Provided by: prerex_6.5.3-1_amd64 
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)
SEE ALSO
ImageMagick(1), convert(1). dvips(1), evince(1), gpdf(1), kpdf(1), latex(1), okular(1), optipng(1), pdflatex(1), prerex(1), prerex(5), ps2pdf(1), tikz(1), tgf(1), vprerex(1), and xpdf(1).