如何像 Tikz 那样绘制用于输入和输出消息的特定形状？

Question

在算法表示中（几个月前我得到了帮助，感谢 tex.stackexchange！），我想使用 2 个特定符号表示输入和输出数据：这是实际的算法图：

Latex 源代码如下：

\documentclass{standalone}
\usepackage[T1]{fontenc} %lien codage fonte en sortie
\usepackage[latin1]{inputenc} %lien codage d'entrée
\usepackage{dejavu}  % fonte en sortie
\usepackage{forest}
\usepackage{amssymb}
\usetikzlibrary{shapes.geometric}
\begin{document}
\pgfkeys{/forest,
  racine/.append style={minimum width=1cm, fill=white!80,circle,
        tikz={
            \draw [circle,draw,line width=0.5pt] ;
            \draw [->,line width=1pt] () ++(160:4mm) arc (-200:40:4mm);}
            },
  affecter/.append style={rectangle, minimum height=5mm},
  ecrire/.append style={trapezium, trapezium left angle=110,trapezium right angle=70, minimum height=5mm},
  lire/.append style={trapezium, trapezium left angle=70,trapezium right angle=-70, minimum height=5mm},
  executer/.append style={below=0ex,draw,cloud,aspect=4,cloud puffs=32},
  retourner/.append style={minimum width=2cm, fill=red!40,rectangle},
  nop/.append style={circle},
  sequence/.append style={fill=red!20, rounded corners},
  decision/.append style={diamond, fill=blue!20, text width=5em, inner sep=.5pt, rounded corners},
  si/.append style={fill=red!20, circle},
  tq/.append style={fill=red!20, circle},
  pour/.append style={fill=red!20, circle},
  nuage/.append style={below=0ex,draw,dotted,cloud,aspect=4,cloud puffs=12}
}
\begin{forest}
for tree={
  child anchor=north,
  parent anchor=south,
  thick,
  draw,
  align=center
}
[{CalculerSomme1\\\hline \mbox{}\\[-1em]VAR entier som,a,b,compteur\\} [seq, racine
 [Initialisation, sequence[{a,b $\leftarrow$ }, lire][{som$\leftarrow$ 0}, affecter ] ] 
 [Traitement, sequence
 [POUR, pour
 [ { compteur\\de 1\\a b\\pas 1}, decision]
 [repeter, sequence, edge label={node[midway,left,font=\scriptsize]{vrai}}[{som$\leftarrow$ som + a}, affecter ] ] ]  ] 
 [Resultat, sequence[{ som}, ecrire] ]  ] ]
\end{forest}
\end{document}

我想用符号替换输入 a 和 b，输出 som ：你能帮助我吗？非常感谢！

Answer 1

这些形状已在shapes.symbols库中可用，它们被称为signal。请查看第 703 页pgfmanual

以下示例摘自该处：

\documentclass[tikz,border=2mm]{standalone}
\usetikzlibrary{shapes.symbols}

\begin{document}

\begin{tikzpicture}
[every node/.style={signal, draw, text=white, signal to=nowhere}]
\node[fill=green!65!black, signal to=east] at (0,1) {To East};
\node[fill=red!65!black, signal from=east] at (0,0) {From East};
\end{tikzpicture}

\end{document}