Ubuntu Manpage: prerex.sty - a LaTeX document style for prerequisite charts

NAME

       prerex.sty  - a LaTeX document style for prerequisite charts

DESCRIPTION

       prerex.sty  defines  macros  that [pdf]latex can use to draw charts consisting of labelled
       course boxes linked by arrows that  represent  pre-  and  co-requisite  requirements.   In
       addition  to  the  usual  [pdf]latex  output, auxiliary files will be generated containing
       image-map data for the hyperlinked nodes in the diagram and a shell script to crop  a  PNG
       image generated from a Postscript or PDF chart.

       If  the source file satisfies the constraints of the prerex(5) format, a chart description
       may be edited using the prerex(1) interactive editor (as well  as  any  conventional  text
       editor).

TERMINOLOGY

       A  prerequisite  chart  consists  of  several course boxes, linked by arrows.  Courses are
       either half or full, and may be required or optional (or neither).  Each  course  box  can
       contain  a  course  code  (upper  left corner), a course title (lower half), and timetable
       information (upper right corner).  An arrow  can  be  either  a  prerequisite  (solid),  a
       corequisite  (dotted),  or  recommended  (dashed).   When  a  conventional  arrow would be
       inappropriate, it is possible to use a mini course "box"  (consisting  of  just  a  course
       code)  just  above  a target box.  An arbitrary line of text may be placed anywhere on the
       chart.

COORDINATE SYSTEM

       A conventional  two-dimensional  Cartesian  coordinate  system  is  used  to  specify  the
       locations  of  diagram  elements.  The origin (where x = 0 and y = 0) is at the lower-left
       corner of the diagram.  The diagram height is configurable; the width is determined by the
       values of \textwidth and an adjustable \unit length, which defines the absolute value of a
       coordinate unit.  It is possible to put a  coordinate  grid  with  labelled  axes  in  the
       background  of  a  chart.   The  coordinates of a box, mini, or text-line are those of its
       centre point.  An arrow is described by the coordinates of the centre points of its source
       and target boxes/minis/text-lines.

USAGE

       The  command \usepackage{prerex} should appear in the document preamble.  This will define
       a LaTeX environment

              \begin{chart} ... \end{chart}

       within which the following commands may be used to  produce  course  boxes,  minis,  text-
       lines,  and arrows.  The order of commands is not significant except that the commands for
       the source and target boxes of an arrow should precede the command for the arrow.

COURSE BOXES

       The commands producing course boxes have the following forms:

              \halfcourse x,y:{code}{title}{timetable}

              \fullcourse x,y:{code}{title}{timetable}

              \reqhalfcourse x,y:{code}{title}{timetable}

              \reqfullcourse x,y:{code}{title}{timetable}

              \opthalfcourse x,y:{code}{title}{timetable}

              \optfullcourse x,y:{code}{title}{timetable}

       where x,y are the coordinates of the centerpoint of the box, relative to the origin of the
       coordinate system at the lower-left corner of the diagram.  The code, title, and timetable
       arguments are arbitrary (well-bracketed) text, possibly with LaTeX markup.

       The following are similar but take an additional argument  to  specify  the  (non-default)
       background color of the course box:

              \halfcoursec x,y:{code}{title}{timetable}{color}

              \fullcoursec x,y:{code}{title}{timetable}{color}

              \reqhalfcoursec x,y:{code}{title}{timetable}{color}

              \reqfullcoursec x,y:{code}{title}{timetable}{color}

              \opthalfcoursec x,y:{code}{title}{timetable}{color}

              \optfullcoursec x,y:{code}{title}{timetable}{color}

MINI COURSE BOXES AND TEXT LINES

       A mini course "box" is produced by a command of the form

              \mini x,y:{code}

       The following instruction places a line of text centered at the coordinates:

              \text x,y:{text-line}

       There  are  several  differences between minis and text-lines.  The maximum length allowed
       for a course-code may be less than that for a text-line. A sans-serif font and  a  reduced
       font  size is used for a course-code.  A course-code may be hyperlinked but a text-line is
       not (except when the coordinate grid is on).  A \parbox command may be used in  the  text-
       line argument if more than one line is desired.

ARROWS

       Arrows  between course boxes (or from a mini or text-line to a course box) are produced by
       commands of the form

              \prereq x0,y0,x1,y1:

              \coreq x0,y0,x1,y1:

              \recomm x0,y0,x1,y1:

       These produce, respectively, solid, dotted, and dashed arrows from the course box (or mini
       or  text-line)  centered  at  coordinates  x0,y0 to the course box centered at coordinates
       x1,y1.

       Arrows by default have a non-zero curvature (unless they are very short).  It is  possible
       to override the default curvature for a particular arrow by using the instructions

              \prereqc x0,y0,x1,y1;c:

              \coreqc x0,y0,x1,y1;c:

              \recommc x0,y0,x1,y1;c:

       where  c  is  an integer in the range 0-100 specifying the desired curvature; for example,
       c=0 will produce a straight arrow. To change the default curvature, the user  program  may
       redefine the \DefaultCurvature command.

WEB LINKS

       Course  boxes  (including  minis) may be hyperlinked.  The default URL for course boxes is
       course-code.html where course-code is the code argument of the course box. The URL  scheme
       may be changed by the user by re-defining the \CourseURL command.

COORDINATE GRID

       The following command produces a coordinate grid, which is useful for editing a diagram:

              \grid

       The  grid  lines  will  be  covered  by  course  boxes and arrows.  The \grid command also
       redefines the \CourseURL command so that, if the mouse cursor is placed over a box or mini
       in (some) PDF viewers, the coordinates of the box, mini, or text-line will be displayed as
       follows: in the status bar in xpdf and gpdf, and in a "tooltip" in recent versions of kpdf
       (now  re-named  okular),  evince, and the Adobe Reader.  Similarly, the coordinates of the
       source and target boxes of arrows are displayed if the mouse hovers over the mid-point  of
       an  arrow,  Such  coordinate displays make it easier to edit chart descriptions.  When the
       grid is on, the mid-point of every arrow is highlighted by a "bullet".

       The prerex package at http://www.ctan.org/tex-archive/graphics/prerex/  has  a  patch  for
       kpdf/okular(1)  to make it display URIs in tooltips and also capture coordinates of course
       boxes, arrows and background points in the X  selection  clipboard  (for  pasting  into  a
       command  being composed at the prerex(1) prompt).  There is also a GUI frontend vprerex(1)
       to the prerex(1) editor which incorporates a minimalistic prerex-enabled PDF viewer.

STAND-ALONE COMMANDS

       The following commands may be used outside a chart environment, such as in the explanatory
       notes for a chart:

              \solidarrow

              \dottedarrow

              \dashedarrow

              \lightbox

              \boldbox

              \dashedbox

CONFIGURATION

       The following are defined by the style file but may be re-defined by the user:

              \newcommand{\DefaultCurvature}{20}

       where the argument should be in the range 0-100; 0 means no curvature.

              \newcommand{\CourseURL}[3]{#3.html}

       where  the  arguments  supplied at the call are the x and y coordinates of the box or mini
       and the course code.

              \newcommand{\background}{LightYellow}

       where LightYellow is defined by

              \definecolor{LightYellow}{rgb}{1.0, 1.0, 0.878431}

              \setlength{\unit}{5.7816pt}

       which defines the absolute size of a coordinate unit; this yields 10 pixels per coordinate
       unit if the chart is converted to an image at 125 dpi.

              \newcommand{\dpi}{125}

              \newcommand{\PixelsPerUnit}{10}

       These must be re-defined together if the image-map data are to be correct.

              \setcounter{diagheight}{75}

       which is the y-coordinate of the top of the diagram (reduced to 65 in landscape mode); the
       nominal diagram width is \textwidth / \unit + 10.

       The following define the thicknesses of the three kinds of arrows, and  the  thickness  of
       bold boxes:

              \newcommand{\solidwidth}{0.5pt}

              \newcommand{\dottedwidth}{0.8pt}

              \newcommand{\dashedwidth}{0.5pt}

              \newcommand{\boldwidth}{1.0pt}

       The  following  command  is  used  to change to a smaller size for course codes, timetable
       information, and mini-course codes:

              \newcommand{\smallersize}{\relsize{-3}}

       The following command defines the baseline  adjustment  for  the  stand-alone  arrows  and
       boxes; this parameter is font-dependent.

              \newcommand{\baselineAdj}{-0.5ex}

DEPEDENCIES

       This  implementation  of  prerex.sty  uses pgf (version 1.18 or later) with add-on package
       tikz.  The following  additional  packages  are  used:  relsize,  calc,  ifthen,  multido,
       textcomp,  zref-savepos and hyperref.  Either pdflatex(1) or latex(1) followed by dvips(1)
       (and possibly ps2pdf(1)) may be used.

       To convert a chart to a compact but reasonably high-quality image, it is suggested to  use
       the convert(1) tool of ImageMagick(1) as follows:

              convert -density 125 chart.ps chart.png

       or

              convert -density 125 chart.pdf chart.png

       The  density  parameter specifies the number of pixels per inch; if this is too small, the
       image is of poor quality, and if it is too large, the image file is too big.  By  default,
       the  shell  script generated by prerex.sty crops the image at the southeast corner.  It is
       possible to use a PNG compression application such as optipng(1) to reduce  the  file-size
       of the cropped image (without loss of quality).

IMPLEMENTATION DETAILS

To improve the appearance, boxes are drawn with slightly rounded corners. The half-course
boxes are assigned a minimum height to give a more uniform appearance to horizontal rows
of such boxes. The mini and text boxes have white frames and their fill colour is white,
which is assumed to be the background colour of the chart. A text box is not normally
hyperlinked; however, if the coordinate grid is on, it is hyperlinked and its chart
coordinates are encoded in the URI.

Arrows with a small height and arrows whose source and target points have equal x or y
coordinates are always draw straight (using a specialized and simpler macro) unless an
explicit non-zero curvature argument is provided. If the coordinate grid is on, a
hyperlink with the source and target coordinates is placed at the mid-point of the arrow.
A wider background white edge is drawn below an arrow to improve the appearance of
crossing arrows; the background also ensures visibility of the arrow when the coordinate
grid is on. A thin white arrow (with a visible arrowhead) is drawn beneath the visible
arrow to obtain a thin arrowhead.

When the coordinate grid is drawn, the CourseURL command is re-defined to pass node
coordinates in URIs. Also, two "anchor" hyperlinks are inserted at the southwest and
northeast corners of the diagram to allow prerex-enabled PDF viewers to compute chart
coordinates.

To support HTML versions of charts, prerex.sty generates a script to crop a chart image at
the southeast corner, allowing descriptive notes below the chart to be treated as ordinary
text. Also, it generates image-map data for use with an HTML image map. To obtain
absolute page coordinates, the zsavepos, zposx and zposy commands are used; the page
coordinates are converted into pixel coordinates for cropping and image-map use.

LICENSE

       prerex.sty and this document may be distributed and/or modified under  the  conditions  of
       the LaTeX Project Public License.

AUTHOR

       R. D. Tennent (rdt@cs.queensu.ca)