Truetype font size question?
Sean
10pt or 12pt. But for CM font, there are cmr10.tfm, cmr8.tfm, I think
tfm file is associated with one specific font size.
When I use ttf2tfm ttf2pfm and t1asm to convert a trebuc.ttf file to
tfm and pfb, and in TeX file, I wrote
\font\myfont=trebuc
how TeX know what is the font size?
Do I have to use a something like
\font\myfont=trebuc at 20pt
to explicitly specify a fontsize?
Ulrike Fischer
> When you use ttf2tfm, you don't need to specify the font size like 8pt
> 10pt or 12pt. But for CM font, there are cmr10.tfm, cmr8.tfm, I think
> tfm file is associated with one specific font size.
Yes, for the cm font there exist specially designed variants in
various sizes.
>
> When I use ttf2tfm ttf2pfm and t1asm to convert a trebuc.ttf file to
> tfm and pfb, and in TeX file, I wrote
> \font\myfont=trebuc
> how TeX know what is the font size?
Every font has a "natural" size.
>
> Do I have to use a something like
> \font\myfont=trebuc at 20pt
> to explicitly specify a fontsize?
Yes. (This is also done with the cm-fonts for intermediary sizes).
--
Ulrike Fischer
Dan Luecking
wrote:
>Am Fri, 20 Nov 2009 00:56:32 -0800 (PST) schrieb Sean:
>
>> When you use ttf2tfm, you don't need to specify the font size like 8pt
>> 10pt or 12pt. But for CM font, there are cmr10.tfm, cmr8.tfm, I think
>> tfm file is associated with one specific font size.
>
>Yes, for the cm font there exist specially designed variants in
>various sizes.
>
>>
>> When I use ttf2tfm ttf2pfm and t1asm to convert a trebuc.ttf file to
>> tfm and pfb, and in TeX file, I wrote
>> \font\myfont=trebuc
>> how TeX know what is the font size?
>
>Every font has a "natural" size.
This doean't answer the question. The answer is: TeX knows
the font's size by examining the "designsize" parameter
stored in the TFM file. It got put there by ttf2tfm, which
might obtain that information from the ttf file (directly
or by inference) or simply selected a standard designsize
like 10pt. [From what little I know about TT fonts their
dimensions are given in tiny units, for example trebuc.ttf
says there are 2048 units per em. Ttf2tfm might simply
designate an em as 10pt, convert all the dimensions
in the ttf to match, and specify 10pt as designsize.]
However, TeX only uses the designsize parameter for one
purpose: to effect scaling when an "at" clause is used,
as below. TeX does not otherwise need to know it.
>
>>
>> Do I have to use a something like
>> \font\myfont=trebuc at 20pt
>> to explicitly specify a fontsize?
>
>Yes. (This is also done with the cm-fonts for intermediary sizes).
And the meaning of "at 20pt" is that TeX supplies a scaling
factor of (20pt/designsize). If trebuc has a 10pt size, then
this will double the size.
You don't "have to" use an explicitly specified pointsize,
but it is the only "sure" way to get the size one wants.
If trebuc happens to have a 12pt design size, this will scale
by 20/12 and still produce a 20pt size.
There are, however, a few badly produced TFM's that have an
arbitrary design size parameter that doesn't remotely match
the actual size of the characters. In that case omitting
the "at" clause gives one something reasonable, but using
it gives one wildly incorrect results.
I recall encountering a metafont source file that failed to
specify the designsize. The TFM that mf produced therefore
contained the default value (128pt) for the designsize
parameter. The characters were actually about 10pt in size,
but using "at 20pt" caused them to be scaled by
20/128 = 1/6.4. They were all made to be less than 2pt high
and unreadable.
Dan
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