TrueType: Components with modified y position (small figures)

yanone

Dear type cracks,
here’s a somewhat beginner’s question to TrueType hinting:

Do you see a chance to have components (of, say, small figures) that are positioned differently from the originals on the y axis?
The original set of small figures in this one font are the numerators. Then, the denominators are components only, so far. But their hinting is of course attached to zones in certain commands that are far off for the components.
And while I don't see the crude distortions I remember from earlier days (like counters being pulled way over the outer outline), they don't look well in the font. They look okay in dimensions and proportions and stroke width, and even completely as supposed in certain ppms, but they also look unhinted in many other ppms.

Is there a way, or should they be decomposed under all circumstances?

Jason Campbell

The hints in the base glyph are applied before the yshift to the component, so the hints should "work". I do this often, actually. But in order to make everything behave as you want, you need an additional Yanchor to the baseline (or other height "zone") in the component(denominator) version, because eventually the yshift will round to a pixel distance that you don't like.
This is a lot easier to do in VTT however, than it would be in FontLab.

yanone

But if the hints are applied before the yshift, as you say, which makes sense, why should they "work"? They are attached to zones that are off.

I applied "Align points" (FL terminology) to the top and bottom points in the component (denominator). I thought that must be what you mean by "Yanchors". Now they align with the zones, but the innards still appear unhinted at certain ppms. But the top and bottoms points are the only ones being attached to zones. The rest of the hinting consists of three stems. And they should be well shiftable.
I don’t get this.

BTW, do you know how FontLab applies additional hinting to components? Do additional hints overwrite identical commands for this particular point or does it scrape all commands taken over from the base glyph and applies only the additional commands?

yanone

I partially answered my last question. FontLab's manual is unclear about this.

Usually all you need to do to hint a composite glyph is to put a few middledelta
instructions on the contours of accent components so they will get a
correct and symmetric position in the composite glyph.

You can however completely override hinting of components and provide
new hinting program for a composite glyph. In this case you may take a
composite glyph as a combination of all components as if it is decomposed.

I guess this means that hinting starts over as soon as hints are applied that are not middledeltas.

Jason Campbell

I think you are right that the "additional hints" blow away the previous hints, if they are not deltas. This is a limitation of FontLab, though. A program like VTT would allow aligning the hinted glyph. I know that doesn't help you though, sorry about that.

yanone

Haha, no problem. Thank you. At least now I understand how FontLab handles the hinting.