Class: PDF::Reader::Content

Class | PDF::Reader::Content
In: | lib/pdf/reader/content.rb
Parent: | Object

Walks the PDF file and calls the appropriate callback methods when something of interest is found.

The callback methods should exist on the receiver object passed into the constructor. Whenever some content is found that will trigger a callback, the receiver is checked to see if the callback is defined.

If it is defined it will be called. If not, processing will continue.

# Available Callbacks

The following callbacks are available and should be methods defined on your receiver class. Only implement the ones you need - the rest will be ignored.

Some callbacks will include parameters which will be passed in as an array. For callbacks that supply no paramters, or where you don‘t need them, the *params argument can be left off. Some example callback method definitions are:

      def begin_document
      def end_page
      def show_text(string, *params)
      def fill_stroke(*params)

You should be able to infer the basic command the callback is reporting based on the name. For further experimentation, define the callback with just a *params parameter, then print out the contents of the array using something like:

      puts params.inspect

## Text Callbacks

All text passed into these callbacks will be encoded as UTF-8. Depending on where (and when) the PDF was generated, there‘s a good chance the text is NOT stored as UTF-8 internally so be careful when doing a comparison on strings returned from PDF::Reader (when doing unit tests for example). The string may not be byte-by-byte identical with the string that was originally written to the PDF.

- end_text_object
- move_to_start_of_next_line
- set_character_spacing
- move_text_position
- move_text_position_and_set_leading
- set_text_font_and_size
- show_text
- show_text_with_positioning
- set_text_leading
- set_text_matrix_and_text_line_matrix
- set_text_rendering_mode
- set_text_rise
- set_word_spacing
- set_horizontal_text_scaling
- move_to_next_line_and_show_text
- set_spacing_next_line_show_text

## Graphics Callbacks

- close_fill_stroke
- fill_stroke
- close_fill_stroke_with_even_odd
- fill_stroke_with_even_odd
- begin_marked_content_with_pl
- begin_inline_image
- begin_marked_content
- begin_text_object
- append_curved_segment
- concatenate_matrix
- set_stroke_color_space
- set_nonstroke_color_space
- set_line_dash
- set_glyph_width
- set_glyph_width_and_bounding_box
- invoke_xobject
- define_marked_content_with_pl
- end_inline_image
- end_marked_content
- fill_path_with_nonzero
- fill_path_with_nonzero
- fill_path_with_even_odd
- set_gray_for_stroking
- set_gray_for_nonstroking
- set_graphics_state_parameters
- close_subpath
- set_flatness_tolerance
- begin_inline_image_data
- set_line_join_style
- set_line_cap_style
- set_cmyk_color_for_stroking,
- set_cmyk_color_for_nonstroking
- append_line
- begin_new_subpath
- set_miter_limit
- define_marked_content_point
- end_path
- save_graphics_state
- restore_graphics_state
- append_rectangle
- set_rgb_color_for_stroking
- set_rgb_color_for_nonstroking
- set_color_rendering_intent
- close_and_stroke_path
- stroke_path
- set_color_for_stroking
- set_color_for_nonstroking
- set_color_for_stroking_and_special
- set_color_for_nonstroking_and_special
- paint_area_with_shading_pattern
- append_curved_segment_initial_point_replicated
- set_line_width
- set_clipping_path_with_nonzero
- set_clipping_path_with_even_odd
- append_curved_segment_final_point_replicated

## Misc Callbacks

- begin_compatibility_section
- end_compatibility_section,
- begin_document
- end_document
- begin_page_container
- end_page_container
- begin_page
- end_page
- metadata
- xml_metadata
- page_count
- begin_form_xobject
- end_form_xobject

## Resource Callbacks

Each page can contain (or inherit) a range of resources required for the page, including things like fonts and images. The following callbacks may appear after begin_page if the relevant resources exist on a page:

- resource_procset
- resource_xobject
- resource_extgstate
- resource_colorspace
- resource_pattern
- resource_font

In most cases, these callbacks associate a name with each resource, allowing it to be referred to by name in the page content. For example, an XObject can hold an image. If it gets mapped to the name "IM1", then it can be placed on the page using invoke_xobject "IM1".

### Methods

callback content_stream current_resources document metadata new resolve_references walk_pages walk_resources walk_xobject_form

### Constants

OPERATORS | = | { 'b' => :close_fill_stroke, 'B' => :fill_stroke, 'b*' => :close_fill_stroke_with_even_odd, 'B*' => :fill_stroke_with_even_odd, 'BDC' => :begin_marked_content_with_pl, 'BI' => :begin_inline_image, 'BMC' => :begin_marked_content, 'BT' => :begin_text_object, 'BX' => :begin_compatibility_section, 'c' => :append_curved_segment, 'cm' => :concatenate_matrix, 'CS' => :set_stroke_color_space, 'cs' => :set_nonstroke_color_space, 'd' => :set_line_dash, 'd0' => :set_glyph_width, 'd1' => :set_glyph_width_and_bounding_box, 'Do' => :invoke_xobject, 'DP' => :define_marked_content_with_pl, 'EI' => :end_inline_image, 'EMC' => :end_marked_content, 'ET' => :end_text_object, 'EX' => :end_compatibility_section, 'f' => :fill_path_with_nonzero, 'F' => :fill_path_with_nonzero, 'f*' => :fill_path_with_even_odd, 'G' => :set_gray_for_stroking, 'g' => :set_gray_for_nonstroking, 'gs' => :set_graphics_state_parameters, 'h' => :close_subpath, 'i' => :set_flatness_tolerance, 'ID' => :begin_inline_image_data, 'j' => :set_line_join_style, 'J' => :set_line_cap_style, 'K' => :set_cmyk_color_for_stroking, 'k' => :set_cmyk_color_for_nonstroking, 'l' => :append_line, 'm' => :begin_new_subpath, 'M' => :set_miter_limit, 'MP' => :define_marked_content_point, 'n' => :end_path, 'q' => :save_graphics_state, 'Q' => :restore_graphics_state, 're' => :append_rectangle, 'RG' => :set_rgb_color_for_stroking, 'rg' => :set_rgb_color_for_nonstroking, 'ri' => :set_color_rendering_intent, 's' => :close_and_stroke_path, 'S' => :stroke_path, 'SC' => :set_color_for_stroking, 'sc' => :set_color_for_nonstroking, 'SCN' => :set_color_for_stroking_and_special, 'scn' => :set_color_for_nonstroking_and_special, 'sh' => :paint_area_with_shading_pattern, 'T*' => :move_to_start_of_next_line, 'Tc' => :set_character_spacing, 'Td' => :move_text_position, 'TD' => :move_text_position_and_set_leading, 'Tf' => :set_text_font_and_size, 'Tj' => :show_text, 'TJ' => :show_text_with_positioning, 'TL' => :set_text_leading, 'Tm' => :set_text_matrix_and_text_line_matrix, 'Tr' => :set_text_rendering_mode, 'Ts' => :set_text_rise, 'Tw' => :set_word_spacing, 'Tz' => :set_horizontal_text_scaling, 'v' => :append_curved_segment_initial_point_replicated, 'w' => :set_line_width, 'W' => :set_clipping_path_with_nonzero, 'W*' => :set_clipping_path_with_even_odd, 'y' => :append_curved_segment_final_point_replicated, '\'' => :move_to_next_line_and_show_text, '"' => :set_spacing_next_line_show_text, }

### Public Class methods

new(receiver, xref)

Create a new PDF::Reader::Content object to process the contents of PDF file

- receiver - an object containing the required callback methods
- xref - a PDF::Reader::Xref object that contains references to all the objects in a PDF file

### Public Instance methods

callback(name, params=[])

calls the name callback method on the receiver class with params as the arguments

content_stream(instructions)

Reads a PDF content stream and calls all the appropriate callback methods for the operators it contains

current_resources()

Return a merged hash of all resources that are current. Pages, page and xobject

document(root)

Begin processing the document

metadata(root, info)

Begin processing the document metadata

resolve_references(obj)

Convert any PDF::Reader::Resource objects into a real object

walk_pages(page)

Walk over all pages in the PDF file, calling the appropriate callbacks for each page and all its content

walk_resources(resources)
walk_xobject_form(label)

Retreive the XObject for the supplied label and if it‘s a Form, walk it like a regular page content stream.

[Validate]