每次调用命令 \chapter{} 时，我都想更改章节标签（小矩形框）的颜色，并可能将颜色作为参数传递。
因此，我需要用参数解决的部分是命令\draw[fill=black]。
这是一个可编译的示例：
\documentclass{book}
\usepackage{color}
\usepackage{tikz}
\usepackage[explicit]{titlesec}
\newcommand*\chapterlabel{}
%\renewcommand{\thechapter}{\Roman{chapter}}
\titleformat{\chapter}[display] % type (section,chapter,etc...) to vary, shape (eg display-type)
{\normalfont\fontsize{24}{26}\bfseries} % format of the chapter
{\gdef\chapterlabel{\thechapter\ }} % the label
{0pt} % separation between label and chapter-title
{\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-8cm] at (current page.north west)
{\begin{tikzpicture}[remember picture, overlay]
\draw[fill=black] (0,0) rectangle(35.5mm,15mm);
\node[anchor=north east,yshift=-7.2cm,xshift=34mm,minimum height=30mm,inner sep=0mm] at (current page.north west)
{\parbox[top][30mm][t]{15mm}{\raggedleft $\phantom{\textrm{l}}$\color{white}\chapterlabel}}; %the black l is just to get better base-line alingement
\node[anchor=north west,yshift=-7.2cm,xshift=37mm,text width=\textwidth,minimum height=30mm,inner sep=0mm] at (current page.north west)
{\parbox[top][30mm][t]{\textwidth}{\color{black}#1}};
\end{tikzpicture}
};
\end{tikzpicture}
\gdef\chapterlabel{}
} % code before the title body
\usepackage[utf8]{inputenc}
\title{test}
\begin{document}
\maketitle
\chapter{Introduction}
\end{document}
我尝试将参数传递给 \chapterlabel 函数，但没有成功。我还发现了一个非常相似的问题“https://tex.stackexchange.com/questions/641554/change-color-for-each-chapter”，但并没有得到真正的答案（我尝试了建议的解决方案，但没有成功）。
如果有人能帮忙我将非常感激。
答案1
我建议定义一系列名称中带有数字的颜色，然后章节将根据当前章节编号使用颜色：
\documentclass{book}
\usepackage{color}
\usepackage{tikz}
\usepackage[explicit]{titlesec}
\colorlet{chapter1}{red}
\colorlet{chapter2}{blue}
\newcommand*\chapterlabel{}
%\renewcommand{\thechapter}{\Roman{chapter}}
\titleformat{\chapter}[display] % type (section,chapter,etc...) to vary, shape (eg display-type)
{\normalfont\fontsize{24}{26}\bfseries} % format of the chapter
{\gdef\chapterlabel{\thechapter\ }} % the label
{0pt} % separation between label and chapter-title
{\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-8cm] at (current page.north west)
{\begin{tikzpicture}[remember picture, overlay]
\draw[fill=chapter\the\value{chapter}] (0,0) rectangle(35.5mm,15mm);
\node[anchor=north east,yshift=-7.2cm,xshift=34mm,minimum height=30mm,inner sep=0mm] at (current page.north west)
{\parbox[top][30mm][t]{15mm}{\raggedleft $\phantom{\textrm{l}}$\color{white}\chapterlabel}}; %the black l is just to get better base-line alingement
\node[anchor=north west,yshift=-7.2cm,xshift=37mm,text width=\textwidth,minimum height=30mm,inner sep=0mm] at (current page.north west)
{\parbox[top][30mm][t]{\textwidth}{\color{black}#1}};
\end{tikzpicture}
};
\end{tikzpicture}
\gdef\chapterlabel{}
} % code before the title body
\usepackage[utf8]{inputenc}
\title{test}
\begin{document}
\maketitle
\chapter{Introduction}
\chapter{foo}
\end{document}
或者，您可以用用户定义的颜色为章节着色，并在每章之前更改其定义：
\documentclass{book}
\usepackage{color}
\usepackage{tikz}
\usepackage[explicit]{titlesec}
\colorlet{chapter}{red}
\newcommand*\chapterlabel{}
%\renewcommand{\thechapter}{\Roman{chapter}}
\titleformat{\chapter}[display] % type (section,chapter,etc...) to vary, shape (eg display-type)
{\normalfont\fontsize{24}{26}\bfseries} % format of the chapter
{\gdef\chapterlabel{\thechapter\ }} % the label
{0pt} % separation between label and chapter-title
{\begin{tikzpicture}[remember picture,overlay]
\node[yshift=-8cm] at (current page.north west)
{\begin{tikzpicture}[remember picture, overlay]
\draw[fill=chapter] (0,0) rectangle(35.5mm,15mm);
\node[anchor=north east,yshift=-7.2cm,xshift=34mm,minimum height=30mm,inner sep=0mm] at (current page.north west)
{\parbox[top][30mm][t]{15mm}{\raggedleft $\phantom{\textrm{l}}$\color{white}\chapterlabel}}; %the black l is just to get better base-line alingement
\node[anchor=north west,yshift=-7.2cm,xshift=37mm,text width=\textwidth,minimum height=30mm,inner sep=0mm] at (current page.north west)
{\parbox[top][30mm][t]{\textwidth}{\color{black}#1}};
\end{tikzpicture}
};
\end{tikzpicture}
\gdef\chapterlabel{}
} % code before the title body
\usepackage[utf8]{inputenc}
\title{test}
\begin{document}
\maketitle
\colorlet{chapter}{green}
\chapter{Introduction}
\colorlet{chapter}{orange}
\chapter{foo}
\end{document}