5 我需要自定义章节样式，想将章节标题与章节描述放在同一个页面

大佬，如果这个环境我想传3个参数，章节名称、章节详情、章节目标。NewDocumentEnvironment这个命名是没办法定义3个参数的吗，我查看日志的时候，好像没有那样定义过。

可以定义多个参数呀，例如

\NewDocumentEnvironment{fancychapter}{mm+b}{%
  \def\@chapter@description{#3}
  \chapter{#1} 
  ... #2
  \newpage
}{}

就可以

\begin{fancychapter}{Introduction \LaTeX}{}
    ....
\end{fancychapter}

不能运行了都，没生效啊，大佬，求解。
`NewDocumentEnvironment{fancychapter}{mm+b}{%
def@chapter@objectives{#3}
def@chapter@description{#2}
chapter{#1}
newpage
}{}
makeatother
begin{document}
setlist[itemize]{noitemsep, leftmargin=*, label=}
% 定义渐变色
definecolor{startcolor}{RGB}{128,128,128} % 起始颜色为黑色
definecolor{stopcolor}{RGB}{245,245,245} % 结束颜色为白色

begin{fancychapter}{Introduction LaTeX}{

 The principles of object-oriented programming, such asmodularity and reusability, are quite popular as they helpin reducing the complexity of programs. In order toimplement such principles in real world applications, suchas library management and nventory management, youneed to make use of an object-oriented language, such asJava.

This chapter focuses on the fundamentals and buildingblocks of the Java programming language. In addition, itexplains how to access the class members.
}
begin{itemize}
item icon{book.png} Some test text.
item icon{book.png} Some test text.
item icon{book.png} Some test text.
itemicon{book.png} Some test text.
end{itemize}
end{fancychapter}`

代码整理好，完整可运行的代码...

HelloLatex.tex

两个问题，

1. 如果你的参数里面需要包含 \par 或者空行，那么需要在参数类型前面加上 +, 即 m+m+b
2. 你定义了 \@chapter@objectives, 但是没看到你使用?

猜测你是想要的是如下效果

\documentclass{book}

\usepackage[explicit]{titlesec}

\usepackage[margin = 2cm]{geometry}
\usepackage{enumitem}
\usepackage{tikz}


\usepackage{graphbox} % provide align = c 

\makeatletter
\def\@chapter@description{}
\def\@chapter@objectives{}
\titleformat{name = \chapter}{}{}{0em}
{%
  \begin{tikzpicture}[remember picture, overlay, every node/.style={inner sep = 0pt, outer sep = 0pt}]
    \node[anchor = north west] at ([shift = {(2cm, -2cm)}]current page.north west) {\includegraphics[width = .2\textwidth, height = \textheight]{example-image}};
    \fill[gray!40] ([shift = {(2cm + .2\textwidth, -2.5cm)}]current page.north west) rectangle ++ (.8\textwidth, -4cm);
    \node[anchor = south west, inner sep = 10pt, scale = 2, font = \bfseries] at ([shift = {(2cm + .2\textwidth, -6.5cm)}]current page.north west) {#1};
    \fill[gray!70] ([shift = {(-2, -2.5)}]current page.north east) rectangle ++ (-1.5, -4);
    \node[rotate = 90, font=\bfseries\Large] at ([shift = {(-2.75, -4.5)}]current page.north east) {\chaptername\ \thechapter};
    \node[anchor = north west, inner sep = 10pt] at ([shift = {(2cm + .2\textwidth, -6.5cm)}]current page.north west) {
      \begin{minipage}{\dimexpr .8\textwidth - 10pt\relax}
        \parindent=2em
        \@chapter@description
      \end{minipage}
    };
    \fill[shading=radial, left color=startcolor, right color=stopcolor] ([shift = {(3cm + .2\textwidth, -10.5cm)}]current page.north west) rectangle ++ (.7\textwidth, -0.8cm);
    \node[anchor = south west, inner sep = 10pt, scale = 1, font = \bfseries] at ([shift = {(3cm + .2\textwidth, -11.40cm)}]current page.north west) {Objectives};
    \node[anchor = north west, inner sep = 10pt] at ([shift = {(2cm + .2\textwidth, -12.5cm)}]current page.north west) {
      \begin{minipage}{\dimexpr .8\textwidth - 10pt\relax}
        \parindent=2em
        \@chapter@objectives
      \end{minipage}
    };
  \end{tikzpicture}
}
\newcommand{\icon}[1]{\includegraphics[height=1em, align = c]{#1}}
\NewDocumentEnvironment{fancychapter}{m+m+b}{%
  \def\@chapter@objectives{#3}
  \def\@chapter@description{#2}
  \chapter{#1}
  \newpage
}{}
\makeatother

\usetikzlibrary{calc, intersections}
\begin{document}
\setlist[itemize]{noitemsep, leftmargin=*, label=}
% 定义渐变色
\definecolor{startcolor}{RGB}{128,128,128} % 起始颜色为黑色
\definecolor{stopcolor}{RGB}{245,245,245} % 结束颜色为白色
\begin{fancychapter}{Introduction \LaTeX}{
     The principles of object-oriented programming, such asmodularity and reusability, are quite popular as they helpin reducing the complexity of programs. In order toimplement such principles in real world applications, suchas library management and nventory management, youneed to make use of an object-oriented language, such asJava.

  This chapter focuses on the fundamentals and buildingblocks of the Java programming language. In addition, itexplains how to access the class members.
}
{
  \begin{itemize}
  \item \icon{example-image} Some test text.
  \item \icon{example-image} Some test text.
  \item \icon{example-image} Some test text.
  \item\icon{example-image}  Some test text.
\end{itemize}
}
\end{fancychapter}



\end{document}

大佬，我使用上述方法，用tableofcontents这个来自动生成目录的时候，他生成了一个content的章节样式，类似这种的：
这是不是因为他生成content的时候默认调用了自定义的这个样式titleformat{name = chapter}{}{}{0em}，导致他content也出现这个样式了。是不是应该再定义一个chapter的样式啊？

@u19850 大佬，而且我将自定义的样式代码移动到我下载的easybook里面去，一直提示You can't use `macro parameter character #' in restricted horizontal mode.这个报错，是因为easybook.sty和eb-elegantbook.sty这两个包里面不能用#吗？

@u101278 这是因为 \tableofcontents 其实内置了一个无编号的 \chapter*, 如果不希望影响 \tableofcontents 的显示，可以重新定义一下无编号格式的样式，参见 titlesec 宏包.
也可以在使用 \tableofcontents 之后再修改标题样式.