Re: Accessing alternate glyphs from plain text

From: William_J_G Overington (
Date: Sat Aug 14 2010 - 03:47:42 CDT

  • Next message: Peter Constable: "RE: Accessing alternate glyphs from plain text"

    Thank you for taking the time to produce the pdf and thank you also for sharing the result.
    On Thursday 12 August 2010, John H. Jenkins <> wrote:
    > You seem to be missing a couple of
    > important points here which Peter is illustrating.
    > First of all, what you want to do can be done with existing
    > technology.  There's no need to add variation selectors
    > or other mechanisms to achieve your goal.
    Well, the test would seem to be as follows regarding OpenType and a pdf.
    1. Copy the plain text from the Unicode post onto the clipboard.
    2. Paste from the clipboard into an OpenType-aware application from which a pdf can be produced.
    3. Select All on the pasted text and choose an appropriate font.
    4. Unselect the text.
    5. Produce a pdf.
    6. Display the pdf using Adobe Reader.
    7. Assess the evidence question number 1. Does the display show text using the basic glyphs for the font for all of the text except for the last character of each verse of the poem; and for the last character of each verse of the poem display an alternate ending glyph?
    8. Copy all of the text from the pdf onto the clipboard.
    9. Paste from the clipboard into a basic wordprocessing program (for example, on a PC, Microsoft WordPad) and format the text using a general TrueType font, such as, for example, Arial.
    10. Assess the evidence question number 2. Is the text of the original poem displayed in WordPad?
    Both questions need answers of yes for the combination of OpenType-aware application program and font to have done the task as required.
    It seems to me that, at the present time, a necessary condition to pass that test is that the font used is an OpenType font that has alternate ending glyphs for e, h and t and has entries in its GSUB table, the table used for storing glyph substitution rules for the font, along the following lines. (Please know that my knowledge of OpenType GSUB tables is not great, so my way of expressing the rules here may well be different from the regular way, but hopefully the ideas that I am trying to express will be clear: experts are welcome to correct my way of expressing it please.)
    e unicode_ee0f -> e_alt_end
    h unicode_ee0f -> h_alt_end
    t unicode_ee0f -> t_alt_end
    Now, I am unaware of any such OpenType font existing at the present time. It is possible that one does, because the encoding information needed to produce it has been available since Thursday when I published the poem in this mailing list.
    > Secondly, fonts are themselves works of art, and a
    > well-designed face will have a set of swashes appropriate
    > face but not necessarily another face.  Simply saying
    > "I want a swash here" isn't enough.  On a Mac, for
    > example, Hoefler Text Italic has one swash available for the
    > "t", whereas Zapfino has three, none of which are like the
    > swash Hoefler Text Italic provides, and one of which is
    > inappropriate for use at the end of a line.  Most fonts
    > won't have any, because swashes are usually seen as the
    > purview of calligraphic fonts. 
    > So what do you do?  Do you provide a variation
    > selector for every kind of swash a font designer might
    > include to make sure you get the "right" one?  Or do
    > you just say, "Put a swash in here, I don't care what it
    > looks like?"  Neither seems like a good idea.
    Well, neither of the choices offered is how I would proceed.
    If the idea becomes incorporated into regular Unicode there would be example glyphs. The encoding would be decided by discussion.
    Yet, to answer your question, I would probably encode several alternatives for an ending glyph. For example, again using Private Use Area codes here for correctness at the present time, U+EE0F for an an ordinary ending glyph that is about twice the width of the basic glyph and U+EE0E for an ending glyph that is about five times the width of the basic glyph (except for an m, where it would be so that it matched the other characters): in each case recommending implementation in the font with the glyph having the same advance width as the basic glyph, so that a following apostrophe could be used following the glyph, for use in Esperanto poetry.
    In order to access an alternate starting glyph, for these experiments one could use U+EE0C. This would mean that the swash capitals of an italic font could be accessed from plain text. For these experiments, if U+EE0C were used with a regular (that is, not italic) font then there would be a wrong display, unless the regular font had rules such as the following within it.
    A unicode_ee0c -> A
    However, if U+FE0C were encoded within regular Unicode for the purpose, then that would not, if I understand variations selector rules correctly, be a problem, as the U+FE0C would be treated much as if a zero width space by the application program if the font did not have a rule using it for the particular character.
    > Typography is not done with plain text. 
    > Just to illustrate *my* point, I'm adding a PDF of four of
    > the huge number of possibilities for laying out your first
    > stanza with Zapfino on a Mac.  Which one did the poet
    > intend?
    Well, what I intended was that all of the characters except for the last character of each verse, a total of three characters, would be typeset using the basic glyphs of the font and that the last character of each verse would be typeset using an alternate ending glyph. Based solely on the glyph complement pdfs that Adobe make available on the web, the Arno Pro and Arno Pro Italic fonts would both seems suitable.

    William Overington
    14 August 2010

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