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diff --git a/graphics/pgf/base/doc/pgfmanual-en-tikz-actions.tex b/graphics/pgf/base/doc/pgfmanual-en-tikz-actions.tex new file mode 100644 index 0000000000..2cd528bfa2 --- /dev/null +++ b/graphics/pgf/base/doc/pgfmanual-en-tikz-actions.tex @@ -0,0 +1,1449 @@ +% Copyright 2019 by Till Tantau +% +% This file may be distributed and/or modified +% +% 1. under the LaTeX Project Public License and/or +% 2. under the GNU Free Documentation License. +% +% See the file doc/generic/pgf/licenses/LICENSE for more details. + + +\section{Actions on Paths} + +\subsection{Overview} + +Once a path has been constructed, different things can be done with it. It can +be drawn (or stroked) with a ``pen'', it can be filled with a color or shading, +it can be used for clipping subsequent drawing, it can be used to specify the +extend of the picture -- or any combination of these actions at the same time. + +To decide what is to be done with a path, two methods can be used. First, you +can use a special-purpose command like |\draw| to indicate that the path should +be drawn. However, commands like |\draw| and |\fill| are just abbreviations for +special cases of the more general method: Here, the |\path| command is used to +specify the path. Then, options encountered on the path indicate what should be +done with the path. + +For example, |\path (0,0) circle (1cm);| means: ``This is a path consisting of +a circle around the origin. Do not do anything with it (throw it away).'' +However, if the option |draw| is encountered anywhere on the path, the circle +will be drawn. ``Anywhere'' is any point on the path where an option can be +given, which is everywhere where a path command like |circle (1cm)| or +|rectangle (1,1)| or even just |(0,0)| would also be allowed. Thus, the +following commands all draw the same circle: +% +\begin{codeexample}[code only] +\path [draw] (0,0) circle (1cm); +\path (0,0) [draw] circle (1cm); +\path (0,0) circle (1cm) [draw]; +\end{codeexample} +% +Finally, |\draw (0,0) circle (1cm);| also draws a path, because |\draw| is an +abbreviation for |\path [draw]| and thus the command expands to the first line +of the above example. + +Similarly, |\fill| is an abbreviation for |\path[fill]| and |\filldraw| is an +abbreviation for the command |\path[fill,draw]|. Since options accumulate, the +following commands all have the same effect: +% +\begin{codeexample}[code only] +\path [draw,fill] (0,0) circle (1cm); +\path [draw] [fill] (0,0) circle (1cm); +\path [fill] (0,0) circle (1cm) [draw]; +\draw [fill] (0,0) circle (1cm); +\fill (0,0) [draw] circle (1cm); +\filldraw (0,0) circle (1cm); +\end{codeexample} + +In the following subsection the different actions that can be performed on a +path are explained. The following commands are abbreviations for certain sets +of actions, but for many useful combinations there are no abbreviations: + +\begin{command}{\draw} + Inside |{tikzpicture}| this is an abbreviation for |\path[draw]|. +\end{command} + +\begin{command}{\fill} + Inside |{tikzpicture}| this is an abbreviation for |\path[fill]|. +\end{command} + +\begin{command}{\filldraw} + Inside |{tikzpicture}| this is an abbreviation for |\path[fill,draw]|. +\end{command} + +\begin{command}{\pattern} + Inside |{tikzpicture}| this is an abbreviation for |\path[pattern]|. +\end{command} + +\begin{command}{\shade} + Inside |{tikzpicture}| this is an abbreviation for |\path[shade]|. +\end{command} + +\begin{command}{\shadedraw} + Inside |{tikzpicture}| this is an abbreviation for |\path[shade,draw]|. +\end{command} + +\begin{command}{\clip} + Inside |{tikzpicture}| this is an abbreviation for |\path[clip]|. +\end{command} + +\begin{command}{\useasboundingbox} + Inside |{tikzpicture}| this is an abbreviation for |\path[use as bounding box]|. +\end{command} + + +\subsection{Specifying a Color} + +The most unspecific option for setting colors is the following: +% +\begin{key}{/tikz/color=\meta{color name}} + \indexoption{color option}% + This option sets the color that is used for fill, drawing, and text inside + the current scope. Any special settings for filling colors or drawing + colors are immediately ``overruled'' by this option. + + The \meta{color name} is the name of a previously defined color. For + \LaTeX\ users, this is just a normal ``\LaTeX-color'' and the |xcolor| + extensions are allowed. Here is an example: + % +\begin{codeexample}[] +\tikz \fill[color=red!20] (0,0) circle (1ex); +\end{codeexample} + + It is possible to ``leave out'' the |color=| part and you can also write: + % +\begin{codeexample}[] +\tikz \fill[red!20] (0,0) circle (1ex); +\end{codeexample} + % + What happens is that every option that \tikzname\ does not know, like + |red!20|, gets a ``second chance'' as a color name. + + For plain \TeX\ users, it is not so easy to specify colors since plain + \TeX\ has no ``standardized'' color naming mechanism. Because of this, + \pgfname\ emulates the |xcolor| package, though the emulation is + \emph{extremely basic} (more precisely, what I could hack together in two + hours or so). The emulation allows you to do the following: + % + \begin{itemize} + \item Specify a new color using |\definecolor|. Only the color models + |gray|, |rgb|, and |RGB| are supported\footnote{Con\TeX t users + should be aware that \texttt{\textbackslash definecolor} has a + different meaning in Con\TeX t. There is a low-level equivalent + named \texttt{\textbackslash pgfutil@definecolor} which can be + used instead.}. + % + \example |\definecolor{orange}{rgb}{1,0.5,0}| + \item Use |\colorlet| to define a new color based on an old one. + Here, the |!| mechanism is supported, though only ``once'' (use + multiple |\colorlet| for more fancy colors). + % + \example |\colorlet{lightgray}{black!25}| + \item Use |\color|\marg{color name} to set the color in the current + \TeX\ group. |\aftergroup|-hackery is used to restore the color + after the group. + \end{itemize} +\end{key} + +As pointed out above, the |color=| option applies to ``everything'' (except to +shadings), which is not always what you want. Because of this, there are +several more specialized color options. For example, the |draw=| option sets +the color used for drawing, but does not modify the color used for filling. +These color options are documented where the path action they influence is +described. + + +\subsection{Drawing a Path} + +You can draw a path using the following option: +% +\begin{key}{/tikz/draw=\meta{color} (default \normalfont is scope's color setting)} + Causes the path to be drawn. ``Drawing'' (also known as ``stroking'') can + be thought of as picking up a pen and moving it along the path, thereby + leaving ``ink'' on the canvas. + + There are numerous parameters that influence how a line is drawn, like the + thickness or the dash pattern. These options are explained below. + + If the optional \meta{color} argument is given, drawing is done using the + given \meta{color}. This color can be different from the current filling + color, which allows you to draw and fill a path with different colors. If + no \meta{color} argument is given, the last usage of the |color=| option is + used. + + If the special color name |none| is given, this option causes drawing to be + ``switched off''. This is useful if a style has previously switched on + drawing and you locally wish to undo this effect. + + Although this option is normally used on paths to indicate that the path + should be drawn, it also makes sense to use the option with a |{scope}| or + |{tikzpicture}| environment. However, this will \emph{not} cause all paths + to be drawn. Instead, this just sets the \meta{color} to be used for + drawing paths inside the environment. + % +\begin{codeexample}[] +\begin{tikzpicture} + \path[draw=red] (0,0) -- (1,1) -- (2,1) circle (10pt); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +The following subsections list the different options that influence how a path +is drawn. All of these options only have an effect if the |draw| option is +given (directly or indirectly). + + +\subsubsection{Graphic Parameters: Line Width, Line Cap, and Line Join} +\label{section-cap-joins} + +\begin{key}{/tikz/line width=\meta{dimension} (initially 0.4pt)} + Specifies the line width. Note the space. + % +\begin{codeexample}[] + \tikz \draw[line width=5pt] (0,0) -- (1cm,1.5ex); +\end{codeexample} + % +\end{key} + +There are a number of predefined styles that provide more ``natural'' ways of +setting the line width. You can also redefine these styles. + +\begin{stylekey}{/tikz/ultra thin} + Sets the line width to 0.1pt. + % +\begin{codeexample}[] + \tikz \draw[ultra thin] (0,0) -- (1cm,1.5ex); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/very thin} + Sets the line width to 0.2pt. + % +\begin{codeexample}[] + \tikz \draw[very thin] (0,0) -- (1cm,1.5ex); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/thin} + Sets the line width to 0.4pt. + % +\begin{codeexample}[] + \tikz \draw[thin] (0,0) -- (1cm,1.5ex); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/semithick} + Sets the line width to 0.6pt. + % +\begin{codeexample}[] + \tikz \draw[semithick] (0,0) -- (1cm,1.5ex); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/thick} + Sets the line width to 0.8pt. + % +\begin{codeexample}[] + \tikz \draw[thick] (0,0) -- (1cm,1.5ex); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/very thick} + Sets the line width to 1.2pt. + % +\begin{codeexample}[] + \tikz \draw[very thick] (0,0) -- (1cm,1.5ex); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/ultra thick} + Sets the line width to 1.6pt. + % +\begin{codeexample}[] + \tikz \draw[ultra thick] (0,0) -- (1cm,1.5ex); +\end{codeexample} + % +\end{stylekey} + + \label{section-line-cap} +\begin{key}{/tikz/line cap=\meta{type} (initially butt)} + Specifies how lines ``end''. Permissible \meta{type} are |round|, |rect|, + and |butt|. They have the following effects: + % +\begin{codeexample}[] +\begin{tikzpicture} + \begin{scope}[line width=10pt] + \draw[line cap=round] (0,1 ) -- +(1,0); + \draw[line cap=butt] (0,.5) -- +(1,0); + \draw[line cap=rect] (0,0 ) -- +(1,0); + \end{scope} + \draw[white,line width=1pt] + (0,0 ) -- +(1,0) (0,.5) -- +(1,0) (0,1 ) -- +(1,0); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/line join=\meta{type} (initially miter)} + Specifies how lines ``join''. Permissible \meta{type} are |round|, |bevel|, + and |miter|. They have the following effects: + % +\begin{codeexample}[] +\begin{tikzpicture}[line width=10pt] + \draw[line join=round] (0,0) -- ++(.5,1) -- ++(.5,-1); + \draw[line join=bevel] (1.25,0) -- ++(.5,1) -- ++(.5,-1); + \draw[line join=miter] (2.5,0) -- ++(.5,1) -- ++(.5,-1); + \useasboundingbox (0,1.5); % enlarge bounding box +\end{tikzpicture} +\end{codeexample} + + \begin{key}{/tikz/miter limit=\meta{factor} (initially 10)} + When you use the miter join and there is a very sharp corner (a small + angle), the miter join may protrude very far over the actual joining + point. In this case, if it were to protrude by more than \meta{factor} + times the line width, the miter join is replaced by a bevel join. + % +\begin{codeexample}[] +\begin{tikzpicture}[line width=5pt] + \draw (0,0) -- ++(5,.5) -- ++(-5,.5); + \draw[miter limit=25] (6,0) -- ++(5,.5) -- ++(-5,.5); + \useasboundingbox (14,0); % make bounding box bigger +\end{tikzpicture} +\end{codeexample} + \end{key} +\end{key} + + +\subsubsection{Graphic Parameters: Dash Pattern} + +\begin{key}{/tikz/dash pattern=\meta{dash pattern}} + Sets the dashing pattern. The syntax is the same as in \textsc{metafont}. + For example following pattern |on 2pt off 3pt on 4pt off 4pt| means ``draw + 2pt, then leave out 3pt, then draw 4pt once more, then leave out 4pt again, + repeat''. + % +\begin{codeexample}[] +\begin{tikzpicture}[dash pattern=on 2pt off 3pt on 4pt off 4pt] + \draw (0pt,0pt) -- (3.5cm,0pt); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/dash phase=\meta{dash phase} (initially 0pt)} + Shifts the start of the dash pattern by \meta{phase}. + % +\begin{codeexample}[] +\begin{tikzpicture}[dash pattern=on 20pt off 10pt] + \draw[dash phase=0pt] (0pt,3pt) -- (3.5cm,3pt); + \draw[dash phase=10pt] (0pt,0pt) -- (3.5cm,0pt); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/dash=\meta{dash pattern}|phase|\meta{dash phase}} + Sets the dashing pattern and phase at the same time. + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw [dash=on 20pt off 10pt phase 0pt] (0pt,3pt) -- (3.5cm,3pt); + \draw [dash=on 20pt off 10pt phase 10pt] (0pt,0pt) -- (3.5cm,0pt); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/dash expand off} + Makes the |off| part of a dash pattern expandable such that it can stretch. + This only works when there is a single |on| and a single |off| field and + requires the |decorations| library. Right now this option has to be + specified on the path where it is supposed to take effect after the + |dash pattern| option because the dash pattern has to be known at the point + where it is applied. + % +\begin{codeexample}[preamble={\usetikzlibrary{decorations}}] +\begin{tikzpicture}[|-|, dash pattern=on 4pt off 2pt] + \draw [dash expand off] (0pt,30pt) -- (26pt,30pt); + \draw [dash expand off] (0pt,20pt) -- (24pt,20pt); + \draw [dash expand off] (0pt,10pt) -- (22pt,10pt); + \draw [dash expand off] (0pt, 0pt) -- (20pt, 0pt); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +As for the line thickness, some predefined styles allow you to set the dashing +conveniently. + +\begin{stylekey}{/tikz/solid} + Shorthand for setting a solid line as ``dash pattern''. This is the default. + % +\begin{codeexample}[] +\tikz \draw[solid] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/dotted} + Shorthand for setting a dotted dash pattern. + % +\begin{codeexample}[] +\tikz \draw[dotted] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/densely dotted} + Shorthand for setting a densely dotted dash pattern. + % +\begin{codeexample}[] +\tikz \draw[densely dotted] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/loosely dotted} + Shorthand for setting a loosely dotted dash pattern. + % +\begin{codeexample}[] +\tikz \draw[loosely dotted] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/dashed} + Shorthand for setting a dashed dash pattern. + % +\begin{codeexample}[] +\tikz \draw[dashed] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/densely dashed} + Shorthand for setting a densely dashed dash pattern. + % +\begin{codeexample}[] +\tikz \draw[densely dashed] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/loosely dashed} + Shorthand for setting a loosely dashed dash pattern. + % +\begin{codeexample}[] +\tikz \draw[loosely dashed] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/dash dot} + Shorthand for setting a dashed and dotted dash pattern. + % +\begin{codeexample}[] +\tikz \draw[dash dot] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/densely dash dot} + Shorthand for setting a densely dashed and dotted dash pattern. + % +\begin{codeexample}[] +\tikz \draw[densely dash dot] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/loosely dash dot} + Shorthand for setting a loosely dashed and dotted dash pattern. + % +\begin{codeexample}[] +\tikz \draw[loosely dash dot] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/dash dot dot} + Shorthand for setting a dashed and dotted dash pattern with more dots. + % +\begin{codeexample}[] +\tikz \draw[dash dot dot] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/densely dash dot dot} + Shorthand for setting a densely dashed and dotted dash pattern with more dots. + % +\begin{codeexample}[] +\tikz \draw[densely dash dot dot] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + +\begin{stylekey}{/tikz/loosely dash dot dot} + Shorthand for setting a loosely dashed and dotted dash pattern with more dots. + % +\begin{codeexample}[] +\tikz \draw[loosely dash dot dot] (0pt,0pt) -- (50pt,0pt); +\end{codeexample} + % +\end{stylekey} + + +\subsubsection{Graphic Parameters: Draw Opacity} + +When a line is drawn, it will normally ``obscure'' everything behind it as if +you had used perfectly opaque ink. It is also possible to ask \tikzname\ to use +an ink that is a little bit (or a big bit) transparent using the |draw opacity| +option. This is explained in Section~\ref{section-tikz-transparency} on +transparency in more detail. + + +\subsubsection{Graphic Parameters: Double Lines and Bordered Lines} + +\begin{key}{/tikz/double=\meta{core color} (default white)} + This option causes ``two'' lines to be drawn instead of a single one. + However, this is not what really happens. In reality, the path is drawn + twice. First, with the normal drawing color, secondly with the \meta{core + color}, which is normally |white|. Upon the second drawing, the line width + is reduced. The net effect is that it appears as if two lines had been + drawn and this works well even with complicated, curved paths: + % +\begin{codeexample}[] +\tikz \draw[double] + plot[smooth cycle] coordinates{(0,0) (1,1) (1,0) (0,1)}; +\end{codeexample} + + You can also use the doubling option to create an effect in which a line + seems to have a certain ``border'': + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw (0,0) -- (1,1); + \draw[draw=white,double=red,very thick] (0,1) -- (1,0); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/double distance=\meta{dimension} (initially 0.6pt)} + Sets the distance the ``two'' lines are spaced apart. In reality, this is + the thickness of the line that is used to draw the path for the second + time. The thickness of the \emph{first} time the path is drawn is twice the + normal line width plus the given \meta{dimension}. As a side-effect, this + option ``selects'' the |double| option. + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw[very thick,double] (0,0) arc (180:90:1cm); + \draw[very thick,double distance=2pt] (1,0) arc (180:90:1cm); + \draw[thin,double distance=2pt] (2,0) arc (180:90:1cm); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/double distance between line centers=\meta{dimension}} + This option works like |double distance|, only the distance is not the + distance between (inner) borders of the two main lines, but between their + centers. Thus, the thickness the \emph{first} time the path is drawn is the + normal line width plus the given \meta{dimension}, while the line width of + the \emph{second} line that is drawn is \meta{dimension} minus the normal + line width. As a side-effect, this option ``selects'' the |double| option. + % +\begin{codeexample}[] +\begin{tikzpicture}[double distance between line centers=3pt] + \foreach \lw in {0.5,1,1.5,2,2.5} + \draw[line width=\lw pt,double] (\lw,0) -- ++(4mm,0); +\end{tikzpicture} +\end{codeexample} + % +\begin{codeexample}[] +\begin{tikzpicture}[double distance=3pt] + \foreach \lw in {0.5,1,1.5,2,2.5} + \draw[line width=\lw pt,double] (\lw,0) -- ++(4mm,0); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{stylekey}{/tikz/double equal sign distance} + This style selects a double line distance such that it corresponds to the + distance of the two lines in an equal sign. + % +\begin{codeexample}[ + preamble={\usepackage{amsmath} +\usetikzlibrary{arrows.meta}} +] +\Huge $=\implies$\tikz[baseline,double equal sign distance] + \draw[double,thick,-{Implies[]}](0,0.55ex) --++(3ex,0); +\end{codeexample} + % +\begin{codeexample}[ + preamble={\usepackage{amsmath} +\usetikzlibrary{arrows.meta}} +] +\normalsize $=\implies$\tikz[baseline,double equal sign distance] + \draw[double,-{Implies[]}](0,0.6ex) --++(3ex,0); +\end{codeexample} + % +\begin{codeexample}[ + preamble={\usepackage{amsmath} +\usetikzlibrary{arrows.meta}} +] +\tiny $=\implies$\tikz[baseline,double equal sign distance] + \draw[double,very thin,-{Implies[]}](0,0.5ex) -- ++(3ex,0); +\end{codeexample} + % +\end{stylekey} + + +\subsection{Adding Arrow Tips to a Path} +\label{section-arrow-tip-action} + +In different situations, \tikzname\ will add arrow tips to the end of a path. +For this to happen, a number of different things need to be specified: +% +\begin{enumerate} + \item You must have used the |arrows| key, explained in detail in + Section~\ref{section-tikz-arrows}, to setup which kinds of arrow tips + you would like. + \item The path may not be closed (like a circle or a rectangle) and, if + it consists of several subpaths, further restrictions apply as + explained in Section~\ref{section-tikz-arrows}. + \item The |tips| key must be set to an appropriate value, see + Section~\ref{section-tikz-arrows} once more. +\end{enumerate} + +For the current section on paths, it is only important that when you add the +|tips| option to a path that is not drawn, arrow tips will still be added at +the beginning and at the end of the current path. This is true even when +``only'' arrow tips get drawn for a path without drawing the path itself. Here +is an example: +% +\begin{codeexample}[width=2cm,preamble={\usetikzlibrary{arrows.meta,bending}}] +\tikz \path[tips, -{Latex[open,length=10pt,bend]}] (0,0) to[bend left] (1,0); +\end{codeexample} +% +\begin{codeexample}[width=2cm,preamble={\usetikzlibrary{arrows.meta,bending}}] +\tikz \draw[tips, -{Latex[open,length=10pt,bend]}] (0,0) to[bend left] (1,0); +\end{codeexample} + + +\subsection{Filling a Path} +\label{section-rules} + +To fill a path, use the following option: +% +\begin{key}{/tikz/fill=\meta{color} (default \normalfont is scope's color setting)} + This option causes the path to be filled. All unclosed parts of the path + are first closed, if necessary. Then, the area enclosed by the path is + filled with the current filling color, which is either the last color set + using the general |color=| option or the optional color \meta{color}. For + self-intersection paths and for paths consisting of several closed areas, + the ``enclosed area'' is somewhat complicated to define and two different + definitions exist, namely the nonzero winding number rule and the even odd + rule, see the explanation of these options, below. + + Just as for the |draw| option, setting \meta{color} to |none| disables + filling locally. + % +\begin{codeexample}[] +\begin{tikzpicture} + \fill (0,0) -- (1,1) -- (2,1); + \fill (4,0) circle (.5cm) (4.5,0) circle (.5cm); + \fill[even odd rule] (6,0) circle (.5cm) (6.5,0) circle (.5cm); + \fill (8,0) -- (9,1) -- (10,0) circle (.5cm); +\end{tikzpicture} +\end{codeexample} + + If the |fill| option is used together with the |draw| option (either + because both are given as options or because a |\filldraw| command is + used), the path is filled \emph{first}, then the path is drawn + \emph{second}. This is especially useful if different colors are selected + for drawing and for filling. Even if the same color is used, there is a + difference between this command and a plain |fill|: A ``filldrawn'' area + will be slightly larger than a filled area because of the thickness of the + ``pen''. + % +\begin{codeexample}[] +\begin{tikzpicture}[fill=yellow!80!black,line width=5pt] + \filldraw (0,0) -- (1,1) -- (2,1); + \filldraw (4,0) circle (.5cm) (4.5,0) circle (.5cm); + \filldraw[even odd rule] (6,0) circle (.5cm) (6.5,0) circle (.5cm); + \filldraw (8,0) -- (9,1) -- (10,0) circle (.5cm); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + + +\subsubsection{Graphic Parameters: Fill Pattern} +\label{section-fill-pattern} + +Instead of filling a path with a single solid color, it is also possible to +fill it with a \emph{tiling pattern}. Imagine a small tile that contains a +simple picture like a star. Then these tiles are (conceptually) repeated +infinitely in all directions, but clipped against the path. + +Tiling patterns come in two variants: \emph{inherently colored patterns} and +\emph{form-only patterns}. An inherently colored pattern is, say, a red star +with a black border and will always look like this. A form-only pattern may +have a different color each time it is used, only the form of the pattern will +stay the same. As such, form-only patterns do not have any colors of their own, +but when it is used the current \emph{pattern color} is used as its color. + +Patterns are not overly flexible. In particular, it is not possible to change +the size or orientation of a pattern without declaring a new pattern. For +complicated cases, it may be easier to use two nested |\foreach| statements to +simulate a pattern, but patterns are rendered \emph{much} more quickly than +simulated ones. + +\begin{key}{/tikz/pattern=\meta{name} (default \normalfont is scope's pattern)} + This option causes the path to be filled with a pattern. If the \meta{name} + is given, this pattern is used, otherwise the pattern set in the enclosing + scope is used. As for the |draw| and |fill| options, setting \meta{name} to + |none| disables filling locally. + + The pattern works like a fill color. In particular, setting a new fill + color will fill the path with a solid color once more. + + Strangely, no \meta{name}s are permissible by default. You need to load for + instance the |patterns| library, see + Section~\ref{section-library-patterns}, to install predefined patterns. + % +\begin{codeexample}[preamble={\usetikzlibrary{patterns}}] +\begin{tikzpicture} + \draw[pattern=dots] (0,0) circle (1cm); + \draw[pattern=fivepointed stars] (0,0) rectangle (3,1); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/pattern color=\meta{color}} + This option is used to set the color to be used for form-only patterns. + This option has no effect on inherently colored patterns. + % +\begin{codeexample}[preamble={\usetikzlibrary{patterns}}] +\begin{tikzpicture} + \draw[pattern color=red,pattern=fivepointed stars] (0,0) circle (1cm); + \draw[pattern color=blue,pattern=fivepointed stars] (0,0) rectangle (3,1); +\end{tikzpicture} +\end{codeexample} + +\begin{codeexample}[preamble={\usetikzlibrary{patterns}}] +\begin{tikzpicture} + \def\mypath{(0,0) -- +(0,1) arc (180:0:1.5cm) -- +(0,-1)} + \fill [red] \mypath; + \pattern[pattern color=white,pattern=bricks] \mypath; +\end{tikzpicture} +\end{codeexample} + % +\end{key} + + +\subsubsection{Graphic Parameters: Interior Rules} + +The following two options can be used to decide how interior points should be +determined: +% +\begin{key}{/tikz/nonzero rule} + If this rule is used (which is the default), the following method is used + to determine whether a given point is ``inside'' the path: From the point, + shoot a ray in some direction towards infinity (the direction is chosen + such that no strange borderline cases occur). Then the ray may hit the + path. Whenever it hits the path, we increase or decrease a counter, which + is initially zero. If the ray hits the path as the path goes ``from left to + right'' (relative to the ray), the counter is increased, otherwise it is + decreased. Then, at the end, we check whether the counter is nonzero (hence + the name). If so, the point is deemed to lie ``inside'', otherwise it is + ``outside''. Sounds complicated? It is. + % +\begin{codeexample}[] +\begin{tikzpicture} + \filldraw[fill=yellow!80!black] + % Clockwise rectangle + (0,0) -- (0,1) -- (1,1) -- (1,0) -- cycle + % Counter-clockwise rectangle + (0.25,0.25) -- (0.75,0.25) -- (0.75,0.75) -- (0.25,0.75) -- cycle; + + \draw[->] (0,1) -- (.4,1); + \draw[->] (0.75,0.75) -- (0.3,.75); + + \draw[->] (0.5,0.5) -- +(0,1) node[above] {crossings: $-1+1 = 0$}; + + \begin{scope}[yshift=-3cm] + \filldraw[fill=yellow!80!black] + % Clockwise rectangle + (0,0) -- (0,1) -- (1,1) -- (1,0) -- cycle + % Clockwise rectangle + (0.25,0.25) -- (0.25,0.75) -- (0.75,0.75) -- (0.75,0.25) -- cycle; + + \draw[->] (0,1) -- (.4,1); + \draw[->] (0.25,0.75) -- (0.4,.75); + + \draw[->] (0.5,0.5) -- +(0,1) node[above] {crossings: $1+1 = 2$}; + \end{scope} +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/even odd rule} + This option causes a different method to be used for determining the inside + and outside of paths. While it is less flexible, it turns out to be more + intuitive. + + With this method, we also shoot rays from the point for which we wish to + determine whether it is inside or outside the filling area. However, this + time we only count how often we ``hit'' the path and declare the point to + be ``inside'' if the number of hits is odd. + + Using the even-odd rule, it is easy to ``drill holes'' into a path. + % +\begin{codeexample}[] +\begin{tikzpicture} + \filldraw[fill=yellow!80!black,even odd rule] + (0,0) rectangle (1,1) (0.5,0.5) circle (0.4cm); + \draw[->] (0.5,0.5) -- +(0,1) [above] node{crossings: $1+1 = 2$}; +\end{tikzpicture} +\end{codeexample} + % +\end{key} + + +\subsubsection{Graphic Parameters: Fill Opacity} +\label{section-fill-opacity} + +Analogously to the |draw opacity|, you can also set the fill opacity. Please +see Section~\ref{section-tikz-transparency} for more details. + + +\subsection{Generalized Filling: Using Arbitrary Pictures to Fill a Path} + +Sometimes you wish to ``fill'' a path with something even more complicated than +a pattern, let alone a single color. For instance, you might wish to use an +image to fill the path or some other, complicated drawing. In principle, this +effect can be achieved by first using the path for clipping and then, +subsequently, drawing the desired image or picture. However, there is an option +that makes this process much easier: + +\begin{key}{/tikz/path picture=\meta{code}} + When this option is given on a path and when the \meta{code} is not empty, + the following happens: After all other ``filling'' operations are done with + the path, which are caused by the options |fill|, |pattern| and |shade|, a + local scope is opened and the path is temporarily installed as a clipping + path. Then, the \meta{code} is executed, which can now draw something. + Then, the local scope ends and, possibly, the path is stroked, provided the + |draw| option has been given. + + As with other keys like |fill| or |draw| this option needs to be given on a + path, setting the |path picture| outside a path has no effect (the path + picture is cleared at the beginning of each path). + + The \meta{code} can be any normal \tikzname\ code like |\draw ...| or + |\node ...|. As always, when you include an external graphic, you need to + put it inside a |\node|. + + Note that no special actions are taken to transform the origin in any way. + This means that the coordinate |(0,0)| is still where is was when the path + was being constructed and not -- as one might expect -- at the lower left + corner of the path. However, you can use the following special node to + access the size of the path: + % + \begin{predefinednode}{path picture bounding box} + This node is of shape |rectangle|. Its size and position are those of + |current path bounding box| just before the \meta{code} of the path + picture started to be executed. The \meta{code} can construct its own + paths, so accessing the |current path bounding box| inside the + \meta{code} yields the bounding box of any path that is currently being + constructed inside the \meta{code}. + \end{predefinednode} + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw [help lines] (0,0) grid (3,2); + \filldraw [fill=blue!10,draw=blue,thick] (1.5,1) circle (1) + [path picture={ + \node at (path picture bounding box.center) { + This is a long text. + };} + ]; +\end{tikzpicture} +\end{codeexample} + +\begin{codeexample}[] +\begin{tikzpicture}[cross/.style={path picture={ + \draw[black] + (path picture bounding box.south east) -- + (path picture bounding box.north west) + (path picture bounding box.south west) -- + (path picture bounding box.north east); + }}] + \draw [help lines] (0,0) grid (3,2); + \filldraw [cross,fill=blue!10,draw=blue,thick] (1,1) circle (1); + \path [cross,top color=red,draw=red,thick] (2,0) -- (3,2) -- (3,0); +\end{tikzpicture} +\end{codeexample} + +\begin{codeexample}[] + \begin{tikzpicture}[path image/.style={ + path picture={ + \node at (path picture bounding box.center) { + \includegraphics[height=3cm]{#1} + };}}] + \draw [help lines] (0,0) grid (3,2); + + \draw [path image=brave-gnu-world-logo,draw=blue,thick] + (0,1) circle (1); + \draw [path image=brave-gnu-world-logo,draw=red,very thick,->] + (1,0) parabola[parabola height=2cm] (3,0); + +\end{tikzpicture} +\end{codeexample} + % +\end{key} + + +\subsection{Shading a Path} + +You can shade a path using the |shade| option. A shading is like a filling, +only the shading changes its color smoothly from one color to another. + +\begin{key}{/tikz/shade} + Causes the path to be shaded using the currently selected shading (more on + this later). If this option is used together with the |draw| option, then + the path is first shaded, then drawn. + + It is not an error to use this option together with the |fill| option, but + it makes no sense. + % +\begin{codeexample}[] +\tikz \shade (0,0) circle (1ex); +\end{codeexample} + +\begin{codeexample}[] +\tikz \shadedraw (0,0) circle (1ex); +\end{codeexample} + % +\end{key} + +For some shadings it is not really clear how they can ``fill'' the path. For +example, the |ball| shading normally looks like this: +\tikz \shade[shading=ball] (0,0) circle (0.75ex);. How is this supposed to +shade a rectangle? Or a triangle? + +To solve this problem, the predefined shadings like |ball| or |axis| fill a +large rectangle completely in a sensible way. Then, when the shading is used to +``shade'' a path, what actually happens is that the path is temporarily used +for clipping and then the rectangular shading is drawn, scaled and shifted such +that all parts of the path are filled. + +The default shading is a smooth transition from gray to white and from top to +bottom. However, other shadings are also possible, for example a shading that +will sweep a color from the center to the corners outward. To choose the +shading, you can use the |shading=| option, which will also automatically +invoke the |shade| option. Note that this does \emph{not} change the shading +color, only the way the colors sweep. For changing the colors, other options +are needed, which are explained below. + +\begin{key}{/tikz/shading=\meta{name}} + This selects a shading named \meta{name}. The following shadings are + predefined: |axis|, |radial|, and |ball|. + % +\begin{codeexample}[] +\tikz \shadedraw [shading=axis] (0,0) rectangle (1,1); +\tikz \shadedraw [shading=radial] (0,0) rectangle (1,1); +\tikz \shadedraw [shading=ball] (0,0) circle (.5cm); +\end{codeexample} + + The shadings as well as additional shadings are described in more detail in + Section~\ref{section-library-shadings}. + + To change the color of a shading, special options are needed like + |left color|, which sets the color of an axis shading from left to right. + These options implicitly also select the correct shading type, see the + following example + % +\begin{codeexample}[] +\tikz \shadedraw [left color=red,right color=blue] + (0,0) rectangle (1,1); +\end{codeexample} + + For a complete list of the possible options see + Section~\ref{section-library-shadings} once more. + + \begin{key}{/tikz/shading angle=\meta{degrees} (initially 0)} + This option rotates the shading (not the path!) by the given angle. For + example, we can turn a top-to-bottom axis shading into a left-to-right + shading by rotating it by $90^\circ$. + % +\begin{codeexample}[] +\tikz \shadedraw [shading=axis,shading angle=90] (0,0) rectangle (1,1); +\end{codeexample} + \end{key} +\end{key} + +You can also define new shading types yourself. However, for this, you need to +use the basic layer directly, which is, well, more basic and harder to use. +Details on how to create a shading appropriate for filling paths are given in +Section~\ref{section-shading-a-path}. + + +\subsection{Establishing a Bounding Box} + +\pgfname\ is reasonably good at keeping track of the size of your picture and +reserving just the right amount of space for it in the main document. However, +in some cases you may want to say things like ``do not count this for the +picture size'' or ``the picture is actually a little large''. For this you can +use the option |use as bounding box| or the command |\useasboundingbox|, which +is just a shorthand for |\path[use as bounding box]|. + +\begin{key}{/tikz/use as bounding box} + Normally, when this option is given on a path, the bounding box of the + present path is used to determine the size of the picture and the size of + all \emph{subsequent} paths are ignored. However, if there were previous + path operations that have already established a larger bounding box, it + will not be made smaller by this operation (consider the + |\pgfresetboundingbox| command to reset the previous bounding box). + + In a sense, |use as bounding box| has the same effect as clipping all + subsequent drawing against the current path -- without actually doing the + clipping, only making \pgfname\ treat everything as if it were clipped. + + The first application of this option is to have a |{tikzpicture}| overlap + with the main text: + % +\begin{codeexample}[] +Left of picture\begin{tikzpicture} + \draw[use as bounding box] (2,0) rectangle (3,1); + \draw (1,0) -- (4,.75); +\end{tikzpicture}right of picture. +\end{codeexample} + + In a second application this option can be used to get better control over + the white space around the picture: + % +\begin{codeexample}[] +Left of picture +\begin{tikzpicture} + \useasboundingbox (0,0) rectangle (3,1); + \fill (.75,.25) circle (.5cm); +\end{tikzpicture} +right of picture. +\end{codeexample} + + Note: If this option is used on a path inside a \TeX\ group (scope), the + effect ``lasts'' only until the end of the scope. Again, this behavior is + the same as for clipping. + + Consider using |\useasboundingbox| together with |\pgfresetboundingbox| in + order to replace the bounding box with a new one. +\end{key} + +There is a node that allows you to get the size of the current bounding box. +The |current bounding box| node has the |rectangle| shape and its size is +always the size of the current bounding box. + +Similarly, the |current path bounding box| node has the |rectangle| shape and +the size of the bounding box of the current path. +% +\begin{codeexample}[] +\begin{tikzpicture} + \draw[red] (0,0) circle (2pt); + \draw[red] (2,1) circle (3pt); + + \draw (current bounding box.south west) rectangle + (current bounding box.north east); + + \draw[red] (3,-1) circle (4pt); + + \draw[thick] (current bounding box.south west) rectangle + (current bounding box.north east); +\end{tikzpicture} +\end{codeexample} + +Occasionally, you may want to align multiple |tikzpicture| environments +horizontally and/or vertically at some prescribed position. The vertical +alignment can be realized by means of the |baseline| option since \TeX\ +supports the concept of box depth natively. For horizontal alignment, things +are slightly more involved. The following approach is realized by means of +negative |\hspace|s before and/or after the picture, thereby removing parts of +the picture. However, the actual amount of negative horizontal space is +provided by means of image coordinates using the |trim left| and |trim right| +keys: + +\begin{key}{/tikz/trim left=\meta{dimension or coordinate or \texttt{default}} (default 0pt)} + The |trim left| key tells \pgfname\space to discard everything which is + left of the provided \meta{dimension or coordinate}. Here, \meta{dimension} + is a single $x$ coordinate of the picture and \meta{coordinate} is a point + with $x$ and $y$ coordinates (but only its $x$ coordinate will be used). + The effect is the same as if you issue |\hspace{-s}| where |s| is the + difference of the picture's bounding box lower left $x$ coordinate and the + $x$ coordinate specified as \meta{dimension or coordinate}: + % +\begin{codeexample}[] +Text before image.% + \begin{tikzpicture}[trim left] + \draw (-1,-1) grid (3,2); + \fill (0,0) circle (5pt); + \end{tikzpicture}% +Text after image. +\end{codeexample} + % + Since |trim left| uses the default |trim left=0pt|, everything left of + $x=0$ is removed from the bounding box. + + The following example has once the relative long label $-1$ and once the + shorter label $1$. Horizontal alignment is established with |trim left|: + % +\begin{codeexample}[pre={\vbox\bgroup\hsize=5cm},post=\egroup,width=8cm] +\begin{tikzpicture} + \draw (0,1) -- (0,0) -- (1,1) -- cycle; + \fill (0,0) circle (2pt); + \node[left] at (0,0) {$-1$}; +\end{tikzpicture} +\par +\begin{tikzpicture} + \draw (0,1) -- (0,0) -- (1,1) -- cycle; + \fill (0,0) circle (2pt); + \node[left] at (0,0) {$1$}; +\end{tikzpicture} +\par +\begin{tikzpicture}[trim left] + \draw (0,1) -- (0,0) -- (1,1) -- cycle; + \fill (0,0) circle (2pt); + \node[left] at (0,0) {$-1$}; +\end{tikzpicture} +\par +\begin{tikzpicture}[trim left] + \draw (0,1) -- (0,0) -- (1,1) -- cycle; + \fill (0,0) circle (2pt); + \node[left] at (0,0) {$1$}; +\end{tikzpicture} +\end{codeexample} + + Use |trim left=default| to reset the value. +\end{key} + +\begin{key}{/tikz/trim right=\meta{dimension or coordinate or \texttt{default}}} + This key is similar to |trim left|: it discards everything which is right + of the provided \meta{dimension or coordinate}. As for |trim left|, + \meta{dimension} denotes a single $x$ coordinate of the picture and + \meta{coordinate} a coordinate with $x$ and $y$ value (although only its + $x$ component will be used). + + We use the same example from above and add |trim right|: + % +\begin{codeexample}[] +Text before image.% + \begin{tikzpicture}[trim left, trim right=2cm, baseline] + \draw (-1,-1) grid (3,2); + \fill (0,0) circle (5pt); + \end{tikzpicture}% +Text after image. +\end{codeexample} + % + In addition to |trim left=0pt|, we also discard everything which is right + of $x$|=2cm|. Furthermore, the |baseline| key supports vertical alignment + as well (using the $y$|=0cm| baseline). + + Use |trim right=default| to reset the value. +\end{key} + +Note that |baseline|, |trim left| and |trim right| are currently the +\emph{only} supported way of truncated bounding boxes which are compatible with +image externalization (see the |external| library for details). + +\begin{key}{/pgf/trim lowlevel=\mchoice{true,false} (initially false)} + This affects only the basic level image externalization: the initial + configuration |trim lowlevel=false| stores the normal image, without + trimming, and the trimming into a separate file. This allows reduced + bounding boxes without clipping the rest away. The |trim lowlevel=true| + information causes the image externalization to store the trimmed image, + possibly resulting in clipping. +\end{key} + + +\subsection{Clipping and Fading (Soft Clipping)} + +\emph{Clipping path} means that all painting on the page is restricted to a +certain area. This area need not be rectangular, rather an arbitrary path can +be used to specify this area. The |clip| option, explained below, is used to +specify the region that is to be used for clipping. + +A \emph{fading} (a term that I propose, fadings are commonly known as soft +masks, transparency masks, opacity masks or soft clips) is similar to clipping, +but a fading allows parts of the picture to be only ``half clipped''. This +means that a fading can specify that newly painted pixels should be partly +transparent. The specification and handling of fadings is a bit complex and it +is detailed in Section~\ref{section-tikz-transparency}, which is devoted to +transparency in general. + +\begin{key}{/tikz/clip} + This option causes all subsequent drawings to be clipped against the + current path and the size of subsequent paths will not be important for the + picture size. If you clip against a self-intersecting path, the even-odd + rule or the nonzero winding number rule is used to determine whether a + point is inside or outside the clipping region. + + The clipping path is a graphic state parameter, so it will be reset at the + end of the current scope. Multiple clippings accumulate, that is, clipping + is always done against the intersection of all clipping areas that have + been specified inside the current scopes. The only way of enlarging the + clipping area is to end a |{scope}|. + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw[clip] (0,0) circle (1cm); + \fill[red] (1,0) circle (1cm); +\end{tikzpicture} +\end{codeexample} + + It is usually a \emph{very} good idea to apply the |clip| option only to + the first path command in a scope. + + If you ``only wish to clip'' and do not wish to draw anything, you can use + the |\clip| command, which is a shorthand for |\path[clip]|. + % +\begin{codeexample}[] +\begin{tikzpicture} + \clip (0,0) circle (1cm); + \fill[red] (1,0) circle (1cm); +\end{tikzpicture} +\end{codeexample} + + To keep clipping local, use |{scope}| environments as in the following + example: + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw (0,0) -- ( 0:1cm); + \draw (0,0) -- (10:1cm); + \draw (0,0) -- (20:1cm); + \draw (0,0) -- (30:1cm); + \begin{scope}[fill=red] + \fill[clip] (0.2,0.2) rectangle (0.5,0.5); + + \draw (0,0) -- (40:1cm); + \draw (0,0) -- (50:1cm); + \draw (0,0) -- (60:1cm); + \end{scope} + \draw (0,0) -- (70:1cm); + \draw (0,0) -- (80:1cm); + \draw (0,0) -- (90:1cm); +\end{tikzpicture} +\end{codeexample} + + There is a slightly annoying catch: You cannot specify certain graphic + options for the command used for clipping. For example, in the above code + we could not have moved the |fill=red| to the |\fill| command. The reasons + for this have to do with the internals of the \pdf\ specification. You do + not want to know the details. It is best simply not to specify any options + for these commands. +\end{key} + + +\subsection{Doing Multiple Actions on a Path} + +If more than one of the basic actions like drawing, clipping and filling are +requested, they are automatically applied in a sensible order: First, a path is +filled, then drawn, and then clipped (although it took Apple two major +revisions of their operating system to get this right\dots). Sometimes, +however, you need finer control over what is done with a path. For instance, +you might wish to first fill a path with a color, then repaint the path with a +pattern and then repaint it with yet another pattern. In such cases you can use +the following two options: + +\begin{key}{/tikz/preaction=\meta{options}} + This option can be given to a |\path| command (or to derived commands like + |\draw| which internally call |\path|). Similarly to options like |draw|, + this option only has an effect when given to a |\path| or as part of the + options of a |node|; as an option to a |{scope}| it has no effect. + + When this option is used on a |\path|, the effect is the following: When + the path has been completely constructed and is about to be used, a scope + is created. Inside this scope, the path is used but not with the original + path options, but with \meta{options} instead. Then, the path is used in + the usual manner. In other words, the path is used twice: Once with + \meta{options} in force and then again with the normal path options in + force. + + Here is an example in which the path consists of a rectangle. The main + action is to draw this path in red (which is why we see a red rectangle). + However, the preaction is to draw the path in blue, which is why we see a + blue rectangle behind the red rectangle. + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw[help lines] (0,0) grid (3,2); + + \draw + [preaction={draw,line width=4mm,blue}] + [line width=2mm,red] (0,0) rectangle (2,2); +\end{tikzpicture} +\end{codeexample} + + Note that when the preactions are preformed, then the path is already + ``finished''. In particular, applying a coordinate transformation to the + path has no effect. By comparison, applying a canvas transformation does + have an effect. Let us use this to add a ``shadow'' to a path. For this, we + use the preaction to fill the path in gray, shifted a bit to the right and + down: + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw[help lines] (0,0) grid (3,2); + \draw + [preaction={fill=black,opacity=.5, + transform canvas={xshift=1mm,yshift=-1mm}}] + [fill=red] (0,0) rectangle (1,2) + (1,2) circle (5mm); +\end{tikzpicture} +\end{codeexample} + + Naturally, you would normally create a style |shadow| that contains the + above code. The |shadows| library, see Section~\ref{section-libs-shadows}, + contains predefined shadows of this kind. + + It is possible to use the |preaction| option multiple times. In this case, + for each use of the |preaction| option, the path is used again (thus, the + \meta{options} do not accumulate in a single usage of the path). The path + is used in the order of |preaction| options given. + + In the following example, we use one |preaction| to add a shadow and + another to provide a shading, while the main action is to use a pattern. + % +\begin{codeexample}[preamble={\usetikzlibrary{patterns}}] +\begin{tikzpicture} + \draw[help lines] (0,0) grid (3,2); + \draw [pattern=fivepointed stars] + [preaction={fill=black,opacity=.5, + transform canvas={xshift=1mm,yshift=-1mm}}] + [preaction={top color=blue,bottom color=white}] + (0,0) rectangle (1,2) + (1,2) circle (5mm); +\end{tikzpicture} +\end{codeexample} + + A complicated application is shown in the following example, where the path + is used several times with different fadings and shadings to create a + special visual effect: + % +\begin{codeexample}[preamble={\usetikzlibrary{fadings,patterns}}] +\begin{tikzpicture} + [ + % Define an interesting style + button/.style={ + % First preaction: Fuzzy shadow + preaction={fill=black,path fading=circle with fuzzy edge 20 percent, + opacity=.5,transform canvas={xshift=1mm,yshift=-1mm}}, + % Second preaction: Background pattern + preaction={pattern=#1, + path fading=circle with fuzzy edge 15 percent}, + % Third preaction: Make background shiny + preaction={top color=white, + bottom color=black!50, + shading angle=45, + path fading=circle with fuzzy edge 15 percent, + opacity=0.2}, + % Fourth preaction: Make edge especially shiny + preaction={path fading=fuzzy ring 15 percent, + top color=black!5, + bottom color=black!80, + shading angle=45}, + inner sep=2ex + }, + button/.default=horizontal lines light blue, + circle + ] + + \draw [help lines] (0,0) grid (4,3); + + \node [button] at (2.2,1) {\Huge Big}; + \node [button=crosshatch dots light steel blue, + text=white] at (1,1.5) {Small}; +\end{tikzpicture} +\end{codeexample} + % +\end{key} + +\begin{key}{/tikz/postaction=\meta{options}} + The postactions work in the same way as the preactions, only they are + applied \emph{after} the main action has been taken. Like preactions, + multiple |postaction| options may be given to a |\path| command, in which + case the path is reused several times, each time with a different set of + options in force. + + If both pre- and postactions are specified, then the preactions are taken + first, then the main action, and then the post actions. + + In the first example, we use a postaction to draw the path, after it has + already been drawn: + % +\begin{codeexample}[] +\begin{tikzpicture} + \draw[help lines] (0,0) grid (3,2); + + \draw + [postaction={draw,line width=2mm,blue}] + [line width=4mm,red,fill=white] (0,0) rectangle (2,2); +\end{tikzpicture} +\end{codeexample} + + In another example, we use a postaction to ``colorize'' a path: + % +\begin{codeexample}[preamble={\usetikzlibrary{fadings}}] +\begin{tikzpicture} + \draw[help lines] (0,0) grid (3,2); + \draw + [postaction={path fading=south,fill=white}] + [postaction={path fading=south,fading angle=45,fill=blue,opacity=.5}] + [left color=black,right color=red,draw=white,line width=2mm] + (0,0) rectangle (1,2) + (1,2) circle (5mm); +\end{tikzpicture} +\end{codeexample} + % +\end{key} + + +\subsection{Decorating and Morphing a Path} + +Before a path is used, it is possible to first ``decorate'' and/or ``morph'' +it. Morphing means that the path is replaced by another path that is slightly +varied. Such morphings are a special case of the more general ``decorations'' +described in detail in Section~\ref{section-tikz-decorations}. For instance, in +the following example the path is drawn twice: Once normally and then in a +morphed (=decorated) manner. +% +\begin{codeexample}[preamble={\usetikzlibrary{decorations.pathmorphing}}] +\begin{tikzpicture} + \draw (0,0) rectangle (3,2); + \draw [red, decorate, decoration=zigzag] + (0,0) rectangle (3,2); +\end{tikzpicture} +\end{codeexample} + +Naturally, we could have combined this into a single command using pre- or +postaction. It is also possible to deform shapes: +% +\begin{codeexample}[preamble={\usetikzlibrary{decorations.pathmorphing,shadows}}] +\begin{tikzpicture} + \node [circular drop shadow={shadow scale=1.05},minimum size=3.13cm, + decorate, decoration=zigzag, + fill=blue!20,draw,thick,circle] {Hello!}; +\end{tikzpicture} +\end{codeexample} |