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Contents
# frozen_string_literal: true
module Renalware
# rubocop:disable Style/AsciiComments
# Prawn uses the Windows-1252 character set so that it can be compatible with the limnited fonts
# built into PDF viewers. This has the advantage that PDF file sizes are very small (5-6KB as
# opposed to 40KB+ if adding a custom TTF font to allow wider glyph support).
# Prawn converts the content to UTF-8 before rendering, and characters, outside
# of the Windows-1252 set will generally be represented as e.g. ♣. However, some characters,
# especially glyphs (e.g. the empty checkbox \x90) will raise:
# Encoding::UndefinedConversionError ("\x90" to UTF-8 in conversion from
# Windows-1252 to UTF-8)
# We trap these and set a (hopefully-useful) validation message, asking the user to find and
# remove them. Hopefully this will not happen very often, though a copy and paste from Word is the
# most likely. If it happens a lot and irritates users, we could attempt to replace the most
# common offending chars.
# It is important we trap these errors early, with the user present, as once the event is created,
# the async generation of PDFs prevents changing the content.
# rubocop:enable Style/AsciiComments
class PdfFriendlyValidator < ActiveModel::EachValidator
PRAWN_PDF_ENCODING = "Windows-1252"
def validate_each(record, attribute, value)
value.to_s.dup.force_encoding(PRAWN_PDF_ENCODING).encode("utf-8")
rescue Encoding::UndefinedConversionError
record.errors.add(
attribute,
"contains unusual characters (e.g. checkboxes, special quotes) which may "\
"stop us from using this content in a PDF. These characters can appear if copying and "\
"pasting from Word for example."
)
end
end
end
Version data entries
31 entries across 31 versions & 1 rubygems