仅在角落处使用 tcolorbox 的虚线边框

Question

我想知道是否可以创建一个边框tcolorbox如下所示的框（即在特定点处有虚线段的连续边框）：

虚线部分应该位于框的左上角（表示内容是前一个框的延续）或右下角（表示在下一个框/页面中继续）。

Answer 1

\documentclass{article}
\usepackage[skins]{tcolorbox}
\usetikzlibrary{calc}
\newtcolorbox{contbox1}{enhanced,colback=white,frame code={%
\draw[dashed,line width=1pt,gray!50] (frame.south east) -- 
 ($(frame.south east)!0.3!(frame.south west)$);
\draw[line width=1pt,gray!50]  ($(frame.south east)!0.3!(frame.south west)$)
 -| (frame.north west) -| (frame.south east) ;
}}
\newtcolorbox{contbox2}{enhanced,colback=white,frame code={%
\draw[dashed,line width=1pt,gray!50] (frame.north west) -- 
 ($(frame.north west)!0.3!(frame.north east)$);
\draw[line width=1pt,gray!50]  ($(frame.north west)!0.3!(frame.north east)$)
 -| (frame.south east) -| (frame.north west);
}}
\begin{document}
\begin{contbox1}
 Some text.
\end{contbox1}
\begin{contbox2}
 Some more text.
\end{contbox2}
\end{document}

Answer 2

以下代码引入了一些更改用户237299解决方案。

1. 仅声明了一个可破坏的 tcolorbox。
2. 虚线片段被改变以绘制正确的角连接。

使用subskins 基于这个例子在tcolorbox文档中。

\documentclass{article}
\usepackage[skins, breakable]{tcolorbox}
\usepackage{lipsum}

\newtcolorbox{contbox}[1][]{empty,
    breakable, colback=white,
    %code for unbroken boxes
    frame code={\draw[line width=1pt, gray!50] (frame.south east) rectangle (frame.north west);},
    %code for first part of broken box
    skin first is subskin of={empty}{%
        frame code={\draw[line width=1pt, gray!50] (frame.south)-| (frame.north west)-|(frame.south east)--++(180:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.south);},
    },
    %code for middle part of broken box
    skin middle is subskin of={empty}{%
        frame code={%
            \draw[line width=1pt, gray!50] (frame.south)-| (frame.north west)--++(0:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.north);
            \draw[line width=1pt, gray!50] (frame.north)-| (frame.south east)--++(180:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.south);},
    },
    %code for last part of broken box
    skin last is subskin of={empty}{%
        frame code={%
            \draw[line width=1pt, gray!50] (frame.north)-| (frame.south east)-|(frame.north west)--++(0:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.north);
        },
    },
    #1
}

\begin{document}
\begin{contbox}
\lipsum[1-12]
\end{contbox}
\end{document}

更新：子皮肤选择

如果您需要强制执行盒子的某个方面，而不管可破坏盒子的哪个部分是独立的，则以下代码可以做到这一点。

它定义了三个subskins，可选参数允许选择应用哪一个。默认情况下，应用可破坏盒子中的“正常”行为。

\documentclass{article}
\usepackage[skins, breakable]{tcolorbox}
\usepackage{lipsum}

\tcbsubskin{myfirst}{empty}{%
        frame code={\draw[line width=1pt, gray!50] (frame.south)-| (frame.north west)-|(frame.south east)--++(180:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.south);},
    }
\tcbsubskin{mymiddle}{empty}{%
        frame code={%
            \draw[line width=1pt, gray!50] (frame.south)-| (frame.north west)--++(0:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.north);
            \draw[line width=1pt, gray!50] (frame.north)-| (frame.south east)--++(180:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.south);},
    }
\tcbsubskin{mylast}{empty}{%
        frame code={%
            \draw[line width=1pt, gray!50] (frame.north)-| (frame.south east)-|(frame.north west)--++(0:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.north);},
    }
    

\newtcolorbox{contbox}[1][]{empty,
    breakable, colback=white,
    %code for unbroken boxes
    frame code={\draw[line width=1pt, gray!50] (frame.south east) rectangle (frame.north west);},
    %skins for breakable boxes
    skin first=myfirst,
    skin middle=mymiddle,
    skin last=mylast,
    #1
}

\begin{document}
\begin{contbox}[skin=mylast]
\lipsum[2]
\end{contbox}
\begin{contbox}[skin=mymiddle]
\lipsum[2]
\end{contbox}
\begin{contbox}[skin=myfirst]
\lipsum[2]
\end{contbox}
\end{document}

第二次更新：使用magazine库

由于 OP 似乎想要将盒子片段放入float环境中，因此可以使用magazine库在需要的地方打破盒子并自动选择相应的方面（第一个、中间、最后一个）。

以下示例将盒子破碎成 3cm 的碎片，并将每个碎片放入环境中figure。可以看出，每个碎片都显示出与破碎盒子相对应的方面。

\documentclass{article}
\usepackage[skins, breakable, magazine]{tcolorbox}
\usepackage{lipsum}

\tcbsubskin{myfirst}{empty}{%
        frame code={\draw[line width=1pt, gray!50] (frame.south)-| (frame.north west)-|(frame.south east)--++(180:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.south);},
    }
\tcbsubskin{mymiddle}{empty}{%
        frame code={%
            \draw[line width=1pt, gray!50] (frame.south)-| (frame.north west)--++(0:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.north);
            \draw[line width=1pt, gray!50] (frame.north)-| (frame.south east)--++(180:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.south);},
    }
\tcbsubskin{mylast}{empty}{%
        frame code={%
            \draw[line width=1pt, gray!50] (frame.north)-| (frame.south east)-|(frame.north west)--++(0:2pt) coordinate (aux); \draw[dashed, line width=1pt, gray!50](aux)--(frame.north);},
    }
    
\newtcolorbox{contbox}[1][]{empty,
    breakable, colback=white,
    %code for unbroken boxes
    frame code={\draw[line width=1pt, gray!50] (frame.south east) rectangle (frame.north west);},
    %skins for breakable boxes
    skin first=myfirst,
    skin middle=mymiddle,
    skin last=mylast,
    reset box array,
    store to box array,
    #1
}

\begin{document}
\begin{contbox}[break at=3cm]
\lipsum[1-5]
\end{contbox}
\boxarraygetsize{\myfragments}

\begin{figure}
\centering
\consumeboxarray{1}
\caption{First fragment}
\end{figure}

\begin{figure}
\centering
\consumeboxarray{\myfragments}
\caption{Last fragment}
\end{figure}

\begin{figure}
\centering
\consumeboxarray{5}
\caption{One middle fragment}
\end{figure}
\end{document}