bugFree UCS Outline Fonts - Bugs: bug #26804, Musical Symbols: font feature...


bug #26804: Musical Symbols: font feature lookups by script

Submitted by:  Steve White <Stevan_White>
Submitted on:  Sun 14 Jun 2009 12:12:57 PM UTC  
Category: character rangeSeverity: 2 - Minor
Item Group: character substitution issueStatus: Need info
Privacy: PublicAssigned to: Steve White <Stevan_White>
Open/Closed: OpenRelease: development

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Sat 04 Sep 2010 11:40:56 PM UTC, comment #1:

FontForge warning (v 20090923)

"On Windows many apps will have problems with this font's kerning, because because 58 of its glyph kern pairs cannot be mapped to unicode-BMP kern pairs"

This was due to trying to use kerns in Musical range, which is not in the Basic Multilingual Plane (is above u+FFFF).

Steve White <Stevan_White>
Project AdministratorIn charge of this item.
Sun 14 Jun 2009 12:12:57 PM UTC, original submission:

So far, have found very limited success in getting font features to work in the Musical Symbols range. This affects at least bug reports:

bug #26803: Musical Symbols: Begin/End Beam, Phrase, Slur, Tie]

bug #26801: Musical Symbols: combining articulations in text]

  • In Linux, kerning and mark positioning works, but only in very

specific circumstances
(I think it's a bug in the text layout engine)

  • Other features (Contextual Alternaties) I tried don't seem to be activated for the Musical Symbols range in Linux. I know these features work in the same font for other ranges. What's going on?
  • I don't see any of the features I tried being used in Windows (in web browsers, anyway)

As to why:

  • The question of what level of software is responsible for handling a feature is complicated and system-dependent.

On Linux, and in some free software such as FireFox, the level is the text-layout library Pango.

  • The question of what feature should be turned on for what script is complex and messy.
    • OpenType has a special script tag 'musc' to identify the Musical Symbols range.

OpenType Script Tags

    • Unicode doesn't specify a special script for Music. This is

really too bad. So it gets labelled as "Common". Unfortunately, this is the way Pango determines its behaviour.
***ISO 15924
***Script database

    • Some font features are script-dependent: For example the 'calt' tag

'calt' feature description
says: "not applicable to ideographic scripts"

I think this results in text layout engines not knowing what specific features to apply to music, and only applying a very restricted, but inconsistent, set.

Steve White <Stevan_White>
Project AdministratorIn charge of this item.


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    Follows 1 latest change.

    Date Changed By Updated Field Previous Value => Replaced By
    Fri 28 Oct 2011 08:21:59 PM UTCStevan_WhiteSeverity3 - Normal=>2 - Minor

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