我在 tikz 中创建了一个漂亮的框架（嗯……以我的标准来说很不错）。从另一个问题中汲取灵感（即使用背景包获取特定类型的页面边框），tikzpagenodes这样边距的改变就不会影响边框。
我还决定在页面边缘放置页码，直接使用我在 stackexchange 上找到的代码（外边距中的页码会影响垂直标尺）。
以下是示例代码：
\documentclass[a4paper,11pt,twoside]{scrreprt}
\usepackage[utf8]{inputenc}
\usepackage[B1,T1]{fontenc}
\usepackage[usenames,dvipsnames,svgnames,table]{xcolor}
\usepackage[margin=45mm]{geometry}
% page number in margins
\usepackage{scrpage2}
\clearscrheadfoot
\pagestyle{scrheadings}
\setlength{\footskip}{0pt}
\rofoot[\centerpageno{o}]{\centerpageno{o}}
\lefoot[\centerpageno{e}]{\centerpageno{e}}
\def\centerpageno#1{\leavevmode
\vbox to 0pt{
\vss
\hbox to 0pt{\large
\if#1o\kern 1.15cm\else\hss\fi\thepage
\if#1o\hss\else\kern 1.15cm\fi}
\vskip.5\textheight
\vskip\baselineskip}}
\usepackage{background}
\usetikzlibrary{calc}
\usepackage{tikzpagenodes}
\backgroundsetup%
{ contents={
\begin{tikzpicture}[overlay]
\checkoddpage
\ifoddpage
\draw[color=BrickRed,line width=5pt, opacity=1] ($(current page text area.south west)+(-1.5,-1.5)$) rectangle ($(current page text area.north east)+(1.5,1.5)$);
\draw[black, opacity=1] ($(current page text area.south west)+(-1.7,-1)$) -- ($(current page text area.north west)+(-1.7,1)$) -- ($(current page text area.north west)+(-1.25,1)$) -- ($(current page text area.north west)+(-1.25,1.7)$) -- ($(current page text area.north west)+(-1.7,1.7)$) -- ($(current page text area.north west)+(-1.7,1.25)$) -- ($(current page text area.north west)+(-1,1.25)$) -- ($(current page text area.north west)+(-1,1.7)$) -- ($(current page text area.north east)+(1,1.7)$) -- ($(current page text area.north east)+(1,1.25)$) -- ($(current page text area.north east)+(1.7,1.25)$) -- ($(current page text area.north east)+(1.7,1.7)$) -- ($(current page text area.north east)+(1.25,1.7)$) -- ($(current page text area.north east)+(1.25,1)$) -- ($(current page text area.north east)+(1.7,1)$) -- ($(current page text area.south east)+(1.7,-1)$) -- ($(current page text area.south east)+(1.25,-1)$) -- ($(current page text area.south east)+(1.25,-1.7)$) -- ($(current page text area.south east)+(1.7,-1.7)$) -- ($(current page text area.south east)+(1.7,-1.25)$) -- ($(current page text area.south east)+(1,-1.25)$) -- ($(current page text area.south east)+(1,-1.7)$) -- ($(current page text area.south west)+(-1,-1.7)$) -- ($(current page text area.south west)+(-1,-1.25)$) -- ($(current page text area.south west)+(-1.7,-1.25)$) -- ($(current page text area.south west)+(-1.7,-1.7)$) -- ($(current page text area.south west)+(-1.25,-1.7)$) -- ($(current page text area.south west)+(-1.25,-1)$) -- ($(current page text area.south west)+(-1.7,-1)$) ;
\draw[color=BrickRed,line width=5pt,opacity=1,fill=white] ($(current page text area.north east)+(1.5,-10.12)$) circle (25pt);
\else
\draw[color=BrickRed,line width=5pt, opacity=1] ($(current page text area.south west)+(-1.5,-1.5)$) rectangle ($(current page text area.north east)+(1.5,1.5)$);
\draw[black, opacity=1] ($(current page text area.south west)+(-1.7,-1)$) -- ($(current page text area.north west)+(-1.7,1)$) -- ($(current page text area.north west)+(-1.25,1)$) -- ($(current page text area.north west)+(-1.25,1.7)$) -- ($(current page text area.north west)+(-1.7,1.7)$) -- ($(current page text area.north west)+(-1.7,1.25)$) -- ($(current page text area.north west)+(-1,1.25)$) -- ($(current page text area.north west)+(-1,1.7)$) -- ($(current page text area.north east)+(1,1.7)$) -- ($(current page text area.north east)+(1,1.25)$) -- ($(current page text area.north east)+(1.7,1.25)$) -- ($(current page text area.north east)+(1.7,1.7)$) -- ($(current page text area.north east)+(1.25,1.7)$) -- ($(current page text area.north east)+(1.25,1)$) -- ($(current page text area.north east)+(1.7,1)$) -- ($(current page text area.south east)+(1.7,-1)$) -- ($(current page text area.south east)+(1.25,-1)$) -- ($(current page text area.south east)+(1.25,-1.7)$) -- ($(current page text area.south east)+(1.7,-1.7)$) -- ($(current page text area.south east)+(1.7,-1.25)$) -- ($(current page text area.south east)+(1,-1.25)$) -- ($(current page text area.south east)+(1,-1.7)$) -- ($(current page text area.south west)+(-1,-1.7)$) -- ($(current page text area.south west)+(-1,-1.25)$) -- ($(current page text area.south west)+(-1.7,-1.25)$) -- ($(current page text area.south west)+(-1.7,-1.7)$) -- ($(current page text area.south west)+(-1.25,-1.7)$) -- ($(current page text area.south west)+(-1.25,-1)$) -- ($(current page text area.south west)+(-1.7,-1)$) ;
\draw[color=BrickRed,line width=5pt,opacity=1,fill=white] ($(current page text area.north west)+(-1.5,-10.12)$) circle (25pt);
\fi
\end{tikzpicture}
},
scale=1,
angle=0
}
\usepackage{lipsum}
\begin{document}
\lipsum
\addtocounter{page}{+10}
\lipsum
\addtocounter{page}{+100}
\end{document}
可以看到，页边距中的页码不在圆圈内居中（为了更好地显示效果，我放大了字体）；这是因为在添加数字时页码没有水平居中。
有没有办法使页码水平居中，以便无论数字有多少位，数字都保持在一个点的中心？
附加问题：有没有办法在同一点绘制圆圈，这样我就不必手动定位它了？
谢谢。
答案1
有一种可能性是：不要\draw使用圆圈并放置页码scrheadings，而是使用圆形\node直接放置页码：
\documentclass[a4paper,11pt,twoside]{scrreprt}
\usepackage[utf8]{inputenc}
\usepackage[B1,T1]{fontenc}
\usepackage[usenames,dvipsnames,svgnames,table]{xcolor}
\usepackage[margin=45mm]{geometry}
\usepackage{scrpage2}
\clearscrheadfoot
\pagestyle{scrheadings}
\setlength{\footskip}{0pt}
\usepackage{background}
\usetikzlibrary{calc}
\usepackage{tikzpagenodes}
\backgroundsetup%
{ contents={
\begin{tikzpicture}[overlay]
\checkoddpage
\ifoddpage
\draw[color=BrickRed,line width=5pt, opacity=1]
($(current page text area.south west)+(-1.5,-1.5)$)
rectangle
($(current page text area.north east)+(1.5,1.5)$);
\draw[black, opacity=1] ($(current page text area.south west)+(-1.7,-1)$) -- ($(current page text area.north west)+(-1.7,1)$) -- ($(current page text area.north west)+(-1.25,1)$) -- ($(current page text area.north west)+(-1.25,1.7)$) -- ($(current page text area.north west)+(-1.7,1.7)$) -- ($(current page text area.north west)+(-1.7,1.25)$) -- ($(current page text area.north west)+(-1,1.25)$) -- ($(current page text area.north west)+(-1,1.7)$) -- ($(current page text area.north east)+(1,1.7)$) -- ($(current page text area.north east)+(1,1.25)$) -- ($(current page text area.north east)+(1.7,1.25)$) -- ($(current page text area.north east)+(1.7,1.7)$) -- ($(current page text area.north east)+(1.25,1.7)$) -- ($(current page text area.north east)+(1.25,1)$) -- ($(current page text area.north east)+(1.7,1)$) -- ($(current page text area.south east)+(1.7,-1)$) -- ($(current page text area.south east)+(1.25,-1)$) -- ($(current page text area.south east)+(1.25,-1.7)$) -- ($(current page text area.south east)+(1.7,-1.7)$) -- ($(current page text area.south east)+(1.7,-1.25)$) -- ($(current page text area.south east)+(1,-1.25)$) -- ($(current page text area.south east)+(1,-1.7)$) -- ($(current page text area.south west)+(-1,-1.7)$) -- ($(current page text area.south west)+(-1,-1.25)$) -- ($(current page text area.south west)+(-1.7,-1.25)$) -- ($(current page text area.south west)+(-1.7,-1.7)$) -- ($(current page text area.south west)+(-1.25,-1.7)$) -- ($(current page text area.south west)+(-1.25,-1)$) -- ($(current page text area.south west)+(-1.7,-1)$) ;
\node[draw=BrickRed,line width=5pt,opacity=1,fill=white,circle,inner sep=17.5pt,align=center,text=black,font=\slshape\large] at ($(current page text area.north east)+(1.5,-10.12)$) {\thepage};
\else
\draw[color=BrickRed,line width=5pt, opacity=1] ($(current page text area.south west)+(-1.5,-1.5)$) rectangle ($(current page text area.north east)+(1.5,1.5)$);
\draw[black, opacity=1] ($(current page text area.south west)+(-1.7,-1)$) -- ($(current page text area.north west)+(-1.7,1)$) -- ($(current page text area.north west)+(-1.25,1)$) -- ($(current page text area.north west)+(-1.25,1.7)$) -- ($(current page text area.north west)+(-1.7,1.7)$) -- ($(current page text area.north west)+(-1.7,1.25)$) -- ($(current page text area.north west)+(-1,1.25)$) -- ($(current page text area.north west)+(-1,1.7)$) -- ($(current page text area.north east)+(1,1.7)$) -- ($(current page text area.north east)+(1,1.25)$) -- ($(current page text area.north east)+(1.7,1.25)$) -- ($(current page text area.north east)+(1.7,1.7)$) -- ($(current page text area.north east)+(1.25,1.7)$) -- ($(current page text area.north east)+(1.25,1)$) -- ($(current page text area.north east)+(1.7,1)$) -- ($(current page text area.south east)+(1.7,-1)$) -- ($(current page text area.south east)+(1.25,-1)$) -- ($(current page text area.south east)+(1.25,-1.7)$) -- ($(current page text area.south east)+(1.7,-1.7)$) -- ($(current page text area.south east)+(1.7,-1.25)$) -- ($(current page text area.south east)+(1,-1.25)$) -- ($(current page text area.south east)+(1,-1.7)$) -- ($(current page text area.south west)+(-1,-1.7)$) -- ($(current page text area.south west)+(-1,-1.25)$) -- ($(current page text area.south west)+(-1.7,-1.25)$) -- ($(current page text area.south west)+(-1.7,-1.7)$) -- ($(current page text area.south west)+(-1.25,-1.7)$) -- ($(current page text area.south west)+(-1.25,-1)$) -- ($(current page text area.south west)+(-1.7,-1)$) ;
\node[draw=BrickRed,line width=5pt,opacity=1,fill=white,circle,inner sep=17.5pt,align=center,text=black,font=\slshape\large] at ($(current page text area.north west)+(-1.5,-10.12)$) {\thepage};
\fi
\end{tikzpicture}
},
scale=1,
angle=0
}
\usepackage{lipsum}
\begin{document}
\lipsum
\addtocounter{page}{+10}
\lipsum
\addtocounter{page}{+100}
\end{document}
