Class: HexaPDF::Layout::Style::LinkLayer

Inherits:

Object

• Object
• HexaPDF::Layout::Style::LinkLayer

Defined in:

lib/hexapdf/layout/style.rb

Overview

The LinkLayer class provides support for linking to in-document or remote destinations for Style objects using link annotations. Typical use cases would be linking to a (named) destination on a different page or executing a URI action.

See: PDF2.0 s12.5.6.5, Layers, HexaPDF::Type::Annotations::Link

Instance Method Summary

• #call(canvas, box) ⇒ Object

  Creates the needed link annotation if possible, i.e.

• #initialize(dest: nil, uri: nil, file: nil, action: nil, border: false, border_color: nil) ⇒ LinkLayer constructor

  Creates a new LinkLayer object.

Constructor Details

#initialize(dest: nil, uri: nil, file: nil, action: nil, border: false, border_color: nil) ⇒ LinkLayer

Creates a new LinkLayer object.

The following arguments are allowed (note that only one of dest, uri, file or action may be specified):

dest

The destination array or a name of a named destination for in-document links. If neither dest, uri, file nor action is specified, it is assumed that the box has a custom property named ‘link’ which is used for the destination.

uri

The URI to link to.

file

The file that should be opened or, if it refers to an application, the application that should be launched. Can either be a string or a Filespec object. Also see: HexaPDF::Type::FileSpecification.

action

The PDF action that should be executed.

border

If set to true, a standard border is used. Also accepts an array that adheres to the rules for annotation borders.

border_color

Defines the border color. Can be an array with 0 (transparent), 1 (grayscale), 3 (RGB) or 4 (CMYK) values.

Examples:

LinkLayer.new(dest: [page, :XYZ, nil, nil, nil], border: true)
LinkLayer.new(uri: "https://my.example.com/path", border: [5 5 2])
LinkLayer.new     # use 'link' custom box property for dest

# File 'lib/hexapdf/layout/style.rb', line 498

def initialize(dest: nil, uri: nil, file: nil, action: nil, border: false, border_color: nil)
  if dest && (uri || file || action) || uri && (file || action) || file && action
    raise ArgumentError, "Only one of dest, uri, file or action is allowed"
  end
  @dest = dest
  @action = if uri
              {S: :URI, URI: uri}
            elsif file
              {S: :Launch, F: file, NewWindow: true}
            elsif action
              action
            end
  @border = case border
            when false then [0, 0, 0]
            when true then nil
            when Array then border
            else raise ArgumentError, "Invalid value for border: #{border}"
            end
  @border_color = border_color
end

Instance Method Details

#call(canvas, box) ⇒ Object

Creates the needed link annotation if possible, i.e. if the context of the canvas is a page.

# File 'lib/hexapdf/layout/style.rb', line 521

def call(canvas, box)
  return unless canvas.context.type == :Page
  @dest = box.properties['link'] unless @dest || @action

  page = canvas.context
  matrix = canvas.graphics_state.ctm
  quad_points = [*matrix.evaluate(0, 0), *matrix.evaluate(box.width, 0),
                 *matrix.evaluate(box.width, box.height), *matrix.evaluate(0, box.height)]
  x_minmax = quad_points.values_at(0, 2, 4, 6).minmax
  y_minmax = quad_points.values_at(1, 3, 5, 7).minmax
  border_color = case @border_color
                 when [], nil
                   @border_color
                 else
                   canvas.color_from_specification(@border_color).components
                 end
  annot = {
    Subtype: :Link,
    Rect: [x_minmax[0], y_minmax[0], x_minmax[1], y_minmax[1]],
    QuadPoints: quad_points,
    Dest: @dest,
    A: @action,
    Border: @border,
    C: border_color,
  }
  (page[:Annots] ||= []) << page.document.add(annot)
end