New features of the diskfont.library 45.1 and above

The diskfont.library 45.1 comes with an optional font directory caching 
mechanism. If turned on, reading the font list is speed up considerably. Hence,
font requesters will pop up much faster than they used to, and keeping hundreds
of fonts on your HD is much less of a problem than it used to be; you don't have
to wait for ages until the font list pops up.

The font cache is competely transparent for the software and for you, you do not
need to care about it when installing new fonts. The library will recognize the
installation of new fonts and will update the cache automatically for you. It is
a "turn on and forget" feature.


  How to enable the automatic font caching

By default, the new release of the diskfont.library will come with the cache dis-
abled. To enable it, proceed as follows:

i)  The global font caching must be turned on.
This switch is located in the environment variable "diskfont". Open a shell, 
and edit the file "ENVARC:diskfont" with an editor of your choice. If this file
did not yet exist, the editor will create it for you. In the following, we 
assume that you use the system editor "Ed". Enter the following command in the
shell

Ed ENVARC:diskfont    

and press RETURN. The editor should now present the contents of the file; it 
might be empty. Please type in the following line:

CACHE=yes 

Now save the file back. For "Ed", either use the menu, or press "Esc" followed
by "x" and RETURN. For details about Ed, please consider its manual.


ii) Font caching directories must be supplied.
The diskfont.library needs a place to store the cache file; it is kept in the
directory "_Cache" in the FONTS: device. To create it, enter the following
command in the shell window:

MakeDir FONTS:_Cache

and press RETURN. This is all; now reboot the machine. The font cache is now
enabled, but not yet created. The diskfont.library will do that for you as
soon as you open a font requester. The FIRST font requester will therefore
be as slow as usual since no caching took place and the library has to create
the cache. However, all subsequent font requesters will be speed up
dramatically. 


  Multiple font caches

In case you work with multiple font sources, as for example disk packages
containing FONT directories, you may build font caches for them as well.
For that, just create the directory "_Cache" within the font directory on
these disks. All the rest is done by the diskfont.library. It will build
the cache as soon as you try to read the font contents of this disk, and
will use it later if you re-insert this disk.

You may mix disks with and without a font cache freely, this causes no
problem for the diskfont.library whatsoever.


  Do I need to update the cache?

No. In case you install new fonts, or delete old fonts, the contents of the 
cache does no longer reflect the contents of the font directory. However, you 
DO NOT NEED to worry about this situation. The diskfont.library will detect 
this automatically and will rebuild the cache file for you.

This will, however, not work on MS-Dos (CrossDos) disks since the FAT filing
system does not keep the modification date of directories correctly. Hence,
do NOT enable font caching, i.e. do not create a _Cache directory on MS-Dos
disks, or in case your computer doesn't include a real time clock.

In case you want to enforce a cache rebuild, for whatever reason, delete the 
file "_Cache/FontCache". 


  Advanced features

The cache comes with an additional feature which is left to experts: The
library may optionally sort the font list for you. This has no advantage for
the system font requester since it sorts the font list itself. It will 
speed up the requester a bit since the sorting algorithm used by the diskfont
library is more advanced than that of the ASL requester. It may also help
other programs which present the font list itself.

However, some old programs expect the font list in a specific order and
will fail, or will return strange results. Note that there has never been any
documented order in the font list, hence programs depending on this should be
considered broken anyhow; nevertheless, FOR MAXIMAL COMPATIBILITY, LEAVE THIS
FEATURE OFF.

To enable it, include the keywords "ASCENDING" or "DESCENDING" in the
ENVARC:diskfont variable, depending on whether the font list should be sorted
in ascending or decreasing order. Even though the system requester sorts 
fonts ascending, you get maximum speed with "DESCENDING" due to the sort
algorithm used by the requester.


  Programmer notes

There is no documented interface to the font cache. The AvailFonts() call
works in the same way as it ever did, except that it will try to load from
the cache, or will try to recreate the cache if it finds it outdated.
Especially, the format of the cache file is undocumented, has changed in
the past and will continue to change. Do not make assumptions about its
contents and do not parse it itself.