Re: XeConTeXt bug report I: strange benchmark

[Yue Wang <yuleopen@gmail.com>]

I can confirm that I am wrong.

2009/5/13 Yue Wang <yuleopen@gmail.com>:
> Hi, Hans:
>
> On Tue, May 12, 2009 at 11:22 PM, Hans Hagen <pragma@wxs.nl> wrote:
>> \setupbodyfont[myzhfont] \dorecurse{10000}{{hello
>> {\switchtobodyfont[myzhfont] 你好}}\par}
>> so it's probably also an operating system issue (caching files in mem, disk access etc)
>
> After debugging for half an hour in the morning, finally I know why
> this is so slow on both XeTeX and pdfTeX.
> This problem is not an operating system issue, But a ConTeXt "feature".
>
> in font-mkii, you use the following to define a actual font
> (\definefontlocal and \definefontglobal):
>  {\expandafter\xdef\csname#1\endcsname  % ! ! ! ! not needed in luatex ! ! ! !
>     {\noexpand\csname#1:\endcsname
>      \noexpand\reactivatefont{\somefontname}{\fontfile}}%
>
> For example, in the previous example, it will define a lot of fonts,
> like \*myzhfont12ptmmexrm*: , is defined as
> \reactivatefont{cmex10}{lmex10}. When define that font, a macro
> \*myzhfont12ptmmexrm* is defined to select the \*myzhfont12ptmmexrm* :
> font.
> \*myzhfont12ptmmexrm* =\csname *myzhfont12ptmmexrm* :\endcsname
> \reactivefont{cmex10}{lmex10}
> TeX then expand your reactivatefont macros to lmex10 at 12.0pt. So the
> \*myzhfont12ptmmexrm*: font will assigned to lmex10 at 12.0pt. This is
> quite right for definition.
>
> However, after switching the font, the problems occurs:
> it tries to call \*myzhfont12ptmmexrm* macro. the macro then expands to
> \csname *myzhfont12ptmmexrm* :\endcsname \reactivefont{cmex10}{lmex10}
> then to
> \*myzhfont12ptmmexrm* :\reactivefont{cmex10}{lmex10}
> and here TeX tries to do the following thing:
> TeX select the font \*myzhfont12ptmmexrm*:, which is lmex10 at 12pt,
> then *changing* into that font environment in order to *typeset*
> \reactivefont.  it then expand the macro of reacitve font, but found
> nothing to typeset...
>
> what's worse, this will occur on every real fonts in the definition.
> So in fact TeX will switching dozens of fonts into the *current* font
> for a "\switchtobodyfont" call, in order to typeset nothing. And
> that's why ConTeXt is so slow on typeface changing.
>
> The solution to this bug (or feature?) is quite easy, just use \font
> to define the \*myzhfont12ptmmexrm*: font, but pay attention not to
> switch the current font to \*myzhfont12ptmmexrm*: . Since it is quite
> slow to switch to dozens of font for one \switchtobodyfont call even
> in Knuth TeX.
>
>
>
>
> Yue Wang
>
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>> so it's probably also an operating system issue (caching files in mem, disk
>> access etc)
>>
>> -----------------------------------------------------------------
>>                                          Hans Hagen | PRAGMA ADE
>>              Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
>>     tel: 038 477 53 69 | fax: 038 477 53 74 | www.pragma-ade.com
>>                                             | www.pragma-pod.nl
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