Frames

Frequently Asked Questions
(or many of the questions I've been asked so far)


Why a font editor, aren't there enough fonts already?
Well... no. Otherwise I wouldn't be writing this.
  1. There are lots of latin fonts. There are far fewer greek, cyrillic, indic, thai, chinese, japanese, korean, unicode...
  2. Researchers into old writing systems often need to design their own fonts
  3. Even for latin, traditionally each new style of art and architecture has an associated style of fonts. New fonts are always being created to reflect the esthetics of the times.
  4. Computer font technology is constantly changing. A font-format that was useful 10 years ago may not be so now.
  5. Even if you are satisfied with the fonts that do exist they may not be complete
    • Missing ligatures
    • Missing accented characters
    • No matching cyrillic or greek characters
  6. Everybody wants a font of his/her own handwriting.
  7. Playing with fonts is fun.

PfaEdit has uses beyond simply creating and modifying fonts. It can convert from one format to another. It can extract information from the font file. Or it can simply show you what the font looks like without having to install it.

Why did I write it?
Why do I give it away?
Why is PfaEdit based on a non-standard widget set?
I wanted a widget set that would handle Unicode reasonably well. In particular I thought support for bidi text was important for hebrew and arabic typography. As I was unaware of any widget sets that did that, I wrote my own.
I also wanted a widget set where I could actually figure out whether the checkbox was checked or not checked. In far too many cases my eyes can't work out which is which...
Why isn't PfaEdit written in C++ (or Why C++ is not my favorite language)?
I've been a little surprised to be asked this question, I had not realized my choice of language needed justification, but it appears to do so...

Basically because I don't find object-oriented practices helpful in most cases, and because I find C++ far too complex and badly designed, and because I can't debug it easily.

The above are my personal opinions based on my experience and are explain why I do not use C++. Your opinions may differ, few people have spent 5 years writing C++ compilers.

Is it legal to modify a font? Is it ethical?
Legal matters vary from country to country (and perhaps within countries). You really should consult a lawyer for a definitive answer. Here are some guide lines:

Look at the license agreement you received with the font and see what it has to say on this issue.

TrueType (and OpenType and potentially CID-keyed fonts) have a field in the OS/2 table called FSType which allows the font designer to place restrictions on what other people can do with the font. If this field prohibits modification pfaedit will ask you to make sure you have an agreement with the font designer which supersedes this field.

My understanding of US law (but check with a lawyer before relying on this) is that:

My understanding is that in most European countries there are laws against copying the design (the shape) of a font.

I would welcome any additions or corrections here, as well as info on the laws governing fonts in other countries.

What is a 12 point font? (What measurement of the font determines the point size?)
A font is 12 points high if the distance between the baselines of two adjacent lines of (unleaded) text is 12 points.

The pointsize is not based on the sizes of any of the glyphs of the font.

Back when fonts were made out of metal, the pointsize of the font was the height of the metal slugs used for that font.

In some sense this is not a very good measure of the size of a font (some fonts may allow more room for accents or ascenders or descenders than others meaning that the height of the actual glyphs will be smaller).

There is also a measurement scheme based on the x-height of the glyphs.

In England and the US a point has traditionally meant the pica point (1/72.27th of an inch), while in Europe the point has been the didot point (1/67.54th of an inch). The Europeans have a slightly larger point, but the glyphs of English and European fonts appear the same size. English does not use accents (except in very rare cases) while most European languages do, and the slight increase in the size of the point allows more room for accents.

(Of course now most Europeans are probably forced to use the pica point by their desktop software, while must computer fonts now contain accented glyphs, so the distinction and the reason for it may have vanished).

How do I install the fonts once I've made them?
Well it rather depends on what system you are working on, and what type of font you've got:
Unix & X (but not KDE)
I'd suggest that you look at the linux font HOWTO file, and the font deuglification HOWTO as good starting points. But I'll run over the highlights

Essentially you designate one (or several) directories as a "font directory". You move your fonts to that directory. You build up certain data structures that X needs, and you tell X to include this directory in your font path. Sadly different versions of X and the X font server use slightly different conventions. You may need to alter these procedures a bit.

For example, if you want to install a bdf font called frabnuts-13.bdf then you might:

$ mkdir my_fonts
$ mv frabnuts-13.bdf my_fonts
$ cd my_fonts
$ bdftopcf frabnuts-13.bdf >frabnuts-13.pcf
$ mkfontdir
$ xset fp+ `pwd`

and your fonts should be installed. After that, whenever you start X you need to remind it of where your fonts live, so you should add
    $ xset fp+ /home/me/my_fonts
to your .xsession (or equivalent).

If you want to install postscript fonts
You should generate them as postscript binary (.pfb) files, then move both the .pfb and the .afm file into (one of) your font directory(ies) and run type1inst in it.
type1inst will probably complain that your font doesn't have a foundry and will probably get the encoding wrong. You can either:

  • Ignore it and nothing bad will happen
  • Manually edit fonts.scale after running type1inst to fix these entries
  • Make your font's Copyright be reasonable, and then edit type1inst and add your foundry (directions for this are in type1inst itself)

If you want to install truetype fonts
You move the .ttf file into your font directory and run mkttfdir and mkfontdir.
(mkttfdir has a small problem with fonts created by PfaEdit, it will almost invariably complain that it doesn't recognize the foundry. You can safely ignore this, but if it bothers you then add a line to ttmkfdir.c at 936
            { "PFED", "PfaEdit" },

Some versions of X (ie, those shipped by redhat) rely on the x font server to do font work rather than the X server itself. You may need to use chkfontpath to add your new directory to the font server's font path (rather than xset fp).
You may also need to insure that the font directory (and all its parent directories) are readable to world. (the font server runs as a non-privileged user)

I haven't seen anything that says X supports opentype fonts yet, but since freetype does (and I think X's rasterizer uses freetype) then X might support them too. Installing them will require manual editing of fonts.scale though (mkttfdir uses freetype1 which doesn't support otf files).

That sounds really confusing. I apologize, I'm not a good writer and there are too many choices in configuring X...

KDE
(I don't know KDE very well, so take my experience with a grain of salt) Under KDE there is a tool called kfontinst which is supposed to do all the configuration work for you. I was only able to get it to work as root and had to reconfigure my system to follow its conventions, but once that was done it installed X fonts quite handily. I never did figure out how to get it to install ghostview fonts. (I experimented with version 0.9.2)
TeX
TeX has its own (platform independent) system for installing fonts. I've described my experiences so far elsewhere in this document.
Windows
You install truetype fonts on windows by dropping them into the \Windows\Fonts directory on your machine.
Do NOT generate the font directly into \Windows\Fonts, this doesn't seem to work (at least on under my XP machine). You must generate the font into another directory and drag & drop it to \Windows\Fonts .
If you want to use type1 fonts you will need to install adobe type manager and follow its instructions.
If you want to install opentype fonts then on old systems (before windows 2000, I think) you need to install ATM, on more recent systems opentype should work the same way truetype does.
I don't know how to install a bdf font. I'd look for a utility to convert bdf files to FON files and then drop the FON files into \Windows\Fonts. Or generate a bitmap-only truetype font.
Macintosh OS 9
Oh dear. The mac sticks fonts into resource forks and wraps them up in its own headers. Mac fonts aren't compatible with anybody else's. PfaEdit can create a resource fork if it wraps the font up in a macbinary encoding. See the following question for more information.
I've also written some utilities designed to convert from one format to another and they may prove useful.
University of Oregon has some links that might be helpful.
Once you've converted your fonts you just drop them into the System Folder and they should be available after that.
Macintosh OS X
On OS/X fonts should be placed either in the top-level Library/Fonts directory (By default /Mac OS X/Library/Fonts/), in the System/Library/Fonts directory, or in the user's appropriate fonts sub-directory (~/Library/Fonts).
Either a resource font (unwrapped from its macbinary wrapper) or a dfont may be used. I'm not sure whether postscript Type1 resource fonts work, but OpenType dfonts do (so if you want to use Postscript use OpenType). You can also use straight ttf and otf files (ie. the same file you might use on Unix or MS).
As far as I can tell the old NFNT bitmap resources do not work on my OS 10.2. If you want to use bitmap fonts wrap them up in a ttf file or an sfnt.
Why won't PfaEdit's fonts install on some MS Windows machines?
Do NOT generate a font directly into the \windows\fonts directory. Generate the font into a different directory and then use windows drag and drop to install the font. (Windows appears to do magic when it moves the font into that directory).

I am told that fonts produced by old versions of PfaEdit will not install on Windows 2000 (and XP) systems.

I believe this problem is fixed now (as of 20-Oct-2003). If you have an older version please upgrade.
If you are copying a font from another machine make sure the execute bit is set in the permissions of the font file (I don't know how to do this with the Windows UI, under cygwin you say $ chmod +x foo.ttf

How do I edit fonts from my macintoy?
Mac OS/9 (or less)
Traditionally the macintosh has stored fonts in the resource fork of files (after about OS/8.5 I believe the mac also supported bare .ttf files). This causes problems for any machine other than a mac, because the very concept of a resource fork is lacking.
There are several programs whose job it is to store all of a macintosh file in one package that can be manipulated on other systems (mac binary and binhex are the most common). PfaEdit knows how to read both of these formats and can extract a postscript or truetype font from either. PfaEdit can also create fonts in macbinary format (I see no reason to support both output formats, and macbinary is slightly simpler).
So to edit a font on your mac:
  1. Find the file in the System Folder:Fonts folder
  2. Copy the file over to your unix machine
    • Use Fetch and specify macbinary format
    • Or use some tool like binhex which can create the file directly
  3. Open it in PfaEdit
  4. Edit it
  5. Save it back in macbinary format
  6. Copy it back to your mac
    • Fetch will automatically undo the macbinary wrappers and make it be correct
    • Or various other tools can unwrap it.
  7. Drop it back into your system folder (where it is automagically moved to Fonts)

Note: make sure you either replace the original font files, or that you rename the font within pfaedit and (for postscript fonts) that you give it a new unique id. See the Font Info dlg.

Caveat: A postscript font is useless on a macintosh unless it is accompanied by at least one bitmap font. If you generate a postscript font make sure you also generate an NFNT as well (this has the FOND).
Caveat: The mac is picky about the filename used to contain a postscript file. It is based on the postscript font name but suffers a transformation. Don't try to rename this file. Basically the rules are (see Adobe Technical Note 0091):

  • The fontname is broken into chunks where each chunk starts with a capital letter.
  • The first chunk may have four lower case letters following the initial capital
  • Subsequent chunks may only have two lower case letters following the capital.
  • Non-letter characters (or at least hyphens) vanish.
    So TimesBold => TimesBol, Helvetica-BoldItalic => HelveBolIta, NCenturySchoolbook => NCenSch
Mac OS/X
On Mac OS/X you can run PfaEdit directly (if you've got XDarwin installed). OS/X has several font formats, some fonts are stored in the old format (see above), while others are stored as data fork resources. The data fork font files generally have the extension ".dfont". On a Mac PfaEdit is able to edit both formats directly. OS/X also supports normal .otf and .ttf font files.

Mac OS/X does not seem to support the old NFNT bitmap format, but it still requires that an bitmap font in NFNT format be present before it will use a resource-based postscript font. (It is probably not the NFNT resource which is required, but the FOND which goes along with it. But I'm not going to write something to produce a bare FOND resource).

How do I create a mac font family? (How do I get the mac to group my fonts so that the italic and bold styles work)?
For the Style menu in most mac applications to work on your fonts, you must create a font family. You do this with the File->Generate Mac Family command.

All the fonts in a family must have the same Family name (See the font info dialog). Mac font families only support Italic, Bold, Outline, Expanded, and Condensed styles, they do not support "Black", "DemiBold", "Light" or "Thin" variants.

The Generate Mac Family command is very limited. I want more extensive families than it permits...
The Generate Mac Family command is limited by the design of the Mac 'FOND' resource, which reflects the computer font technology of the early 1980s. Modern computer fonts often have varients that can't be expressed in it. FONDs support any combination (except one containing both Extend and Condense) of the following styles:

The following suggestion is determined empirically after looking at the way Apple distributes fonts. It might be wrong or incomplete. It's the best suggestion I can make however.

Apple appears to store all the fonts that should be in one family in the one file. That file may contain several 'FOND's (which is what I call a mac family). The 'FOND's appear to be distributed as follows:

Suppose you have a family of fonts with the following styles:
Regular, Bold, Italic, Bold-Italic, Condense, Condense-Italic, Oblique, Light, Light-Italic, Black
Then you should create a font family with the styles that the FOND does support, which in this case would be
Regular, Bold, Italic, Bold-Italic, Condense, Condense-Italic

Change the family name of the other styles, so that the Oblique style has Oblique in the family name, the two Light styles have Light in the family name, and so on. Set the Mac Style on the "Light" variant of the font to be Regular (everything unselected) and set the style of the "Light-Italic" variant to be "Italic" -- that is, forget about the "Light", the FOND can't handle it, that's why we moved it into the family.

For the "families" that just contain one variants use the File->Generate Fonts command, for the families that contain two or more variants use the File->Generate Mac Families command. Put everything into mac dfonts.

Then use the stand-alone program lumper (or some other mac resource editor) to move all these families into one font file.

lumper Foo.dfont FooOblique.dfont FooLight.dfont FooBlack.dfont

The final result is that Foo.dfont will contain all the variants of the font distributed into appropriate 'FOND's.

Why doesn't ATM work on my fonts?
Insure that the font has an encoding of Macintosh Latin when you generate it.

This is really a limitation on ATM's part and there's nothing PfaEdit can do about it.

If you generate a font with an encoding other than Macintosh Latin, then the Mac's default behavior is to force the postscript font to have a Macintosh Latin encoding. There is a mechanism to turn this behavior off, but if it is turned off then ATM won't work at all.

How do I edit fonts on MS windows?
To run PfaEdit under MS windows you must first install the cygwin environment.

If you want to be able to build PfaEdit under cygwin, you will need to grab some other cygwin components, like gcc, the image processing libraries, freetype, etc.

Why don't my fonts work on windows?
Here's one possibility: Windows sometimes (and I don't know when) insists on having a name for the font in the appropriate language (ie. a Japanese entry for a SJIS font). Try going to Element->Font Info->TTF Names and adding a set of strings for your language.

Another posibility is discussed here.

Does Pfaedit read in the old kerning information from fonts?
This question needs to be broken down into cases:
TrueType and OpenType fonts
Yes. The kerning information is stored in either the 'kern' or 'GPOS' tables of these fonts and PfaEdit can read the most common formats (Apple has made a number of extensions beyond the original truetype spec, and PfaEdit does not handle all the Apple formats).
PostScript Type1 fonts anywhere other than the Mac.
The kerning information is not stored in a Type 1 font file. Instead it is stored in a file with the same filename as the font file but with the extension ".afm". When PfaEdit reads a PostScript font it will check for an associated afm file, and if found will read the kerning information from it.
PostScript Type1 fonts on the Mac.
No. Again the kerning information is not stored in the font file (it is stored in a bitmap font file), but on the mac it is impossible to guess what name to use for the associated bitmap file, and PfaEdit does not even try.
See the info below on how to load kerning from a FOND.
AFM and TFM files.
PfaEdit can read kerning information directly from these files and apply those data to a font. See the File->Merge Kern Info menu command.
Mac resource files containing FOND resources.
The mac stores kerning information in the FOND resource associated with a bitmap font (it is not stored in the file with the postscript font). If you wish kerning data for a mac postscript font, you must find a font file containing a bitmap font with the same family and style as the postscript. PfaEdit can read kerning information directly from these files and apply those data to a font. See the File->Merge Kern Info menu command.
How do I make PfaEdit use hint substitution?
It happens automagically.
How do I make Pfaedit use flex hints?
It happens automagically. PfaEdit will generate flex hints in situations where it is appropriate to do so. You don't need to do anything. If flex hints are used then the necessary subroutines will be added to the font. If they are not needed then the subroutines will not be added.
How can I tell if it is going to use flex hints?
If you want to see whether PfaEdit is going to use flex hints, turn on the UpdateFlex preference item and open a view on the character. PfaEdit displays a green halo around the center point of a flex hint.
My characters are all perfectly hinted, why do some stems have different widths (or appear fuzzy, or fade away completely)?
Both PostScript and TrueType require that characters be drawn in a clockwise fashion. Some rasterizers don't care. But other rasterizers will have difficulties with counter-clockwise paths and produced stems of different widths when they should be the same, or fuzzy stems, or even nothing at all. The solution to this is to run Element->Correct Direction on all your characters before generating a font.
But sometimes the poor rasterizer just can't do the right thing...
How do I set a particular bit in the OS/2 table (or any other)?
PfaEdit does not do this, but I have written a companion program, mensis (Latin for: "to or for, by, with or from tables") which gives you bit access to tables. It provides both UI and scripting access.
How do I mark a font as monospaced?
You don't. Just insure that all the characters in the font have the same width and then PfaEdit will automatically mark it as monospaced for you. (If you mark it as monospaced incorrectly some rasterizers will give strange results).

If you are unsure whether all the characters in your font have the same advance width use Element->Find Problems->Random->Check Advance.

How I do tell pfaedit about a new encoding
First ask yourself if you really need a new encoding? If you are using OpenType or TrueType fonts you can usually get by with the standard unicode encoding. But if you really need a new one here is a rough idea of what to do:

Figure out what your encoding looks like. Often this will involve searching around the web to find an example of that encoding. For instance if you want a devanagari encoding you might look at a site which shows the ISCII encodings

These encodings only show the top 96 characters, presumably the others are the same as US ASCII. Look at the images and figure out how they map to unicode (or more precisely what the appropriate postscript names are for those characters).

Create a file (call it "Devanagari.ps" in this case). It should start with a line:

/Devanagari {

This tells PfaEdit that the encoding is called "Devanagari", then follow this with a list of all the character names (preceded by a slash). We start with ASCII which starts with 32 .notdef characters, then space, etc.

/Devanagari {
 /.notdef
 /.notdef
 ...
 /.notdef
 /space
 /exclam
 /quotedbl
 ...
 /braceright
 /asciitilde
 /.notdef
 ...
 /.notdef
 /uni0901
 /uni0902
 ...
 /uni096F
}

Now load this file into PfaEdit's list of encodings with Element->Font Info->Encoding->Load, and then apply it to whatever fonts you want.

How do I add a character with a new name?
Let's say you wanted to add a "dotlessi" character to an ISO-8859-1 font (this encoding does not include dotlessi). There are two ways to approach the problem:
  1. Bring up Element->Font Info
    Select the Encoding tab
    Increment the Number of Characters field by one (probably to 257)
    Press OK
    Scroll down to the end of the font and find the new character
    Select it
    Bring up Element->Character Info
    Type your new name into the Unicode Name field (in this case you'd type in dotlessi)
    Press the Set From Name button
    Press OK
    Now draw a dotlessi in the character.
  2. Bring up Element->Font Info
    Select the Encoding tab
    Change the Encoding to ISO-10646-1 (Unicode)
    Press OK
    Bring up View->Goto
    Type in dotlessi
    Press OK
    Now draw the dotlessi character in the selected character slot
    Bring up Element->Font Info again
    Change the Encoding back to whatever it was
Why isn't my Open Type font much smaller than the .pfb file?
This is probably because you didn't round to int before saving the font. PfaEdit will save the font using fixed point numbers which take up a lot more space than normal integers.
What's the difference between OpenType and PostScript (or TrueType) fonts?
Both PostScript and TrueType define a file format and a glyph format. OpenType uses the TrueType file format with a PostScript glyph format (actually OpenType includes the TrueType glyph format as well, but the OpenType definition says such fonts should still be called TrueType fonts so I ignore that aspect).

The PostScript used in OpenType is slightly different from that used in .pfa and .pfb files. pfa/b files are Type1 fonts while OpenType uses Type2 fonts. Type2 is almost a superset of Type1 with a few minor changes and many extensions. Adobe's subroutine based extensions to Type1 (flex hints, hint substitution, counter hints) have been added to Type2 as direct instructions.

After I generate a font and quit, why does PfaEdit ask if I want to save the font? I didn't change anything.
There are two reasons why this might be happening.
  1. Even though you haven't changed anything in this session, PfaEdit may need to (re)generate hinting information on one or several characters (if, for example those characters have been changed (in an earlier session) but no hints have been generated for them since). These new hints will mark the font as changed.
  2. If your font has an XUID field in the Font Info, then PfaEdit will increment the final number in the XUID each time a postscript font is generated -- and this also counts as a change. (Why does PfaEdit do this? Because Adobe says it should. A minor annoyance, but it avoids some problems with font caching when you change an old version of the font for a new one).
Why doesn't TeX work with my fonts?
I'm a total novice with TeX. I am told that TeX (or some part of the TeX chain, dvips perhaps) expects fonts to be encoded in TeX base Encoding -- sometimes called "Adobe Standard" by the TeX docs, but it isn't it's TeX base. So if you are having printing problems, missing glyphs, etc. try changing the encoding of your font to TeX Base (Go to Element->Font Info, select the Encoding tab, select TeX Base from the pulldown list).
Why doesn't PfaEdit let me edit an '.mf' file?
As Knuth said "(the problem with WSYWYG is that...) What you see is all you get." PfaEdit suffers from this.

Let us take a simple example. Suppose we have a point defined by
     top1y2 = CapHeight
And the user tries to drag point 2 to a new y location. How should PfaEdit interpret this? It could:

So PfaEdit's method for moving a point around is ambiguous. And I haven't been able to come up with any reasonable way for disambiguating it. Suggestions are welcome (but there's no guarantee they'll be implemented).

Why does my window get iconified when I want to minify the view?
Some window managers (gnome-sawtooth for one) steal meta (alt) clicks from PfaEdit. So you can't use meta-middle-click to minify a character, you have to use the View menu->Zoom Out instead.
Why isn't there a character named "mu" in my greek font?
Adobe was thinking more of backwards compatibility than sense when they assigned the names of the greek letters in their unicode encoding. Thus the name "mu" refers to the Micro Sign (U+00B5) and not to the letter mu. They also assigned Delta to Increment, and Omega to Ohm Sign.

Adobe has also decided that the character at U+03D6 (said by the Unicode consortium to refer to "GREEK PI SYMBOL") should be named "omega1", when "pi1" seems more appropriate.

Why doesn't Edit->Copy copy character names as well as glyph info?
Firstly because I believe that any attempt to copy a character's name will almost certainly be better done by defining a custom encoding.
Secondly because most of the time you don't want the name copied.
Thirdly because it is esthetically better that copy should only work with data and not meta-data.
HOWEVER... enough people have asked this question that I've enabled a mode in Edit->Copy From->Char Name which allows you to change the default behavior.
Why does Edit->Paste complain about name duplication?
Because you have Edit->Copy From->Copy Metadata checked. Uncheck it.
What on earth are cidmap files and should I care about them?
Some background:

When postscript was invented every character in a font was given a name, and an encoding which was specified by a 256 element array mapping character codes to names.

Then they started thinking about CJK fonts (and perhaps Unicode), which have huge character sets, and coming up with reasonable ASCII names for 10,000 characters was a) a waste of space, b) fairly meaningless. So then adobe created CID-keyed fonts which have no character names and no encodings. Every character has an index (a CID), which is just a number, and this is sort of treated as a name. Then external to the font is an additional resource (a cmap) which provides the encoding for the font (and can support really grungy encoding schemes like SJIS), by mapping a sequence of input bytes to a CID.

Adobe provides certain standard cmap resources (ie. one for SJIS, one for JIS, one for Extended Unix whatever). Because these files are fairly painful to write Adobe has assigned standard meanings to CIDs so that everyone can use the same cmap file. -- Well actually there are 5 or 6 different standards, Japanese (JIS208), Japanese (JIS212), Korean, Chinese (Hong Kong, Taiwan), Chinese (Mainland, Singapore), Identity (Unicode) -- So CID 1 might be space, CID 2 might be "!", CID 935 might be "Katakana ka", etc.

My cidmap files just give me a mapping between Adobe's CIDs and Unicode. This allows PfaEdit to know what character it is working on. If they aren't present things should work ok, but PfaEdit would fill the font view with "?" rather than the appropriate character. And PfaEdit wouldn't be able to reencode the font into Unicode or anything else.

So the cidmap files are only useful for people working on CID keyed CJK fonts. So many europeans/americans won't need them.

Does the simplify command lose accuracy?
Yes it does.
But not much.
It is designed to replace a set of splines with another spline that nowhere differs from the original by more than one unit in the local coordinate system.
If this level of accuracy is not good enough then (In the outline view):

This will replace a set of splines with a spline that differs from the original by no more than .1 unit.

How does PfaEdit convert a cubic spline into a quadratic spline for truetype?
Again this can involve a loss of accuracy.
First PfaEdit checks to see if the spline happens to be a quadratic already (this would happen if you'd just read in a truetype font, or if a miracle occurred when you generated the spline).
Otherwise PfaEdit will divide the original spline into smaller chunks and try to find a set of quadratic splines that differ from the cubic by no more than one unit anywhere. (Once you have picked two end-points and know the slope at those end-points there is only one quadratic spline possible between the two).
How does PfaEdit convert a quadratic spline into a cubic (when reading truetype)?
This is easy since any quadratic spline can already be represented as a cubic, it will just happen that the cubic term is always 0.
How do I set the default character of a font?
If the character at encoding 0 is named ".notdef" and if it contains some splines (but no references) then it will be used as the default character (that is the character used when an unencoded character is called for).
I loaded a ttf font, made a few changes and generated a new font. The changed characters don't look anywhere near as nice as the originals. Why?
Unfortunately PfaEdit does not hint truetype fonts at all well. And when PfaEdit reads in a truetype font it saves all the hinting (instructions) that were present in the original. But if you change a character in any significant way those instructions are no longer valid (they depend intimately on the details of the outlines), so PfaEdit removes them when you make a change. The result is that changing a character with PfaEdit will degrade its appearance in most truetype fonts (not all, some have no hints).
PfaEdit can hint vertical and horizontal stems, but not diagonals. In many characters PfaEdit's attempt at hinting makes things worse (because the diagonals don't match the horizontals/verticals). So if you want this to happen you must explicitly call the Hints->AutoInstr command.
Why doesn't pfaedit support Type 42 fonts?
A Type 42 font is a postscript wrapper around a truetype font. It is used for downloading truetype fonts to postscript printers.

PfaEdit does not support these because support for truetype hints (such as it is) is relatively recent and I haven't had time to look at type42 recently. You are much better off using ttftot42 for now.

I generated an opentype font and windows wouldn't install it. Why not?
Unfortunately Apple and MicroSoft (and Adobe) do not agree on the proper format for open and truetype fonts. PfaEdit has a check box on the Generate Font dialog labelled [] Apple. Make sure this is checked when you are generating a font for the mac. Make sure this is not checked when generating a font for Windows (and probably for unix too, though unix tends to be less picky).

The major differences I've stumbled onto so far are:

I looked at kaiu.ttf or mingliu.ttf and the outlines looked nothing like the correct characters. What's wrong?
Some truetype fonts (kaiu and mingliu) do not store the correct outline. Instead they rely on using the instructions to move points around to generate the outline. The outline does not appear to be grid-fit at all, just positioned. PfaEdit will not process the instructions as it reads the font. In most fonts this would be the wrong thing to do, and I don't know how I could tell when it needs to be done...
When I use Element->Build Accented Character to build one of the Extended Greek characters (U+1F00-U+1FFF) PfaEdit picks the wrong accents. Why?
For some reason Unicode has unified greek and latin accents even though they don't look at all alike. When PfaEdit follows the simplistic unicode definitions it will probably pick a latin accent for greek characters. Fortunately Unicode also contains code points for the greek accents starting around U+1FBD, if you fill these code points with the appropriate accents then PfaEdit will use these rather than the latin accents.
When I use Element->Build Accented Character to build accents over "u" or "y" I get the accent over one of the stems not centered on the character. Why?
One of your stems is a little taller than the other. PfaEdit centers accents over the tallest point on the character. If there are several points with the same height, then an average is used.

If you make all your stems be the same height then the accent should be properly centered.

Why does ttf2afm crash on PfaEdit ttf files?
I don't know. The ttf2afm that was distributed with my redhat 7.3 linux certainly did crash. When I downloaded the source from pdftex area of ctan and built it (with debug) the resultant program did not crash. Therefore I believe this is a bug in ttf2afm and that bug has been fixed.
The afm files produced by ttf2afm don't conform to Adobe's specifications.
Why is PfaEdit so unstable?
I don't bother much with doing QA. This is a problem. I don't enjoy doing it, and no one is paying me to do it, so little gets done.
If you would like to volunteer to do QA let me know. It's a thankless job, but important!

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