> Do you really see a clear cap-height (and baseline, to measure it from) here?
I absolutely do. Do you... not? You can do a quick web search for "Arabic type anatomy" that will make it crystal clear for you.
I mean it obviously has nothing to do with "capital" letters (so a more inclusive term would be better, probably), but there are clear upper and lower "bounds" beyond which ascenders/descenders poke out.
The relative sizing of fonts (and line heights) across languages is a separate issue, and is complex. But it's a disaster in interfaces today, where e.g. traditional Chinese characters sized to cap height become virtually illegible they're so small.
> I absolutely do. Do you... not? You can do a quick web search for "Arabic type anatomy" that will make it crystal clear for you.
I also do not. When I search for that, I find articles like https://www.type-together.com/arabic-type-anatomy which say things like "Do not use ‘x-height’ and ‘cap height’ simply because there are no ‘x’ or capitals in Arabic."
So since you do see such a thing, maybe you could show us? You could give a specific link or make a drawing.
The article you linked clearly shows lines labeled "baseline", "descender", "Latin x-height" and "ascender".
And yes, it says do not use the term "cap height" but I already stated that a more inclusive term would be better. It's still obvious what's being referred to.
In current practice (e.g. put roman and Arabic fonts next to each other on the same line in your browser), the Latin "baseline" and "cap height" lines clearly are conceptually equivalent to the Arabic "descender" and "ascender" lines.
Do you see it now?
I don't understand how anyone's trying to argue that there are languages that don't have obvious logical top/bottom boundaries (or right/left for vertical scripts) for basing font metrics on.
> I don't understand how anyone's trying to argue that there are languages that don't have obvious logical top/bottom boundaries (or right/left for vertical scripts) for basing font metrics on.
I don't argue that at all. I agree that Arabic has ascent and descent. I just don't see that Arabic ascent corresponds to Latin cap height (rather than, say, Latin ascent).
The argument that the article is, essentially, trying to make is that some such correspondence obviously does exist visually - i.e. that you can write e.g. English and Arabic text in the same line, sized such that they look the same size.
However, referring to your link all the text is arrange into nice equally space lines that are pleasing to the eye.
Doesn't that nice layout suggest there is some sort of 'cap height' value at play which then allows those vertical lines to work together so well?
Edit: The way I see 'cap height' is it is some sort of maximum guaranteed value. Now it turns out for English all capitals will have that exact same maximum value.
But the value is not saying all capital letters must take on that maximum value, instead it is that all the characters in the font will not be bigger than that size.
> Doesn't that nice layout suggest there is some sort of 'cap height' value at play which then allows those vertical lines to work together so well?
The em size? The thing the article is suggesting is worse than cap height?
> Edit: The way I see 'cap height' is it is some sort of maximum guaranteed value. Now it turns out for English all capitals will have that exact same maximum value.
No, it's not a maximum guaranteed value, it's the height of capital letters. In a Latin font, the ascenders of lower-case letters exceed it.
This is exactly where my difficulty is: some Arabic letters have ascenders and descenders. Depending on the font, it may or may not have a baseline. Letters that don't have ascenders and descenders have a height which I would say corresponds roughly to the x-height. The one thing that I can't see any correspondence to is the height of capital letters!
I absolutely do. Do you... not? You can do a quick web search for "Arabic type anatomy" that will make it crystal clear for you.
I mean it obviously has nothing to do with "capital" letters (so a more inclusive term would be better, probably), but there are clear upper and lower "bounds" beyond which ascenders/descenders poke out.
The relative sizing of fonts (and line heights) across languages is a separate issue, and is complex. But it's a disaster in interfaces today, where e.g. traditional Chinese characters sized to cap height become virtually illegible they're so small.