View Issue Details
|ID||Project||Category||View Status||Date Submitted||Last Update|
|0016242||Scribus||Fonts||public||2020-09-14 14:39||2020-09-15 08:58|
|Summary||0016242: Some fonts force ligatures of certain character combinations|
|Description||Fonts from the Arkandis Digital Foundry contain ligatures for the character combinations ae and oe, turning them into æ and œ respectively. When used in Scribus, those ligatures are forcibly applied. The ligature checkboxes in text properties do not disable the ligatures. This is problematic because the ligatures are actually different characters.|
|Steps To Reproduce||1. Download the font Tribun-Std from the supplied link, or install the package fonts-adf-tribun on a Debian system|
2. Create a text frame containing text with the letter combinations ae and oe
3. Apply the Tribun font to the text
|Tags||No tags attached.|
||I can also reproduce this issue in Word with ligatures explicitly disabled. So it seems the culprit is the font. It probably has OpenType instructions which force the substitution.|
I tried it in Gimp and Inkscape and the issue reproduces in both. And with fontforge I can see the ligature substitutions in the required ligatures (rlig) table. So it does seem to be an issue with the font. However, when I last used these fonts in a publication a year ago, I didn't have ligature issues. Yet it appears that the incorrect rlig table has been in Debian since at least 2018 and probably as early as 2016. I wonder what has changed? Maybe something in harfbuzz, if Scribus uses that for text layout (I can see the package dependency but not what it's used for).
Would it make sense to allow disabling all ligatures, even the "required" ones, to deal with broken fonts? I can edit out the incorrect ligatures or use an older version of the font, but not all users may be familiar with editing tools or OTF structure or able to locate the old versions. I have also reported the issue to Debian but it may take time before it's fixed (an earlier report about incorrect ligatures took several years).
older versions of scribus (1.4, early 1.5.x) simply ignored ligatures in the fonts...
can you try to get in touch with the creators / maintainers of the font and see
- why they are doing this?
- if scribus can do something to fix the behavior?
||I'll try asking. Meanwhile, if Scribus is indeed using harfbuzz for text shaping, disabling the rlig feature would probably help: https://harfbuzz.github.io/shaping-opentype-features.html|