关于将此 DropCap/Lettrine 代码转换为宏的思考

Question

当我编写宏时，我首先考虑的是用户界面。为了您的目的，我们建议\Capinsert在段落之前使用以下宏：

\Capinsert First letter is scaled, this means F in this case.

用户可以插入可选的左侧材料。我们可以\optdef使用 OPmac 技巧 0067但是可选参数是用括号隔开的[]，用户可以在这里写\thefontscale[...]（例如），而且括号[] 不能嵌套。因此，用户可能会感到困惑。这就是我建议用作{}可选参数的原因。例如：

\Capinsert {material llaped to the left} First letter is scaled ...

这个决定需要更多的宏编程：

\def\Capinsert{\def\leftCapmaterial{}\futurelet\next\CapinsertA}
\def\CapinsertA{\ifx\next\bgroup \expandafter\CapinsertB \else \expandafter\CapinsertC \fi}
\def\CapinsertB #1{\def\leftCapmaterial{#1}\CapinsertC}
\def\CapinsertC #1{...

\Capinsert检查\futurelet是否有开括号\bgroup。如果是，则\CapinsertB扫描可选参数并将其保存到 \leftCapmaterial宏中。否则，\CapinsertC在实现宏的核心处进行处理。

现在，我们建议数据声明的方式。它可能看起来像：

\newdimen\ptem     \ptem=.1em
\newdimen\Capsize  \Capsize=44\ptem
\newdimen\Capabove \Capabove=8\ptem

\declCap {default} {0;0,0,0}
\declCap A {1;6,2,-2}
...
\declCap W {3;0,4,6}
...

首先，\ptem这里声明了。使用 10pt 字体时，它是 1pt。但是，如果用户\typosise[12/14]在数据声明之前声明（例如）并且整个文档被缩放，那么用于字母校正的单位也会被缩放。这是期望的行为。意思\ptem是“pt 单位依赖于 em”。

声明\Capsize缩放字母的大小。并\Capabove 声明缩放字母在段落第一条基线上方的升高量。如果它为零，则缩放字母的顶部等于第一条基线。

有关字母的数据按以下方式声明：

\declCap <letter> {protrude left; first line left, second line left, etc.}

{default}当字母没有自己的声明时使用数据。逗号分隔的列表可以包含任意数量的数字。段落中的相应行数将被移动。数字可以包括小数点，可以是负数，并且以单位\ptem表示。

宏代码如下。\declCap仅将数据保存到名为的宏中\cap:=<letter>。\sxdef这里使用了来自 OPmac 的：

\def\declCap #1#2{\sxdef{cap:=#1}{#2}}

读取\CapinsertC要缩放的字母#1并执行以下操作：

\def\CapinsertC #1{\par
  \isdefined{cap:=#1}\iftrue \edef\tmp{\csname cap:=#1\endcsname}%
                     \else   \edef\tmp{\csname cap:=default\endcsname}\fi
  \setbox0=\hbox{{\thefontsize[\expandafter\ignorept\the\Capsize]#1}}%
  \expandafter \CapinsertD \tmp,,%  
  \noindent\kern-\firstlineindent 
      \rlap{\kern-\protrudeCap\ptem\llap{\leftCapmaterial}%
              \vbox to0pt{\kern-\Capabove\box0\vss}}%
  \kern\firstlineindent
}

包括\tmp声明的数据或默认值。包括\box0缩放后的字母。\thefontsize参数需要不带的 dimen pt。因此，\ignoreptOPmac 中的宏会删除由原始pt扩展的字母。执行后跟数据和两个逗号。它准备并执行原始并将第一行的缩进保存到。以缩进开头。因此，我们需要返回负 kern，执行并返回。通过实现\the\Capinsert\parshape\firstlineindent\noindent\firslineindent\rlap{scaled letter}\kern\firstindentscaled letter

\kern-\protrudeCap\ptem \llap{left material}\vbox{shifted \box0}

最后一件事是扫描表格准备的数据

\CapinsertD protrude left; first line left, second line left, ... ,,%

这是通过以下方式完成的：

\def\CapinsertD #1;{\tmpnum=1 \let\firstlineindent=\undefined
   \def\parshapeparams{}\def\protrudeCap{#1}\CapinsertE}
\def\CapinsertE #1,{\ifx,#1,\parshape =\tmpnum \parshapeparams 0pt \hsize
  \else
     \advance\tmpnum by1
     \tmpdim=\wd0 \advance\tmpdim by-#1\ptem \advance\tmpdim by-\protrudeCap\ptem
     \edef\parshapeparams{\parshapeparams\the\tmpdim}%
     \ifx\firstlineindent\undefined \let\firstlineindent\parshapeparams \fi
     \advance\tmpdim by-\hsize \tmpdim=-\tmpdim
     \edef\parshapeparams{\parshapeparams\the\tmpdim}%
     \expandafter \CapinsertE \fi
}

首先，\CapinsertD读取protrude left，将其保存到。、的\protrudeCap初始值在这里设置。在循环中读取行缩进。当为空时，即在附加到数据的最后两个逗号之间，循环结束。counts 缩进的行数加 1。缩进是通过减去数据项减去来计算的。结果加到。接下来，将行宽计算为减去缩进并将其也加到 parshapeparams 中。当循环结束时，我们已经为原始数据做好了准备。只有被添加到前面并被附加（这声明了正常行）。\tmpnum\firstlineindent\parshapeparams\CapinsertE#1\tmpnum\wd0protrude\parshapeparams\hsize\parshapeparams\parshape\tmpnum0pt \hsize

最后，工作示例如下：

\input opmac
\input cs-schola
%\typosize[12/15]

%% macros

\def\declCap #1#2{\sxdef{cap:=#1}{#2}}
\def\Capinsert{\def\leftCapmaterial{}\futurelet\next\CapinsertA}
\def\CapinsertA{\ifx\next\bgroup \expandafter\CapinsertB \else \expandafter\CapinsertC \fi}
\def\CapinsertB #1{\def\leftCapmaterial{#1}\CapinsertC}
\def\CapinsertC #1{\par
  \isdefined{cap:=#1}\iftrue \edef\tmp{\csname cap:=#1\endcsname}%
                     \else   \edef\tmp{\csname cap:=default\endcsname}\fi
  \setbox0=\hbox{{\thefontsize[\expandafter\ignorept\the\Capsize]\Capprefix#1}\kern\Capafter}%
  \expandafter \CapinsertD \tmp,,%  
  \noindent\kern-\firstlineindent
      \rlap{\kern-\protrudeCap\ptem\llap{\leftCapmaterial}%
              \vbox to0pt{\kern-\Capabove\box0\vss}}%
  \kern\firstlineindent
}
\def\CapinsertD #1;{\tmpnum=1 \let\firstlineindent=\undefined
   \def\parshapeparams{}\def\protrudeCap{#1}\CapinsertE}
\def\CapinsertE #1,{\ifx,#1,\parshape =\tmpnum \parshapeparams 0pt \hsize
  \else
     \advance\tmpnum by1
     \tmpdim=\wd0 \advance\tmpdim by-#1\ptem \advance\tmpdim by-\protrudeCap\ptem
     \edef\parshapeparams{\parshapeparams\the\tmpdim}%
     \ifx\firstlineindent\undefined \let\firstlineindent\parshapeparams \fi
     \advance\tmpdim by-\hsize \tmpdim=-\tmpdim
     \edef\parshapeparams{\parshapeparams\the\tmpdim}%
     \expandafter \CapinsertE \fi
}
\def\hboxshift#1#2{\vbox to0pt{\vss\hbox{#2}\kern-#1}}

%% data declarations:

\newdimen\ptem     \ptem=.1em
\newdimen\Capsize  \Capsize=44\ptem
\newdimen\Capabove \Capabove=8\ptem
\newdimen\Capafter \Capafter=1\ptem
\def\Capprefix{\localcolor\Red}

\declCap {default} {0;0,0,0}
\declCap W {3;0,4,6}
\declCap A {1;6,2,-2}
\declCap L {0;9,0,0}
% \declCap B ... etc.

%% document:

\Capinsert {\thefontscale[\magstep3]\localcolor\Grey\hboxshift{4pt}{``}\kern.1em}
           W{\caps\rm e're here,''}
Mother called out, waking me from my nap on the back seat of the car. When 
you're a kid who can get carsick just being driven around the block, you
learn to sleep as much as possible on long motor trips. This one was
{\caps\rm 139} curvy miles. Our {\caps\rm 1928} black Buick sedan crunched
up the gravel driveway to the {\em cottage}. Well, that's what summer homes
were called then, even large ones like the Schuneman's. We were in {\em
Eagles~Mere,} a Victorian village in the Pocono Mountains of Pennsylvania  
$\ldots$

\Capinsert Another example is here.
Mother called out, waking me from my nap on the back seat of the car. When 
you're a kid who can get carsick just being driven around the block, you
learn to sleep as much as possible on long motor trips. This one was
{\caps\rm 139} curvy miles. Our {\caps\rm 1928} black Buick sedan crunched
up the gravel driveway to the {\em cottage}. Well, that's what summer homes
were called then, even large ones like the Schuneman's. We were in {\em
Eagles~Mere,} a Victorian village in the Pocono Mountains of Pennsylvania
$\ldots$

\Capinsert Lettrine package does something similar.
Mother called out, waking me from my nap on the back seat of the car. When
you're a kid who can get carsick just being driven around the block, you
learn to sleep as much as possible on long motor trips. This one was
{\caps\rm 139} curvy miles. Our {\caps\rm 1928} black Buick sedan crunched
up the gravel driveway to the {\em cottage}. Well, that's what summer homes
were called then, even large ones like the Schuneman's. We were in {\em 
Eagles~Mere,} a Victorian village in the Pocono Mountains of Pennsylvania
$\ldots$

\bye

编辑：我添加了全局参数\Capafter，\Capprefix如下图：

Answer 1