Can I have the \overfullrule rule colored in pdfLaTeX?

Question

I know that I can use \overfullrule=5pt to get overfull lines marked with a black marker. I am using pdfLaTeX. Is there a way I can get this marker or something similar in magenta instead?

Answer 1

I am not sure if this is possible with old fashioned TeX/pdfTeX, but it is with LuaTeX (of course, it is!)

\documentclass{article}
\usepackage{luatexbase,luacode}
\overfullrule 5pt
\begin{luacode}

local VLIST = node.id("vlist")
local HLIST = node.id("hlist")
local GLUE = node.id("glue")
local RULE = node.id("rule")

magentabox = function(head)
  while head do
    if head.id == VLIST or head.id == HLIST then
      -- go through the hlists (the rows)
      magentabox(head.head)

    -- if there's a rule after the rightskip, this is the overfull box
    -- node id 10 == glue, glue subtype 9 is rightskip, node id 2 is a rule

    elseif head.id == GLUE and head.subtype == 9 and head.next and head.next.id == RULE then
       -- this must be an overfull box
       local w1, w2
       w1 = node.new("whatsit","pdf_literal")
       w1.data = "q 1 0 1 rg"
       w1.mode = 1
       w2 = node.new("whatsit","pdf_literal")
       w2.data = " Q"
       w2.mode = 1

       w1.next = head.next -- the rule
       head.next = w1      -- color start
       w1.next.next = w2   -- color end

       node.slide(head)    -- adjust prev pointers
    end
    head = head.next
  end
  return true
end
luatexbase.add_to_callback("post_linebreak_filter",magentabox,"magentabox")

\end{luacode}

\begin{document}
\hsize 1.7in A verylongword verylongword verylongword
\end{document}

Answer 2

Copied from a TeX pearl by Paweł Jackowski. In his words, never underestimate TeX's bells and whistles.

\def\ooops{\hbox to\wd0{\setbox0=\hbox to\wd0{\unhbox0}%
    \unhbox0 \ifnum\badness>10000 \rlap{\tiny\quad Ooops!}\fi}}

\interlinepenalty=-50000 % force the break between each two lines
\maxdeadcycles=50        % allow upto 50 \outputs with no \shipout
\newtoks\orioutput \orioutput=\output % wrap the original \output routine
\output
    {\ifnum\outputpenalty>-20000 \the\orioutput
     \else \ifnum\outputpenalty<-\maxdimen \the\orioutput
     \else
     \unvbox255        % flush the entire list back
     \setbox0=\lastbox % strip the very last box
     \nointerlineskip  % avoid doubled interline glue
     \ooops            % make the test and return the box back.
     \advance\outputpenalty by50000
     \penalty\outputpenalty % weak lie that nothing happened...
     \fi\fi}

\documentclass{article}
\usepackage[textwidth=1.5in,a6paper]{geometry}

\begin{document}
\pagestyle{empty}

This completely useless example shows a not-so-useless trick, which might be
used for quite advanced applications, such as line-numbering, some kind of
paragraph decoration, page optimization and probably many others. Things become
much more complicated if math displays, \verb|\marks|, \verb|\inserts| or
\verb|\vadjusts| come into play, but they don-F¢t spoil all of the game.
\end{document}

which gives

The definition of ooops can be changed to give a colored rule instead of the text. For example (thanks to Jake)

\def\ooops{\hbox to\wd0{\setbox0=\hbox to\wd0{\unhbox0}%
    \unhbox0 \ifnum\badness>10000 \rlap{\color{magenta}{\rule{0.5em}{3ex}}}\fi}}

and loading xcolor.

Answer 3

Aditya gave a very nice, portable solution (Patrick's is very nice, too, but less portable).

I've made a little package called overcolored out of it, which can currently be found on github:

\documentclass[pagesize=pdftex,paper=10cm:10cm]{scrbook}

\usepackage{lipsum}
\usepackage[color=blue,
            width=3pt,
            height=0.5\baselineskip]{overcolored}

\begin{document}

\lipsum[1-3]

\end{document}

Edit: I've seen quite a few shortcomings in complex environments using Aditya's code, while Patrick's code has no side effects that I could see. For this reason, the package now supports both implementations. When compiled with LuaTeX, it will use Patrick's code, otherwise, Aditya's code is used.

I still have to adapt the options to work with Patrick's code. Supporting the width parameter was quite straightforward, the height is a bit more tricky, and supporting color names with PDF annotations seems much more tricky still...

Answer 4

Much has happened since topskip gave a LuaTeX solution. Relevant to us is the new callback hpack_quality. Just turn off the \overfullrule and replace topskip's luatex block with the following, adapting b.width and the colour in a.data to taste. Also, if you prefer overfullrules of fixed height and width, just assign those to b.height and b.depth:

\begin{luacode}
  ofbox = function(incident, detail, head, first, last)
    if incident == "overfull" then
      local a, b, c
      b = node.new("rule",0)
      b.width = tex.sp("1mm")
      a = node.new("whatsit","pdf_literal")
      a.data = "q 1 0 1 rg"
      a.mode = 1
      c = node.new("whatsit","pdf_literal")
      c.data = " Q"
      c.mode = 1
      a.next = b
      b.next = c
      node.slide(a)
      return a
    end
  end
  luatexbase.add_to_callback("hpack_quality",ofbox,"ofbox")
\end{luacode}

This has the added benefit of working with overfull display math as well.