This is Info file texdraw, produced by Makeinfo-1.64 from the input file texdraw.texi. This file documents TeXdraw, a system for producing PostScript drawings from TeX. Copyright (C) 1993-95 Peter Kabal Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.  File: texdraw, Node: Top, Next: Introduction, Prev: (dir), Up: (dir) TeXdraw ******* TeXdraw is a collection of macros that allow drawings to be created from *within* TeX. This is edition 2.0 of the TeXdraw documentation. * Menu: * Introduction:: * TeXdraw Commands:: * Drawing Segments and Scaling:: * Using TeXdraw with LaTeX:: * More Details:: * PostScript Commands:: * TeXdraw Toolbox:: * Examples:: * Command Listing:: Indices * Concept Index:: * Command Index:: -- The Detailed Node Listing -- Introduction * Distribution:: TeXdraw Commands * Accessing TeXdraw:: * Command syntax:: * TeXdraw coordinates:: * Coordinate specification:: * Line vectors:: * TeX text:: * Circles and arcs:: * Bezier curves:: * Fill commands:: Drawing Segments and Scaling * Drawing segments:: * Drawing paths:: * Saving positions:: * Scaling coordinates:: * Drawing size:: * Initial current position:: Using TeXdraw with LaTeX * PostScript printer drivers:: More Details * Errors while using TeXdraw:: * Extending TeXdraw:: * How TeXdraw merges graphics and text:: Extending TeXdraw * Scaling:: * Resolution:: * Text placement:: * Intermediate PostScript file:: PostScript Commands TeXdraw Toolbox * Coordinate parsing:: * Real arithmetic:: * Arrow curve:: Examples * Block diagram:: * Filter response graph:: * Geometric construction:: Command Listing Command Index Concept Index  File: texdraw, Node: Introduction, Next: TeXdraw Commands, Prev: Top, Up: Top Introduction ************ TeX is a powerful typesetting program which allows for complex text layouts but by itself lacks a general graphics capability. However, when coupled with an appropriate printer driver program, external graphics files can be inserted into the printed document. In this mode, TeX is instructed to leave space for a drawing. The drawing is inserted by the printer driver program. The TeXdraw macros described here generate the external graphics file from within TeX and generate the instructions to the the print driver program to position the graphics at the appropriate position on the page. TeXdraw consists of a set of TeX macros that create line drawings and other figures. The drawing primitives include solid lines, patterned lines, Bezier curves, circles and arrows. Other commands allow for the filling of a region with a gray level. The drawing commands generate PostScript code. This limits TeXdraw to systems which use PostScript printers. TeXdraw also provides commands to position TeX text, including mathematics, on the drawing. The final drawing, with text and graphics, can be positioned on the page like any other TeX box. The basic TeXdraw macros for TeX use the `\special' syntax recognized by the printer driver program `dvips'. However, when invoked as a LaTeX2e package, the TeXdraw macros can be used with any of the PostScript printer driver programs supported by the standard `graphics' package for LaTeX2e. The basic TeXdraw macros provide only simple drawing commands. However, TeXdraw provides a drawing segment environment which allows parameter changes and coordinate scaling changes to be kept local to the drawing segment. This facility, together with TeX's macro capabilities allows one to modularize drawing units and extend TeXdraw by building more complex graphics entities from simpler elements. * Menu: * Distribution::  File: texdraw, Node: Distribution, Up: Introduction Distribution information ======================== The TeXdraw routines are provided free of charge without warranty of any kind. Note that the TeXdraw routines are copyrighted. They may be distributed freely provided that the recipients also acquire the right to distribute them freely. The notices to this effect must be preserved when the source files are distributed.  File: texdraw, Node: TeXdraw Commands, Next: Drawing Segments and Scaling, Prev: Introduction, Up: Top Using the TeXdraw Commands ************************** The main TeXdraw macros (commands) are defined in the file `texdraw.tex'. These macros may be used directly in TeX. The file `texdraw.sty' provides an interface for use with LaTeX2e. The following sections describe the basic commands for TeXdraw. * Menu: * Accessing TeXdraw:: * Command syntax:: * TeXdraw coordinates:: * Coordinate specification:: * Line vectors:: * TeX text:: * Circles and arcs:: * Bezier curves:: * Fill commands::  File: texdraw, Node: Accessing TeXdraw, Next: Command syntax, Up: TeXdraw Commands Accessing TeXdraw ================= The form of the user command to run the TeX program depends on which version of TeX is being used, and which other macro packages are preloaded as format files. Typically, installations have at least two versions of TeX -- plain TeX which includes basic typesetting macros (usually invoked as `tex') and LaTeX2e which includes the LaTeX2e typesetting macros (usually invoked as `latex'). An older version of LaTeX, version 2.09, may also be available. The TeXdraw macros can be used with plain TeX and with either version of LaTeX. For use with plain TeX, the user must read in the TeXdraw macros from the file `texdraw.tex'. \input texdraw % Read in the TeXdraw macros ... \btexdraw ... % TeXdraw commands to generate a drawing \etexdraw For use with LaTeX version 2.09, the user reads in the TeXdraw macros from the file `texdraw.tex' and optionally defines the `\begin{texdraw}' / `\end{texdraw}' environment. \documentstyle[11pt]{article} % Article style with the 11pt size options ... \input texdraw % Read in the TeXdraw macros \newenvironment{texdraw}{\leavevmode\btexdraw}{\etexdraw} ... \begin{texdraw} ... % TeXdraw commands to generate a drawing \end{texdraw} ... \end{document} For use with LaTeX2e, the user must load the `texdraw' package (file `texdraw.sty'). This package file defines the `\begin{texdraw}' / `\end{texdraw}' environment, brings in the standard `graphics' package and reads in the file `texdraw.tex' containing the definitions of the TeXdraw macros. \documentclass[11pt]{article} % Article class with the 11pt size option \usepackage{texdraw} % TeXdraw commands \begin{document} ... \begin{texdraw} ... % TeXdraw commands to generate a drawing \end{texdraw} ... \end{document} As the TeXdraw commands are processed by TeX, an intermediate PostScript file is generated. The intermediate PostScript has a name of the form `NAME.ps1'. The name part is derived from the name of the main TeX file being processed. If more than one drawing is produced, the digit in the file name extension is incremented.(1) The TeXdraw commands to produce a drawing are inserted between `\btexdraw' and `\etexdraw' commands, or for LaTeX, between `\begin{texdraw}' and `\end{texdraw}' commands. This results in a TeX box of appropriate size containing the drawing generated by the TeXdraw commands. The TeXdraw box can be positioned in a document like any other TeX box. The `\centertexdraw{...}' macro centers the box generated by TeXdraw. The vertical space taken up is equal to the vertical size of the drawing. The `\centertexdraw' macro is normally used in vertical mode (between paragraphs). A `\par' command (a blank line will do also) before a `\centertexdraw' command will terminate horizontal mode and return to vertical mode. For LaTeX, a structured equivalent to the `\centertexdraw{...}' command is shown below. \begin{center} \begin{texdraw} ... \end{texdraw} \end{center} The `\everytexdraw' command can be used to define a set of TeXdraw commands that will be executed at the beginning of every TeXdraw drawing. It is invoked as `\everytexdraw{ ...}', with the desired TeXdraw commands as arguments. `\btexdraw' Start a TeXdraw drawing. The drawing is terminated with an `\etexdraw' command. `\etexdraw' End a TeXdraw drawing started with a `\btexdraw' command. The resulting TeXdraw drawing is placed in a box with height equal to the height of the drawing and width equal to the width of the drawing. The depth of the box is zero. `\begin{texdraw}' Start a TeXdraw drawing. The drawing is terminated with an `\end{texdraw}' command. This command is for use with LaTeX. `\end{texdraw}' End a TeXdraw drawing started with a `\begin{texdraw}' command. The resulting TeXdraw drawing is placed in a box with height equal to the height of the drawing and width equal to the width of the drawing. The depth of the box is zero. This command is for use with LaTeX. `\centertexdraw{ ... }' Center a TeXdraw box horizontally. The argument contains TeXdraw commands. The resulting box has the horizontal size `\hsize' and height equal to the height of the drawing. `\everytexdraw{ ... }' Specify TeXdraw commands to be executed at the beginning of every TeXdraw drawing. ---------- Footnotes ---------- (1) After the ninth PostScript file, the name of the intermediate PostScript file takes the form `NAME.p10', with the number increasing from 10 with each file.  File: texdraw, Node: Command syntax, Next: TeXdraw coordinates, Prev: Accessing TeXdraw, Up: TeXdraw Commands Command syntax ============== Generally TeXdraw commands that take a single argument need a terminating blank or newline after the argument. Arguments that are self-delimiting, such as coordinates within parentheses and text within braces, do not need the terminating blank. However, even when not needed by the defining syntax of the command, blanks following command arguments are allowed and ignored within the TeXdraw environment. On entering the TeXdraw environment, TeX is in internal vertical mode (vertical mode inside a `\vbox'). In this mode, spaces can be placed freely between commands. However, any other extraneous input that generates output that is not part of the TeXdraw environment is disallowed. Blank lines are interpreted as paragraph breaks, equivalent to a `\par' command. The TeXdraw macro `\centertexdraw' is defined with the `\long' attribute to allow `\par' commands and blank lines to be interspersed between TeXdraw commands. The `\btexdraw' and `\etexdraw' commands also allow `\par' command and blank lines to be included.  File: texdraw, Node: TeXdraw coordinates, Next: Coordinate specification, Prev: Command syntax, Up: TeXdraw Commands TeXdraw coordinates =================== The TeXdraw coordinate system has increasing X to the right and increasing Y upward. The coordinates (without the unit) are floating point numbers. Integer values can be written without a decimal point. The size of the drawing is determined by the maximum excursions of the coordinates specified in TeXdraw commands. Consider the following example of TeXdraw commands to draw a simple figure. \centertexdraw{ \drawdim cm \linewd 0.02 \move(2 2) \lvec(3 3) \lvec(2 4) \lvec(1 3) \lvec(2 2) \textref h:C v:C \htext(2 3){$\sum \rho_n$} } This drawing uses units of centimetres, with a line width of 0.02 cm. The X coordinate ranges between 1 and 3 while the Y coordinate ranges between 2 and 4. When included into a document, the size of the drawing is 2 cm by 2 cm. The drawing is placed in a TeX box, with the lower lefthand corner of the box corresponding to TeXdraw coordinate `(1 2)' and the upper righthand corner at `(3 4)'. The `\centertexdraw' command centers the drawing horizontally. The `\textref' command controls the centering of the text. The text in this drawing is centered (both horizontally and vertically) at the coordinate `(2 3)'.  File: texdraw, Node: Coordinate specification, Next: Line vectors, Prev: TeXdraw coordinates, Up: TeXdraw Commands Coordinate specification ======================== Coordinates are specified within parentheses, with blanks (but no comma) between the values. Leading blanks and trailing blanks are permitted within the parentheses. The coordinates refer to units, which are specified by the `\drawdim' command. The default is inches, but any valid TeX dimension unit can be specified. Symbolic specification of saved coordinate values will be discused later (*note Saving positions::.). `\drawdim DIM' Set the units to DIM. The argument DIM can be any valid TeX dimension unit. The units are used to interpret coordinate values. Examples of valid units: `cm', `mm', `in', `pt', and `bp'. Examples of coordinate and scaling specifications: `\drawdim {cm} \move(2 2)' Set the units to centimetres, move to a position 2 cm to the right and 2 cm up from the origin of the drawing coordinate system. `\drawdim bp' Set the units to big points. `\lvec ( 2.2 +5.5) \lvec(2.3 -2) \lvec(2.2 5.4 )' Examples of acceptable coordinate specifications.  File: texdraw, Node: Line vectors, Next: TeX text, Prev: Coordinate specification, Up: TeXdraw Commands Line vectors ============ TeXdraw implements moves, line vectors and arrow vectors. There are both absolute and relative motion versions of these vector commands. TeXdraw maintains a current position. Lines are drawn from the current position to a new coordinate, with the new coordinate becoming the new current position. An explicit move can be used to establish a new current position. The position `(0 0)' is used if there is no move to an initial current position. The `\move' and `\rmove' commands establish a new current position without drawing a line. The `\lvec' and `\rlvec' commands draw a line from the current position to a new position, which then becomes the new current position. The `\avec' and `\ravec' commands draw a line with an arrowhead from the current position to a new coordinate, which then becomes the new current position. The tip of the arrow is at the new current position. The direction of the arrow follows the direction of the line. Since this direction is undefined for zero length vectors, these are not allowed for `\avec' or `\ravec'. Zero length arrow vectors will generate a PostScript print error: `undefinedresult'. For any non-zero length vector, the full size arrowhead is drawn, even if that arrowhead is longer than the line length. The absolute motion versions of these commands specify the coordinate of the final position. `\move (X Y)' Move to coordinate `(X Y)'. The new current position is `(X Y)'. `\lvec (X Y)' Draw a line from the current position to coordinate `(X Y)'. The new current position is `(X Y)'. `\avec (X Y)' Draw a line with an arrowhead from the current position to `(X Y)'. The new current position is `(X Y)'. The arrowhead is aligned with the line, with the tip at `(X Y)'. The relative motion versions of these commands interpret the coordinates as displacements relative to the current position. Given the displacements `(DX DY)' as a parameter, each of the relative motion commands moves DX units in the X direction and DY units in the Y direction. `\rmove (DX DY)' Move from the current position, DX units in the X direction and DY units in the Y direction. The final position becomes the new current position. `\rlvec (DX DY)' Draw a line from the current position, DX units in the X direction and DY units in the Y direction. The final position becomes the new current position. `\ravec (DX DY)' Draw a line with an arrowhead from the current position, DX units in the X direction and Y units in the Y direction. The final position becomes the new current position. The arrowhead is aligned with the line, with the tip at the new current position. Lines can be customized with commands to change the line width, line pattern and line gray level rendition. In addition, commands for changing the type and size of the arrowhead are available. `\linewd WIDTH' Set the line width to WIDTH units. Initially WIDTH is 0.01 inches (corresponding to 3 pixels at 300 pixels to the inch). `\lpatt (PATTERN)' Set lines to have the pattern `(PATTERN)'. A pattern is a sequence of on/off lengths separated by blanks and enclosed in parentheses. The lengths alternately specify the length of a dash and the length of a gap between dashes. Each length is interpreted using the current scaling and drawing units. The pattern is used cyclically. The empty pattern signifies a solid line. The initial line pattern is a solid line, corresponding to the empty pattern `\lpatt ()'. `\setgray LEVEL' Set the gray level of lines. Gray levels are real values from 0 (black) through intermediate values (gray) to 1 (white). The initial gray level is 0 corresponding to black. `\arrowheadtype t:TYPE' Set the arrowhead type to TYPE, where TYPE is one of `F', `T', `W', `V', or `H'. There are two kinds of arrowheads. The first kind is a triangle. There are 3 variants: type `T' is an empty triangle, type `F' is a filled triangle (using the current gray level for lines), type `W' is a triangle filled with white. The second kind of arrowhead is an open ended Vee. There are 2 variants: type `V' has the stem continue to the tip, type `H' has the stem stop at the base of the arrowhead. The initial arrowhead type is `T'. `\arrowheadsize l:LENGTH w:WIDTH' Set the arrowhead size to be LENGTH units long and WIDTH units wide. The width is measured across the "base" of the arrowhead. The initial arrowhead size has a LENGTH of 0.16 inches and a WIDTH of 0.08 inches. Note that the lines which outline the arrowhead will be drawn with the same line pattern used for the stem. Normally, arrow vectors are drawn with the line pattern set for a solid line. Note that the fill level used for the `F' variant of the arrowhead uses the same gray level as used for lines. The difference between the `T' variant and the `W' variant only shows up if the arrowhead is placed over non-white areas of the drawing. The `W' variant obliterates the area under the arrowhead. Examples of line parameter and arrowhead settings are shown in the following code. \centertexdraw{ \drawdim in \linewd 0.03 \setgray 0.6 \arrowheadtype t:F \avec(0 0.5) \linewd 0.01 \setgray 0 \arrowheadtype t:V \avec(0.5 0.5) \linewd 0.015 \lpatt(0.067 0.1) \lvec (1 0) \linewd 0.02 \lpatt() \arrowheadtype t:T \avec(1.5 0.5) \arrowheadtype t:H \avec(2.0 0.5) \setgray 0.4 \arrowheadtype t:W \avec(3.0 0) }  File: texdraw, Node: TeX text, Next: Circles and arcs, Prev: Line vectors, Up: TeXdraw Commands TeX text ======== Text may be superimposed on the drawing. The text argument of the `\htext' command is in horizontal mode. This text can be ordinary text, math mode expressions, or even more complicated boxes consisting of tables and the like. The resulting TeX text is placed in a box. The reference point of the box can be chosen to be one of nine locations: horizontally left, center or right; vertically top, center or bottom. The `\htext' command takes one of two forms. `\htext (X Y){TEXT}' `\htext {TEXT}' The first form of this command places the TeX text TEXT horizontally with the text reference point at the coordinate `(X Y)'. The new current position is `(X Y)'. The second form of this command places the TeX text TEXT horizontally with the text reference point at the current position. The text reference point is set with the `\textref' command. Text can be placed vertically using the `\vtext' command. The text argument is in horizontal mode. The TeX text is placed in a box and then rotated counterclockwise. The reference point is the point in the box, *before* rotation of the text. Not all PostScript printer drivers support vertical text. `\vtext (x y){TEXT}' `\vtext {TEXT}' The first form of this command places the TeX text TEXT vertically with the text reference point at the coordinate `(X Y)'. The new current position is `(X Y)'. The second form of this command places the TeX text TEXT vertically with the text reference point at the current position. In both cases, the TeX text is placed in a box and the box is rotated counterclockwise by 90 degrees about the text reference point. The text reference point is set with the `\textref' command. Text can be placed at an arbitrary angle using the `\rtext' command. The text argument is in horizontal mode. The TeX text is placed in a box and then rotated counterclockwise. The reference point is the point in the box, *before* rotation of the text. Not all PostScript printer drivers support rotated text. `\rtext td:ANGLE (x y){TEXT}' `\rtext td:ANGLE {TEXT}' The first form of this command places the TeX text TEXT at an angle with the text reference point at the coordinate `(X Y)'. The new current position is `(X Y)'. The second form of this command places the TeX text TEXT at an angle with the text reference point at the current position. In both cases, the TeX text is placed in a box and the box is rotated counterclockwise by ANGLE degrees about the text reference point. The text reference point is set with the `\textref' command. The reference point for subsequent TeX text in a `\htext', `\vtext' or `\rtext' command is set with the `\textref' command. `\textref h:H-REF v:V-REF' Set the text reference point for subsequent text commands. The horizontal reference point H-REF is one of `L', `C' or `R' (left, center or right). The vertical reference point V-REF is one of `T', `C' or `B' (top, center or bottom). For rotated text, the reference point is determined before rotation. The initial text reference point corresponds to `\textref h:L v:B'. The font used to render the text is determined as for any other TeX text. Normally the font used outside of TeXdraw is in effect. If desired, other fonts can be specified as part of the text. Any font changes within a TeXdraw text command remain local to that command. Only the coordinate of the text reference point in a `\htext', `\vtext' or `\rtext' command is used in calculating the size of the drawing. This means that text itself can spill outside of the drawing area determined by TeXdraw. The area of the drawing can be increased to include the text by issuing additional `\move' commands. \centertexdraw{ \avec(-0.75 -0.25) \textref h:R v:C \htext{H-text} \move(0 0) \avec(-0.75 +0.25) \textref h:R v:B \htext{H-text} \move(0 0) \avec(0 +0.5) \textref h:L v:T \vtext{V-text} \move(0 0) \avec(+0.75 +0.25) \textref h:L v:B \htext{H-text} \move(0 0) \avec(+0.75 -0.25) \textref h:L v:C \htext{H-text} }  File: texdraw, Node: Circles and arcs, Next: Bezier curves, Prev: TeX text, Up: TeXdraw Commands Circles, ellipses and arcs ========================== TeXdraw supplies commands to generate circles, ellipses and arcs. There are two forms of the circle command. The `\lcir' command draws a circle of given radius. The `\fcir' command draws a filled circle. In the latter case, the circle is filled by a specified gray level. For the filled circle, the line defining the circumference of the circle is not drawn. Note that the gray level area filled in by the `\fcir' command is opaque, even if the fill is chosen to be white. For either form of the circle command, the drawing size is increased if necessary to contain the circle. The `\lellip' command generates an ellipse specified by the radius of the ellipse in the X direction and the radius of the ellipse in the Y direction. The ellipse is symmetrical about horizontal and vertical lines drawn through the current point. The `\fellip' command draws a filled ellipse. In the latter case, the ellipse is filled by a specified gray level. For the filled ellipse, the line defining the boundary of the ellipse is not drawn. For either form of the ellipse command, the drawing size is increased if necessary to contain the ellipse. The `\larc' command generates a counterclockwise arc specified by a start angle in degrees and an end angle in degrees. The center of the arc is the current position. Only the arc is drawn, not the line joining the center to the beginning of the arc. Note that the `\larc' command does not affect the size of the drawing. `\lcir r:RADIUS' Draw a circle with center at the current position. The radius is specified by RADIUS. This command draws a line along the circumference of the circle. The drawing size is increased if necessary to contain the circle. `\fcir f:LEVEL r:RADIUS' Draw a filled circle with center at the current position. The radius is specified by RADIUS. The circle is painted with the gray level specified by LEVEL. A gray level of 1 corresponds to white, with decreasing values getting darker. The level 0 is full black. This command does not draw a line along the circumference. The drawing size is increased if necessary to contain the circle. `\lellip rx:X-RADIUS ry:Y-RADIUS' Draw an ellipse with center at the current position. The radius in the X direction is specified by X-RADIUS. The radius in the Y direction is specified by Y-RADIUS. The drawing size is increased if necessary to contain the ellipse. `\fellip f:LEVEL rx:X-RADIUS ry:Y-RADIUS' Draw a filled ellipse with center at the current position. The radius in the X direction is specified by X-RADIUS. The radius in the Y direction is specified by Y-RADIUS. The ellipse is painted with the gray level specified by LEVEL. A gray level of 1 corresponds to white, with decreasing values getting darker. The level 0 is full black. This command does not draw a line along the boundary of the ellipse. The drawing size is increased if necessary to contain the ellipse. `\larc r:RADIUS sd:START-ANGLE ed:END-ANGLE' Draw a counterclockwise arc. The center of the arc is at the current position. The radius is specified by RADIUS. The start and end angles (in degrees) are specified by START-ANGLE and END-ANGLE. This command does not affect the limits (size) of the drawing. As an example, the following commands draw a filled circle, and superimpose an arc. \centertexdraw{ \linewd 0.02 \fcir f:0.7 r:1 \larc r:1 sd:45 ed:135 \lvec (+0.707 +0.707) \move (0 0) \lvec (-0.707 +0.707) } Note that for the arc command, the resulting figure can spill outside of the TeXdraw box as determined by the maximum excursions of the coordinates. Extra moves can be used to compensate for the size of the arc.  File: texdraw, Node: Bezier curves, Next: Fill commands, Prev: Circles and arcs, Up: TeXdraw Commands Bezier curves ============= Bezier curves in TeXdraw use 4 reference coordinates, two as the end points and two others to control the shape of the curve. Let the 4 points be `(X0 Y0)', `(X1 Y1)', `(X2 Y2)' and `(X3 Y3)'. The curve starts out tangent to the line joining the first two points and ends up tangent to the line joining the second two points. The control points "pull" at the curve to control the curvature. The amount of pull increases with the distance of the control point from the endpoint. As the parameter u varies from 0 to 1, the coordinates of the Bezier curve are given by a pair of parametric cubic equations, x(u) = (1-u)^3 x0 + 3u (1-u)^2 x1 + 3u^2 (1-u) x2 + u^3 x3 y(u) = (1-u)^3 y0 + 3u (1-u)^2 y1 + 3u^2 (1-u) y2 + u^3 y3 . `\clvec (X1 Y1)(X2 Y2)(X3 Y3)' Draw a Bezier curve from the current position to the coordinate `(X3 Y3)' which becomes the new current position. The coordinates `(X1 Y1)' and `(X2 Y2)' serve as control points for the curve. Only the last coordinate given is used to update the size of the drawing. Note that only 3 coordinate pairs are specified. The other point is the current position before the `\clvec' command is executed. Only the last coordinate specified in the `\clvec' command is used to determine the extent of the drawing. While the Bezier curve passes through the old current position and the new current position, in general the curve will not reach the intermediate control points. The curve is always entirely enclosed by the convex quadrilateral defined by the two end points and the two control points. Note that the curve may pass outside the limits of the drawing as determined by the end point of the curve. A simple Bezier curve is produced by the following example. \btexdraw \move (0 0) \clvec (0 1)(1 0)(1 1) \etexdraw  File: texdraw, Node: Fill commands, Prev: Bezier curves, Up: TeXdraw Commands Fill commands ============= PostScript deals with paths consisting of line segments. The paths can be closed and the interior of the closed region filled. From TeXdraw, paths start with a `\move' or `\rmove' command and continue with `\lvec', `\rlvec' or `\clvec' commands. The TeXdraw fill commands close the path and fill the interior of the closed region. Closing the path means that effectively another `\lvec' line is drawn from the last point specified to the initial point. TeXdraw provides two forms of the fill command. The `\ifill' fills the interior of the region with the given gray level. The lines defining the path are not drawn. The `\lfill' command fills the region defined by the closed path and draws a line along the enclosing path. Note for both forms of the fill command, the gray level used for filling is opaque, even if the gray level is chosen to be white. `\lfill f:LEVEL' Close the current path, draw the line around the path using the current grey level for lines and paint the interior of the region with specified gray level LEVEL. Gray levels are real values from 0 (black) through intermediate values (grays) to 1 (white). `\ifill f:LEVEL' Close the current path and paint the interior of the region with gray level LEVEL. The line around the path is not drawn. Gray levels are real values from 0 (black) through intermediate values (grays) to 1 (white). The following example draws a "flag" with the interior filled in. The path around the boundary is given in a clockwise order to define a closed path. We could take advantage of the fact that the fill command will close an open path to eliminate one of the `\lvec' commands. \centertexdraw{ \move (0.5 0) \lvec (0 0.5) \clvec (0.5 0.85)(1 0.65)(1.5 1) \lvec (2 0.5) \clvec (1.5 0.15)(1 0.35)(0.5 0) \lfill f:0.8 } In TeXdraw, the `\move' command always terminates any previous paths and starts a new path. Commands that change line parameters (e.gŪ `\setgray' or `\lpatt') also terminate paths and start new paths. The circle, ellipse and arc commands do not affect the definition of the current path. The `\avec' command is not appropriate for defining a path to be filled. It ends a subpath at its tail and begins a new subpath at its tip. Filling a region defined by a path with subpaths is more complicated in that each subpath is closed before filling.  File: texdraw, Node: Drawing Segments and Scaling, Next: Using TeXdraw with LaTeX, Prev: TeXdraw Commands, Up: Top Drawing Segments and Scaling **************************** TeXdraw provides individually scaled segments which can be used to create relocatable drawing modules. * Menu: * Drawing segments:: * Drawing paths:: * Saving positions:: * Scaling coordinates:: * Drawing size:: * Initial current position::  File: texdraw, Node: Drawing segments, Next: Drawing paths, Up: Drawing Segments and Scaling Drawing segments ================ A TeXdraw drawing segment allows for local modifications of parameters and relative positioning. A TeXdraw segment is delimited by a `\bsegment' command and an `\esegment' command. Inside the segment, the initial current position is `(0 0)'. Any changes to parameters such as the gray level and the line width, remain local to the segment. Segments are implemented in TeX using a `\begingroup' and `\endgroup'. Segments can be nested. `\bsegment' Start a drawing segment. The coordinate system is shifted such that the current position corresponds to the coordinate `(0 0)'. Changes to scaling, position and line parameters stay local to the drawing segment. `\esegment' End a drawing segment. The current position in effect before the corresponding `\bsegment' command is restored. The scaling and line parameter values revert to those in effect before the corresponding `\bsegment' command was invoked.  File: texdraw, Node: Drawing paths, Next: Saving positions, Prev: Drawing segments, Up: Drawing Segments and Scaling Drawing paths ============= Certain subtle interactions occur between drawing segments and fill operations. In PostScript, lines are drawn by first defining a path, then later stroking the path to draw the line. In TeXdraw, this stroking occurs when the line is terminated, say by a `\move' command. PostScript paths are interrupted by, but continue after a drawing segment. This means that a path started before a segment may not be stroked (drawn) until after the segment ends. Consider the following example. \move (0 0) \lvec (1 1) \bsegment \move (-0.25 -0.25) \fcir f:0.8 r:0.5 \esegment \move (0 0) A PostScript path is started at `(0 0)' and continues with a line to `(1 1)'. This path is interrupted by the segment. The filled circle is drawn next. After the segment, the path continues and is not stroked until the `\move (0 0)' command after the end of the segment. This means that the line appears on top of the filled region. If the fill operation is to cover the line, the path must be stroked before the fill operation. From TeXdraw, the move commands `\move' and `\rmove', and the end TeXdraw command `\etexdraw' terminate a path and cause it to be stroked. Within a segment, the end segment command `\esegment' also terminates and strokes a path. In the example above, the line can be stroked by inserting a move command (such as a `\rmove (0 0)' which does not affect the position), before the start of the segment.  File: texdraw, Node: Saving positions, Next: Scaling coordinates, Prev: Drawing paths, Up: Drawing Segments and Scaling Saving positions ================ The `\savecurrpos' command saves the current position. The saved position is an absolute position, not one relative to a segment. The position saving mechanism is global; the position can be saved within a nested segment and then used outside of the segment. The X and Y coordinates of the position are saved separately as named coordinates. The names are of the form `*NAME', with the leading `*' being obligatory. A companion command, `\savepos', saves a given coordinate (relative to the current segment) as an absolute symbolic position. `\savecurrpos (*PX *PY)' Save the current position as the absolute position referenced by `(*PX *PY)'. `\savepos (X Y)(*PX *PY)' Save the coordinate position `(X Y)' as the absolute position referenced by `(*PX *PY)'. The coordinate `(X Y)' is interpreted in the normal fashion as a coordinate relative to the current segment, using the current scaling factors and drawing unit. The symbolic names used to specify a saved position can consist of any characters that are not special to TeX, but must start with a `*' character. The symbolic names can be used as the X and/or Y coordinate in any command that needs a coordinate. Symbolic coordinates are not normally used with relative motion commands such as `\rlvec' or `\rmove'. If used with relative motion, the corresponding displacement is equal to the symbolic coordinate value. On exit from a segment, the position and graphics state on entry is restored. Any changes to line types, scaling and position are discarded. However, it is sometimes useful alter the position on exit from a segment. The `\savepos' command allows for the saving of a position within the segment. This position can be restored after the `\esegment' with a `\move' command using the saved symbolic position. This approach can be used to build modules which operate in a manner analogous to the basic relative motion line vector commands. The following example defines a macro which draws a box 0.75 inches wide by 0.5 inches high containing centered text. On leaving the macro the position will be set at a point on the righthand side of the box. \def\tbox #1{\bsegment \lvec (0 +0.25) \lvec (0.75 +0.25) \lvec (0.75 -0.25) \lvec (0 -0.25) \lvec (0 0) \textref h:C v:C \htext (0.375 0){#1} \savepos (0.75 0)(*ex *ey) \esegment \move (*ex *ey)} With this definition, we can treat `\tbox' in the same way as the basic vector commands, stringing them together to form a block diagram as in this example. \centertexdraw{ \ravec (1 0) \tbox{$H(z)$} \ravec (1 0) }  File: texdraw, Node: Scaling coordinates, Next: Drawing size, Prev: Saving positions, Up: Drawing Segments and Scaling Scaling coordinates =================== There are two scale factors available, the unit scale factor and the segment scale factor. The overall scale factor is the product of these two. There are absolute and relative versions of commands to change these scale factors. The unit scale factor is normally used to affect global scale changes. Changes to the unit scale factor remains local to a segment, but propagate to inferior segments. The default value is unity. The segment scale factor is used for local scale changes. It remains local to a segment. The segment scale factor is reset to unity on entry into each segment. This means that changes to the segment scale factor do not propagate to inferior segments. `\setunitscale SCALE' Set the unit scaling to SCALE. The argument SCALE is a real number which is used to scale coordinate values. The overall scaling factor is the product of the unit scale factor and the segment scale factor. `\relunitscale VALUE' Adjust the unit scale factor by multiplying by VALUE. This has the effect of multiplying the overall scale factor by the same factor. The overall scaling factor is the product of the unit scale factor and the segment scale factor. `\setsegscale SCALE' Set the segment scale factor. The argument SCALE is a real number which is used to scale coordinate values. The overall scale factor is the product of the unit scale factor and the segment scale factor. `\relsegscale VALUE' Adjust the segment scale factor by multiplying by VALUE. This has the effect of multiplying the current overall scale factor by the same factor. The overall scaling factor is the product of the unit scale factor and the segment scale factor. In addition to the unit scale factor and the segment scale factor, the scaling can be controlled by the choice of drawing units with the command `\drawdim' (*note Coordinate specification::.). `\drawdim cm \setunitscale 2.54' Set the units to centimetres scaled by 2.54. Together these commands are effectively the same as `\drawdim in'. The segment scale can be used to allow scale changes in segments so that values are in more convenient units. For example suppose dimensions in a segment are multiples of one third of an inch. The segment scale can be set once to make 1 drawing unit equal 0.3333 inches. From that point on, coordinates can be specified with integer values. The following example defines a macro to draw a rectangular box which is twice as wide as it is high. The width is specified as an argument. \def\mybox #1{\bsegment \setsegscale #1 \lvec (0 +0.25) \lvec (1 +0.25) \lvec (1 -0.25) \lvec (0 -0.25) \lvec (0 0) \esegment}  File: texdraw, Node: Drawing size, Next: Initial current position, Prev: Scaling coordinates, Up: Drawing Segments and Scaling Drawing size ============ The effective size of the drawing is determined by the maximum excursions of the coordinates supplied to TeXdraw commands. The minimum and maximum scaled X and Y coordinates are tallied. Note that `\move' commands contribute to the determination of the calculated size of the drawing, even though they do not generate visible lines. The circle and ellipse commands add a compensation for the radii of circles and ellipses. The final TeXdraw drawing is placed in a TeX box with lower lefthand corner corresponding to `('X-min Y-min`)' and upper righthand corner at `('X-max Y-max`)'. Text generated by `\htext', `\vtext' or `\rtext' can spill outside the box as determined above. Only the text reference point is guaranteed to be in the drawing box. Arcs can also spill outside the drawing box. Note also that the widths of lines, and the sizes of arrowheads do not affect the size of the drawing. The calculated size of the drawing will never be larger than the actual size of the drawing. In extreme cases in which text or lines extend far outside the drawing, extra `\move' commands should be used to establish the size of the drawing so that the TeXdraw box includes all of the drawing. TeXdraw provides the `\drawbb' command to draw a box which indicates the effective size of the drawing. Whenever `\drawbb' is invoked, a ruled box is drawn around the drawing as it has been sized up to that point. Normally `\drawbb' is invoked just before the end of a drawing to indicate the effective size of the final drawing. `\drawbb' Draw a ruled box around the effective size of a drawing produced by TeXdraw commands.  File: texdraw, Node: Initial current position, Prev: Drawing size, Up: Drawing Segments and Scaling Initial current position ======================== The first operation in a drawing should be a move to establish the current position. The current position can be established explicitly through a `\move' command or a text positioning command such as `\htext' with a coordinate. However, if an attempt is made to use a drawing command which needs a current position and none has been established, TeXdraw implicitly sets the initial current position to `(0 0)'. The size of the TeXdraw figure is normally determined from the sequence of coordinates specified, but will include the implicit initial position in case another initial position has not been explicitly specified.  File: texdraw, Node: Using TeXdraw with LaTeX, Next: More Details, Prev: Drawing Segments and Scaling, Up: Top Using TeXdraw with LaTeX ************************ The LaTeX typesetting system uses a structured approach to declaring typesetting environments. For LaTeX2e, the `texdraw' package defines the `texdraw' environment. The TeXdraw environment is started with a `\begin{texdraw}' command and terminated with an `\end{texdraw}' command. All of the basic TeXdraw commands can be used within the `texdraw' environment. As an example, a LaTeX2e variant of an earlier example can be constructed as follows. \documentclass{article} \usepackage{texdraw} ... \begin{document} ... \newcommand{\tbox}[1]{% \bsegment \lvec (0 +0.25) \lvec (0.75 +0.25) \lvec (0.75 -0.25) \lvec (0 -0.25) \lvec (0 0) \textref h:C v:C \htext (0.375 0){#1} \savepos (0.75 0)(*ex *ey) \esegment \move (*ex *ey)} \begin{center} \begin{texdraw} \ravec (1 0) \tbox{$H(z)$} \ravec (1 0) \end{texdraw} \end{center} ... \end{document} This example illustrates the use of the LaTeX command `\newcommand' as an alternative to the plain TeX command `\def'. Instead of the basic TeXdraw command `\centertexdraw', a nested combination of the LaTeX centering environment and the TeXdraw environment is used. * Menu: * PostScript printer drivers::  File: texdraw, Node: PostScript printer drivers, Up: Using TeXdraw with LaTeX PostScript printer drivers ========================== The `texdraw' package uses the printer driver interface provided by the standard LaTeX2e `graphics' package. Any options to the `texdraw' package are passed to the `graphics' package. Specifically, the name of the PostScript driver to be used can be specified as an option to the `texdraw' package. With no explicit printer driver option, the default printer driver associated with the `graphics' package is used. The `texdraw' package can be used with any of the printer drivers supported by the `graphics' package that allow for the importation of PostScript graphics files, viz., `dvips', `xdvi', `dvi2ps', `dvialw', `dvilaser', `dvipsone', `dviwindo', `dvitops', `oztex', `psprint', `textures', `pctexps', and `pctexwin'. Not all of these drivers support the text rotation needed for the TeXdraw commands `\vtext' and `\rtext'. Of the drivers listed above, only the following support support text rotation: `dvips', `xdvi', `dvi2ps', `dvitops', `textures', and `pctexps'.  File: texdraw, Node: More Details, Next: PostScript Commands, Prev: Using TeXdraw with LaTeX, Up: Top More Details ************ The first part of this chapter offers some suggestions for strategies to isolate errors in TeX and TeXdraw input. The second part of this chapter discusses implementational issues. An awareness of these issues is useful if TeXdraw is to be extended. * Menu: * Errors while using TeXdraw:: * Extending TeXdraw:: * How TeXdraw merges graphics and text::  File: texdraw, Node: Errors while using TeXdraw, Next: Extending TeXdraw, Up: More Details Errors while using TeXdraw ========================== TeX input is notoriously difficult to debug. If TeX reports errors, so much the better. If the cause is not immediately obvious, consider using a binary search strategy, removing sections of code with the premature insertion of the `\bye' (or `\end{document}' for LaTeX) command (with the appropriate closing of any open groups and the like). Other strategies include the insertion of `\message{I am here}' at appropriate places. Try using `\tracingmacros=1'. Many problems turn out to be due to an incorrect number of macro arguments or incorrectly delimited macro arguments. The `\tracingmacros=1' option writes the macro arguments and macro expansions to the TeX log file. Certain errors may not manifest themselves until well after the offending command. For instance, if a closing parenthesis is missing from a TeXdraw coordinate, TeX continues searching for the parenthesis. If one is found, perhaps many lines later, the TeXdraw error message `invalid coordinate' will be printed at this later point. All input in the TeXdraw environment should be intended for interpretation by TeXdraw commands. TeXdraw places text inside a zero size box (the text itself extends outside the box). Extraneous input manifests itself as a non-zero size TeXdraw text box. This causes the TeXdraw text and the PostScript graphics to be displaced from one another. An error message is issued if a non-zero width TeXdraw text box is detected. If this error message appears, look for unintended character sequences amongst the commands to TeXdraw. Several TeXdraw commands pass their arguments "raw" to the PostScript file. That means that invalid arguments can generate PostScript errors when the document is printed. For instance the argument of the `\setgray' command is passed straight through to the PostScript file. If this argument is non-numeric, a PostScript error results. Not all PostScript printers report errors back to the user. The print may just stop prematurely. One approach to debugging is to use a PostScript previewer on a workstation. That way, one can determine at which point in the drawing the PostScript error occurs.