xglyph.tex

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  character map is
  between 20 and 30 points at 72 dpi resolution.  
\item \fbox{{\bfseries About}}\\
  Shows an `about' message 
  telling you that you are using \verb+xglyph+ and \tonelib\ in the current
  version.
\item \fbox{{\bfseries Exit Program}}\\
  This button does what it says and exits the program.
\end{itemize}

\subsection{The Message Window}
This area is located below the dialog box for the test
string. Information potentially useful to the user is given here.
There should be nothing needed to be said about the info---it is
self-explaining. 
But two things should be noted:
\begin{itemize}
\item The elapsed time that is displayed is exactly the time spent in
  the respective rastering function. There might
  have been other actions in force which might make the user believe the
  time value given as being incorrect.\footnote{For example, there might have
  been size-dependent data to be deleted and recreated, or an encoding
  file might have needed
  to be loaded before rastering.} Moreover, the transfer to the
  X-server may become significant if 32 bits per pixel are used, the
  image is large and
  the program is running on a remote machine.
\item The message \verb+t1lib: Couldn't generate Bitmap, T1_errno=...!+ simply
  tells the user that no bitmap could be generated. There may be
  several reasons. E.g., the \verb+FontID+-value given might have been
  out of range. Another possibility is that you have specified a
  character index which has no encoded character associated. The value of
  \verb+T1_errno+ might give a hint of what the problem was.
\end{itemize}
If a character map is displayed, the message window is giving no
information apart from the font name and the final value of
\verb+T1_errno+ because there have been executed
up to 256 rastering operation and it would be impossible to keep track
of all single operations.

\subsection{The Output Window}
The output window shows the output of the rastering operations. Its type is
different for the standard and the X11 rastering functions.  For the standard
rastering functions, it is always adapted to the size of the glyph which is
displayed plus a margin of 5 pixels on each side. For this reason, leading and
trailing white space is not shown in the output window, it only shows up in
the glyph's metrics in the message windows. 

The X11 rastering functions
generate an output window of constant size (\hbox{600 $\times $ 400} pixels)
with a logical origin in its center. This center is marked by a cross-hair of
color cyan. The glyph is placed with respect to this origin. If it is too
large to fit, the glyph simply is clipped. A second cross-hair is shown at the
place where the origin of the next glyph would be located in color magenta.

If a character map of a font is displayed, the output window contains
a map of $16\times 16$ cells whose size depends on the metrics of the
font that is displayed.


\subsection{{\tt xglyph} Commandline Parameters}
The syntax of the \verb+xglyph+ commandline is 
\begin{verbatim}
 xglyph [options] [fontfile1 [fontfile2 [...]]]
\end{verbatim}
If no options and no font files are specified on the commandline \verb+xglyph+
reads the fonts from the font database file. The details depend on which
configuration file is found and on this file's contents. If at least one font
file is specified on the commandline, the font database---being existent and
accessible or not---is ignored and the database is built using the fonts from
the commandline. \verb+fontfile1+ is assigned the font ID 0, \verb+fontfile2+
is assigned the ID 1 and so forth. Files that cannot be opened for some reason
are simply skipped. 

\verb+xglyph+ also recognizes a few options. Notice that these options are not
intended for an average user. Rather, they provide a means of (a) controlling
debugging output from the rasterizer, (b) controlling generation and verbosity
of the \tonelib-logfile, (c) disabling certain features of the rasterizer and
(d) checking some \tonelib\ functions which otherwise would not be required
because of the limited functionality of \verb+xglyph+.

All commandline arguments that start with ``\verb+--+'' are considered to be
options to \verb+xglyph+. The following is a complete list of valid options
and a brief description of their effect:
\begin{itemize}
\item\verb+--help+: Display the commandline syntax of \verb+xglyph+ as well as
  a brief list of the available options for an average user and exit.
\item\verb+--Help+: Display the commandline syntax of \verb+xglyph+ as well as
  a brief list of all available options.
\item\verb+--noGrid+: The cross-hairs marking start and end position of a
  glyph in the output of one of the X11 rastering functions will be
  suppressed. This might be useful at small sizes because the grid overwrites
  the glyphs' pixels.
\item\verb+--setPad+: The padding value \verb+xglyph+ should use can be
  specified here. This has to be followed by either ``8'', ``16'' or ``32'',
  separated by a space. Notice that the value ``32'' might be rejected as
  described in \ref{queryconfiguration}. The value actually used can be found
  by writing a logfile and examining this after a session.
\item\verb+--logError+:
\item\verb+--logWarning+:
\item\verb+--logStatistic+:
\item\verb+--logDebug+: These options firstly instruct \verb+xglyph+ to create
  a \tonelib\ logfile and secondly set the loglevel to the respective value
  (see \ref{logfile}). Without specifying one of these options, no logfile
  will be generated.
\item\verb+--ignoreForceBold+: Instructs the rasterizer to ignore a {\tt
    ForceBold} hint in the Type 1 font file.   
\item\verb+--ignoreFamilyAlignment+: Instructs the rasterizer always to
  compute font level alignment according to \verb+BlueValues+ and
  \verb+OtherBlues+, even if \verb+FamilyBlues+ and \\
  \verb+FamilyOtherBlues+
  exist and all conditions for substitution are fulfilled for that combination
  of font and size.
\item\verb+--ignoreHinting+: Instructs the rasterizer to omit hinting completely.
\item\verb+--ignoreAFM+: The use of AFM information is ignored, no matter
  whether it could be accessed via an appropriate AFM file or
  self-generated. When using this option the string functions would not
  work. It may, however, be useful because self-generation of AFM data fails
  as soon as at least one character of all defined characters can not be
  processed and thus, the font will refuse to load. Using this option,
  consequently, one has access to all character that are processible, e.g.,
  for generating a font table.
  characters that can be rasterized 
\item\verb+--debugLine+:
\item\verb+--debugRegion+:
\item\verb+--debugPath+:
\item\verb+--debugFont+:
\item\verb+--debugHint+: All these instruct the rasterizer to write particular
  debug messages from intermediate steps of rasterization to the terminal. In
  order to understand and interprete them, a thorough understanding of the
  Type 1 font format specification and this special rasterizer implementation
  is crucial.
\item\verb+--checkPerformance+: This option affects the X11 string rastering
  functions. An additional output window is created and the output of
  before-mentioned functions is directly written into this window. Note that
  this window is not managed as might be expected. Text is only drawn at the
  visible parts and after partially or completely hiding and again
  raising the respective areas are lost. This mechanism should simply give an
  idea of how fast the X11 rastering function work, admittedly a critical
  topic in \tonelib.
\item\verb+--checkCopyFont+: This option is used to check the proper
  functioning of the \verb+T1_CopyFont()+ function. It copies all fonts from
  the database to new logical fonts and slants these fonts by 0.3. Finally an
  additional fontfile is added to the database. For each step the new font ID
  is printed to the terminal and the initial and final number of fonts are
  printed. 
\item\verb+--checkConcatGlyphs+: This option affects the buttons \fbox{\bf
    String} and \fbox{\bf AAString}. The requested string glyph is generated
  twice, first time using the current value of font ID and second time using
  this 
  values plus 1. Both resulting glyphs are concatenated and the result is
  shown in the output window. 
\item\verb+--checkConcatOutlines+: This option, too, affects the standard
  string rastering functions. The current test string will be fetched as an
  outline using the current font ID. The result is then concatenated with a
  horizontal movement of 1000 charspace unit which is followed by the
  identical string using a font ID advanced by 1. The result of the
  concatenated outlines is then filled and converted to a \tonelib-glyph. 
  For details on outline handling and what it is meant for see \ref{outlines}.
  
  When \verb+--checkConcatGlyphs+ and \verb+--checkConcatOutlines+ both are
  specified on commandline, the \verb+--checkConcatGlyphs+ is respected.
\item\verb+--checkBadCharHandling+: This option provides a means of
  examining the effects of problematic/bad characters on string handling in
  \tonelib with \verb+xglyph+. It affects only the \fbox{\bf String} button.
  The character to be specified in the test character field is inserted in
  the middle of the test string. This enables the user to insert arbitrary
  character codes in the middle of a test string and to watch the effect in
  \verb+T1_SetString()+. For example, starting \verb+xglyph+ with this
  option exclusively and immediately clicking \fbox{\bf String} will show
  the string {\em TeAt} in the output window because the character `s' has
  been overwritten by character $65_{10}$ (`A'), the default test character.
\item\verb+--checkDefaultEncoding+: This option proves that the default
  encoding feature works correct. If set, all fonts should be encoded in
  IsoLatin1 encoding immediately after startup and without any slow down at
  startup. 
\item\verb+--checkSmartAntialiasing+: Enables smart antialiasing as described
  in \ref{antialiasing}. The effect is that \tonelib\ will determine the
  antialiasing level by itself.  For sizes below 20~bp, $4\times$ antialiasing
  will be used and up to 60~bp $2\times$ antialiasing is used. For size of
  60~bp and larger a ``bytemap'' is created which in fact consists only of
  pure background and foreground pixels. When this options has been
  specified, toggling the antialiasing level has no effect.
\item\verb+--checkAACaching+: This option enables caching of antialiased
  character glyphs. For a discussion of this issue see \ref{aacaching}. The
  string rastering functions are not affected by this option.
\end{itemize}
For those who are wondering about special X11 options like ``\verb+-display+'',
\verb+xglyph+ does not support these. The widgets are built straight ahead and
the layout is fixed. \verb+xglyph+ is meant to be a tool for testing some of
the functionalities of \tonelib\ and nothing more. Of course, a display other
than \verb+localhost:0.0+ may be specified by environment variable
\verb+DISPLAY+. 


\subsection{Fonts Included in the \tonelib-Package}
\label{fonts}%
Included in the \tonelib-package are 8 fonts of two families which
are freely available. 
\begin{enumerate}
\item The CharterBT-fonts in Roman, Italic, Bold and BoldItalic
  variants. These are good quality fonts containing kerning
  information. Notable kerning pairs are ``T''--``e'', ``A''--``V''
  and ``A''--``T''.
\item The ComputerModern-fonts by Donald E.~Knuth in the variants
  Roman, Italic, BoldExtended and BoldExtendedItalic. In addition to
  kerning information, there are many ligatures in these
  fonts. Most people will know about the present ligatures from using
  \TeX, the typesetting system. Notable examples are: 
  \verb+--+ $\rightarrow$ ``--'', 
  \verb+---+ $\rightarrow$ ``---'', 
    \verb+fi+ $\rightarrow$ ``fi'' and
  \verb+ffi+ $\rightarrow$ ``ffi''. 
  These fonts have the disadvantage that no ordinary space character
  is included, only a visible space. \TeX\ itself does not need a
  dedicated space character. 
\end{enumerate}
Note that working with ligatures requires the ligatures to be
encoded at the positions they are expected. Thus, if you reencode one of the
dc-fonts with the IsoLatin1-encoding funny effects may occur.

\subsection{Some General Remarks on {\tt xglyph}}
The program \verb+xglyph+ is just intended to check whether \tonelib\ works on
a particular system. It is written straight forward and does not care much on
performance and such. Especially, it is not a typical application for a
rasterizer library. The bitmaps are generated and then the output window is
adapted to the size of the bitmap/pixmap generated by the rastering
function. This contradicts the X11 principle of ``drawing into a drawable''
and requires some overhead if one wants a fitted output window. In that sense,
the performance of the X11 rastering functions is not directly comparable to
the performance of the standard rastering functions. This should always be
kept in mind.



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