GNOME Bugzilla – Bug 440975
wrong Kerning with TTF and OTF?
Last modified: 2008-01-15 13:27:29 UTC
As a typographer I see a strange kerning behaviour with gimp. It seems (thouh OTF-Fonts are rendered and ligature substitution is enabled and actually works) that GPOS-kerning doesn't work as I expect it. While (old) TrueType-Kerning seems double as strong. So GIMPs kerning mechanism should be revised! Wrong kerning is extremely ugly. Perhaps you'd also implement a checkbox to disable automatic positioning. Additionally it would be great if one could also choose from the other opentype tables (besides "liga"). You can use LinuxLibertine as an example: http://linuxlibertine.sf.net
Thanks for your report. We don't do the kerning ourselves, we use the text rendering as provided by Pango. This particular problem sounds a lot like bug #334758 for pango. Since you seem to know a lot about fonts, could you please check if this is a duplicate? I.e. check if your font has the same kerning pair in multiple GPOS tables? As for selecting multiple tables: Yeah, would be useful, but Pango AFAIK does not yet offer an API for this. Lets keep this bug report limited to the Kerning problem and since I myself am interested in using alternate tables of OT-fonts we won't forget about this.
Yes, this seems to be a dublicate. Pango seems just not to have a good, reliable and true OpenType-interpretation-system. Remains the question, what you from GIMP should do for the next version. If the pango-bug is not fixed until then, it might be wise to disable kerning altogether (because no kerning is much better than wrong kerning). Hereby I want again motivate you to deal with OpenType-features and implement them soon! As a help (what can be useful and how it works) I recommend MinionPro from Adobe (released with acroread and so on nearly every second Linux installation) and of course our Libertine (at least the next version 2.6.x has stable and proofed OpenType tables). Philipp Poll http://linuxlibertine.sf.net
Please open a bug report against Pango then or offer your help to the Pango developers. It is pointless to duplicate this effort in GIMP.
Sorry, I meant to mark this as a duplicate, reopening.
*** This bug has been marked as a duplicate of 334758 ***
Pango as of now does not have the API to control kerning from the application. This would be a prerequisite to be able to fix this. I am also unable to spot an API to specifically control open type features. Unfortunately I don't have a real clue how the API would have to look like and how these features in fonts actually do work. If you want to help please help the pango developers to come up with a sane API and rest assured that we will implement those features in GIMP when the API in pango is available.