TikZ中的路径双色渐变

Question

我正在尝试绘制一条具有双色渐变的路径，首先从洋红色到青色，然后从青色到洋红色。

我曾尝试使用以下代码这线程，但我能做的最好的是这样的：

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{decorations.markings}


\tikzset{multicolor/.style={
        postaction={
            decorate,
            decoration={
                markings,
                mark=between positions 0 and 0.5*\pgfdecoratedpathlength step 0.5pt with {
                    \pgfmathsetmacro\myval{multiply(divide(
                        \pgfkeysvalueof{/pgf/decoration/mark info/distance from start}, 1*\pgfdecoratedpathlength),200)};
                    \pgfsetfillcolor{cyan!\myval!magenta};
                    \pgfpathcircle{\pgfpointorigin}{#1};
                    \pgfusepath{fill};},
                mark=between positions 0.5*\pgfdecoratedpathlength and \pgfdecoratedpathlength step 0.5pt with {
                    \pgfmathsetmacro\myval{300+multiply(divide(
                        \pgfkeysvalueof{/pgf/decoration/mark info/distance from start}, 1*\pgfdecoratedpathlength),200)};
                    \pgfsetfillcolor{magenta!\myval!cyan};
                    \pgfpathcircle{\pgfpointorigin}{#1};
                    \pgfusepath{fill};},
}}}}


\begin{document}
    
    \begin{tikzpicture}
        \path [multicolor=0.3mm,draw] (0,0) .. controls (1,3) and (5,-7) .. (4,1)  {};
    \end{tikzpicture}
    
    
\end{document}

结果是：

我希望路径的第二部分逐渐从青色变为洋红色。

提前致谢

Answer 1

只是对公式进行了调整。

我还添加了overlay路径本身，以便边界框不包含控制点，但\pgf@relevantforpicturesizetrue（即overlay = false）圆圈本身被计入图片的边界框。

路径本身没有被绘制，并且multicolor样式不再包含任何内容postaction，因为无论如何该线都会被圆圈隐藏。

代码

\documentclass[tikz]{standalone}
%\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{decorations.markings}
\tikzset{
  multicolor/.style={
    decorate,
    decoration={
      markings,
      mark=between positions 0 and 0.5*\pgfdecoratedpathlength step 0.5pt with {
        \csname pgf@relevantforpicturesizetrue\endcsname % overlay = false
        \pgfmathparse{multiply(divide(
          \pgfkeysvalueof{/pgf/decoration/mark info/distance from start},
          \pgfdecoratedpathlength),200)}
        \pgfsetfillcolor{cyan!\pgfmathresult!magenta}
        \pgfpathcircle{\pgfpointorigin}{#1}
        \pgfusepath{fill}},
      mark=between positions 0.5*\pgfdecoratedpathlength and
        \pgfdecoratedpathlength step 0.5pt with {
        \csname pgf@relevantforpicturesizetrue\endcsname % overlay = false
        \pgfmathparse{subtract(multiply(divide(
          \pgfkeysvalueof{/pgf/decoration/mark info/distance from start},
          \pgfdecoratedpathlength),200),100)}
        \pgfsetfillcolor{magenta!\pgfmathresult!cyan}
        \pgfpathcircle{\pgfpointorigin}{#1}
        \pgfusepath{fill}}}}}

\begin{document}
\tikz % overlay because of control points
  \path[multicolor=0.3mm, overlay] (0,0) .. controls (1,3) and (5,-7) .. (4,1);
\end{document}

输出