Re: [Groff] rationale for italic correction mechanism?

[Tadziu Hoffmann]

> You're allowing your typesetting software to paginate, to fill
> lines, to kern, to convert character sequences to appropriate
> ligatures, to stretch spaces for justification, to hyphenate.

To be a bit pedantic here, pagination is something that's not
completely done automatically by troff itself, but only with
the help of a macro package.

As the Troff User's Manual says,

  Such common formatting needs as page margins and footnotes
  are deliberately not built into nroff and troff. Instead,
  the macro and string definition, number register, diversion,
  environment switching, page-position trap, and conditional
  input mechanisms provide the basis for user-defined
  implementations.

> My argument is not to take control away from users,
> but to provide sensible default behavior.  

Like Werner says, the currently preferred solution is a macro
that simplifies the process.  Additionally, using a macro
has the advantage that something like

  ... words set in
  .I italic ,
  but ...

is much easier to type and read than

  ... words set in \fIitalic\/\fP, but ...


> If you can make a case that overlapping glyphs in certain
> roman/italic transitions is sensible default behavior, and
> that every such case should require individual correction
> rather than a global setting saying "fix all of these," I
> would be quite interested to hear it.

A thing to keep in mind is that what we call "italic correction"
is the space needed between the italic character and a *tall*
upright character.  This is often what you want to insert,
but not always.  For example, in a situation like

  ... our ship was called the _Stroganoff_, and it ...

you don't want this italic correction at all between the italic
"f" and the comma (but perhaps a thinspace after the comma,
if the overhang of the italic "f" is very wide).


So what we *really* want is the ability to define appropriate
amounts of kerning between characters belonging to different
fonts.  Gunnar Ritter has implemented this for Heirloom troff,
but I know of no other software which provides this capability.
Until we have such a feature, I'm afraid we have to leave
these things at least partly up to the person setting the text.