary via the page_object accessor. You will need to use the objects accessor to help walk the page dictionary in any useful way.

Attributes

cache[R]

a Hash-like object for storing cached data. Generally this is scoped to the current document and is used to avoid repeating expensive operations

objects[R]

lowlevel hash-like access to all objects in the underlying PDF

page_object[R]

the raw PDF object that defines this page

Public Class Methods

new(objects, pagenum, options = {}) click to toggle source

creates a new page wrapper.

  • objects - an ObjectHash instance that wraps a PDF file

  • pagenum - an int specifying the page number to expose. 1 indexed.

# File lib/pdf/reader/page.rb, line 32
def initialize(objects, pagenum, options = {})
  @objects, @pagenum = objects, pagenum
  @page_object = objects.deref(objects.page_references[pagenum - 1])
  @cache       = options[:cache] || {}

  unless @page_object.is_a?(::Hash)
    raise ArgumentError, "invalid page: #{pagenum}"
  end
end

Public Instance Methods

attributes() click to toggle source

Returns the attributes that accompany this page, including attributes inherited from parents.

# File lib/pdf/reader/page.rb, line 57
def attributes
  @attributes ||= {}.tap { |hash|
    page_with_ancestors.reverse.each do |obj|
      hash.merge!(@objects.deref(obj))
    end
  }
  # This shouldn't be necesary, but some non compliant PDFs leave MediaBox
  # out. Assuming 8.5" x 11" is what Acobat does, so we do it too.
  @attributes[:MediaBox] ||= [0,0,612,792]
  @attributes
end
inspect() click to toggle source

return a friendly string representation of this page

# File lib/pdf/reader/page.rb, line 50
def inspect
  "<PDF::Reader::Page page: #{@pagenum}>"
end
number() click to toggle source

return the number of this page within the full document

# File lib/pdf/reader/page.rb, line 44
def number
  @pagenum
end
raw_content() click to toggle source

returns the raw content stream for this page. This is plumbing, nothing to see here unless you're a PDF nerd like me.

# File lib/pdf/reader/page.rb, line 110
def raw_content
  contents = objects.deref(@page_object[:Contents])
  [contents].flatten.compact.map { |obj|
    objects.deref(obj)
  }.map { |obj|
    obj.unfiltered_data
  }.join(" ")
end
text() click to toggle source

returns the plain text content of this page encoded as UTF-8. Any characters that can't be translated will be returned as a ▯

# File lib/pdf/reader/page.rb, line 72
def text
  receiver = PageTextReceiver.new
  walk(receiver)
  receiver.content
end
Also aliased as: to_s
to_s() click to toggle source
Alias for: text
walk(*receivers) click to toggle source

processes the raw content stream for this page in sequential order and passes callbacks to the receiver objects.

This is mostly low level and you can probably ignore it unless you need access to something like the raw encoded text. For an example of how this can be used as a basis for higher level functionality, see the text() method

If someone was motivated enough, this method is intended to provide all the data required to faithfully render the entire page. If you find some required data isn't available it's a bug - let me know.

Many operators that generate callbacks will reference resources stored in the page header - think images, fonts, etc. To facilitate these operators, the first available callback is page=. If your receiver accepts that callback it will be passed the current PDF::Reader::Page object. Use the Page#resources method to grab any required resources.

It may help to think of each page as a self contained program made up of a set of instructions and associated resources. Calling walk() executes the program in the correct order and calls out to your implementation.

# File lib/pdf/reader/page.rb, line 102
def walk(*receivers)
  callback(receivers, :page=, [self])
  content_stream(receivers, raw_content)
end

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