Text Layouter - Inline Boxes

The HexaPDF::Layout::TextLayouter class can be used to easily lay out text mixed with inline boxes.

It is not advised to use the TextLayouter class directly but instead via the HexaPDF::Layout::TextBox class and the general document layout functionality.

Inline boxes are used for showing graphics that follow the flow of the text. This means that their horizontal and their general vertical position is determined by the text layout functionality. However, inline boxes may be vertically aligned to various positions, like the baseline, the top/bottom of the text and the top/bottom of the line.

This example shows some text containing emoticons that are replaced with their graphical representation, with normal smileys being aligned to the baseline and winking smileys to the top of the line.

An inline box is a simple wrapper around a generic box that adheres to the necessary interface. Therefore they don’t do any drawing operations themselves but delegate to their wrapped box. This means, for example, that inline boxes can use background colors or borders without doing anything special.

Usage:: ruby text_layouter_inline_boxes.rb
Resulting PDF:: text_layouter_inline_boxes.pdf
Preview:

Code

require 'hexapdf'

include HexaPDF::Layout

sample_text = "Lorem ipsum :-) dolor sit amet, consectetur adipiscing
;-) elit, sed do eiusmod tempor incididunt :-) ut labore et dolore magna
aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco
laboris nisi ut aliquip ex ea commodo consequat ;-). Duis aute irure
dolor in reprehenderit in voluptate velit esse cillum :-) dolore eu
fugiat nulla pariatur. ".tr("\n", ' ') * 4

doc = HexaPDF::Document.new
emoji_smile = doc.images.add(File.join(__dir__, "emoji-smile.png"))
emoji_wink = doc.images.add(File.join(__dir__, "emoji-wink.png"))
size = 10

items = sample_text.split(/(:-\)|;-\))/).map do |part|
  case part
  when ':-)'
    InlineBox.create(width: size * 2, height: size * 2, content_box: true,
                     background_color: "hp-blue-light", padding: 2) do |canvas, box|
      canvas.image(emoji_smile, at: [0, 0], width: box.content_width)
    end
  when ';-)'
    InlineBox.create(width: size, height: size, content_box: true,
                     valign: :top, padding: 5, margin: [0, 10],
                     border: {width: [1, 2], color: "hp-blue"}) do |canvas, box|
      canvas.image(emoji_wink, at: [0, 0], width: box.content_width)
    end
  else
    TextFragment.create(part, font: doc.fonts.add("Times"), font_size: 18)
  end
end

layouter = TextLayouter.new
layouter.style.text_align = :justify
layouter.style.line_spacing(:proportional, 1.5)
layouter.fit(items, 500, 700).draw(doc.pages.add.canvas, 50, 800)

doc.write("text_layouter_inline_boxes.pdf")