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HP48 Universal Font Library (UFL)
Andre Schoorl <aschoorl@engr.uvic.ca>
UFL v1.0.2
______________________________________________________________________
Table of Contents:
1. Introduction
1.1 Terms of Distribution
1.2 Scope
2. Using the UFL and Font Maintenance Libraries
2.1 Library Numbering
2.2 Libraries in this Package
2.3 To Install a Library
2.4 To Delete a Library
2.5 UFL Commands
2.5.1 FNT
2.5.2 Remaining Access Routines
2.6 FMnt Commands
2.6.1 FSTAT
2.6.2 sFED
2.6.3 ->F1
2.6.4 F1->
2.6.5 ->F2
2.6.6 F2->
2.7 List of Possible Errors
3. User RPL Access Routines
3.1 Supplied Directory
3.1.1 UFL?
3.1.2 FNT1?
3.1.3 FNT2?
3.1.4 U->GROB
3.1.5 F1->G
3.1.6 SGROB
3.1.7 SDISP
3.1.8 SDISP9
3.1.9 SSTAT
3.1.10 F2->G
3.1.11 MGROB
3.1.12 DISPN
3.2 Error Handling Hierarchy
4. Replacements Fonts
4.1 Changes to FNT2
4.2 Zip Files
4.3 Credited Fonts
5. System RPL Specifications
5.1 Programmer's Interface
5.2 Behaviour of each XLIB
5.3 Coding Standards
5.4 Summary of Usage
5.5 Examples
5.6 Conversion of Existing Programs to the UFL
5.7 Stack Access and Purging
6. Credits
______________________________________________________________________
1. Introduction
================
1.1. Terms of Distribution
---------------------------
HP48 Universal Font Library, distributed under the GPL (see file
COPYING). Copyright (C) 1996, 1997 Andre Schoorl
<aschoorl@engr.uvic.ca>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
1.2. Scope
-----------
An increasing number of HP48 programs are being developed that have
their own fonts rather than using the fonts built into the HP48. This
is due to a number of reasons:
o Accessing the built-in fonts is slow.
o The built-in fonts do not support all the characters and cannot be
modified.
o There is no way to distinguish between lower and upper case
characters with the built-in small font.
A number of popular HP48 programs overcome these problems by providing
their own copies of the fonts. Almost all of these are based on FNT1
and FNT2 from the Jazz library. Before the UFL, the authors of such
programs were forced to either:
o Keep their own copy of one or more fonts in their program so that
it would still run if the user does not have Jazz.
o Rely on the existence of Jazz in order for the program to run.
Both options are not ideal, because in the first case with just a few
such programs the user ends up having multiple copies of the same
font, which is a waste of room. The second case relies on the
presence of Jazz, which most people don't have room for. The
Universal Font Library (UFL) is a standard designed to alleviate both
of the above problems.
The basic idea is to have a separate, standardized library containing
FNT1 and/or FNT2. Various levels of the UFL are provided that contain
the various font combinations, so users don't need to have fonts
around that none of their programs require.
Also, the UFL allows for the separation of fonts and utilities to
maintain them. We have developed a library for the UFL known as the
Font Maintenance Library (FMnt) that can be downloaded separately from
the UFL. It allows the user to check the status of their UFL library
as well as recall and edit fonts. Once they are satisfied with their
setup, they can purge the Font Maintenance Library to save room.
Furthermore, the FMnt library is distributed with several alternate
fonts.
The benefits to such a system are immediately evident. Most
importantly, if the user has even more than one program using the same
font, they start saving valuable room on their calculators. In
addition, if the font in the UFL is edited, all of their favorite
programs using the UFL immediately start using the updated font.
Furthermore, the UFL opens the doors for programmers who were
previously unwilling to add an extra 1 or 2K to their library to use
the fast FNT1 and/or FNT2 routines. With the UFL, they no longer need
to worry about keeping their own copy of the font.
2. Using the UFL and Font Maintenance Libraries
================================================
2.1. Library Numbering
-----------------------
Each UFL library is assigned a "level" that indicates which fonts it
contains. If we assign one bit for each font, we can come up with a
binary representation as follows:
MSB 8 4 2 1 LSB
. . x y
^ ^
FNT2 FNT1
Using this scheme, we see that a library with only FNT1 would be
assigned level # 01b (1), a library with only FNT2 would be assigned
level # 10b (2), and a library with both FNT1 and FNT2 would be
assigned level # 11b (3). Notice that with this numbering convention,
if an addition FNT3 is ever added, the numbering of the existing
libraries would remain unchanged.
2.2. Libraries in this Package
-------------------------------
Using the decimal levels for FNT1 and FNT2 we see there are currently
three UFL libraries, as follows:
o ufl1.lib - Contains only FNT1 (Font level 1)
o ufl2.lib - Contains only FNT2 (Font level 2)
o ufl3.lib - Contains both FNT1 and FNT2 (Font level 3)
All UFL libraries have the same library number of 257 (# 101h).
You only need to load one of these libraries on your calculator.
Which particular one you need will depend on what applications you use
that require the UFL. See the documentation that came with the
programs you are using to determine whether you need FNT1, FNT2, or
both. If you are getting lots of "Font not Found" errors, most likely
you do not have the correct UFL level loaded on your calculator.
There is only one Font Maintenance Library (FMnt) and it is in the
file `fmnt.lib'. It has library number 258 (# 102h).
You only need to load the FMnt library if you wish to check the status
of your UFL or if you want to edit or recall the fonts in it. If you
are satisfied with the fonts that come with the UFL, you do not need
the FMnt library. However, if you decide to change the fonts, you are
free to purge the FMnt library once you have edited the fonts to your
liking.
2.3. To Install a Library
--------------------------
1. Download it into a variable of the calc.
2. Place the library on the stack.
3. Type the number of the port in which you want to store the library
in. 0 is appropriate if you do not have any expansion cards.
4. Press STO to store the library in that port.
5. Turn the calculator off and then on, or press ON-C, to finish
installation of the library.
Sometimes you have to purge the variable containing the library before
storing it in a port, if you are low on memory.
2.4. To Delete a Library
-------------------------
Say you have library 257 in port 0 that you want to delete.
1. Go to the directory to which the library is attached. In most
cases this will be HOME.
2. Enter :0: 257
3. Press [ENTER] or type DUP
4. Type DETACH
5. Type PURGE
2.5. UFL Commands
------------------
2.5.1. FNT
-----------
Usage: ( size -> fnt )
FNT is the user interface to the UFL's fonts. It takes the size of
desired font and recalls the font as a library data object if it
exists. The size should be a real number or system binary. Indexing
is one relative so 1 corresponds to FNT1 and 2 corresponds to FNT2.
Will error with "Font not Found" if the level of UFL you are using
does not contain the requested font.
2.5.2. Remaining Access Routines
---------------------------------
The remaining access routines in the UFL are hidden from the library
menu as a means of encapsulation, and to protect the general user from
routines that do not perform argument checking. The interface to
these is given in detail for System RPL programmers in the "System RPL
Specifications" section of this document.
2.6. FMnt Commands
-------------------
2.6.1. FSTAT
-------------
FSTAT shows a simple screen that allows you check the status of your
UFL library. The information shown includes yes or no answers for the
following:
o Whether the UFL is installed or not.
o Whether FNT1 is present.
o Whether FNT2 is present.
o Whether the fonts are editable.
Whether FNT1 or FNT2 is present will depend on what level of UFL you
have installed. In order for the fonts to be editable the UFL must be
in port 0 or an uncovered RAM card (0/1/2 on SX, 0/1 on GX). If the
UFL is on a RAM card it must be unlocked for the fonts to be editable.
2.6.2. sFED
------------
Usage: ( grob -> grob )
sFED is a FNT1 editor designed for the FMnt library. It takes a 128 x
48 FNT1 grob, allows you to edit it, and leaves the edited grob on the
stack. You can use F1-> to provide your current FNT1 as the initial
input to sFED. Once you are done you can update your UFL library by
using the output of sFED as input to ->F1 (see below). For a G/GX
FNT2 editor, see the README in the `contrib' directory.
sFED will error under the following conditions:
o The provided grob does not have the correct dimensions.
Usage instructions for sFED:
Main Screen:
Edit or [ENTER]
Edit the currently highlighted character.
Quit or [ON]
Quit sFED. If you made any changes, you will be prompted if
you want to save your changes upon exit.
About
About information
Edit Screen:
Dot+
Continuous draw
Dot-
Continous erase
[+/-]
Toggle "pixel"
Abort or [ON]
Abort any changes made to the character
Keep or [ENTER]
Keep all changes made to the character
2.6.3. ->F1
------------
Usage: ( grob -> )
Takes a 128 x 48 grob and changes FNT1. Modifies the UFL library with
the new FNT1 if it is in an accessible port. Will error under the
following conditions:
o The UFL library does not exist (install the UFL first).
o FNT1 is not supported in the level of UFL you are using (install a
level of UFL that supports FNT1).
o The UFL is not editable. In order to edit the fonts you must have
the UFL in an accessible port.
o The provided grob does not have the correct dimensions.
The original FNT1 is stored in the file `fnt1.zip' as `ufl1.fnt'.
2.6.4. F1->
------------
Usage: ( -> grob )
Returns the current FNT1 as a 128 x 48 grob. This output can be
edited to taste and then used as input to the ->F1 command. The
output of F1-> can be used as input to sFED. Will error under the
following conditions:
o The UFL library does not exist (install the UFL first).
o FNT1 is not supported in the level of UFL you are using (install a
level of UFL that supports FNT1).
2.6.5. ->F2
------------
Usage: ( grob -> )
Takes a 192 x 64 or 6,7,8 x 2048 grob and changes FNT2. Modifies the
UFL library with the new FNT2 if it is in an accessible port. Will
error under the following conditions:
o The UFL library does not exist (install the UFL first).
o FNT2 is not supported in the level of UFL you are using (install a
level of UFL that supports FNT2).
o The UFL is not editable. In order to edit the fonts you must have
the UFL in an accessible port.
o The provided grob does not have the correct dimensions.
The original FNT2 is stored in the file `fnt2.zip' as `ufl2.fnt'.
2.6.6. F2->
------------
Usage: ( -> grob )
Returns the current FNT2 as a 192 x 64 grob. This output can be
edited to taste and then used as input to the ->F2 command. Will
error under the following conditions:
o The UFL library does not exist (install the UFL first).
o FNT2 is not supported in the level of UFL you are using (install a
level of UFL that supports FNT2).
2.7. List of Possible Errors
-----------------------------
There are several errors that can occur with the above commands due to
non-existence of the UFL, the combinations of fonts, and locking of
RAM cards. The possible errors are:
UFL not Found
You have either not installed the UFL library, or not installed
a valid UFL library. Install an appropriate level of the UFL as
described above for the programs you are using.
Font not Found
The specific font required by the program you executed was not
found in the UFL you have installed. You need to determine what
font is missing and install a different level of the UFL that
contains it.
Cannot edit UFL
You tried to modify one of the fonts with the UFL installed in a
locked or covered port. In order for the fonts to be editable
the UFL must be in port 0 or an uncovered RAM card (0/1/2 on SX,
0/1 on GX). If the UFL is on a RAM card it must be unlocked for
the fonts to be editable.
G/GX Only
You cannot use this binary on an S/SX machine. The only place
this should occur is in the contributed FNT2 editor, FED.
3. User RPL Access Routines
============================
3.1. Supplied Directory
------------------------
The UFL comes with a directory of routines in `access.dir' which allow
you to use the UFL's fonts in your own programs. These perform
argument checking and can be used in User RPL programs or as the basis
for System RPL programs. Included in this directory are the following
access routines.
3.1.1. UFL?
------------
Usage: ( -> flag )
Returns 0 or 1 on whether the UFL library exists.
3.1.2. FNT1?
-------------
Usage: ( -> flag )
Returns 0 or 1 depending on whether the FNT1 exists. Errors if the
UFL does not exist, so check UFL? first.
3.1.3. FNT2?
-------------
Usage: ( -> flag )
Returns 0 or 1 depending on whether FNT2 exists. Errors if the UFL
does not exist, so check UFL? first.
3.1.4. U->GROB
---------------
Usage: ( obj size -> grob )
Converts the specified object to a grob with the requested size font.
This access routine is designed to ease User RPL access to the UFL,
and is meant to be as compatible as possible with the built in ->GROB
command.
U->GROB will not error if the UFL does not exist or if the requested
font in the UFL does not exist. Instead, it will fall back on calling
the built in ->GROB. This means users of U->GROB do not have to do
many of the checks normally associated with use of the UFL and do not
have to trap UFL errors.
Only strings will be be converted with the UFL fonts; all other
objects are passed to ->GROB. Because there is currently no FNT3 in
the UFL, a size of 0 or 3 will always be passed to the built in
->GROB.
3.1.5. F1->G
-------------
Usage: ( -> grob )
Recalls the current FNT1 as a 6 x 2048 grob. Errors for insufficient
memory or if FNT1 does not exist. The output of this command is
suitable for some older packages.
3.1.6. SGROB
-------------
Usage: ( string -> grob )
Takes a string and converts it to a graphics objects using FNT1.
Errors for bad argument, insufficient memory, UFL does not exist, or
FNT1 does not exist.
3.1.7. SDISP
-------------
Usage: ( string x y -> )
Takes a string on level 3, a real x coordinate on level 2, and a real
y coordinate on level 1, then displays string on the screen with the
supplied coordinates using FNT1.
o x is in steps of four pixels, so 0 <= x <= 33.
o y is in steps of one pixel, but will not display in the menu bar,
so 0 <= < y <= 51.
o If the string runs beyond the screen boundary, SDISP stops
displaying.
o If the given coordinates are out of range, SDISP does nothing.
o SDISP does no special handling for newline characters, and treats
them like any other character.
3.1.8. SDISP9
--------------
Usage: ( string -> )
Clears the stack grob and displays the first 9 lines of the string
from stack level 1 with FNT1. String can be any size. Leaves menu
area alone.
3.1.9. SSTAT
-------------
Usage: ( string -> )
Clears the status area and displays the first 2 lines of the string
from stack level 1 with FNT1. String can be any size.
3.1.10. F2->G
--------------
Usage: ( -> grob )
Recalls the current FNT2 as a 8 x 2048 grob. Errors for insufficient
memory or if FNT2 does not exist. The output of this command is
suitable for the contributed font editors or for StringWriter's `FONT'
variable.
3.1.11. MGROB
--------------
Usage: ( string -> grob )
Takes a string and converts it to a graphics objects using FNT2.
Errors for bad argument, insufficient memory, UFL does not exist, or
FNT2 does not exist.
3.1.12. DISPN
--------------
Usage: ( string line -> )
Takes a string on level 2 and a real number on level 1, then displays
the string on the screen using FNT2. The real number should be a line
number between 1 and 7, where 1 is the top of the screen and 7 is the
bottom. Errors for insufficient or bad arguments, UFL does not exist,
FNT2 does not exist, or if the specified level is not between 1 and 7.
3.2. Error Handling Hierarchy
------------------------------
To avoid bogging down the main access routines, each level of error
checking assumes you have properly checked the previous level. For
example, if the UFL does not exist and you try to use DISPN, you will
find you get "Error: Undefined XLIB Name" rather than a nice error
message.
4. Replacements Fonts
======================
4.1. Changes to FNT2
---------------------
FNT2 has been changed slightly from the previous copy in Jazz to be
more universably suitable. A total of 7 characters are affected, as
follows:
ASCII Previous Now
===================================================================
0 Ellipsis Null star from old FNT1
9 Diamond Tab character from Java
10 Inverse Diamond Newline character from Java
12 Female Symbol Formfeed character from Java
13 Music Note Carriage Return from Java
30 Up Arrow Scrolled off to left in edit line (...)
31 Down Arrow Scrolled off to right in edit line (...)
The tab, newline, and two scrolling characters are the most important
for general use; the other characters were changed to be consistent
with Java.
4.2. Zip Files
---------------
The UFL comes with two zip files, `fnt1.zip' and `fnt2.zip'. These
contain several alternate fonts to the ones that come with the UFL.
However, not all may be suitable for the applications you are using.
o The original FNT1 is stored in the file `fnt1.zip' as `ufl1.fnt'.
o The original FNT2 is stored in the file `fnt2.zip' as `ufl2.fnt'.
4.3. Credited Fonts
--------------------
These fonts deserve special credit since they were designed
specifically for the UFL. A description of each follows.
If you come up with some good alternative fonts, please mail them to
me so I can include them in future releases of this package.
fnt1/euro1.fnt and fnt1/euro2.fnt
From: Joergen Blomgren
euro1.fnt:
o Character 0-31: Designed on fnt2/ufl2.fnt, except a few
characters.
o Character 3-6: Cards are replaced with the first letter of
the name.
o Character 29: Single plus sign instead of double plus sign.
euro2.fnt:
o Characters 0-31: ASCII/character-value except:
o Character 0: Star as in UFL
o Character 7: A musical note (bell)
o Character 8: BS (backspace)
o Character 9: >| (tab forward)
o Character 10: LF (line feed)
o Character 12: FF (form feed)
o Character 13: CR (carriage return)
o Character 27: EC (escape)
o Character 30: .. (left continue)
o Character 31: .. (right continue)
Both:
o Characters 32-126: Standard characters, with small
modifications.
o Character 101: Is changed in style of fnt1/euro3.fnt
o Character 127: In style of the HP48 font.
o Characters 128-159: Greek and graphic characters in style of
the HP48 font.
o Characters 160-255: International and some graphic characters
in style of HP48, all characters are on the same baseline, so
some characters are a bit squashed, but I think it looks bad
when characters are unaligned in the base line. Lowercase e
umlauts are changed in the style of fnt1/euro3.fnt.
fnt1/euro3.fnt
From: Rodney Hess
o The baseline for this font is the original FNT1 contained in the
UFL release (fnt1/ufl1.fnt).
o The lowercase e (char 101) has been modified to look like
Java's. As Java's e is more readable with accents than the
original, a consistent look among the lowercase e's is
maintained with this change.
o Character 127 has been replaced with a greyscale block along the
lines of the one found in the built-in big font.
o Character 161 replaced with a cent symbol.
o The original upside-down question mark (char 191) was facing the
wrong direction. This has been fixed.
o Characters 192-214, 217-221: Capital characters. Some of these
sit below the baseline to aid legibility. For clarification,
the twiddle mark is represented as two pixels right justified,
for example, as in character 209.
o Characters 224-246, 249-253, 255: Lowercase characters.
fnt1/euro4.fnt
From: Ivan Rivera Rodriguez
This is an european-suitable small font for use with the UFL.
It contains the same characters and ordering as the HP standard
font, except for the first 30 characters, which are the same
used in the standard UFL FNT1. The different accentuations are
nearly always discernible, except for the circumflex, which had
to be reduced to a single point in order to properly identify
the vowels under it.
5. System RPL Specifications
=============================
This section is designed for System RPL programmers who wish to use
FNT1 and/or FNT2 in their own applications. If you just need the UFL
for an application you want to use, you don't have to read this
section.
In order to use System RPL or HP48 machine language you need a
compiler/assembler such as Jazz or GNU-Tools. See the HP48 FAQ for
more information on how to get started programming in System RPL.
5.1. Programmer's Interface
----------------------------
The programmers' interface to the UFL has been designed to simplify
checking existence of fonts as well as allowing for future expansion
if necessary.
Due to the requirements of the Font Maintenance Package (FMnt) we had
to go with fixed XLIBs for each font. However, we tried to do this in
a way that didn't restrict further growth of the UFL, while at the
same time minimizing overhead. This is the result we came up with:
ROMPTR 101 0 xFNT ( user-accessible )
ROMPTR 101 1 Font
ROMPTR 101 2 Font?
ROMPTR 101 3 FNT1
ROMPTR 101 4 FNT2
ROMPTR 101 5 and on are for future expansion if necessary.
Notice that once the checking for fonts has been done, there is no
performance loss imposed by using the UFL because the application
using the fonts can call the appropriate XLIBs directly.
Libraries that do not have FNT1 or FNT2 respectively will still have
the XLIBs in the above order, however if you try to recall the font
that doesn't exist you will get an error. See the next section for
more information.
5.2. Behaviour of each XLIB
----------------------------
Since there is more than one UFL library, the behaviour of the XLIBs
in each library must be consistently defined. The following standard
is defined:
xFNT (ROMPTR 101 0)
This is a user-accessible XLIB that accepts either a real or
system binary and recalls the specified font if it exists.
Otherwise it issues the error "Font not Found" and leaves the
original argument on the stack.
Font (ROMPTR 101 1)
This is a nullnamed equivalent to xFNT that only accepts a
system binary. It either recalls the specified font or issues
the error "Font not Found" and drops the system binary.
Font? (ROMPTR 101 2)
Accepts a system binary and returns TRUE or FALSE depending on
whether the font number specified exists or not.
FNT1 (ROMPTR 101 3)
Either returns FNT1 directly as a Library Data object or issues
the error "Font not Found" if you neglected to check if FNT1
actually exists with Font or Font? first.
FNT2 (ROMPTR 101 4)
Either returns FNT2 directly as a Library Data object or issues
the error "Font not Found" if you neglected to check if FNT2
actually exists with Font or Font? first.
5.3. Coding Standards
----------------------
With font standards come coding standards. We recommend you create a
file called ufl.h containing the following defines:
DEFINE xFNTSTR $ "FNT"
DEFINE xFNT ROMPTR 101 0
DEFINE Font ROMPTR 101 1
DEFINE Font? ROMPTR 101 2
DEFINE FNT1 ROMPTR 101 3
DEFINE FNT2 ROMPTR 101 4
You should then include this at the start of your program with:
INCLUDE ufl.h
Furthermore, the check for existence of the UFL has been standardized
with the following code, which will return TRUE or FALSE depending on
whether the UFL library exists or not:
NULLNAME UFL?
::
xFNTSTR palparse DROP ' xFNT EQUAL
;
You should check this at the start of your program. If it returns
FALSE you should generate the error "UFL not Found".
The only exception to the above check should be if you need to check
for the UFL in a library config routine. In that case the above code
will not work because palparse is not valid at config time. If this
is the case, you will have to use the following, inferior check:
NULLNAME UFL?
::
' Font ROMPTR@ NOTcaseFALSE DROPTRUE
;
Once again, do not use this alternative method if you do not have to!
The only case where there should be a need for this check is in
replacement stack programs such as Java.
For the font checks themselves, you do not have to provide the error
message yourself. Instead, you can take advantage of the fact that
the UFL will generate an error for you. See the Examples section for
details.
5.4. Summary of Usage
----------------------
Named XLIBs:
o UserRPL programs can use xFNT and/or the access routines
provided with the UFL.
o SysRPL programmers can use palparse on "FNT" if they don't want
to hardcode any XLIBs.
Nullnamed XLIBs:
o SysRPL programmers can pass Font a system binary to get a font
if they are willing to do error trapping, or if they don't mind
their application exiting (i.e. at the beginning of their
program)
o SysRPL programmers should check Font? before accessing any fonts
directly. After they have confirmed the font they want exists,
they are free to call them directly for speed.
5.5. Examples
--------------
Let's say someone wants to write a library that only needs FNT1. The
simplest way to use the UFL would be something like:
xNAME UFLTEST
::
CK0
FNT1 DROP ( Two possible errors - see below )
...
FNT1
...
;
Notice that FNT1 (or ONE Font) will provide an appropriate error
message "Font not Found" for you if the font you want doesn't exist.
Another possibility is that the UFL library doesn't exist at all, in
which case the above example will cause Error: Undefined XLIB Name.
This error isn't very informative, so if possible you should use the
UFL? check given earlier to generate the standard error "UFL not
Found". If you are making a library you should add this error to your
message table. With these changes the improved code segment becomes
something like:
ASSEMBLE
=xxMESSAGE
RPL
ARRY
[
"UFL not Found"
]
DEFINE UFLErr #xxxxx
xNAME MYLIB
::
CK0
UFL? NOTcase :: UFLErr ERROROUT ;
FNT1 DROP
...
FNT1
...
;
NULLNAME UFL?
::
xFNTSTR palparse DROP ' xFNT EQUAL
;
The UFL? check does not necessarily have to be its own nullnamed XLIB,
but it is handier that way if you have more than one place to check it
in. Alternatively, for the above example we could use the following
method that does everything in one place and is slightly smaller:
NULLNAME UFL?DoErr
::
xFNTSTR palparse DROP ' xFNT EQUALNOTcase :: UFLErr ERROROUT ;
FNT1 DROP
;
This checks both for the existence of the UFL and errors if FNT1 does
not exist. This way, each user accessible XLIB only needs to call
UFL?DoErr once. After it has passed the checks you are free to use
FNT1 directly. These methods also have the benefit that they allow
error trapping for your routines when called by external programs.
Of course, everything above applies to FNT2 as well, you would just
replace all references to ONE with TWO and FNT1 calls with FNT2. If
you need both then you would just use an appropriate combination of
FNT1, FNT2, Font, and/or Font? calls that check both.
5.6. Conversion of Existing Programs to the UFL
------------------------------------------------
Conversion of existing programs that have their own copies of FNT1 or
FNT2 should be relatively straightforward. The two steps are:
o Add code on startup of the program to check for the UFL and if the
required font(s) exist. If the UFL is not found, exit with the
standard error "UFL not Found".
o Replace all calls to your own copy of the font with corresponding
calls to the UFL fonts, using the given DEFINE's for consistency.
5.7. Stack Access and Purging
------------------------------
One gotcha when using the UFL is the fact that if your program allows
access to the stack, the user might actually purge the UFL while you
are using it! This also applies if you are writing some sort of file
browser that allows people to purge files. In Java we deal with this
by simply binding a LAM to something small in the UFL to prevent
purging. For example:
::
... Check existence of UFL as above ...
' Font? ROMPTR@ DROP { LAM #whatever } BIND
...
ABND
;
If the user tries to purge the UFL with the above LAM bound, they will
get Error: Object in Use.
6. Credits
===========
The UFL was co-developed by a group of programmers who deserve special
credit. Their names in alphabetical order and respective roles are as
follows:
o Alfred Arduengo: Design ideas and testing.
o Mika Heiskanen: Design ideas and the original FNT1 and FNT2 from
Jazz.
o Nathanael Morriss: Contribution of extra FNT1 access routines.
o Arnold Moy: Design and implementation of FNT1 editor/recaller.
o Jarno Peschier: User RPL access suggestions and testing.
o Jack Levy: Design ideas, testing, and FNT1 access routines.
o Andre Schoorl: Original concept, documentation, maintainer.
o Richard Steventon: Design ideas and the FNT2 recalling, editing,
and resizing routines.
Font Designers:
o Joergen Blomgren for fnt1/euro1.fnt and fnt1/euro2.fnt
o Rodney Hess for fnt1/euro3.fnt
o Ivan Rivera Rodriguez for fnt1/euro4.fnt
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