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我有一个带有开放（白色）箭头的图形。我绘制的路径可能会与 TikZ 先前绘制的箭头重叠，因此被放置在前景中。我不喜欢这种外观，我希望所有箭头都放置在前景中，这样就不会将路径放置在箭头之上。

这个描述很模糊，但希望通过 MWE 能够理解。

平均能量损失

\documentclass{standalone}

\usepackage{pgfplots}
\pgfplotsset{compat = newest}
\usetikzlibrary{arrows.meta}

\tikzset{%
    state/.style = {%
        draw, circle, minimum size = 4, inner sep = 0, fill = black
    }%
}% 

\tikzset{%
    dashedarrow/.style = {%
        draw, densely dashed, > = {Latex[width = 1.7mm, length = 2.2mm, open, fill = white]}, ->
    }%
}% 

\begin{document}%
\begin{tikzpicture}%

\node[state] (0) at (0,0) {};
\node[state] (1) at (1,0) {};
\node[state] (2) at (0,1) {};

\path[dashedarrow] (1) edge[bend left = 20] (2);
\path[dashedarrow] (2) edge[bend left = 20] (0);

\end{tikzpicture}%
\end{document}%

MWE 制作

MWE 的结果

通过简单地改变两行的顺序\path[dashedarrow] ...我得到了我想要的结果：

所需结果

但是，当我增加箭头的数量时，不能保证这个解决方案有效：可能不存在每个箭头在前景中的顺序。

有什么方法可以强制将所有箭头绘制在前景上，以致于没有任何东西绘制在它们上面？您可以假设箭头之间的距离不会太近以至于它们可能会接触或重叠。

答案1

使用该markings库，您可以指示 tikz 在顶层绘制箭头。这需要将符号更改edge为to（因为edge似乎没有添加到路径中，因此无法应用标记）。

\documentclass{standalone}

\usepackage{tikz}
\pgfplotsset{compat = newest}
\usetikzlibrary{arrows.meta, decorations.markings}
\pgfdeclarelayer{arrowlayer}
\pgfsetlayers{main,arrowlayer}
\tikzset{%
    state/.style = {%
        draw, circle, minimum size = 4, inner sep = 0, fill = black
    }%
}%

\tikzset{%
    dashedarrow/.style = {%
        draw, densely dashed, > = {Latex[width = 1.7mm, length = 2.2mm, open, fill = white]},
        decoration={markings, mark=at position 1 with {\begin{pgfonlayer}{arrowlayer}\arrow{>}\end{pgfonlayer}}},
        postaction={decorate}
    }%
}%


\begin{document}%
\begin{tikzpicture}%

\node[state] (0) at (0,0) {};
\node[state] (1) at (1,0) {};
\node[state] (2) at (0,1) {};

\path[dashedarrow] (1) to[bend left = 20] (2);
\path[dashedarrow] (2) to[bend left = 20] (0);

\end{tikzpicture}%
\end{document}%

顶层的箭头

答案2

更新

经过一些源代码检查后，我终于搞定了。考虑将这些行添加到您的代码中。

\pgfdeclarelayer{foreground}
\pgfsetlayers{main,foreground}

\makeatletter
\let\pgf@arrow@draw@arrow@old\pgf@arrow@draw@arrow
\def\pgf@arrow@draw@arrow#1#2{
    \begin{pgfonlayer}{foreground}
        \pgf@arrow@draw@arrow@old{#1}{#2}
    \end{pgfonlayer}
}
\makeatother

例子

请注意，虽然箭头相互覆盖，但它们并没有被其他任何东西覆盖。

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows.meta}

\pgfdeclarelayer{background}
\pgfdeclarelayer{foreground}
\pgfsetlayers{background,main,foreground}

\makeatletter
\let\pgf@arrow@draw@arrow@old\pgf@arrow@draw@arrow
\def\pgf@arrow@draw@arrow#1#2{
    \begin{pgfonlayer}{foreground}
        \pgf@arrow@draw@arrow@old{#1}{#2}
    \end{pgfonlayer}
}
\makeatother

\begin{document}

\tikz[scale=10]{
    \foreach\i in{1,...,100}{
        \draw[->,>={Latex[length=30,open,fill=yellow]}](rnd,rnd)--(rnd,rnd);
    }
}

\end{document}

旧答案

以下的想法是，通过设置较大的值，dash phase可以隐藏路径，只绘制箭头。如果您想重复每个\draw命令两次：一次用于路径，一次用于箭头，则不需要图层系统。

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows.meta}
\tikzset{%
    state/.style = {%
        draw, circle, minimum size = 4, inner sep = 0, fill = black
    }%
}% 
\tikzset{%
    dashed only/.style = {
        draw, densely dashed
    },
    arrow only/.style = {%
        draw, >={Latex[width = 1.7mm, length = 2.2mm, open, fill = white]}, ->,
        dash pattern=on 0 off1000, dash phase=500
    }%
}% 

\begin{document}
\begin{tikzpicture}[]%
\node[state] (0) at (0,0) {};
\node[state] (1) at (1,0) {};
\node[state] (2) at (0,1) {};
\path[dashed only] (1) to[bend left = 20] (2);
\path[dashed only] (2) to[bend left = 20] (0);
\path[arrow only] (1) to[bend left = 20] (2);
\path[arrow only] (2) to[bend left = 20] (0);
\end{tikzpicture}%

\end{document}%

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