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Accents calculated in size of ascender?
Posted by Adam Lemon in
11 Sep 2007 — 9:16am
11 Sep 2007 — 9:16am
I'm very new to typophile. Just picked fontlab up in the past 2 weeks. While I have a many fonts designed in Illustrator it's not until I actually started transfering them into fontlab that I found out my mistakes... Which is great. Love to learn.
However I get all through placing my caps, numbers, and some punctuation in fontlab when I'm looking at some accented glyph windows and think to myself I never took accents above the ascender into account... Doh! And I can't find my answer anywhere.
When setting up the UPM of the font do accents get calculated in the size of the ascender? I noticed most accents use the ascender line as the base line for them to start which really nulls the getting calculated in the ascender part. Of course I used the fontlab forum sticky "using illustrator to make fonts" post to determine my UPM=1000, Ascender=742, Cap Height=714, Descender=-258. I wanted my Ascender to barely break cap height.
How do accents or any symbol above the ascender get calculated in the font UPM or does it? Am I going to have change Ascender UPM or will Line height compensate for it?
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11 Sep 2007 — 11:07am
The accents don't have to figure in the calculation of the ascender, but they DO have to be used in calculating the bounding box (FontBBox), or else clipping could occur in some instances.
The way I do it (which may not be the best way or even the correct way, but it seems to work) is, AFTER you've placed your accents, to go to the "Additional Font Metrics" page of the font info dialog, choose "Set Custom Values" and hit "Recalculate." This process will set the correct numbers for the bounding box. Then go back one page, enter the Ascender and Descender values (making sure, as in your example, that their positive values equal 1,000), check the "Copy values to TrueType metrics" box, and hit "Apply."
This latter step helps avoid FontLab's erroneous error message of "[WARNING] The feature file OS/2 overrides TypoAscender and TypoDescender do not sum to the font bbox size!" when testing or generating an OpenType font. If you follow the procedure outlined, you won't get that message.
11 Sep 2007 — 11:10am
Typically, in a Latin font, the Ascender value should equal the height of the lowercase d and the Descender should equal the depth of the lowercase p. So accent marks or anything else extending above these heights may fall outside the body height (UPM height).
If you are making OpenType or TTF fonts, you also need to set the OS/2 WinMetrics and hhea Metrics, and these should be generous enough to avoid clipping the accent marks or other elements that extend beyond the body height.
See this Typowiki article for more details:
http://typophile.com/node/13081?
Be sure to read the whole article, because it involves some revisions to recommended practices.
11 Sep 2007 — 11:54am
Awesome! Thanks!