如何使用 scrlayer-scrpage 包为偶数页和奇数页的页眉分隔线设置不同的颜色？

Question

我已经尝试了很长时间，但仍无法弄清楚如何根据页面是奇数还是偶数来实现不同颜色的头部分隔线。

\documentclass[
11pt,
a4paper,
titlepage,
toc=listof,            
toc=bibliography,       
headings=standardclasses,       
%headings=big,
chapterprefix=true,            
numbers=noenddot,               
twoside=semi,               
]{scrreport}        

\usepackage{lipsum}
\usepackage{xcolor}
\usepackage[automark,headsepline]{scrlayer-scrpage}


\clearpairofpagestyles
\lehead{\large{\normalfont{\textsc{\thepage}}}}
\rehead{\large{\normalfont{\textsc{{\headmark}}}}}

\rohead{\large{\normalfont{\textsc{\thepage}}}}
\lohead{\large{\normalfont{\textsc{{\headmark}}}}}


\pagestyle{scrheadings}
\addtokomafont{headsepline}{\color{blue}}
\addtokomafont{footsepline}{\color{blue}}
\setheadsepline{2}
\setfootsepline{2}

\begin{document}
\lipsum[1-20]
\end{document}

Answer 1

一种可能性是

\KOMAoptions{
  onpsoddpage={\colorlet{headsepline}{green}},
  onpsevenpage={\colorlet{headsepline}{red}}
}
\addtokomafont{headsepline}{\color{headsepline}}

例子：

\documentclass[
  %11pt,% default
  %a4paper,% default
  titlepage,
  toc=listof,
  toc=bibliography,
  headings=standardclasses,
  %headings=big,% default
  chapterprefix=true,
  numbers=noenddot,
  twoside=semi,
]{scrreport}

\usepackage{lipsum}
\usepackage{xcolor}
\usepackage[
  automark,
  headsepline=2pt,% <- changed
  footsepline=2pt% <- changed
]{scrlayer-scrpage}% sets pagestyle scrheadings automatically

\clearpairofpagestyles
\ohead{\pagemark}% <- changed
\ihead{\headmark}% <- changed
\addtokomafont{pagehead}{\normalfont\large\scshape}% <- added
\setkomafont{pagenumber}{}% <- added

\KOMAoptions{
  onpsoddpage={\colorlet{headsepline}{green}},% green on odd pages
  onpsevenpage={\colorlet{headsepline}{red}}% red on even pages
}
\addtokomafont{headsepline}{\color{headsepline}}% <- changed
\addtokomafont{footsepline}{\color{blue}}

\begin{document}
\chapter{Foo}
\section{Bar}
\lipsum[1-20]
\end{document}

补充说明：\setheadsepline和\setfootsepline已弃用。请使用选项headsepline=2pt和footsepline=2pt代替。