Positioning of Diacritic Marks when doing Optical Metrics

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PJMiller
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Positioning of Diacritic Marks when doing Optical Metrics

Post by PJMiller » Tue Jan 30, 2018 11:25 pm

A change which was introduced in FC 11 was that if a composite glyph has the 'use this glyphs metrics' flag set then Optical Metrics will not change the bearings of that glyph, the glyph will continue to use the bearings of the base glyph.

This was a very welcome change and FC 11 is better for having it, but there is a consequence to this behaviour.

If the base glyph has its left side bearing adjusted then this moves the relative position of any diacritic marks used with that base glyph in composite glyphs.

For example consider the letter 'A', if optical metrics decides to adjust the position of 'A' by 30 then this will be like the 'Â' character having its circumflex moved by -30.

This means that after performing an Optical Metrics operation one has to go through the font adjusting the positions of many of the diacritic marks.

It would be nice if when performing an Optical Metrics operation if a character has its left side bearing adjusted and that character is used in a composite with the 'use this glyphs metrics' flag set then the same horizontal adjustment should be applied to any other glyphs (diacritic marks) used with that base character in a composite glyph.

Bhikkhu Pesala
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Re: Positioning of Diacritic Marks when doing Optical Metrics

Post by Bhikkhu Pesala » Tue Jan 30, 2018 11:44 pm

What you can do is select all composites, tag them, make simple, then complete composites on the tagged glyphs. This may be a problem if you did a lot of manual adjustment of diacritics after using Complete Composites.
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PJMiller
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Re: Positioning of Diacritic Marks when doing Optical Metrics

Post by PJMiller » Wed Jan 31, 2018 7:22 am

It is a matter of aesthetic judgement as to where to place the diacritic, complete composites usually gets it close enough for upright characters but the results for italics are less good.

Complete composites is a good starting point for the placement of diacritics.

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