Provided by: prerex_6.2-6.3.1-1_amd64 bug


       prerex.sty  - a LaTeX document style for prerequisite charts


       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


       A  prerequisite  chart  consists  of  several course boxes, linked by arrows.  Courses are
       either half or full, and may be required.  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.


       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.


       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, and the
       grid command should precede all other commands.


       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}

       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}


       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  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

       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.


       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.


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


       This  is normally placed before all the other chart commands so that grid lines are in the
       background, covered by course boxes, minis, 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 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.


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







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


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


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


       where LightYellow is defined by

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


       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.



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


       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:





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


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



       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.png


              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).


       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

       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.


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


       R. D. Tennent (


       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