Module: AdvertisementHelper

Defined in:
app/helpers/advertisement_helper.rb

Constant Summary collapse

RTL_BLOCK_START =

Character ordinal for the start of the Unicode RTL characters block.

0x0590
RTL_BLOCK_END =

Character ordinal for the end of the Unicode RTL characters block.

0x06FF

Instance Method Summary collapse

Instance Method Details

#community_icon(icon_path) ⇒ Magick::ImageList

Loads and returns a Magick image either from local files or from a URI for use in generating composite Magick images.

Examples:

Load an image from app/assets/images:

# This uses the path from which the image would be accessed via HTTP.
helpers.community_icon('/assets/codidact.png')

Parameters:

  • icon_path (String) —

    A path or URI from which to load the image. If using a path this should be the asset path as it would be accessible through the Rails server - see example.

Returns:

  • (Magick::ImageList) —

    An ImageList containing the icon.



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# File 'app/helpers/advertisement_helper.rb', line 85

def community_icon(icon_path)
  if icon_path.start_with? '/assets/'
    icon = Magick::ImageList.new("./app/assets/images/#{File.basename(icon_path)}")
  else
    icon = Magick::ImageList.new
    icon_path_content = URI.open(icon_path).read # rubocop:disable Security/Open
    icon.from_blob(icon_path_content)
  end
  icon
end

#do_rtl_witchcraft(str) ⇒ String

Used to artificially fix RTL text in environments that are incapable of rendering mixed LTR and RTL text. Parses the given string in sections of LTR and RTL; at each boundary between sections, dumps the section into an output buffer - forwards if the section was LTR, reversed if the section was RTL - and clears the scan buffer. This has the effect of reversing RTL sections in-place, which seems to correct their direction.

Parameters:

  • str (String) —

    The mixed-text string on which to do witchcraft.

Returns:

  • (String) —

    A “fixed” string suitable to render in RTL-ignorant environments. ImageMagick, for instance.



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# File 'app/helpers/advertisement_helper.rb', line 13

def do_rtl_witchcraft(str)
  chars = str.chars
  output_buffer = ''
  scan_buffer = []
  current_mode = rtl?(chars[0]) ? :rtl : :ltr
  chars.each.with_index do |c, i|
    new_mode = if c.match?(/\s/)
                 if chars[i - 1].present? && chars[i + 1].present? && rtl?(chars[i - 1]) && rtl?(chars[i + 1])
                   :rtl
                 else
                   :ltr
                 end
               else
                 rtl?(c) ? :rtl : :ltr
               end
    next if new_mode.nil?

    if new_mode != current_mode
      output_buffer += if current_mode == :rtl
                         scan_buffer.join.reverse
                       else
                         scan_buffer.join
                       end
      scan_buffer = []
    end
    current_mode = new_mode
    scan_buffer << c
  end

  output_buffer += if current_mode == :rtl
                     scan_buffer.join.reverse
                   else
                     scan_buffer.join
                   end
end

#rtl?(char) ⇒ Boolean

Returns true if the provided character is part of an RTL character set.

Parameters:

  • char (String) —

    A single-character string.

Returns:

  • (Boolean)

Raises:

  • (ArgumentError) —

    If the string provided is longer than one character.



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# File 'app/helpers/advertisement_helper.rb', line 54

def rtl?(char)
  return false if char.nil?
  raise ArgumentError, 'More than one character provided' if char.length > 1

  char.ord >= RTL_BLOCK_START && char.ord <= RTL_BLOCK_END
end

#wrap_text(text, width, font_size) ⇒ String

Estimates the width of text for rendering in ImageMagick and attempts to wrap it over multiple lines to avoid text being cut off or too short.

Parameters:

  • text (String) —

    The text to wrap.

  • width (Integer) —

    The available width in pixels.

  • font_size (Integer) —

    The font size in which the text will be rendered.

Returns:

  • (String) —

    The wrapped text, as one string with line breaks in the right places.



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# File 'app/helpers/advertisement_helper.rb', line 68

def wrap_text(text, width, font_size)
  columns = (width * 2.5 / font_size).to_i
  # Source: http://viseztrance.com/2011/03/texts-over-multiple-lines-with-rmagick.html
  text.split("\n").collect do |line|
    line.length > columns ? line.gsub(/(.{1,#{columns}})(\s+|$)/, "\\1\n").strip : line
  end * "\n"
end