% author    : Hans Hagen
% copyright : PRAGMA ADE & ConTeXt Development Team
% license   : Creative Commons Attribution ShareAlike 4.0 International
% reference : pragma-ade.nl | contextgarden.net | texlive (related) distributions
% origin    : the ConTeXt distribution
%
% comment   : Because this manual is distributed with TeX distributions it comes with a rather
%             liberal license. We try to adapt these documents to upgrades in the (sub)systems
%             that they describe. Using parts of the content otherwise can therefore conflict
%             with existing functionality and we cannot be held responsible for that. Many of
%             the manuals contain characteristic graphics and personal notes or examples that
%             make no sense when used out-of-context.
%
% comment   : Some chapters might have been published in TugBoat, the NTG Maps, the ConTeXt
%             Group journal or otherwise. Thanks to the editors for corrections. Also thanks
%             to users for testing, feedback and corrections.

\usemodule[abr-02]

\usemodule[setups-basics] \loadsetups[i-chart.xml]

\setupexternalfigures
  [location={local,default}]

\setuplayout
  [topspace=15mm,
   header=15mm,
   headerdistance=0mm,
   footer=0cm,
   width=middle,
   height=middle]

\setuppagenumbering
  [alternative=doublesided]

\definetypeface [mainface] [rm] [serif] [pagella] [default]
\definetypeface [mainface] [ss] [sans]  [heros]   [default] % [rscale=1.1]
\definetypeface [mainface] [tt] [mono]  [modern]  [default] % [rscale=1.1]
\definetypeface [mainface] [mm] [math]  [pagella] [default]

\setupbodyfont[mainface,12pt]

% \definecolor[maincolor][r=.4,g=.2,b=.6]
\definecolor[maincolor][r=.2,g=.1,b=.3]

\setupwhitespace
  [big]

\setuptolerance
  [verytolerant,stretch]

\setuptype
  [color=maincolor]

\setuptyping
  [color=maincolor]

\setuphead
  [section]
  [style=\bfb,
   color=maincolor]

\setupinteraction
  [state=start,
   color=,
   contrastcolor=,
   style=]

\startsetups titlepage
    \startpagemakeup[doublesided=no,page=no]
        \useMPgraphic{titlepage}
    \stoppagemakeup
    \startstandardmakeup[doublesided=no,page=no]
        \vfill
        \startsubject[title=Contents]
            \startcolumns[distance=4em]
                \placelist[section][alternative=c,width=2em]
            \stopcolumns
        \stopsubject
    \stopstandardmakeup
\stopsetups

\startsetups colofon
    \blank[2*big]
    \testpage[3]
    \startpacked
        \documentvariable{author}\par
        \documentvariable{affiliation}\par
        \documentvariable{location}\par
    \stoppacked
\stopsetups

\setupdocument
  [title=No Title,
   before=\setups{titlepage},
   after=\setups{colofon}]

% specific for this document

\usemodule[chart]

\setupFLOWcharts
  [width=2.25cm,
   height=1.25cm,
   dx=.25cm,
   dy=.25cm]

\startuseMPgraphic{titlepage}
    numeric width, height, delta ;
    color a, b, c, d ;

    width    := PaperWidth ;
    height   := PaperHeight ;
    delta    := width/10 ;
    ahlength := 6delta ;

    a := white/2 ;
    b := white/3 ;
    c := resolvedcolor ("maincolor") ;
    d := c ;

    path p ; p := unitsquare xscaled width yscaled height ;

    fill p withcolor c ;

    drawarrow llcorner p -- urcorner p withpen pencircle scaled (3.0delta) withcolor a ;
    draw      llcorner p -- urcorner p withpen pencircle scaled (4.0delta) withcolor a ;
    drawarrow urcorner p -- llcorner p withpen pencircle scaled (2.5delta) withcolor b ;
    draw      llcorner p -- urcorner p withpen pencircle scaled (3.0delta) withcolor b ;
    drawarrow llcorner p -- urcorner p withpen pencircle scaled (2.0delta) withcolor d ;
    drawarrow urcorner p -- llcorner p withpen pencircle scaled (1.5delta) withcolor d ;

    draw anchored.lrt(
        textext("\ss\bf \documentvariable{title}") rotated 90 xsized (3delta/4),
        lrcorner p shifted (-delta,3delta/4)
    ) withcolor white ;

    resetarrows ;

    setbounds currentpicture to p ;
\stopuseMPgraphic

\startdocument
  [title=Flowcharts,
   author= Hans Hagen,
   affiliation=PRAGMA ADE,
   location=Hasselt NL]

\startsection[reference=introduction,title={Introduction}]

This is just another story of \TEX\ meeting \METAPOST. This time we will focus on
charts, especially flowcharts. In \CONTEXT\ flowchart support is not part of the
core functionality, but is provided as a module. Therefore, before you can
actually define a chart, this module must be loaded:

\starttyping
\usemodule[chart]
\stoptyping

Once loaded, you has access to the functionality described here. Before we go
into detail on the features, we will say some words on history.

When dealing with graphics, it makes sense to use a drawing program. In fact,
before we started using this module, we did use such programs, and they have
without doubt their advantages. As soon as \CONTEXT\ supported interactive
documents, there were means to make graphics interactive, and as long as only a
few graphics are involved, this mechanism works ok.

And then we suddenly had to make a document with thousands of pages and hundreds
of often rather complicated flowcharts. Because these charts were tightly
integrated in the main document, they not only had to be consistent in the use of
fonts, but also had to be interactive and were to be presented both as a whole
and in subchart parts. We wanted fonts, colors and the overall appearance as well
as names of people, places, steps, activities and more to be consistent,
especially because these charts are constantly updated.

I use the term flowchart here because I want to stress that this module typesets
charts which cells are connected by lines (often arrows). Our first application
of this module concerned diagrams that expressed actions and relations between
those actions, using some techniques originating years ago in programming
environments: lines were not to cross, one should read from top to bottom and
left to right, etc. However, the module presented here can be used to draw all
kind of charts, and all kind of connections. But there are limits.

{\em This manual is mostly the one written of end 1998 when the flowchart module
showed up in the distribution. In the meantime the code has been rewritten for
\MKIV\ and some functionality is adapted. But the interface hasn't changed much.}

\stopsection

\startsection[title={The grid}]

A flowchart consists of shapes, positioned on a grid, connected by lines. The
grid enables the user to anchor the shapes and enables the drawing routines to
determine connections. One can either explicitly specify the grid, or let it be
calculated automatically.

\startbuffer[grid]
\setupFLOWcharts
  [option=test,
   nx=4,
   ny=3,
   dx=\bodyfontsize,
   dy=\bodyfontsize,
   width=6\bodyfontsize,
   height=4\bodyfontsize,
   maxwidth=\textwidth]

\startFLOWchart [grid]
\stopFLOWchart
\stopbuffer

\placefigure
  [here][fig:grid]
  {The grid.}
  {\getbuffer[grid]\FLOWchart[grid]}

Normally the grid is not visible, unless one enters test mode. The grid in \in
{figure} [fig:grid] is the result of the definition:

\typebuffer[grid]

The most straightforward way of calling up this chart is by saying:

\starttyping
\FLOWchart[grid]
\stoptyping

In \in {figure} [fig:grid] we see a grid an dwithin each cell a shape. Normally
shapes are smaller than grid cells. This is necessary because connecting lines
need some room. The offset is important, because when a connection follows the
outer lines, a little extra space outside that line not only looks better, but
also prevents the line from being clipped. It makes sense to keep the offset as
well as the space between shapes constant across a document. The numbers are
typeset outside the bounding box of the figure.

Grid cells are numbered from top to bottom starting at the left side, so the left
topmost cell is $(1,1)$. Later we will see that because cells have names, these
numbers play a minor role.

\stopsection

\startsection[title={Shapes}]

A shape is something, typically a text, within a frame. The frame has certain
dimensions and can have some color and background. In this respect it looks like
the \CONTEXT\ command \type {\framed}. The most important shapes have been
assigned names as indicated in \in {figure} [fig:shapes]. There are more shapes,
but they are identified by a number only. The total number of shapes will quite
certainly increase. The shapes {\em up}, {\em down}, {\em left} and {\em right}
are not really shapes, but lines that can be used to force a direction.

\startFLOWchart [shapes]
\startFLOWcell \name{a} \location{1,1} \shape{node}           \text{node}           \stopFLOWcell
\startFLOWcell \name{b} \location{2,1} \shape{action}         \text{action}         \stopFLOWcell
\startFLOWcell \name{c} \location{3,1} \shape{procedure}      \text{procedure}      \stopFLOWcell
\startFLOWcell \name{d} \location{4,1} \shape{product}        \text{product}        \stopFLOWcell
\startFLOWcell \name{e} \location{1,2} \shape{decision}       \text{decision}       \stopFLOWcell
\startFLOWcell \name{f} \location{2,2} \shape{archive}        \text{archive}        \stopFLOWcell
\startFLOWcell \name{g} \location{3,2} \shape{loop}           \text{loop}           \stopFLOWcell
\startFLOWcell \name{h} \location{4,2} \shape{wait}           \text{wait}           \stopFLOWcell
\startFLOWcell \name{i} \location{1,3} \shape{subprocedure}   \text{sub procedure}   \stopFLOWcell
\startFLOWcell \name{j} \location{2,3} \shape{singledocument} \text{single document} \stopFLOWcell
\startFLOWcell \name{k} \location{3,3} \shape{multidocument}  \text{multi document}  \stopFLOWcell

\startFLOWcell \name{l} \location{1,4} \shape{right}          \text{right}          \stopFLOWcell
\startFLOWcell \name{m} \location{2,4} \shape{left}           \text{left}           \stopFLOWcell
\startFLOWcell \name{n} \location{3,4} \shape{up}             \text{up}             \stopFLOWcell
\startFLOWcell \name{o} \location{4,4} \shape{down}           \text{down}           \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:shapes]
  {The shapes.}
  {\tx\FLOWchart[shapes]}

When no shape is specified, the default shape is used. One can change this
default value with the \type {\setupFLOWshapes} command.

\startbuffer[cells]
\startFLOWchart [cells]
  \startFLOWcell
    \name     {first}
    \location {1,1}
    \shape    {singledocument}
    \text     {not realy a document}
  \stopFLOWcell
\stopFLOWchart
\stopbuffer

\typebuffer[cells]

\getbuffer[cells]

A flow chart consists of cells. Each cell has a name, is positioned somewhere on
the grid, has a certain shape, and normally this shape surrounds text. The shape
is drawn by \METAPOST, and the text is placed by \TEX. Later we will see that
there are some more fields to fill. Names are local to a chart.

\placefigure
  [][fig:cells]
  {}{\tx\FLOWchart[cells]}

\stopsection

\startsection[title={Connections}]

Shapes can be connected. As shown in \in {figure} [fig:points] each shape has
four connection points: top, bottom, left and right. When connecting shapes we
refer to their logical names and specify two of the four directions.

\startFLOWchart [points]
\startFLOWcell \name{a} \location{1,1} \shape{procedure}     \stopFLOWcell
\startFLOWcell \name{b} \location{2,1} \shape{product}       \stopFLOWcell
\startFLOWcell \name{c} \location{3,1} \shape{archive}       \stopFLOWcell
\startFLOWcell \name{d} \location{4,1} \shape{multidocument} \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:points]
  {The connection points.}
  {\tx\setupFLOWcharts[dot=con]\FLOWchart[points]}

In \in {figure} [fig:connect] we see three connections. The lines have smooth
curves and run across the grid lines. By using smooth curves, an option that can
be turned off, the direction of touching curves is always clear. Here we use
arrows. Smoothing, arrows and dashed lines are some of the attributes of lines.

\startFLOWchart [connect]
  \startFLOWcell
    \name       {alpha}
    \location   {1,1}
    \shape      {procedure}
    \text       {first}
    \connection [rl] {beta}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {2,1}
    \shape      {product}
    \text       {second}
    \connection [bl] {alpha}
    \connection [rl] {gamma}
  \stopFLOWcell
  \startFLOWcell
    \name     {gamma}
    \location {3,1}
    \shape    {action}
    \text     {third}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:connect]
  {A few connections.}
  {\tx\setupFLOWcharts[dot=con]\FLOWchart[connect]}

\startFLOWchart [two]
  \startFLOWcell
    \name       {alpha}
    \location   {1,1}
    \shape      {action}
    \text       {first}
    \connection [rl] {beta}
    \connection [rl] {alpha}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {2,1}
    \shape      {loop}
    \text       {second}
    \connection [tr] {beta}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  {A few more connections.}
  {\tx\setupFLOWcharts[dot=con]\FLOWchart[two]}

There can be more than one connection per shape. When defining such a connection
we first specify the direction. In this example \type {[rl]} means connect the
right point to the left one, while \type {[tr]} results in a connection between
the top and the right point. The second argument specifies the shape to connect
to. As we can see, connections can point back to their origin shape.

\startFLOWchart [around]
  \startFLOWcell
    \name       {alpha}
    \location   {1,1}
    \shape      {procedure}
    \text       {first}
    \connection [rl] {gamma}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {2,1}
    \shape      {product}
    \text       {second}
  \stopFLOWcell
  \startFLOWcell
    \name       {gamma}
    \location   {3,1}
    \shape      {action}
    \text       {third}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:around]
  {Going around shapes.}
  {\tx\setupFLOWcharts[dot=con]\FLOWchart[around]}

\startFLOWchart [straight]
  \startFLOWcell
    \name       {alpha}
    \location   {2,1}
    \shape      {procedure}
    \text       {first}
    \connection [lt] {gamma}
    \connection [rt] {delta}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {3,1}
    \shape      {product}
    \text       {second}
    \connection [tl] {gamma}
  \stopFLOWcell
  \startFLOWcell
    \name       {gamma}
    \location   {1,2}
    \shape      {action}
    \text       {third}
    \connection [rr] {delta}
  \stopFLOWcell
  \startFLOWcell
    \name       {delta}
    \location   {3,2}
    \shape      {archive}
    \text       {fourth}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:straight]
  {Following grid lines.}
  {\tx\setupFLOWcharts[dot=con]\FLOWchart[straight]}

The connection drawing routines have a rather strong urge to follow grid lines.
\in {Figure} [fig:straight] demonstrates this several times. From the first shape
to the third one, we see that the connection takes the shortest route possible
without crossing other shapes. I have to admit that the routines in themselves
are rather stupid, but for normal use they suffice.

\startFLOWchart [straightagain]
  \startFLOWcell
    \name       {alpha}
    \location   {2,1}
    \shape      {procedure}
    \text       {first}
    \connection [lt] {gamma}
    \connection [rt] {delta}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {3,1}
    \shape      {product}
    \text       {second}
    \connection [tl] {gamma}
    \connection [tt] {alpha}
    \connection [bt] {delta}
  \stopFLOWcell
  \startFLOWcell
    \name       {gamma}
    \location   {1,2}
    \shape      {action}
    \text       {third}
    \connection [rr] {delta}
  \stopFLOWcell
  \startFLOWcell
    \name       {delta}
    \location   {3,2}
    \shape      {archive}
    \text       {fourth}
    \connection [bb] {gamma}
  \stopFLOWcell
\stopFLOWchart

Generally speaking, when two lines end at the same point, it makes sense to
connect these. When on the other hand lines originate at the same point or cross
eachother, readers can get confused. Therefore such lines are drawn in such a way
that they don't touch. In this respect, \in {figure} [fig:white] demonstrates a
less than optimal chart.

\placefigure
  [here][fig:white]
  {Confusing (crossing) grid lines.}
  {\tx\setupFLOWcharts[dot=con]\FLOWchart[straightagain]}

\stopsection

\startsection[title={Adding text}]

In \in {figure} [fig:comment] we have added some comment to a connection. Like
the dots at the connections, the point halfway the connection shows up in a
special debugging mode. The comment will be placed relative to this point. In \in
{figure} [fig:comment] this is to the left of the point.

\startFLOWchart [comment]
  \startFLOWcell
    \name       {alpha}
    \location   {1,1}
    \shape      {action}
    \text       {here}
    \connection [bl] {beta}
    \comment    [l] {from here to there}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {2,2}
    \shape      {action}
    \text       {there}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:comment]
  {Comment to connections.}
  {\tx\setupFLOWcharts[dot=mid]\FLOWchart[comment]}

It will be no surprise that a comment is defined using \type {\comment}. Comments
can be anchored to eight locations, simply \type {l}, \type {r}, \type {t}, \type
{b}, or a combination like \type {tr}.

\starttyping
\startFLOWcell
  ...
  \comment [l] {from here to there}
  ...
\stopFLOWcell
\stoptyping

\startFLOWchart [labels]
  \startFLOWcell
    \name       {alpha}
    \location   {1,1}
    \shape      {action}
    \text       {here}
    \connection [bl] {beta}
    \label      [b] {from here}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {2,2}
    \shape      {action}
    \text       {there}
    \label      [l] {to there}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:labels]
  {Labels to connection points.}
  {\tx\setupFLOWcharts[dot=con]\FLOWchart[labels]}

We can also put labels at the connection points. Often this is preferred over
comment halfway along a connection. Like comments, labels have a dedicated
command. Here we specify the connection point \type {l}, \type {r}, \type {t} or
\type {b}.

\starttyping
\startFLOWcell
  ...
  \label [l] {to there}
  ...
\stopFLOWcell
\stoptyping

\startFLOWchart [text]
  \startFLOWcell
    \name       {alpha}
    \location   {1,1}
    \shape      {action}
    \text       {here}
    \connection [bl] {beta}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {2,2}
    \shape      {action}
    \text       {there}
  \stopFLOWcell
  \startFLOWcell
    \shape      {none}
    \location   {2,1}
    \text       {Is there any reason to go
                 from here to there?}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:text]
  {Text without shapes.}
  {\tx\setupFLOWcharts[dot=con]\FLOWchart[text]}

In \in {figure} [fig:text] we see some text without any shapes around it. When
shape \type {none} is specified, the whole shape area is available for text.

\starttyping
\startFLOWcell
  \shape    {none}
  \location {2,1}
  \text     {Is there any reason to go
             from here to there?}
\stopFLOWcell
\stoptyping

One can force the alignment with the key characters \type {l}, \type {r}, \type
{c}, \type {t} and \type {b}. So, the next definition only places text.

\stopsection

\startsection[title={Inheritance}]

When explaining something by using a chart, we often show successive versions of
the chart, where each version adds a new feature. To prevent us from retyping the
same components again and again, it helps to partition the source code of the
complete chart into subcharts. Inclusion of a part is straightforward: the
subchart is called by name and positioned on the grid.

\startbuffer[include]
\startFLOWchart [include]

  \includeFLOWchart[labels][x=1,y=1]

  \startFLOWcell
    \shape    {none}
    \location {2,1}
    \text     {There is no reason to go
               from here to there!}
  \stopFLOWcell

\stopFLOWchart
\stopbuffer

\typebuffer[include]

The included sub chart has its own reference point, so one does not have to
bother about positions.

\getbuffer[include]

\placefigure
  [here][fig:include]
  {Sharing components.}
  {\tx\FLOWchart[include]}

\stopsection

\startsection[title={How it works}]

The charting module, loaded by \type {\usemodule[chart]} is only responsible for
the \TEX\ part of the job, which means positioning text and graphics generated by
\METAPOST. The grid, shape and connection drawing routines are grouped together
in a dedicated \METAPOST\ module.

Because of the mix of \TEX\ and \METAPOST, and because we want to be able to
scale charts, the buffer mechanism is used. The communication between \TEX\ and
\METAPOST\ uses the \METAPOST\ embedding macros that are native to \CONTEXT.
Additional communication from \METAPOST\ to \CONTEXT\ is handled in the module
itself. This rather fuzzy description is visualized in \in {figure}
[fig:process]. Depending on the general color settings, among the other processes
involved are: color conversion and|/|or reduction to grayscales, and conversion
to \PDF. When watching this module in action, don't feel disturbed by the many
steps involved.

\startFLOWchart [process]
  \startFLOWcell
    \name       {user file}
    \location   {1,2}
    \shape      {action}
    \text       {User File}
    \connection [rl] {context}
  \stopFLOWcell
  \startFLOWcell
    \name       {context}
    \location   {2,2}
    \shape      {action}
    \text       {\CONTEXT}
    \connection [nrnl] {buffer}
    \connection [prl] {metapost}
  \stopFLOWcell
  \startFLOWcell
    \name       {buffer}
    \location   {3,2}
    \shape      {action}
    \text       {scalable buffer}
    \connection [nlnr] {context}
  \stopFLOWcell
  \startFLOWcell
    \name       {metapost}
    \location   {4,2}
    \shape      {action}
    \text       {\METAPOST}
    \connection [rr] {graphic}
    \connection [rr] {datafile}
  \stopFLOWcell
  \startFLOWcell
    \name       {graphic}
    \location   {4,1}
    \shape      {action}
    \text       {\POSTSCRIPT}
    \connection [lt] {context}
  \stopFLOWcell
  \startFLOWcell
    \name       {datafile}
    \location   {4,3}
    \shape      {action}
    \text       {Data File}
    \connection [lb] {context}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:process]
  {The process.}
  {\tx\FLOWchart[process]}

\startbuffer[collection]
\startFLOWchart [collection]
  \dorecurse{10}
    {\dorecurse{8}
       {\scratchcounter=\numexpr\numexpr##1-1\relax*10+#1\relax
        \startFLOWcell
           \name     {#1-##1}
           \location {#1,##1}
           \shape    {\the\scratchcounter}
           \normalexpanded{\label[bc]{\hbox{\tt\the\scratchcounter}}}
        \stopFLOWcell}}
\stopFLOWchart

\setupFLOWcharts
  [width=.08\textwidth,
   height=.06\textwidth,
   dx=.01\textwidth,
   dy=.02\textwidth,
   linewidth=1pt,
   dot=yes]

\FLOWchart[collection]
\stopbuffer

A few pages back we introduced the named shapes. There are however some more
shapes. Each shape is identified by a number. In \in {figure} [fig:collection]
all currently available shapes are shown. The zero numbered shape is actually a
shape, but with zero dimensions. It can be used as a meeting point for lines. The
unused numbers can be used for new shapes. The maximum number of shapes is
limited to 4095, which is a \METAPOST\ limitation.

\placefigure
  [here][fig:collection]
  {All shapes by number. Shape 0 is valid and has zero dimensions.}
  {\tx\getbuffer[collection]}

\stopsection

\startsection[title={Bonus points}]

Sometimes charts can become rather large, due to the many shapes used or lines
drawn. At the same time charts can become unclear because more than one
connection starts or ends at a shape. \in {Figure} [fig:bonus 1] shows a way out
of this situation.

\startFLOWchart [bonus 1]
  \startFLOWcell
    \name       {tex}
    \location   {1,1}
    \shape      {action}
    \text       {\TEX}
    \connection [prpl] {pdf}
    \connection [nrnl] {dvi}
  \stopFLOWcell
  \startFLOWcell
    \name       {dvi}
    \location   {2,1}
    \shape      {action}
    \text       {\DVI}
    \connection [prpl] {ps}
    \connection [nrr]  {pdf}
  \stopFLOWcell
  \startFLOWcell
    \name       {ps}
    \location   {3,1}
    \shape      {action}
    \text       {\POSTSCRIPT}
    \connection [rnl] {pdf}
  \stopFLOWcell
  \startFLOWcell
    \name       {pdf}
    \location   {4,1}
    \shape      {action}
    \text       {\PDF}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:bonus 1]
  {Even more points.}
  {\tx\setupFLOWcharts[dot=all]\FLOWchart[bonus 1]}

\startFLOWchart [bonus 2]
  \startFLOWcell
    \name       {tex}
    \location   {1,1}
    \shape      {action}
    \text       {\TEX}
    \connection [bt] {pdf}
    \connection [rl] {dvi}
  \stopFLOWcell
  \startFLOWcell
    \name       {dvi}
    \location   {2,1}
    \shape      {action}
    \text       {\DVI}
    \connection [rl] {ps}
    \connection [br] {pdf}
  \stopFLOWcell
  \startFLOWcell
    \name       {ps}
    \location   {3,1}
    \shape      {action}
    \text       {\POSTSCRIPT}
    \connection [br] {pdf}
  \stopFLOWcell
  \startFLOWcell
    \name       {pdf}
    \location   {1,2}
    \shape      {action}
    \text       {\PDF}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:bonus 2]
  {An alternative for \in {figure}[fig:bonus 1].}
  {\tx\FLOWchart[bonus 2]}

\startFLOWchart [bonus 3]
  \startFLOWcell
    \name       {tex}
    \location   {1,1}
    \shape      {action}
    \text       {\TEX}
    \connection [bb] {pdf}
    \connection [rl] {dvi}
  \stopFLOWcell
  \startFLOWcell
    \name       {dvi}
    \location   {2,1}
    \shape      {action}
    \text       {\DVI}
    \connection [rl] {ps}
    \connection [tt] {pdf}
  \stopFLOWcell
  \startFLOWcell
    \name       {ps}
    \location   {3,1}
    \shape      {action}
    \text       {\POSTSCRIPT}
    \connection [rl] {pdf}
  \stopFLOWcell
  \startFLOWcell
    \name       {pdf}
    \location   {4,1}
    \shape      {action}
    \text       {\PDF}
  \stopFLOWcell
\stopFLOWchart

\placefigure
  [here][fig:bonus 3]
  {Yet another alternative for \in {figure}[fig:bonus 1].}
  {\tx\FLOWchart[bonus 3]}

Defining such a chart is not so much harder than previous cases. Each left,
right, top and bottom point has two companion points: positive and negative. In
connections the left points are: \type {pl}, \type {l} and \type {nl}: positive
left, left and negative left, so the first cell in \in {figure} [fig:bonus 1] is
defined as:

\starttyping
\startFLOWcell
  \name       {tex}
  \location   {1,1}
  \shape      {action}
  \text       {\TEX}
  \connection [prpl] {pdf}
  \connection [nrnl] {dvi}
\stopFLOWcell
\stoptyping

Alternatively to \type {p} and \type {n} one may use \type {+} and \type {-}. As
soon as the positive and negative points are used, the connection drawing
routines will take into account the fact that they are off||center. This does not
free users from thinking about better ways to draw such a chart.

\stopsection

\startsection[title={Clip and focus}]

The flowcharter automatically calculates the size of the grid. When needed, one
can force the dimensions and/or clip pieces of a chart. \in {Figure}
[fig:clipped] shows such a clip. This example also shows why the offset, the
small area around the outer grid lines, is important. \in {Figure} [fig:clipped]
was produced while the next settings were in action.

\startbuffer[clip]
\setupFLOWcharts
  [x=1,y=1,nx=2,ny=1]
\stopbuffer

\typebuffer[clip]

\placefigure
  [here][fig:clipped]
  {Clipping a piece of a chart.}
  {\tx\getbuffer[clip]\FLOWchart[connect]}

Sometimes, for instance when explaining a chart, it makes sense to emphasize one
or more particular cells. Therefore this module offers the ability to focus on
cells. In \in {figure} [fig:focus] we see that the focus is on the cell with name
\type {dvi}. This is accomplished by saying:

\startbuffer
\setupFLOWfocus
  [framecolor=pragmacolor]
\setupFLOWcharts
  [focus=dvi]
\stopbuffer

\typebuffer

\placefigure
  [here][fig:focus]
  {Gaining some focus.}
  {\tx\getbuffer\FLOWchart[bonus 3]}

Clipping and focus bring us to the third way of zooming in: autofocus. \in
{Figure} [fig:autofocus] shows what happens when we say:

\startbuffer
\setupFLOWfocus
  [framecolor=pragmacolor]
\setupFLOWcharts
  [focus=dvi,autofocus=dvi,
   nx=1,ny=1]

\startFLOWchart [bonus 3]
  \startFLOWcell
    \name       {tex}
    \location   {1,1}
    \shape      {action}
    \text       {\TEX}
    \connection [rl] {pdf}
  \stopFLOWcell
  \startFLOWcell
    \name       {pdf}
    \location   {4,1}
    \shape      {action}
    \text       {\PDF}
  \stopFLOWcell
\stopFLOWchart
\stopbuffer

\typebuffer

\placefigure
  [here][fig:autofocus]
  {Applying autofocus.}
  {\tx\getbuffer\FLOWchart[bonus 3]}

In \in {figure}[fig:autofocus] we see both focus and auto focus in action.

\stopsection

\startsection[title={Line types}]

As is to be expected, we can set up some characteristics of a chart, the shapes,
the connecting lines, and the focus. When we want dashed lines and a different
shape color, we just say:

\startbuffer
\setupFLOWshapes
  [framecolor=pragmacolor]
\setupFLOWlines
  [framecolor=pragmacolor,
   dash=yes]
\stopbuffer

\typebuffer

\placefigure
  [here][fig:lines]
  {Dashed and colored lines.}
  {\tx\getbuffer\FLOWchart[bonus 3]}

We can change the characteristics at several levels: chart, line, shape and|/|or
focus. In the near future some more options will be added. Once the \METAPOST\
module is stable and documented, the graphic code will also be accessible. The
formal definition of the four setup commands is as follows (these diagrams
conform the \CONTEXT\ conventions):

\setup{setupFLOWcharts}

\setup{setupFLOWfocus}

\setup{setupFLOWlines}

\setup{setupFLOWshapes}

\stopsection

\startsection[title={Overlays}]

Why should we limit ourselves to text? In \CONTEXT\ most frames||related features
can have overlays. Because in this flowchart module shapes are drawn by
\METAPOST, we use a slightly different approach: there can be overlays but they
are sort of clipped by the shape. \in {Figure} [fig:overlay] illustrates this.

\startbuffer
\defineoverlay
  [coward]
  [{\externalfigure
      [cow]
      [width=\overlaywidth,
       height=\overlayheight]}]

\startFLOWchart [overlay]
  \startFLOWcell
    \name       {alpha}
    \location   {1,1}
    \shape      {procedure}
    \connection [rl] {beta}
    \figure     {cow}
    \text       [lt] {\darkred \bfb COW 1}
  \stopFLOWcell
  \startFLOWcell
    \name       {beta}
    \location   {2,1}
    \shape      {product}
    \connection [rl] {gamma}
    \overlay    {cow}
    \text       {\darkgreen \bfb COW 2}
  \stopFLOWcell
  \startFLOWcell
    \name       {gamma}
    \location   {3,1}
    \shape      {action}
    \connection [rl] {alpha}
    \overlay    {cow}
    \text       [rb] {\darkblue \bfb COW 3}
  \stopFLOWcell
\stopFLOWchart
\stopbuffer

\typebuffer \getbuffer

\placefigure
  [here][fig:overlay]
  {Overlays.}
  {\tx\FLOWchart[overlay]}

There are two commands related to overlays. In our example we used: which
automatically scales figure {\em cow} to the shape size. The normal rules for
overlays apply. The width and height of the overlay are available at the moment
the overlay is typeset.

The text is aligned differently in this example and driven by an optional
argument that can take one of the following values: \type {l}, \type {r}, \type
{m}, \type {c}, \type {t}, \type {b}, \type {lt}, \type {rt}, \type {mt}, \type
{ct}, \type {lb}, \type {rb}, \type {mb}, \type {cb}.

\stopsection

\startsection[title={Interaction}]

One of the reasons for writing this module was that we wanted interactive
flowcharts. The shape text can contain references. \footnote {Currently this only
works ok when the chart is not scaled.} The shape as a whole becomes a button as
soon as we add the \type {\destination} entry:

\starttyping
\startFLOWcell
  ...
  \destination {destination}
  ...
\stopFLOWcell
\stoptyping

\startbuffer[movie]
\defineoverlay
  [fun]
  [{\externalfigure
      [texwork.mov]
      [width=\framedwidth,
       height=\framedheight,
       preview=yes,
       repeat=yes]}]
\stopbuffer

\getbuffer[movie]

\starthelptext [alpha]
  \input knuth \blank D.E.~Knuth
\stophelptext

\starthelptext [beta]
  \input tufte \blank E.R.~Tufte
\stophelptext

\starthelptext [delta]
  \externalfigure[cow][width=\hsize]
\stophelptext

\startFLOWchart [interactive]

  \startFLOWcell
    \name        {alpha}
    \location    {1,1}
    \shape       {procedure}
    \connection  [rl] {beta}
    \text        {\goto{introduction}[introduction]}
  \stopFLOWcell

  \startFLOWcell
    \name       {beta}
    \location   {2,1}
    \shape      {product}
    \connection [rl] {gamma}
    \text       {Did you\\read me\\indeed?}
    \destination{introduction}
  \stopFLOWcell

  \setupFLOWlines[dash=yes]

  \startFLOWcell
    \name       {gamma}
    \location   {3,1}
    \shape      {action}
    \connection [rl] {alpha}
    \overlay    {fun}
  \stopFLOWcell

  \setupFLOWlines[dash=no]

  \startFLOWcell
    \name       {delta}
    \location   {4,1}
    \shape      {decision}
    \connection [tt] {alpha}
    \connection [tt] {beta}
    \connection [tt] {gamma}
    \figure     {cow}
  \stopFLOWcell

\stopFLOWchart

\placefigure
  [here][fig:interactive]
  {Interactive buttons.}
  {\tx\FLOWchart[interactive]}

When read as \PDF\ file, \in {figure} [fig:interactive] shows quite a few
interactive features. The first cell has a \type {\goto} included in the text,
like:

\starttyping
\startFLOWcell
  ...
  \text {\goto{introduction}[introduction]}
  ...
\stopFLOWcell
\stoptyping

The second shape is interactive as a whole. This is accomplished by saying:

\starttyping
\startFLOWcell
  ...
  \text        {Did you\\read me\\indeed?}
  \destination {introduction}
  ...
\stopFLOWcell
\stoptyping

The third cell is a movie, which is only visible in suitable viewers. The movie
is included as an overlay.

\typebuffer[movie]

The last cell is an illustration.

\stopsection

\startsection[title={Splitting charts}]

Sometimes a chart does not fit comfortably on the page. In such cases, it makes
sense to split up the chart. There is a dedicated setup command to serve
splitting:

\setup{setupFLOWsplit}

An example of splitting is:

\starttyping
\setupFLOWsplit
  [nx=5,ny=10,
   dx=1,dy=1,
   before=,after=\page]

\FLOWcharts[mybigflow]
\stoptyping

For easy alignment of the split pages, cut marks are added. This can be turned
off by setting \type {marking} to \type {off}. The \type {n} parameters determine
the number of cells per split off subject, and the \type {d} parameters specify
the overlap: a value of~1 means that each split off subject has one row and|/|or
columns in common with its neighbour.

The splitter can be used with the split float placement macro:

\starttyping
\splitfloat
  {\placefigure{What a big flowchart this is!}}
  {\FLOWcharts[mybigflow]}
\stoptyping

Here every flowchart gets an caption with a decent subnumber.

Related to splitting up charts is the option to define exit points as
demonstrated in the next chart.

\startbuffer
\startFLOWchart[metatex]
  \setupFLOWcharts
    [width=6\bodyfontsize,
     height=3\bodyfontsize,
     dx=\bodyfontsize,
     dy=\bodyfontsize]
   \startFLOWcell
    \name       {texexec 1}
    \location   {1,1}
    \shape      {action}
    \text       {\TEXEXEC}
    \connection [rl] {context 1}
  \stopFLOWcell
  \startFLOWcell
    \name       {context 1}
    \location   {2,1}
    \shape      {action}
    \text       {\CONTEXT}
    \connection [bt] {metapost 1}
    \connection [rl] {texexec  2}
    \exit       [r] {123}
  \stopFLOWcell
  \startFLOWcell
    \name       {metapost 1}
    \location   {2,2}
    \shape      {action}
    \text       {\METAPOST}
  \stopFLOWcell
  \startFLOWcell
    \name       {texexec 2}
    \location   {3,1}
    \shape      {action}
    \text       {\TEXEXEC}
    \connection [rl] {context  2}
    \connection [bt] {metapost 2}
    \exit       [l] {123}
  \stopFLOWcell
  \startFLOWcell
    \name       {context 2}
    \location   {4,1}
    \shape      {action}
    \text       {\CONTEXT}
  \stopFLOWcell
  \startFLOWcell
    \name       {metapost 2}
    \location   {3,2}
    \shape      {action}
    \text       {\METAPOST}
  \stopFLOWcell
\stopFLOWchart
\stopbuffer

\typebuffer \getbuffer

\startbuffer[a]
\FLOWchart [metatex] [x=1,nx=2,frame=on]
\stopbuffer

\startbuffer[b]
\FLOWchart [metatex] [x=3,nx=2,frame=on]
\stopbuffer

When we ask for subcharts, the exit points will show up. Because they don't
attribute to the dimensions of the chart, you can still align charts as expected.

\startlinecorrection[blank] \getbuffer[a] \stoplinecorrection
\typebuffer[a]

\startlinecorrection[blank] \getbuffer[b] \stoplinecorrection
\typebuffer[b]

\stopsection

\startsection[title={Other features}]

It is possible to predefine flow charts in a way similar to external figures.
Currently this mechanism is under construction, so describing it would be a bit
premature.

Crossing lines, which are often forbidden in charts, can be made less confusing
by adding a gap in the lines to be crossed. This is one of the features that are
already implemented but not yet accessible by the \CONTEXT\ user interface.

Another feature, used in this document, concerns automatic down||scaling. As soon
as we start scaling illustrations, we introduce inconsistent typography,
especially in the bodyfontsize. Therefore, the flow chart macros, when told to,
are able to automatically scale down in steps of 1~point.

{\em This manual was first published in GUST magazine and presented at the anual
meeting of the Polish user group in Bachotek 1999. Next it was published in the
MAPS volume 23. After that it became Up||To||Date number 1999-003, and now it's
part of the manual series. This version is for \MKIV.}

\stopsection

\stopdocument