New output mode to write CHM files directly.

I became aware a few months ago that enough is known about CHM files
that free software _can_ write them without benefit of the MS HTML
Help compiler - in particular there's a thing called 'chmcmd' in the
Free Pascal Compiler software distribution which is more or less a
drop-in replacement for hhc.exe itself.

But although depending on chmcmd would be a bit nicer than depending
on hhc.exe, Halibut has always preferred to do the whole job itself if
it can. So here's my own from-scratch code to generate CHM directly
from Halibut source.

The new output mode is presented as a completely separate top-level
thing independent of HTML mode. Of course, in reality, the two back
ends share all of the HTML-generation code, differing only in a few
configuration defaults and the minor detail of what will be _done_
with each chunk of HTML as it's generated (this is what the recent
refactoring in b3db1cce3 was in aid of). But even so, the output modes
are properly independent from a user-visible-behaviour perspective:
they use parallel sets of config directives rather than sharing the
same ones (you can set \cfg{html-foo} and \cfg{chm-foo} independently,
for a great many values of 'foo'), and you can run either or neither
or both as you choose in a given run of Halibut.

The old HTML Help support, in the form of some config directives for
HTML mode to output the auxiliary files needed by hhc.exe, is still
around and should still work the same as it always did. I have no real
intention of removing it, partly for the reasons stated in the manual
(someone might find it useful to have Halibut generate the .HHP file
once and then make manual adjustments to it, so that they can change
styling options that the direct CHM output doesn't permit), and mostly
because it wouldn't save a great deal of code or complexity in any
case - the big two of the three auxiliary files (the HHC and HHK) have
to be generated _anyway_ to go inside the .CHM, so all the code would
have to stay around regardless.

1 files changed, 14 insertions, 10 deletions

diff --git a/doc/running.but b/doc/running.but
index 39e1715..6c2b6c6 100644
--- a/doc/running.but
+++ b/doc/running.but
@@ -12,22 +12,19 @@ This will generate a large set of \i{output files}:
 \b \i\c{output.txt} will be a \i{plain text} version of the input
 document.
 
+\b \i\c{output.chm} will be a Windows \i{HTML Help} version of the
+same thing. (Note that to do this Halibut does not require any
+external software such as a \i{Help compiler}. It \e{directly}
+generates Windows HTML Help files, and therefore it doesn't need to be
+run on Windows to do so: it can generate them even when run from an
+automated script on a Unix machine.)
+
 \b \i\c{output.hlp} and \i\c{output.cnt} will be an old-style
 \i{Windows Help} version of the same thing. (Most of the text is in
 \c{output.hlp}; \c{output.cnt} contains additional contents data
 used by the Windows help topic selector. If you lose the latter, the
 former should still be usable, but it will look less modern.)
 
-\lcont{
-
-Note that to do this Halibut does not require any external software
-such as a \i{Help compiler}. It \e{directly} generates old-style
-Windows Help files, and therefore it doesn't need to be run on
-Windows to do so: it can generate them even when run from an
-automated script on a Unix machine.
-
-}
-
 \b \c{output.1} will be a Unix \i{\cw{man} page}.
 
 \b The set of files \c{*.html} will contain an \i{HTML} version of
@@ -79,6 +76,13 @@ line, using the \c{-C} option).
 
 \dd Synonym for \c{--html}.
 
+\dt \i\cw{--chm}[\cw{=}\e{filename}]
+
+\dd Specifies that you want to generate Windows HTML Help
+output. You can optionally specify a file name (e.g.
+\c{\-\-chm=myfile.chm}), in which case Halibut will change the
+name of the output file as well.
+
 \dt \i\cw{--winhelp}[\cw{=}\e{filename}]
 
 \dd Specifies that you want to generate old-style Windows Help