TikZ：如何画一个钻石小孩

Question 1

正如 Claudio Fiandrino 所说，您也需要加载shapes（或shapes.geometric）tikzlibrary，才能完成diamond工作。

当我尝试您的代码时，设置every node./style={...}出现了一些问题，因为它覆盖了decision样式（以及所有其他样式）：

由于您已经为每个节点定义了一种样式，因此我建议您使用它们：

这是代码：

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{trees,shapes.geometric}

\usepackage[active,tightpage]{preview}% just for showing image
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}%
%-------definisce stile dei nodi---------------
\tikzstyle{startstop} = [rectangle, rounded corners, minimum width=5cm, minimum height=1cm,text centered, draw=black, fill=red!50]

\tikzstyle{io} = [trapezium, trapezium left angle=70, trapezium right angle=110, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=blue!30]

\tikzstyle{process} = [rectangle, minimum width=2cm, minimum height=1cm, text centered, text width=2cm, draw=black, fill=orange!30]

\tikzstyle{decision} = [diamond, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=green!30]

\tikzstyle{arrow} = [thick,->,>=stealth]
%--------------------------------------

\begin{document}
\begin{tikzpicture}[
thick,
every node/.style = {
      font = \sffamily,
      text=white
                    },
sibling distance = 7em,
edge from parent fork down                  
  ]
\node[startstop,text width=10em] (T0) {test0}
    child {node[process] (T1) {test1}
    %child {node[ellipse,draw] (right node) {right}};
        child {node[decision,text=red] (T4) {test4}
            child {node[process] (T5) {test5}}
        }}
    child {node[process] (T2) {test2}}
       ;
\end{tikzpicture}
\end{document}

编辑：感谢 Claudio Fiandrino 的评论，还有一些建议：

为了仅显示图像，standalone类更好，并且您不需要此代码：

\usepackage[active,tightpage]{preview}% just for showing image
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{5pt}%

但只有\documentclass{standalone}。

通常使用\tikset{...}比\tikzstyle{...}定义节点的样式更好。有关更多信息，您可以阅读 Claudio Fiandrino 链接的答案（应该使用 \tikzset 还是 \tikzstyle 来定义 TikZ 样式？）。

产生相同输出的新改进代码如下：

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{trees,shapes.geometric}

%-------definisce stile dei nodi---------------
\tikzset{%
        startstop/.style={rectangle, rounded corners, minimum width=5cm, minimum height=1cm,text centered, draw=black, fill=red!50},
        io/.style={trapezium, trapezium left angle=70, trapezium right angle=110, minimum width=3cm, minimum height=1cm, text centered, draw=black, fill=blue!30},
        process/.style={rectangle, minimum width=2cm, minimum height=1cm, text centered, text width=2cm, draw=black, fill=orange!30},
        decision/.style={diamond, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=green!30},
        arrow/.style={thick,->,>=stealth},
        every node/.style={font = \sffamily,text=white}
}

%--------------------------------------

\begin{document}
\begin{tikzpicture}[
    thick,
    sibling distance = 7em,
    edge from parent fork down                  
  ]
\node[startstop,text width=10em] (T0) {test0}
    child {node[process] (T1) {test1}
    %child {node[ellipse,draw] (right node) {right}};
        child {node[decision,text=red] (T4) {test4}
            child {node[process] (T5) {test5}}
        }}
    child {node[process] (T2) {test2}}
       ;
\end{tikzpicture}
\end{document}

编辑2：经过反复试验，我得到了这个结果：

edge我为和之间的diamond定义了三种不同的样式child：

\tikzset{%
        MyEdgeA/.style={edge from parent path={(\tikzparentnode.west) -| (\tikzchildnode.north)}},
        MyEdgeB/.style={edge from parent path={(\tikzparentnode.south) -| (\tikzchildnode.north)}},
        MyEdgeC/.style={edge from parent path={(\tikzparentnode.east) -| (\tikzchildnode.north)}}
}

您可以设置您想要的边缘类型并将其作为child选项给出：

child[MyEdgeA]{...}

此外，我还改变了菱形和后续节点之间的距离：

level 3/.style={level distance=5em}

完整代码如下：

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{trees,shapes.geometric}

%-------definisce stile dei nodi---------------
\tikzset{%
        startstop/.style={rectangle, rounded corners, minimum width=5cm, minimum height=1cm,text centered, draw=black, fill=red!50},
        io/.style={trapezium, trapezium left angle=70, trapezium right angle=110, minimum width=3cm, minimum height=1cm, text centered, draw=black, fill=blue!30},
        process/.style={rectangle, minimum width=2cm, minimum height=1cm, text centered, text width=2cm, draw=black, fill=orange!30},
        decision/.style={diamond, minimum width=2cm, minimum height=1cm, text centered, draw=black, fill=green!30},
        arrow/.style={thick,->,>=stealth},
        every node/.style={font=\sffamily,text=white}
}

\tikzset{%
        MyEdgeA/.style={edge from parent path={(\tikzparentnode.west) -| (\tikzchildnode.north)}},
        MyEdgeB/.style={edge from parent path={(\tikzparentnode.south) -| (\tikzchildnode.north)}},
        MyEdgeC/.style={edge from parent path={(\tikzparentnode.east) -| (\tikzchildnode.north)}}
}
%--------------------------------------

\begin{document}
\begin{tikzpicture}[
    thick,
    sibling distance = 7em,
    edge from parent fork down,
    level 3/.style={level distance=5em}
  ]
\node[startstop,text width=10em] (T0) {test0}
    child {node[process] (T1) {test1}
    %child {node[ellipse,draw] (right node) {right}};
        child {node[decision,text=red] (T4) {test4}
            child[MyEdgeA] {node[process] (T5) {test5}
                edge from parent
                node[pos=0.5,above,text=black] {No}}
            child[MyEdgeB] {node[process] (T6) {test6}
                edge from parent
                node[pos=0.7,right,text=black] {bla bla..}}
            child[MyEdgeC] {node[process] (T7) {test7}
                edge from parent
                node[pos=0.5,above,text=black] {Yes}}
        }}
    child {node[process] (T2) {test2}}
       ;
\end{tikzpicture}
\end{document}

Answer