Re: MkII vs. MkIV

[Hans Hagen <pragma@wxs.nl>]

Aditya Mahajan wrote:
> On Tue, 4 Nov 2008, Wolfgang Schuster wrote:
> 
>> Am 04.11.2008 um 21:20 schrieb Aditya Mahajan:
>>
>>> On Tue, 4 Nov 2008, Marcin Borkowski wrote:
>>>
>>>> Hi,
>>>>
>>>> Is it normal that output from MkII and MkIV are different in terms of
>>>> page breaks?
>>> Yes. In MKII the interline space is hard coded. MKIV gets the
>>> interline
>>> space from the font. So, you will get different page breaks. I
>>> experienced
>>> around 2-5 pages difference in a 100 page document.
>> The interlinespace in MkII and MkIV is the same and both use a distance
>> of 2.8ex between the lines.
> 
> Yes, but ex means different dimensions in pdftex and luatex. For example
> 
> \starttext
> 
> 1ex = \the\dimexpr1ex\relax \crlf
> 2.8ex = \the\dimexpr2.8ex\relax
> 
> \stoptext
> 
> gives in MKII
> 
> 1ex = 5.16667pt
> 2.8ex = 14.46669pt
> 
> and in MKIV gives
> 
> 1ex = 5.172pt
> 2.8ex = 14.4816pt
> 
> The reason is that what ex means is hardcoded in MKII but MKIV gets this 
> info from the font. For example, if I use palatino at 12pt, the result in 
> MKII does not change, but MKIV gives
> 
> 1ex = 5.388pt
> 2.8ex = 15.08641pt
> 
> So, depending on the font, MKII and MKIV can have considerably different 
> lines per page.

- for type 1, mkiv gets the info from the afm file and has some 
heuristics if it's not in there; in mkii it's set in the tfm and such 
values can depends on decisions made while making the tfm file

- for otf again the info is taken from the font file

in both cases, there is no longer the limitations imposed by the tfm 
format (like discrete number of ht/dp) and as such there can be 
differences between mkii and mkiv

Hans


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