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authorKarl Berry <karl@freefriends.org>2018-02-23 21:54:14 +0000
committerKarl Berry <karl@freefriends.org>2018-02-23 21:54:14 +0000
commit87d871a3d83784d48b71fa3712b9f525bfc710d2 (patch)
treef12f9ffdc697b5af9ee14c06874ec0e2f72c9f94 /Master/texmf-dist/source/latex/l3experimental/l3draw/l3draw.dtx
parentccc63194ce7813106830c8a8755c54d89de831b4 (diff)
l3 (22feb18)
git-svn-id: svn://tug.org/texlive/trunk@46720 c570f23f-e606-0410-a88d-b1316a301751
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+% \iffalse meta-comment
+%
+%% File: l3draw.dtx Copyright(C) 2018 The LaTeX3 Project
+%
+% It may be distributed and/or modified under the conditions of the
+% LaTeX Project Public License (LPPL), either version 1.3c of this
+% license or (at your option) any later version. The latest version
+% of this license is in the file
+%
+% http://www.latex-project.org/lppl.txt
+%
+% This file is part of the "l3experimental bundle" (The Work in LPPL)
+% and all files in that bundle must be distributed together.
+%
+% -----------------------------------------------------------------------
+%
+% The development version of the bundle can be found at
+%
+% https://github.com/latex3/latex3
+%
+% for those people who are interested.
+%
+%<*driver|package>
+\RequirePackage{expl3}
+%</driver|package>
+%<*driver>
+\documentclass[full]{l3doc}
+\begin{document}
+ \DocInput{\jobname.dtx}
+\end{document}
+%</driver>
+% \fi
+%
+% \title{^^A
+% The \pkg{l3draw} package\\ Core drawing support^^A
+% }
+%
+% \author{^^A
+% The \LaTeX3 Project\thanks
+% {^^A
+% E-mail:
+% \href{mailto:latex-team@latex-project.org}
+% {latex-team@latex-project.org}^^A
+% }^^A
+% }
+%
+% \date{Released 2018/02/21}
+%
+% \maketitle
+%
+% \begin{documentation}
+%
+% \section{\pkg{l3draw} documentation}
+%
+% The \pkg{l3draw} package provides a set of tools for creating (vector)
+% drawings in \pkg{expl3}. It is heavily inspired by the \pkg{pgf} layer of
+% the Ti\textit{k}Z system, with many of the interfaces having the same form.
+% However, the code provided here is build entirely on core \pkg{expl3} ideas
+% and uses the \LaTeX3 FPU for numerical support.
+%
+% Numerical expressions in \pkg{l3draw} are handled as floating point
+% expressions, unless otherwise noted. This means that they may contain or
+% omit explicit units. Where units are omitted, they will automatically be
+% taken as given in (\TeX{}) points.
+%
+% The code here is \emph{highly} experimental.
+%
+% \subsection{Drawings}
+%
+% \begin{function}{\draw_begin:, \draw_end:}
+% \begin{syntax}
+% \cs{draw_begin:}
+% ...
+% \cs{draw_end:}
+% \end{syntax}
+% Each drawing should be created within a \cs{draw_begin:}/\cs{draw_end:}
+% function pair. The \texttt{begin} function sets up a number of key
+% data structures for the rest of the functions here: unless otherwise
+% specified, use of |\draw_...| functions outside of this
+% \enquote{environment} is \emph{not supported}.
+%
+% The drawing created within the environment will be inserted into
+% the typesetting stream by the \cs{draw_end:} function, which will
+% switch out of vertical mode if required.
+% \end{function}
+%
+% \subsection{Graphics state}
+%
+% Within the drawing environment, a number of functions control how drawings
+% will appear. Note that these all apply \emph{globally}, though some are
+% rest at the start of each drawing (\cs{draw_begin:}).
+%
+% \begin{function}{\g_draw_linewidth_default_dim}
+% The default value of the linewidth for stokes, set at the start
+% of every drawing (\cs{draw_begin:}).
+% \end{function}
+%
+% \begin{function}{\draw_linewidth:n, \draw_inner_linewidth:n}
+% \begin{syntax}
+% \cs{draw_linewidth:n} \Arg{width}
+% \end{syntax}
+% Sets the width to be used for stroking to the \meta{width} (an
+% \meta{fp expr}).
+% \end{function}
+%
+% \begin{function}{\draw_nonzero_rule:, \draw_evenodd_rule:}
+% \begin{syntax}
+% \cs{draw_nonzero_rule:}
+% \end{syntax}
+% Active either the non-zero winding number or the even-odd rule,
+% respectively, for determining what is inside a fill or clip area.
+% For technical reasons, these command are not influenced by scoping
+% and apply on an ongoing basis.
+% \end{function}
+%
+% \begin{function}
+% {
+% \draw_cap_butt: ,
+% \draw_cap_rectangle: ,
+% \draw_cap_round:
+% }
+% \begin{syntax}
+% \cs{draw_cap_butt:}
+% \end{syntax}
+% Sets the style of terminal stroke position to one of butt, rectangle or
+% round.
+% \end{function}
+%
+% \begin{function}
+% {
+% \draw_join_bevel: ,
+% \draw_join_miter: ,
+% \draw_join_round:
+% }
+% \begin{syntax}
+% \cs{draw_cap_butt:}
+% \end{syntax}
+% Sets the style of stroke joins to one of bevel, miter or round.
+% \end{function}
+%
+% \begin{function}{\draw_miterlimit:n}
+% \begin{syntax}
+% \cs{draw_miterlimit:n} \Arg{limit}
+% \end{syntax}
+% Sets the miter \meta{limit} of lines joined as a miter, as described in the
+% PDF and PostScript manuals. The \meta{limit} is an \meta{fp expr}.
+% \end{function}
+%
+% \subsection{Points}
+%
+% Functions supporting the calculation of points (co-ordinates) are expandable
+% and may be used outside of the drawing environment. When used in this
+% way, they all yield a co-ordinate tuple, for example
+% \begin{verbatim}
+% \tl_set:Nx \l_tmpa_tl { \draw_point:nn { 1 } { 2 } }
+% \tl_show:N \l_tmpa_tl
+% \end{verbatim}
+% gives
+% \begin{verbatim}
+% > \l_tmpa_tl=1pt,2pt.
+% <recently read> }
+% \end{verbatim}
+%
+% This output form is then suitable as \emph{input} for subsequent point
+% calculations, \emph{i.e.}~where a \meta{point} is required it may be
+% given as a tuple. This \emph{may} include units and surrounding
+% parentheses, for example
+% \begin{verbatim}
+% 1,2
+% (1,2)
+% 1cm,3pt
+% (1pt,2cm)
+% 2 * sind(30), 2^4in
+% \end{verbatim}
+% are all valid input forms. Notice that each part of the tuple may itself
+% be a float point expression.
+%
+% Point co-ordinates are relative to the canvas axes, but can be transformed
+% by \cs{draw_point_transform:n}. These manipulation is applied by many
+% higher-level functions, for example path construction, and allows parts of
+% a drawing to be rotated, scaled or skewed. This occurs before writing any
+% data to the driver, and so such manipulations are tracked by the drawing
+% mechanisms. See \cs{driver_draw_transformcm:nnnnnn} for driver-level
+% manipulation of the canvas axes themselves.
+%
+% Notice that in contrast to \pkg{pgf} it is possible to give the positions
+% of points \emph{directly}.
+%
+% \subsubsection{Basic point functions}
+%
+% \begin{function}[EXP]{\draw_point:nn}
+% \begin{syntax}
+% \cs{draw_point:nn} \Arg{x} \Arg{y}
+% \end{syntax}
+% Gives the co-ordinates of the point at \meta{x} and \meta{y}, both of
+% which are \meta{fp expr}.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_polar:nn, \draw_point_polar:nnn}
+% \begin{syntax}
+% \cs{draw_point_polar:nn} \Arg{angle} \Arg{radius}
+% \cs{draw_point_polar:nnn} \Arg{angle} \Arg{radius-a} \Arg{radius-b}
+% \end{syntax}
+% Gives the co-ordinates of the point at \meta{angle} (an \meta{fp expr} in
+% \emph{degrees}) and \meta{radius}. The three-argument version accepts
+% two radii of different lengths.
+%
+% Note the interface here is somewhat different from that in \pkg{pgf}:
+% the one- and two-radii versions in \pkg{l3draw} use separate functions,
+% whilst in \pkg{pgf} they use the same function and a keyword.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_add:nn}
+% \begin{syntax}
+% \cs{draw_point_add:nn} \Arg{point1} \Arg{point2}
+% \end{syntax}
+% Adds \meta{point1} to \meta{point2}.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_diff:nn}
+% \begin{syntax}
+% \cs{draw_point_diff:nn} \Arg{point1} \Arg{point2}
+% \end{syntax}
+% Subtracts \meta{point1} from \meta{point2}.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_scale:nn}
+% \begin{syntax}
+% \cs{draw_point_scale:nn} \Arg{scale} \Arg{point}
+% \end{syntax}
+% Scales the \meta{point} by the \meta{scale} (an \meta{fp expr}).
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_unit_vector:n}
+% \begin{syntax}
+% \cs{draw_point_unit_vector:n} \Arg{point}
+% \end{syntax}
+% Expands to the co-ordinates of a unit vector joining the \meta{point}
+% with the origin.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_transform:n}
+% \begin{syntax}
+% \cs{draw_point_transform:n} \Arg{point}
+% \end{syntax}
+% Evaluates the position of the \meta{point} subject to the current
+% transformation matrix. This operation is applied automatically by
+% most higher-level functions (\emph{e.g.}~path manipulations).
+% \end{function}
+%
+% \subsubsection{Points on a vector basis}
+%
+% As well as giving explicit values, it is possible to describe points
+% in terms of underlying direction vectors. The latter are initially
+% co-incident with the standard Cartesian axes, but may be altered by
+% the user.
+%
+% \begin{function}{\draw_xvec_set:n, \draw_yvec_set:n, \draw_zvec_set:n}
+% \begin{syntax}
+% \cs{draw_xvec_set:n} \Arg{point}
+% \end{syntax}
+% Defines the appropriate base vector to point toward the \meta{point}
+% on the canvas. The standard settings for the $x$- and $y$-vectors are
+% $1\,\mathrm{cm}$ along the relevant canvas axis, whilst for the
+% $z$-vector an appropriate direction is taken.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_vec:nn, \draw_point_vec:nnn}
+% \begin{syntax}
+% \cs{draw_point_vec:nn} \Arg{xscale} \Arg{yscale}
+% \cs{draw_point_vec:nnn} \Arg{xscale} \Arg{yscale} \Arg{zscale}
+% \end{syntax}
+% Expands to the co-ordinate of the point at \meta{xscale} times the
+% $x$-vector and \meta{yscale} times the $y$-vector. The three-argument
+% version extends this to include the $z$-vector.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_vec_polar:nn, \draw_point_vec_polar:nnn}
+% \begin{syntax}
+% \cs{draw_point_vec_polar:nn} \Arg{angle} \Arg{radius}
+% \cs{draw_point_vec_polar:nnn} \Arg{angle} \Arg{radius-a} \Arg{radius-b}
+% \end{syntax}
+% Gives the co-ordinates of the point at \meta{angle} (an \meta{fp expr} in
+% \emph{degrees}) and \meta{radius}, relative to the prevailing
+% $x$- and $y$-vectors. The three-argument version accepts two radii of
+% different lengths.
+%
+% Note the interface here is somewhat different from that in \pkg{pgf}:
+% the one- and two-radii versions in \pkg{l3draw} use separate functions,
+% whilst in \pkg{pgf} they use the same function and a keyword.
+% \end{function}
+%
+% \subsubsection{Intersections}
+%
+% \begin{function}[EXP]{\draw_point_intersect_lines:nnnn}
+% \begin{syntax}
+% \cs{draw_point_intersect_lines:nnnn} \Arg{point1} \Arg{point2} \Arg{point3} \Arg{point4}
+% \end{syntax}
+% Evaluates the point at the intersection of one line, joining
+% \meta{point1} and \meta{point2}, and a second line joining \meta{point3}
+% and \meta{point4}. If the lines do not intersect, or are coincident, and
+% error will occur.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_intersect_circles:nnnn}
+% \begin{syntax}
+% \cs{draw_point_intersect_circles:nnnnn}
+% \Arg{center1} \Arg{radius1} \Arg{center2} \Arg{radius2} \Arg{root}
+% \end{syntax}
+% Evaluates the point at the intersection of one circle with
+% \meta{center1} and \meta{radius1}, and a second circle with \meta{center2}
+% and \meta{radius2}. If the circles do not intersect, or are coincident, and
+% error will occur.
+%
+% Note the interface here has a different argument ordering from that in
+% \pkg{pgf}, which has the two centers then the two radii.
+% \end{function}
+%
+% \subsubsection{Interpolations}
+%
+% \begin{function}[EXP]{\draw_point_interpolate_line:nnn}
+% \begin{syntax}
+% \cs{draw_point_interpolate_line:nnn} \Arg{part} \Arg{point1} \Arg{point2}
+% \end{syntax}
+% Expands to the point which is \meta{part} way along the line joining
+% \meta{point1} and \meta{point2}. The \meta{part} may be an interpolation or
+% an extrapolation, and is a floating point value expressing a percentage
+% along the line, \emph{e.g.}~a value of \texttt{0.5} would be half-way
+% between the two points.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_interpolate_distance:nnn}
+% \begin{syntax}
+% \cs{draw_point_interpolate_distance:nnn} \Arg{distance} \Arg{point expr1} \Arg{point expr2}
+% \end{syntax}
+% Expands to the point which is \meta{distance} way along the line joining
+% \meta{point1} and \meta{point2}. The \meta{distance} may be an interpolation
+% or an extrapolation.
+% \end{function}
+%
+% \begin{function}[EXP]{\draw_point_interpolate_curve:nnnnnn}
+% \begin{syntax}
+% \cs{draw_point_interpolate_curve:nnnnnn} \Arg{part}
+% \Arg{start} \Arg{control1} \Arg{control2} \Arg{end}
+% \end{syntax}
+% Expands to the point which is \meta{part} way along the curve between
+% \meta{start} and \meta{end} and defined by \meta{control1} and
+% \meta{control2}. The \meta{part} may be an interpolation or
+% an extrapolation, and is a floating point value expressing a percentage
+% along the curve, \emph{e.g.}~a value of \texttt{0.5} would be half-way
+% along the curve.
+% \end{function}
+%
+% \subsection{Paths}
+%
+% Paths are constructed by combining one or more operations before applying
+% one or more actions. Thus until a path is \enquote{used}, it may be
+% manipulated or indeed discarded entirely. Only one path is active at
+% any one time, and the path is \emph{not} affected by \TeX{} grouping.
+%
+% \begin{function}{\draw_path_corner_arc:n}
+% \begin{syntax}
+% \cs{draw_path_corner_arc:n} \Arg{length}
+% \end{syntax}
+% Sets the degree of rounding applied to corners in a path: if the
+% \meta{length} is \texttt{0pt} then no rounding applies. The value of the
+% \meta{length} is local to the current \TeX{} group. \emph{At present,
+% corner arcs are not activated in the code.}
+% \end{function}
+%
+% \begin{function}{\draw_path_moveto:n}
+% \begin{syntax}
+% \cs{draw_path_moveto:n} \Arg{point}
+% \end{syntax}
+% Moves the reference point of the path to the \meta{point}, but will
+% not join this to any previous point.
+% \end{function}
+%
+% \begin{function}{\draw_path_lineto:n}
+% \begin{syntax}
+% \cs{draw_path_lineto:n} \Arg{point}
+% \end{syntax}
+% Joins the current path to the \meta{point} with a straight line.
+% \end{function}
+%
+% \begin{function}{\draw_path_curveto:nnn}
+% \begin{syntax}
+% \cs{draw_path_curveto:nnn} \Arg{control1} \Arg{control2} \Arg{end}
+% \end{syntax}
+% Joins the current path to the \meta{end} with a curved line defined by
+% cubic Bézier points \meta{control1} and \meta{control2}.
+% \end{function}
+%
+% \begin{function}{\draw_path_curveto:nn}
+% \begin{syntax}
+% \cs{draw_path_curveto:nn} \Arg{control} \Arg{end}
+% \end{syntax}
+% Joins the current path to the \meta{end} with a curved line defined by
+% quadratic Bézier point \meta{control}.
+% \end{function}
+%
+% \begin{function}{\draw_path_arc:nnn, \draw_path_arc:nnnn}
+% \begin{syntax}
+% \cs{draw_path_arc:nnn} \Arg{angle1} \Arg{angle2} \Arg{radius}
+% \cs{draw_path_arc:nnnn} \Arg{angle1} \Arg{angle2} \Arg{radius-a} \Arg{radius-b}
+% \end{syntax}
+% Joins the current path with an arc between \meta{angle1} and \meta{angle2}
+% and of \meta{radius}. The four-argument version accepts two radii of
+% different lengths.
+%
+% Note the interface here has a different argument ordering from that in
+% \pkg{pgf}, which has the two centers then the two radii.
+% \end{function}
+%
+% \begin{function}{\draw_path_arc_axes:nnnn}
+% \begin{syntax}
+% \cs{draw_path_arc_axes:nnn} \Arg{angle1} \Arg{angle2} \Arg{vector1} \Arg{vector2}
+% \end{syntax}
+% Appends the portion of an ellipse from \meta{angle1} to \meta{angle2} of an
+% ellipse with axes along \meta{vector1} and \meta{vector2} to the current path.
+% \end{function}
+%
+% \begin{function}{\draw_path_ellipse:nnnn}
+% \begin{syntax}
+% \cs{draw_path_ellipse:nnn} \Arg{center} \Arg{vector1} \Arg{vector2}
+% \end{syntax}
+% Appends an ellipse at \meta{center} with axes along \meta{vector1} and
+% \meta{vector2} to the current path.
+% \end{function}
+%
+% \begin{function}{\draw_path_circle:nn}
+% \begin{syntax}
+% \cs{draw_path_circle:nn} \Arg{center} \Arg{radius}
+% \end{syntax}
+% Appends a circle of \meta{radius} at \meta{center} to the current path.
+% \end{function}
+%
+% \begin{function}{\draw_path_rectangle:nn, \draw_path_rectangle_corners:nn}
+% \begin{syntax}
+% \cs{draw_path_rectangle:nn} \Arg{lower-left} \Arg{displacement}
+% \cs{draw_path_rectangle_corners:nn} \Arg{lower-left} \Arg{top-right}
+% \end{syntax}
+% Appends a rectangle starting at \meta{lower-left} to the current path,
+% with the size of the rectangle determined either by a \meta{displacement}
+% or the position of the \meta{top-right}.
+% \end{function}
+%
+% \begin{function}{\draw_path_grid:nnnn}
+% \begin{syntax}
+% \cs{draw_path_grid:nnnn} \Arg{xspace} \Arg{yspace} \Arg{lower-left} \Arg{upper-right}
+% \end{syntax}
+% Constructs a grid of \meta{xspace} and \meta{yspace} from the
+% \meta{lower-left} to the \meta{upper-right}, and appends this to the
+% current path.
+% \end{function}
+%
+% \begin{function}{\draw_path_close:}
+% \begin{syntax}
+% \cs{draw_path_close:}
+% \end{syntax}
+% Closes the current part of the path by appending a straight line from
+% the current point to the starting point of the path.
+% \end{function}
+%
+% \begin{function}{\draw_path_use:n, \draw_path_use_clear:n}
+% \begin{syntax}
+% \cs{draw_path_use:n} \Arg{action(s)}
+% \end{syntax}
+% Inserts the current path, carrying out one ore more possible \meta{actions}
+% (a comma list):
+% \begin{itemize}
+% \item \texttt{clear} Resets the path to empty
+% \item \texttt{clip} Clips any content outside of the path
+% \item \texttt{draw}
+% \item \texttt{fill} Fills the interior of the path with the current
+% file color
+% \item \texttt{stroke} Draws a line along the current path
+% \end{itemize}
+% \end{function}
+%
+% \subsection{Color}
+%
+% \begin{function}{\draw_color:n, \draw_fill:n, \draw_stroke:n}
+% \begin{syntax}
+% \cs{draw_color:n} \Arg{color expression}
+% \end{syntax}
+% Evaluates the \meta{color expression} as described for \pkg{l3color}.
+% \end{function}
+%
+% \subsection{Transformations}
+%
+% Points are normally used unchanged relative to the canvas axes. This can
+% be modified by applying a transformation matrix. The canvas axes themselves
+% may be adjusted using \cs{driver_draw_transformcm:nnnnnn}: note that this
+% is transparent to the drawing code so is not tracked.
+%
+% \begin{function}{\draw_transform_reset:}
+% \begin{syntax}
+% \cs{draw_transform_reset:}
+% \end{syntax}
+% Resets the matrix to the identity.
+% \end{function}
+%
+% \begin{function}{\draw_transform_concat:nnnnn}
+% \begin{syntax}
+% \cs{draw_transform_concat:nnnnn}
+% \Arg{a} \Arg{b} \Arg{c} \Arg{d} \Arg{vector}
+% \end{syntax}
+% Appends the given transformation to the currently-active one. The
+% transformation is made up of a matrix \meta{a}, \meta{b}, \meta{c} and
+% \meta{d}, and a shift by the \meta{vector}.
+% \end{function}
+%
+% \begin{function}{\draw_transform:nnnnn}
+% \begin{syntax}
+% \cs{draw_transform:nnnnn}
+% \Arg{a} \Arg{b} \Arg{c} \Arg{d} \Arg{vector}
+% \end{syntax}
+% Applies the transformation matrix specified, over-writing any existing
+% matrix. The transformation is made up of a matrix \meta{a}, \meta{b},
+% \meta{c} and \meta{d}, and a shift by the \meta{vector}.
+% \end{function}
+%
+% \begin{function}{\draw_transform_triangle:nnn}
+% \begin{syntax}
+% \cs{draw_transform_triangle:nnn}
+% \Arg{origin} \Arg{point1} \Arg{point2}
+% \end{syntax}
+% Applies a transformation such that the co-ordinates $(0, 0)$, $(1, 0)$
+% and $(0, 1)$ are given by the \meta{origin}, \meta{point1} and
+% \meta{point2}, respectively.
+% \end{function}
+%
+% \begin{function}{\draw_transform_invert:}
+% \begin{syntax}
+% \cs{draw_transform_invert:}
+% \end{syntax}
+% Inverts the current transformation matrix and reverses the current
+% shift vector.
+% \end{function}
+%
+% \end{documentation}
+%
+% \begin{implementation}
+%
+% \section{\pkg{l3draw} implementation}
+%
+% \begin{macrocode}
+%<*initex|package>
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<@@=draw>
+% \end{macrocode}
+%
+% \begin{macrocode}
+%<*package>
+\ProvidesExplPackage{l3draw}{2018/02/21}{}
+ {L3 Experimental core drawing support}
+%</package>
+% \end{macrocode}
+%
+% \begin{macrocode}
+\RequirePackage { l3color }
+% \end{macrocode}
+%
+% Everything else is in the sub-files!
+%
+% \begin{macrocode}
+%</initex|package>
+% \end{macrocode}
+%
+% \end{implementation}
+%
+% \PrintIndex