Simple Text Metrics

README.md

This is the code for the HexaPDF post "Simple Text Metrics": https://hexapdf.gettalong.org/news/2017/simple-text-metrics.html

text-fragment-test.rb

# -*- coding: utf-8 -*-
require 'hexapdf'
require 'hexapdf/content/text_fragment'

def draw_fragment(canvas, items, origin_baseline: false, **options)
  fragment = HexaPDF::Content::TextFragment.new(font: canvas.font, font_size: 20, items: items, **options)
  canvas.translate(0, origin_baseline ? -fragment.baseline_offset : 0) do
    canvas.horizontal_scaling(fragment.horizontal_scaling).
      character_spacing(fragment.character_spacing).
      word_spacing(fragment.word_spacing).
      text_rise(fragment.text_rise)
    canvas.move_text_cursor(offset: [0, fragment.baseline_offset])
    canvas.show_glyphs_only(fragment.items)

    canvas.line_width = 0.3
    canvas.fill_color(0, 128, 0).circle(0, 0, 1).fill.fill_color(0)
    canvas.stroke_color(255, 0, 0)
    canvas.rectangle(fragment.x_min, fragment.baseline_offset + fragment.y_min,
      fragment.x_max - fragment.x_min, fragment.y_max - fragment.y_min).stroke
    canvas.stroke_color(0, 255, 0)
    canvas.rectangle(0, 0, fragment.width, fragment.height).stroke
    canvas.stroke_color(0, 0, 255)
    canvas.line(0, fragment.baseline_offset, fragment.width, fragment.baseline_offset).stroke
  end
  fragment
end

doc = HexaPDF::Document.new(config: {"font.map" => {"test" => {none: "LinLibertine_Rah.ttf"}}})
canvas = doc.pages.add(doc.add(Type: :Page, MediaBox: [0, 0, 180, 130])).canvas
canvas.font("test", size: 20)

canvas.translate(10, 110) do
  items = canvas.font.decode_utf8("Hallo")
  draw_fragment(canvas, items)
end

canvas.translate(10, 90) do
  items = canvas.font.decode_utf8("Hallo")
  draw_fragment(canvas, items, horizontal_scaling: 200, character_spacing: 2)
end

canvas.translate(10, 70) do
  items = canvas.font.decode_utf8("Hallo").insert(1, 120).insert(5, -200)
  draw_fragment(canvas, items)
end

canvas.translate(70, 70) do
  items = canvas.font.decode_utf8("Hallo").insert(0, 300).insert(-1, 300)
  draw_fragment(canvas, items)
end

canvas.translate(120, 70) do
  items = canvas.font.decode_utf8("Hallo").insert(0, -300).insert(-1, -300)
  draw_fragment(canvas, items)
end

canvas.translate(10, 45) do
  items = canvas.font.decode_utf8("Hallo")
  draw_fragment(canvas, items, text_rise: 5)
end

canvas.translate(70, 45) do
  items = canvas.font.decode_utf8("Hallo")
  draw_fragment(canvas, items, text_rise: -5)
end

canvas.translate(120, 45) do
  items = canvas.font.decode_utf8("Hallo")
  draw_fragment(canvas, items, text_rise: -20)
end

canvas.translate(10, 10)
frag = draw_fragment(canvas, canvas.font.decode_utf8("This"), origin_baseline: true)
canvas.translate(frag.width, 0)
frag = draw_fragment(canvas, canvas.font.decode_utf8(" is"), origin_baseline: true,
                    character_spacing: 2, text_rise: -3)
canvas.translate(frag.width, 0)
frag = draw_fragment(canvas, canvas.font.decode_utf8("some"), origin_baseline: true)
canvas.translate(frag.width, 0)
frag = draw_fragment(canvas, canvas.font.decode_utf8("text"), origin_baseline: true,
                    text_rise: 3, horizontal_scaling: 200)

doc.write("test.pdf")