[pdftex] Problems with pdftex.map

[Mark Wicks]

On Thu, 16 May 2002, Reinhard Kotucha wrote:

>     > And this from Mark Wicks:

>     > embedded font. I believe that the only way to change the font
>     > matrix is to re-embed a new copy of the font using different
>     > font matrix for each instance, and that's apparently what pdftex
>     > is doing.

    My statement above may have been misinterpreted.  I said the only way
to change the "FontMatrix" is to reembed the font.  I did not say that you
couldn't achieve the same effect using Tm.  In fact, dvipdfm (and Acrobat
Distiller) produce slanted fonts by using the Tm operator similar to the
way your propose.  Since FontMatrix is not modified, they embed only one
copy of a font for both slanted and regular shapes.

> I think it is possible to change the FontMatrix on the fly using the
> Tm operator.

    Tm does NOT change the FontMatrix; it changes the Text Matrix.  
FontMatrix and Text Matrix are different.

> I just prepared the following file:
[...]
> \a a \pdfliteral{1 0 0.2 1 0 0 Tm} b
[...]

> The result was an upright "a" and a slanted "b" with the font only
> loaded once.  AR was able to display it.

   Your example is too simple.  If you want to see the real problem, try
the following experiments using your method:

   1) Typeset a multi-line paragraph in slanted type.
   2) Typeset a multi-line paragraph with mixed regular and slanted type.
 
[...]
> Thanh, are there any problems using the Tm operator to change the
> FontMatrix rather than modifying the font itself?  I think it's even
> easier to implement.

    You are right that you can use the Tm operator can achieve the same
result as changing the FontMatrix, but I don't think it's easier.

-- 
______________________________________________________________________

  Mark A. Wicks                                mwicks at kettering.edu
  Associate Professor and Interim Head
  ECE Department, Kettering University         Voice: (810) 762-7992
  1700 West Third Ave, Flint, MI 48504-4898    Fax:   (810) 762-9830