%% $Id: xyline.doc,v 3.6 1998/03/06 01:28:05 krisrose Exp $
%%
%% Xy-pic ``Line Width'' extension.
%% Copyright (c) 1993-1996	Ross Moore	<ross@mpce.mq.edu.au>
%%
%% This file is part of the Xy-pic package for graphs and diagrams in TeX.
%% See the companion README and INSTALL files for further information.
%% Copyright (c) 1991-1996	Kristoffer H. Rose  <krisrose@ens-lyon.fr>
%%
%% The Xy-pic package is free software; you can redistribute it and/or modify
%% it under the terms of the GNU General Public License as published by the
%% Free Software Foundation; either version 2 of the License, or (at your
%% option) any later version.
%%
%% The Xy-pic package is distributed in the hope that it will be useful, but
%% WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
%% or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
%% for more details.
%%
%% You should have received a copy of the GNU General Public License along
%% with this package; if not, write to the Free Software Foundation, Inc.,
%% 675 Mass Ave, Cambridge, MA 02139, USA.
%%
\ifx\xyloaded\undefined \input xy \fi

\xyprovide{line}{Line styles extension}{\stripRCS$Revision: 3.6 $}%
 {Ross Moore}{ross@mpce.mq.edu.au}%
 {Mathematics Department, Macquarie University, NSW~2109, Australia}

\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 This extension provides the ability to request various effects related
 to the appearance of straight lines; \eg. thickness, non-standard dashing,
 and colour.

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\paragraph*{Header:}\leavevmode
\DOCHEADER

\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

These are effects which are not normally available within \TeX.
Instead they require a suitable `back-end' option to provide the necessary
|\special| commands, or extra fonts, together with appropriate 
commands to implement the effects.  Thus
$$
\xy
 *+\txt<.8\hsize>{Using this extension will have no effect on the output
	unless used with a backend that explicitly supports it.}
 *\frm{-}
\endxy
$$

The extension provides special effects that can be used with any \Xy-pic
<object>, by defining |[|<shape>|]| modifiers.
The modification is local to the <object> currently being built,
so will have no effect if this object is never actually used.

\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\paragraph*{Adjusting line thickness}


The following table lists the modifiers primarily to alter the thickness
of lines used by \Xy-pic. They come in two types --- either a single keyword, 
or using the key-character |||| with the following text parsed.
%
\begin{defs}%
 |[thicker]| & double line thickness \cr
 |[thinner]| & halve line thickness \cr
 |[||(|<num>|)]| & multiple of usual thickness\cr
 |[||<|<dimen>|>]| & set thickness to <dimen>\cr
 |[|||<dimen>|]| & also sets to <dimen>\cr
 |[||=|<word>|]| & make |[|<word>|]| set current style settings\cr
 |[||*]| & reuse previous style\cr
 |[butt]| & butt cap at ends\cr
 |[roundcap]| & round cap at ends\cr
 |[projcap]| & projecting square cap.\cr
\end{defs}
%
\noindent
Later settings of the linewidth override earlier settings; 
multiple calls to |[thicker]| and |[thinner]| compound,
but the other variants set an absolute thickness.
The line-thickness specification affects arrow-tips as well as the
thickness of straight lines and curves. 
Three kinds of line-caps are available; they are discussed below
in the section on `poly-lines'.
%
\begin{code}
\xy/r8pc/:*++\txt\huge{C}="c"
,0*++\txt\huge{P}="p",
,"p",{\ar@*{[|(1)]}"p";"c"<20pt>}
,"p",{\ar@*{[|(4)]}"p";"c"<14pt>}
,"p",{\ar@*{[|(10)]}"p";"c"<4pt>}
,"p",{\ar@*{[|(20)]}"p";"c"<-16pt>}
\endxy
\end{code}
$$\docode$$
\medskip
\displaycode
%
Using the \PS\ back-end, the size of the arrow-head grows 
aesthetically with the thickness of the line used to draw it. 
This growth varies as the square-root of the thickness; 
thus for very thick lines (20+ times normal) the arrowhead 
begins to merge with the stem. 

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Load the |style| extension to establish the necessary infra-structure.

\DOCMODE(
%\xydefcsname@{shape [|...]}#1{\xyFN@\xywidthchar@#1@@}%
\xydefcsname@{*stylechar@|@}#1{\xyFN@\xywidthchar@#1@@}%

%\xydefcsname@{shape [thinner]}{\xyshape@thinner@}
%\xydefcsname@{shape [thicker]}{\xyshape@thicker@}
\xydefcsname@{style [thinner]}{\xyshape@thinner@}
\xydefcsname@{style [thicker]}{\xyshape@thicker@}
\DOCMODE)

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\paragraph*{Implementation}

Record the line thickness locally in a dimen register.
The initial value is read from the |xydash10| font.
Each time |\xylinethick@| is changed, its previous value is stored
as the expansion of |\xyprevwidth@@|, in case this is needed by
a specific back-end.

\DOCMODE(
\xynew@{dimen}\xylinethick@ \xylinethick@=\xydashw@

\xydef@\xyshape@thicker@{\xylinewidth@i{\multiply\xylinethick@\tw@}}
\xydef@\xyshape@thinner@{\xylinewidth@i{\divide\xylinethick@\tw@}}

\xydef@\xylinewidth@i#1{\edef\xyprevwidth@@{\the\xylinethick@}%
 #1\edef\next@{\xylinethick@=\the\xylinethick@}%
 \edef\next@ii{\noexpand\addtotoks@{%
  \noexpand\xylinewidth@@{\next@}{\xyprevwidth@@}}}%
 \next@ii }


\xydef@\xywidthchar@{%
 \ifx \space@\next \expandafter\DN@\space{\xyFN@\xywidthchar@}%gobble spaces
% \else\ifx @\next \DN@ @@{\addtotoks@{\checkXyStyle@}}%
 \else\ifx @\next \DN@ @@{\checkXyStyle@}%
 \else\ifx (\next \DN@ (##1)##2@@{%
  \xylinewidth@i{\xylinethick@=##1\xydashw@}}%
 \else\addLT@\ifx \next \addGT@{\addLT@\DN@ ##1}##2@@{%
  \xylinewidth@i{\xylinethick@=##1\relax}}%
% \else\ifx *\next \DN@ *@@{\addtotoks@{\checkXyStyle@}}%
% \else\ifx *\next \DN@ *@@{\checkXyStyle@}%
 \else\ifx *\next \DN@ *@@{\recoverXyStyle@}%
% \else\addEQ@\ifx \next \addEQ@\DN@##1@@{%
%  \addtotoks@{\checkXyStyle@\xynamestyle@{##1}}}%
 \else\addEQ@\ifx \next \addEQ@\DN@##1@@{\checkXyStyle@
  \addtotoks@{\xynamestyle@{##1}}}%
 \else\ifx C\next \DN@ C##1@@{\xysetlinecap@{##1}@}%
 \else\ifx J\next \DN@ J##1@@{\xysetlinejoin@{##1}@}%
 \else\ifx M\next \DN@ M(##1)@@{\xymiterlimit@{##1}@}%
 \else \DN@##1@@{\xylinewidth@i{\xylinethick@=##1\relax}}%
 \fi\fi\fi\fi\fi\fi\fi\fi\fi \next@}
\DOCMODE)

\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

The diagram in figure~??g[xyrotate.doc:rotate and flips],
page~??gp[xyrotate.doc:rotate and flips], uses different line-thicknesses 
and colours.

\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\paragraph*{Poly-lines}

By a `poly-line' we mean a path built from straight line segments having no
gaps where each segment abuts the next. The poly-line could be the edges of 
a polygon, either closed or open if the end-points are different. 

The reason for considering a poly-line as a separate <object>, rather than 
simply as a <path> built from straight lines, becomes apparent only when
the lines have appreciable thickness. Then there are several standard ways 
to fashion the `joins' (where segments meet). Also the shape of the `caps'
at either end of the poly-line can be altered. 

The following modifiers are used to determine the shapes of the line `caps'
and `joins': 
%
\begin{defs}%
 |[||J|<val>|]| & join style, <val> = 0, 1 or 2\cr
 |[mitre]| & mitre-join, same as |[||J0]|\cr
 |[roundjoin]| & round join, same as |[||J1]|\cr
 |[bevel]| & bevel-join, same as |[||J2]|\cr
 |[||C|<val>|]| & end-cap, <val> = 0, 1 or 2\cr
 |[butt]| & ``butt'' cap, same as |[||C0]|\cr
 |[roundcap]| & round cap, same as |[||C1]|\cr
 |[projcap]| & ``projecting square'' cap,\hfil\break same as |[||C2]|\cr
 |[||M(|<num>|)]| & set mitrelimit to <num>$\ge1$\cr
\end{defs}
%
\noindent
These effects are currently implemented only with the \PS\ back-end
or when using |\xypolyline| (described below) with a \PS\ <driver>.
In this case the `cap' setting can be applied to any segment, straight  
or curved, whether part of a poly-line or not; however the `join' setting 
applies only to poly-lines. Arrow-tips are not affected. 
The defaults are to use round joins and round-cap ends. 

Adjusting the miter-limit affects how far miters are allowed to protrude 
when two wide lines meet at small angles. The <num> is in units of the 
line-thickness. Higher values mean using bevels only at smaller angles, 
while the value of 1 is equivalent to using bevels at all angles. 
The default miter-limit is 10.

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Current values are stored in case these are needed within nested portions 
of diagrams.

\DOCMODE(
\xydef@\xylinecap@{2}
\xydef@\xylinejoin@{2}
\xydef@\xylinemiter@{10}
\DOCMODE)

%These are simple methods that alter the stored values.
%
%\DOCMODE(
%\xydef@\xysetlinecap@@#1{\xylinestyle@{C}{#1}{\def\xylinecap@{#1}}}
%\xydef@\xysetlinejoin@@#1{\xylinestyle@{J}{#1}{\def\xylinejoin@{#1}}}
%\xydef@\xysetmiterlimit@@#1{\xylinestyle@{M}{#1}{\def\xylinemiter@{#1}}}
%\DOCMODE)
%
%Finally we need the interface to pass the new values to a <driver>.
%
%\DOCMODE(
%\xydef@\xynolinestyle@@#1#2#3{\let\next=#1\relax #3%
% \ifx\next C\DN@{\xyundefinedLine@{linecap}{#2}@@}%
% \else\ifx\next J\DN@{\xyundefinedLine@{linejoin}{#2}@@}%
% \else\ifx\next M\DN@{\xyundefinedLine@{miterlimit}{#2}@@}%
% \fi\fi\fi \next@ }
%
%\xylet@\xylinestyle@\xynolinestyle@@
%\DOCMODE)

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Recognise keywords for `line-caps' and `line-joins':

\DOCMODE(
\xydefcsname@{style [bevel]}{\xyshape@bevel@}
\xydefcsname@{style [roundjoin]}{\xyshape@rdjoin@}
\xydefcsname@{style [miter]}{\xyshape@miter@}
%
\xydefcsname@{style [butt]}{\xyshape@butt@}
\xydefcsname@{style [roundcap]}{\xyshape@rdcap@}
\xydefcsname@{style [projcap]}{\xyshape@projcap@}
\DOCMODE)

\DOCMODE(
\xydef@\xyshape@butt@{\xysetlinecap@@0}
\xydef@\xyshape@rdcap@{\xysetlinecap@@1}
\xydef@\xyshape@projcap@{\xysetlinecap@@2}

\xydef@\xyshape@miter@{\xysetlinejoin@@0}
\xydef@\xyshape@rdjoin@{\xysetlinejoin@@1}
\xydef@\xyshape@bevel@{\xysetlinejoin@@2}

\xydef@\xysetlinecap@#1@{\DN@ii{#1}\count@=#1\relax
 \expandafter\DN@\expandafter{\the\count@}%
 \ifx\next@\next@ii\else
  \xywarning@{ignoring extra tokens in line-cap: \next@}\fi
 \expandafter\xysetlinecap@@\expandafter{\next@}}

\xydef@\xysetlinejoin@#1@{\DN@ii{#1}\count@=#1\relax
 \expandafter\DN@\expandafter{\the\count@}%
 \ifx\next@\next@ii\else
  \xywarning@{ignoring extra tokens in line-join: \next@}\fi
 \expandafter\xysetlinejoin@@\expandafter{\next@}}

\xydef@\xysetmiterlimit@#1@{\DN@ii{#1}\dimen@=#1\p@\relax
 \edef\next@{\expandafter\removePT@\the\dimen@}%
 \ifx\next@\next@ii\else
  \xywarning@{ignoring extra tokens in miter-limit: \next@}\fi
 \expandafter\xysetmiterlimit@@\expandafter{\next@}}
\DOCMODE)

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

These use the more sophisticated approach that is easier to adjust for
different <driver>s.

\DOCMODE(
\xydef@\xysetlinecap@@#1{\xy@linecap@i{\def\xylinecap@{#1}}}
\xydef@\xysetlinejoin@@#1{\xy@linejoin@i{\def\xylinejoin@{#1}}}
\xydef@\xysetmiterlimit@@#1{%
 \xy@linemiter@i{\def\xylinemiter@{#1}}}

\xydef@\xy@linecap@i#1{#1\addtotoks@{\xy@linecap@@{#1}}}
\xydef@\xy@linejoin@i#1{#1\addtotoks@{\xy@linejoin@{#1}}}
\xydef@\xy@linemiter@i#1{#1\addtotoks@{\xy@linemiter@{#1}}}
\DOCMODE)

Implementation of line-caps:

\DOCMODE(
\xydef@\xy@linecap@#1{\checkXyStyle@ \edef\xyprevcap@@{\xylinecap@}%
 #1\let\prexylinecap@=\prexylinecap@@ \let\postxylinecap@=\postxylinecap@@
 \applyLIFOstyle@\prexylinecap@{\xylinecap@}%
  \postxylinecap@{\xyprevcap@@}}

\xydef@\prexylinecap@@{\let\prexylinecap@=\eat@    
 \let\postxylinecap@=\postxylinecap@@ \outputxylinecap@ }
\xydef@\postxylinecap@@{\let\postxylinecap@=\eat@  
 \let\prexylinecap@=\prexylinecap@@ \resetxylinecap@@ }
\xylet@\prexylinecap@=\prexylinecap@@
\xylet@\postxylinecap@=\postxylinecap@@

\xydef@\outputxylinecap@#1{\xycapSpecial@@{#1}}
\xydef@\resetxylinecap@#1{\resetxylinecap@i{#1}\outputxylinecap@{#1}}
\xydef@\resetxylinecap@i#1{\def\xylinecap@{#1}}
\xylet@\resetxylinecap@@=\resetxylinecap@

\xylet@\xycapSpecial@@=\eat@
\DOCMODE)

Implementation of line-joins:

\DOCMODE(
\xydef@\xy@linejoin@#1{\checkXyStyle@
 \edef\xyprevjoin@@{\xylinejoin@}#1%
 \let\prexylinejoin@=\prexylinejoin@@
 \let\postxylinejoin@=\postxylinejoin@@
 \applyLIFOstyle@\prexylinejoin@{\xylinejoin@}%
  \postxylinecap@{\xyprevjoin@@}}

\xydef@\prexylinejoin@@{\let\prexylinejoin@=\eat@    
 \let\postxylinejoin@=\postxylinejoin@@ \outputxylinejoin@ }
\xydef@\postxylinejoin@@{\let\postxylinejoin@=\eat@  
 \let\prexylinejoin@=\prexylinejoin@@ \resetxylinejoin@@ }
\xylet@\prexylinejoin@=\prexylinejoin@@
\xylet@\postxylinejoin@=\postxylinejoin@@

\xydef@\outputxylinejoin@#1{\xyjoinSpecial@@{#1}}
\xydef@\resetxylinejoin@#1{\resetxylinejoin@i{#1}\outputxylinejoin@{#1}}
\xydef@\resetxylinejoin@i#1{\def\xylinejoin@{#1}}
\xylet@\resetxylinejoin@@=\resetxylinejoin@

\xylet@\xyjoinSpecial@@=\eat@
\DOCMODE)

Implementation of miter-limit:

\DOCMODE(
\xydef@\xy@linemiter@#1{\checkXyStyle@
 \edef\xyprevmiter@@{\xylinemiter@}#1%
 \let\prexylinemiter@=\prexylinemiter@@
 \let\postxylinemiter@=\postxylinemiter@@
 \applyLIFOstyle@\prexylinemiter@{\xylinemiter@}%
  \postxylinecap@{\xyprevmiter@@}}

\xydef@\prexylinemiter@@{\let\prexylinemiter@=\eat@    
 \let\postxylinemiter@=\postxylinemiter@@ \outputxylinemiter@ }
\xydef@\postxylinemiter@@{\let\postxylinemiter@=\eat@  
 \let\prexylinemiter@=\prexylinemiter@@ \resetxylinemiter@@ }
\xylet@\prexylinemiter@=\prexylinemiter@@
\xylet@\postxylinemiter@=\postxylinemiter@@

\xydef@\outputxylinemiter@#1{\xymiterSpecial@@{#1}}
\xydef@\resetxylinemiter@#1{\resetxylinemiter@i{#1}\outputxylinemiter@{#1}}
\xydef@\resetxylinemiter@i#1{\def\xylinemiter@{#1}}
\xylet@\resetxylinemiter@@=\resetxylinemiter@

\xylet@\xymiterSpecial@@=\eat@
\DOCMODE)

\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

The path taken by the `poly-line' this is read as the list of <pos>itions 
in the current `stack', ignoring size extents. 
The macro |\xypolyline| is used as a <decor>; it reads the <pos>itions from 
the stack, but leaves the stack intact for later use. 

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Implementation of `poly-lines'.

\DOCMODE(
\xydef@\xypolyline#1{\xypolyline@{#1}}

\xydef@\xypolyline@#1{\hbox\bgroup
 \enter@{\pfromthep@ \basefromthebase@ \cfromthec@}%
  \def\xyps@list{}\edef\smapp@@{\s@bot}%
  \smapxy@i{\enter@{\pfromthep@ \basefromthebase@ }%
   \edef\xyps@list{\expandafter\removePT@\the\X@c\space
    \expandafter\removePT@\the\Y@c\space \xyps@list}\leave@}%
 \leave@ \xy@polystyle@@{#1}\xydopoly@style\egroup
 \def\Drop@@{\styledboxz@}\def\Connect@@{\styledboxz@}}%
\DOCMODE)

\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

The following diagram illustrates the use of line-thickness, line-joins
and line-caps with poly-lines. It contains an example of each of the styles.

\begin{code} 
\xycompileto{poly}%
{/r4pc/:,*[|<5pt>][thicker]\xybox{%
 *+(3,2){}="X"
;@={p+CU,p+LU,p+LD,p+RD,p+RU,p+CU}
 ,{0*[miter]\xypolyline{}}
 ,{\xypolyline{*}},@i@)
,"X",*+(2.5,1.5){}="X"
,@={!CU,!LU,!LD,!RD,!RU,!CU}
 ,{0*[gray][roundjoin]\xypolyline{}}
 ,{0*[gray]\xypolyline{*}},@i@)
,"X",*+(2,1){}="X"
,@={!CU,!LU,!LD,!RD,!RU,!CU}
 ,{0*[white]\xypolyline{*}}
 ,{0*[bevel]\xypolyline{}},@i@)
,"X"-(.7,0)*++\txt\LARGE{A}="a"
,"X"+(.7,0)*++\txt\LARGE{B}="b" 
,{\ar@{-}@*{[butt][thinner]}"a";"b"<1pc>}
,{\ar@{-}@*{[roundcap][thinner]}"a";"b"}
,{\ar@{-}@*{[projcap][thinner]}"a";"b"<-1pc>}
}}
\end{code} 
$$\docode$$
\displaycode
\noindent
Note the use of |{0*[...]\xypolyline{..}}| to apply style-modifiers 
to a polyline. The |@={!..}| method for loading the stack gives 
equivalent results to using |;@={p+..}|, since |\xypolyline| 
ignores the edge extents of each <pos> in the stack. 

Note also that the argument |#1| to |\xypolyline| affects what
is typeset. Allowable arguments are:
%
\begin{defs}
|\xypolyline{}| & solid line\cr
|\xypolyline{.}| & dotted line\cr
|\xypolyline{-}| & dashed line\cr
|\xypolyline{*}| & fill enclosed polygon\cr
|\xypolyline{?}| & fill enclosed polygon using even-odd rule\cr
|\xypolyline{{*}}| & use |\dir{*}| for lines\cr
|\xypolyline{<toks>}|\kern-20pt & \kern20pt using |\dir{<toks>}| \cr
\end{defs}
\noindent
The latter cases one has |**\dir{...}| being used to connect the vertices 
of the polyline, with |{{*}}| being needed to get |**\dir{*}|. 
Similarly |**\dir| is used when a <driver> is not available to specifically
support polylines; in particular the two `fill' options |*| and |?| will
result in a dotted polygon outline the region intended to be filled. 

In all cases it is up to the user to load the stack before calling 
|\xypolyline{|\dots|}|. A particularly common case is the outline of
an existing \Xy-pic <object>, as in the example above. Future extensions
to |\frm| will provide a simplified mechanism whereby the user need not
call |\xypolyline| explicitly for such effects.

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\DOCMODE(
\xylet@\xypolyline@Special=\eat@
\xylet@\xypolyfill@Special=\eat@
\xylet@\xypolyeofill@Special=\eat@
\xylet@\xypolydot@Special=\eat@
\xylet@\xypolydash@Special=\eat@

\xydef@\UnloadpolySpecials@{%
 \let\xypolyline@Special=\eat@
 \let\xypolyfill@Special=\eat@
 \let\xypolyeofill@Special=\eat@
 \let\xypolydot@Special=\eat@
 \let\xypolydash@Special=\eat@
}

\xydef@\xy@polystyle@#1{%
 \let\poly@style@@=\xypolyline@Special
 \DNii@{#1}\ifx\nextii@\empty 
 \else\DN@{*}\ifx\next@\nextii@ \let\poly@style@@=\xypolyfill@Special
 \else\DN@{?}\ifx\next@\nextii@ \let\poly@style@@=\xypolyeofill@Special
 \else\expandafter\DN@\expandafter{\addDOT@{}}\ifx\next@\nextii@
  \let\poly@style@@=\xypolydot@Special
 \else\expandafter\DN@\expandafter{\addDASH@{}}\ifx\next@\nextii@
  \let\poly@style@@=\xypolydash@Special
 \else\DN@{{*}}\ifx\next@\nextii@ \def\poly@style@@{\xypolystraight@{*}}%
 \else \def\poly@style@@{\xypolystraight@{#1}}%
 \fi\fi\fi\fi\fi\fi }

\xydef@\xydopoly@style{\expandafter\poly@style@@\expandafter{\xyps@list}}
\xydef@\xynopolystyle@#1#2{\xyundefinedLine@{polyline}{{#1}}@@}
\DOCMODE)

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

When there is no special support this handles the various cases using 
ordinary thin line types.

\DOCMODE(
\xydef@\xypolynospec@#1{\DNii@{#1}%
 \ifx\nextii@\empty\def\poly@style@@{\xypolystraight@{-}}%
 \else\DN@{.}\ifx\next@\nextii@ \def\poly@style@@{\xypolystraight@{.}}%
 \else\DN@{-}\ifx\next@\nextii@ \def\poly@style@@{\xypolystraight@{--}}%
 \else\DN@{*}\ifx\next@\nextii@ \def\poly@style@@{\xypolystraight@{.}}%
 \else\DN@{?}\ifx\next@\nextii@ \def\poly@style@@{\xypolystraight@{.}}%
 \else\DN@{{*}}\ifx\next@\nextii@ \def\poly@style@@{\xypolystraight@{*}}%
 \else \def\poly@style@@{\xypolystraight@{#1}}%
 \fi\fi\fi\fi\fi\fi }
\DOCMODE)

Gobble the collected positions in |{\xyps@list}|; recover the vertices
from the stack, then set straight lines in the appropriate style.

\DOCMODE(
\xydef@\xypolystraight@#1#2{%
 \enter@{\pfromthep@ \basefromthebase@ \cfromthec@}%
 \edef\smapp@@{\s@bot}\csname S@0\endcsname\czeroEdge@\pfromc@\def\smapp@@{0}%
 \smapxy@i{\czeroEdge@\enter@{\pfromthec@}{\connect@\dir{#1}}\leave@}\leave@ }
\DOCMODE)

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Initially poly-lines are uninstalled, until loaded by a <driver>.

\DOCMODE(
\xylet@\xy@polystyle@@=\xypolynospec@

\xydef@\UninstallPolylines@{%
 \UnloadpolySpecials@
 \let\xy@polystyle@@=\xypolynospec@ }
\UninstallPolylines@
\DOCMODE)

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\paragraph*{Installation}

Initially there is no support for the actual effects. 

\DOCMODE(
\xydef@\xyundefinedLine@#1#2@@{%
 \xywarning@{The #1 #2 effect is not implemented with the current driver.}}%

\xydef@\xynolinewidth@#1#2{%
 \xyundefinedLine@{linewidth}{\the\xylinethick@}@@}%
\xydef@\xynolinecap@#1{\xyundefinedLine@{linecap}{\xylinecap@}@@}%
\xydef@\xynolinejoin@#1{\xyundefinedLine@{linejoin}{\xylinejoin@}@@}%
\xydef@\xynolinemiter@#1{\xyundefinedLine@{miterlimit}{\xylinemiter@}@@}%
\DOCMODE)

Nothing further can be done unless allowed by a specific <driver>, which 
must establish an alternative expansions to be bound to |\xylinewidth@@|
and the other hooks.

\DOCMODE(
\xylet@\xylinewidth@@=\xynolinewidth@
\xylet@\xy@linecap@@=\xynolinecap@
\xylet@\xy@linejoin@@=\xynolinejoin@
\xylet@\xy@linemiter@@=\xynolinemiter@

\xydef@\UnloadLine@#1{%
 \ifx#1\relax\else\xyunload@{line width extension}\fi
 \let\resetxyline@@=\resetxyline@
 \let\resetxylinecap@@=\resetxylinecap@
 \let\resetxylinejoin@@=\resetxylinejoin@
 \let\resetxylinemiter@@=\resetxylinemiter@
 \let\transxyline@@=\DN@
 \let\xylineSpecial@@=\eat@
 \let\xycapSpecial@@=\eat@
 \let\xyjoinSpecial@@=\eat@
 \let\xymiterSpecial@@=\eat@
 \let\xylinewidth@@=\xynolinewidth@
 \let\xy@linecap@@=\xynolinecap@
 \let\xy@linejoin@@=\xynolinejoin@
 \let\xy@linemiter@@=\xynolinemiter@
 \UninstallPolylines@ }

\xyaddunsupport{line}{\UnloadLine@\relax}
\DOCMODE)

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

This is a possible alternative for |\xylinewidth@@|. Indeed it is used
with the \PS\ support, which then redefines just |\xylineSpecial@@|.

\DOCMODE(
\xydef@\xylinewidth@#1#2{\checkXyStyle@
 #1\let\prexyline@=\prexyline@@ \let\postxyline@=\postxyline@@
 \applyLIFOstyle@\prexyline@{\the\xylinethick@}\postxyline@{#2}}
\xydef@\prexyline@@{\let\prexyline@=\eat@    
 \let\postxyline@=\postxyline@@ \outputxyline@ }
\xydef@\postxyline@@{\let\postxyline@=\eat@  
 \let\prexyline@=\prexyline@@ \resetxyline@@ }
\xylet@\prexyline@=\prexyline@@
\xylet@\postxyline@=\postxyline@@

\xydef@\resetxyline@#1{\resetxyline@i{#1}\outputxyline@{#1}}
\xydef@\resetxyline@i#1{\xylinethick@=#1\relax}
\xydef@\outputxyline@#1{\transxyline@@{#1}%
 \expandafter\xylineSpecial@@\expandafter{\next@}}
\xylet@\resetxyline@@=\resetxyline@
\DOCMODE)

These need to be rebound by a back-end which supports variation in the
line-thickness.

\DOCMODE(
\xydef@\transxyline@#1{\edef\next@{\removePT@#1}}

\xylet@\transxyline@@=\DN@
\xylet@\xylineSpecial@@=\eat@
\DOCMODE)

\DOCMODE2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\paragraph*{The end \& Log}\leavevmode
 
\DOCMODE(
\xyendinput

% $Log: xyline.doc,v $
% Revision 3.6  1998/03/06 01:28:05  krisrose
% Releasing (with Y&Y fonts).
%
% Revision 3.3  1996/12/18  09:22:29  ross
% adjustments for styles now within the kernel code
% fixed problem with line-widths
%
% Revision 3.2  1995/09/19  18:21:41  ross
% Bug fix release.
%
% Revision 3.1  1995/09/05  20:36:33  ross
% Release!
%
% Revision 3.0  1995/07/07  20:13:19  ross
% Major release w/new User's Guide!
%
% Revision 2.13  1995/07/04  15:04:51  ross
% Ready for release of v3.
%
% Revision 2.12  1994/10/25  03:01:14  ross
% Final 3beta release [bug fixes & AMS-LaTeX fitting].
%
% Revision 2.11  1994/07/05  09:27:49  ross
% fixed documentation bug
%
% Revision 2.10  1994/06/15  12:46:03  ross
% Second release 3beta.
% Colour and line style saving works; label colouring bug fixed.
%
% Revision 2.9  1994/06/09  14:39:49  ross
% Release 3beta.
%
% NEW for version 2.9 by Ross Moore.
\DOCMODE)

\DOCMODE3%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% Tell Emacs that this is a LaTeX document and how it is formatted:
% Local Variables:
% mode:latex
% fill-column:77
% fill-prefix:""
% End: