如何调整上一页的行距？

Question

我正在研究一种自动处理机制孤儿和寡妇在我自己定义的文档类中。

Tex 版本：xelatex-2022

目前的进展是引用widows-and-orphans包并重写相应的方法

怀疑：

1. 寡妇惩罚何时发生/发现？是在渲染之后吗？是可预测的吗？
2. 使用原始命令后再行书写，上一页每段间距都会变大\widowpenalties，这个现象是不是说明当出现widowpenalty时，可以缩小上一页的行距，把widow line挤进上一页呢？

代码：

\documentclass{book}
%\widowpenalties=4 10000 10000 10000 150  ===> In fact, only 1 row needs to be processed, but it is written as 4 for the sake of testing
\begin{document}
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
\end{document}

Qa1：为什么出现孤行时要调整上一页的间距？

回答 1：我不希望在上一页插入寡行时出现过满的情况。

问题2：为什么\enlargethispage{\baselineskip}？

回答2：我知道这个解决方案但不适合我的目标。

Answer 1

您的问题标题询问行距，但代码表明您想询问的是段落之间的间距，而不是行之间的间距。

在您的示例中，如果取消注释 widowpenalties 行，则更多行将移动到第 2 页，而使第 1 页未满（而不是像您的注释所暗示的那样过满）。

由于默认情况下book课堂上\parskip所有的段落间空间都是可拉伸的，所以新的最后一行被放置在页面的底部。

默认值是，0.0pt plus 1.0pt在这种情况下拉伸不够，所以你得到

Underfull \vbox (badness 10000) has occurred while \output is active [1

添加

 \setlength\parskip{0pt plus 3pt}

这里的拉伸就足够了，但是为了确保即使页面上只有一个段落分隔符，也有足够的空间来获得行空间，请使用

 \setlength\parskip{0pt plus \baselineskip}

所以

\documentclass{book}
\widowpenalties=4 10000 10000 10000 150 % ===> In fact, only 1 row needs to be processed, but it is written as 4 for the sake of testing

\setlength\parskip{0pt plus \baselineskip}
\begin{document}
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\\
a text a text a text a text a text a text a text a text\par
\end{document}

Answer 2

寡妇惩罚何时发生/发现？是在渲染之后吗？是可预测的吗？

\widowpenalty和\clubpenalty通常在序言中设置一次，尽管它们可以在任何时候自由更改。当页面以孤行结尾时， 的值\widowpenalty将添加到页面的 中\outputpenalty，对于孤行/俱乐部也是如此。

一般来说，您只想设置和的值\widowpenalty并\clubpenalty读取的值\outputpenalty；读取\widowpenalty或设置\outputpenalty很少有意义。

有关这些值如何工作的详细描述，请参阅我关于寡妇和孤儿的文章第 4 部分。

我使用原来的命令 \widowpenalties 后，上一页每段的间距都会变大，这个现象是不是说明当出现 widowpenalty 时，我可以缩小上一页的行距，把寡行挤进上一页呢？

通常，您需要手动执行此操作。请参阅大卫·卡莱尔的评论。

我正在研究一种自动机制，用于处理我自己定义的文档类中的孤儿和寡妇。

我写了一个包lua-widow-control旨在实现这一点。它要求 LuaLaTeX 使用不同的方法来删除孤行和寡行，但它在自动删除孤行和寡行方面非常有效。