[NTG-context] what defines the font size?

Hans Hagen j.hagen at xs4all.nl
Wed Oct 17 19:05:09 CEST 2018

On 10/17/2018 6:14 PM, Pablo Rodriguez wrote:
> On 10/17/18 11:02 AM, Arthur Reutenauer wrote:
>> On Tue, Oct 16, 2018 at 07:48:41PM +0200, Pablo Rodriguez wrote:
>> [...]
>>    It’s less clear what you’re trying to do next:
>>> [...]
>>    What are you trying to demonstrate with this?  If you change the size
>> of the font, obviously the glyphs have different sizes.  The initial
>> size at \starttext is 12pt, then \tfxx and \tfd change the sizes, to 8pt
>> and 20.736pt respectively.  Hence the former looks quite small in the
>> box, and the latter looks very large.  All that’s perfectly normal, and
>> since you’re not changing the font, or even the glyph, it’s not a good
>> illustration of the points raised in your initial email.
> I tried to show that the em square is the fixed measure. But the glyphs
> may relate in different ways to that square.
> I know that \tfxx and \tfd are different sizes. But there would be
> nothing against taking each of them to develop a new font (at 12 points)
> with their diverse glyph sizes.
> Or am I missing something.

I don't understand what you issue is. Each font (size) has its own emwidth.

Why design a \tfxx ? Of course, there are fonts with multiple 
designsizes but if that is the case then shapes differ (just compare 5pt 
7pt 10pt latin modern) but 'develop a new font' is often quite some 
effort (esp now that we have unicode fonts).

>>> The issue with units per em is something I didn’t understand.
>>    That’s irrelevant for you as a font user.  Don’t worry about it.
> A user that asks why different fonts have glyphs with different sizes
> given the same point for both, doesn’t remain a font user anymore.

Just explain that it's design side. And compare it to sizing dogs or so 
... what do you measure? Its tail or its legs.

> (I only wanted to understand, in order to be able to illustrate other
> people.)

                                           Hans Hagen | PRAGMA ADE
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