如何填充 tikz 创建的页面边框外的颜色？

Question

这就是我制作边框的方式：

\documentclass{article}

\usepackage{background}
\usepackage{tikz}
\usetikzlibrary{calc}

\backgroundsetup{angle = 0, scale = 1, vshift = -2ex,
  contents = {\tikz[overlay, remember picture]
    \draw [rounded corners = 15pt, line width = 2pt, color = black]
           ($(current page.north west)+(2cm,-2cm)$)
           rectangle ($(current page.south east)+(-2,2)$);}}

\begin{document}
Hello World!
\end{document}

Answer 1

作为一种快速的解决方法，您可以使用彩色页面并用白色填充您的框架：

\documentclass{article}

\usepackage{background}
\usepackage{tikz}
\usetikzlibrary{calc}
\pagecolor{red}

\backgroundsetup{angle = 0, scale = 1, vshift = -2ex, opacity=1,
  contents = {\tikz[overlay, remember picture]
    \path [fill=white,rounded corners = 15pt, line width = 2pt, draw=black]
           ($(current page.north west)+(2cm,-2cm)$)
           rectangle ($(current page.south east)+(-2,2)$);}}

\begin{document}
Hello World!
\end{document}

如果你需要透明背景，例如因为你使用了包pdfpages，你可以使用来自的反向剪辑方法https://tex.stackexchange.com/a/290508/36296

\documentclass{article}

\usepackage{background}
\usepackage{tikz}
\usetikzlibrary{calc}

\tikzset{
    clip even odd rule/.code={\pgfseteorule}, % Credit to Andrew Stacey 
    invclip/.style={
        clip,insert path=
            [clip even odd rule]{
                [reset cm](-\maxdimen,-\maxdimen)rectangle(\maxdimen,\maxdimen)
            }
    }
}

\backgroundsetup{
  angle = 0, 
  scale = 1, 
  vshift = -2ex,
  opacity= 1,
  contents = {
    \begin{tikzpicture}[overlay, remember picture]
      \draw [rounded corners = 15pt, line width = 4pt, color = black]
           ($(current page.north west)+(2cm,-2cm)$)
           rectangle ($(current page.south east)+(-2,2)$);
      \clip[invclip,rounded corners=15pt]   ($(current page.north west)+(2cm,-2cm)$) rectangle ($(current page.south east)+(-2,2)$);
      \fill[red] (current page.south west) rectangle (current page.north east);    
    \end{tikzpicture}
  }
}

\begin{document}
Hello World!
\end{document}