class PDF::Reader::FormXObject

High level representation of a single PDF form xobject. Form xobjects are contained pieces of content that can be inserted onto multiple pages. They’re generally used as a space efficient way to store repetative content (like logos, header, footers, etc).

This behaves and looks much like a limited PDF::Reader::Page class.

Attributes

xobject[R]

: untyped

Public Class Methods

new(page, xobject, options = {}) click to toggle source

: (untyped, untyped, ?Hash[untyped, untyped]) -> void

# File lib/pdf/reader/form_xobject.rb, line 33
def initialize(page, xobject, options = {})
  @page    = page
  @objects = page.objects
  @cache   = options[:cache] || {}
  @xobject = @objects.deref_stream(xobject)
end

Public Instance Methods

font_objects() click to toggle source

return a hash of fonts used on this form.

The keys are the font labels used within the form content stream.

The values are a PDF::Reader::Font instances that provide access
to most available metrics for each font.

: () -> untyped

# File lib/pdf/reader/form_xobject.rb, line 48
def font_objects
  raw_fonts = @objects.deref_hash(fonts)
  ::Hash[raw_fonts.map { |label, font|
    [label, PDF::Reader::Font.new(@objects, @objects.deref_hash(font) || {})]
  }]
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.

: () -> untyped

# File lib/pdf/reader/form_xobject.rb, line 72
def raw_content
  @xobject.unfiltered_data
end

walk(*receivers) click to toggle source

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

See the comments on PDF::Reader::Page#walk for more detail.

: (*untyped) -> untyped

# File lib/pdf/reader/form_xobject.rb, line 61
def walk(*receivers)
  receivers = receivers.map { |receiver|
    ValidatingReceiver.new(receiver)
  }
  content_stream(receivers, raw_content)
end

Private Instance Methods

cached_tokens_key() click to toggle source

: () -> untyped

# File lib/pdf/reader/form_xobject.rb, line 98
def cached_tokens_key
  @cached_tokens_key ||= "tokens-#{content_stream_md5}"
end

callback(receivers, name, params=[]) click to toggle source

: (untyped, untyped, ?Array) -> untyped

# File lib/pdf/reader/form_xobject.rb, line 86
def callback(receivers, name, params=[])
  receivers.each do |receiver|
    receiver.send(name, *params) if receiver.respond_to?(name)
  end
end

content_stream(receivers, instructions) click to toggle source

: (untyped, untyped) -> untyped

# File lib/pdf/reader/form_xobject.rb, line 116
def content_stream(receivers, instructions)
  params       = []

  tokens.each do |token|
    if token.kind_of?(Token) and PagesStrategy::OPERATORS.has_key?(token)
      callback(receivers, PagesStrategy::OPERATORS[token], params)
      params.clear
    else
      params << token
    end
  end
rescue EOFError
  raise MalformedPDFError, "End Of File while processing a content stream"
end

content_stream_md5() click to toggle source

: () -> untyped

# File lib/pdf/reader/form_xobject.rb, line 93
def content_stream_md5
  @content_stream_md5 ||= Digest::MD5.hexdigest(raw_content)
end

resources() click to toggle source

Returns the resources that accompany this form.

: () -> untyped

# File lib/pdf/reader/form_xobject.rb, line 81
def resources
  @resources ||= Resources.new(@objects, @objects.deref_hash(@xobject.hash[:Resources]) || {})
end

tokens() click to toggle source

: () -> untyped

# File lib/pdf/reader/form_xobject.rb, line 103
def tokens
  @cache[cached_tokens_key] ||= begin
                buffer = Buffer.new(StringIO.new(raw_content), :content_stream => true)
                parser = Parser.new(buffer, @objects)
                result = []
                while (token = parser.parse_token(PagesStrategy::OPERATORS))
                  result << token
                end
                result
              end
end