Fill pixel size area with text, adjust point size automatically

Question

Can Latex fill an area of a certain aspect ratio (e.g. 3:1) with centered text using a ttf font so that it can be export to a specific pixel size image (600x200, probably using convert)?

Word- or letter-spacing should not be changed (as seen in \Shapepar attempt below).

Imagemagick's convert can do it:

convert -size 600x200 -font Montserrat-Regular -gravity center \
        caption:"I am curious about area-filling text rendering options" test.png

\Shapepar modifies word-spacing, which affects readability:

\documentclass[preview]{standalone}
\usepackage{fontspec}
\setmainfont{Montserrat-Regular}
\usepackage{shapepar}
\begin{document}
\Shapepar{\rectangleshape{200}{600}}I am curious about area-filling text rendering options\par
\end{document}

I also tried increasing point size and restricting the page size using \geometry but this causes errors

Can \Shapepar center text rather than modify word-spacing? Or is there another way of filling a specific rectangle with text in Latex?

Answer 1

Thankfully, very similar problems have been solved. Here is an adaptation:

\documentclass[preview]{standalone}
\usepackage{fontspec}
\setmainfont{Montserrat-Regular}
\sloppypar

\usepackage{environ}% http://ctan.org/pkg/environ
\newdimen\fontdim
\newdimen\upperfontdim
\newdimen\lowerfontdim
\newif\ifmoreiterations
\fontdim12pt

\newbox\trialbox
\newbox\linebox
\global\newcount\maxbad
\newcount\linebad
\newcount\currenthbadness

\makeatletter
\NewEnviron{fitbox}[2]{% \begin{fitbox}{<width>}{<height>} stuff \end{fitbox}
    % Store environment body
    \def\stuff{%
        \BODY%
    }%
    % prepare badness box
    \def\badnessbox{%
        \global\maxbad=0\relax%
        \currenthbadness=\hbadness% save old \hbadness
        \hbadness=10000000\relax% make sure, TeX reports overfull boxes
        \message{Starting measureline recursion with width #1^^J}%
        \setbox\trialbox=\vbox{%
            \hsize#1\relax%
            \fontsize{\fontdim}{1.2\fontdim}%
            \selectfont%
            \stuff\par%
            \measurelines% start recursion
        }%
%       \noindent\usebox\trialbox\par
        \hbadness=\currenthbadness% restore old \hbadness
    }
    % prepare recursion to measure line badness
    \def\measurelines{%
        \message{Iteration of measurelines^^J}%
        \begingroup%
            \setbox\linebox=\lastbox% get the last line
            \setbox0=\hbox to \hsize{\unhcopy\linebox}% put the last line into box0 to provoke badness calculation
            \linebad=\the\badness\relax% \badness now reflects the last typeset box, i.e. box0
            \message{Badness: \the\badness\space\the\linebad\space with max \the\maxbad\space at Fontsize: \the\fontdim\space^^J}%
            \ifnum\linebad>\maxbad% store the maximum badness
                \global\maxbad=\linebad% Uncomment this line to ignore overfull hboxes!
            \fi%
            \ifvoid% end of recursion
                \linebox%
            \else%
                \unskip\unpenalty\measurelines% do the recursion
                \ifhmode%
                    \newline%
                \fi%
                \noindent\box\linebox% do the output
            \fi%
        \endgroup%
    }%
    % Prepare measurement box
    \def\buildbox{%
        \badnessbox% measure badness
        \setbox0\vbox{% measure height
            \hbox{%
                \fontsize{\fontdim}{1.2\fontdim}%
                \selectfont%
                \minipage{#1}%
                    \vbox{%                     
                        \stuff\par%
                    }%
                \endminipage%
            }%
        }%
        \message{Measured badness: \the\maxbad\space at Fontsize: \the\fontdim\space^^J}%
        \dimen@\ht0
        \advance\dimen@\dp0
        \message{Measured box height: \the\dimen@\space^^J}%
    }%
    \def\shrinkheight{%
        \loop
            \fontdim.5\fontdim % Reduce font size by half
            \buildbox
            \message{Shrinking, new box height: \the\dimen@\space at Fontsize: \the\fontdim\space^^J}%
        \ifdim\dimen@>#2 \repeat
        \lowerfontdim\fontdim
        \upperfontdim2\fontdim
        \fontdim1.5\fontdim
    }%
    \def\shrinkwidth{%
        \loop
            \fontdim.5\fontdim % Reduce font size by half
            \buildbox
        \ifnum\maxbad>10000 \repeat
        \lowerfontdim\fontdim
        \upperfontdim2\fontdim
        \fontdim1.5\fontdim
    }%
    \def\growheight{%
        \loop
            \fontdim2\fontdim % Double font size
            \buildbox
            \message{Growing, new box height: \the\dimen@\space at Fontsize: \the\fontdim\space^^J}%
        \ifdim\dimen@<#2 \repeat
        \upperfontdim\fontdim
        \lowerfontdim.5\fontdim
        \fontdim.75\fontdim
    }%
    \buildbox
    % Compute upper and lower bounds
    \ifdim\dimen@>#2
        \message{Need to shrink box height: \the\dimen@\space^^J}%
        \shrinkheight
    \else
        \message{Need to grow box height: \the\dimen@\space to target: #2^^J}%
        \growheight
    \fi
    \message{Max font: \the\upperfontdim\space^^J}%
    \message{Min font: \the\lowerfontdim\space^^J}%
    % Potentially further reduce bounds for overfull box
    \ifnum\maxbad>10000
        \shrinkwidth
    \fi 
    \message{Max font adjusted: \the\upperfontdim\space^^J}%
    \message{Min font adjusted: \the\lowerfontdim\space^^J}%
    % Now try to find the optimum height and width
    \loop
        \buildbox
        \message{Height: \the\dimen@\space^^J}%
        \ifdim\dimen@>#2
            \moreiterationstrue
            \upperfontdim\fontdim
            \advance\fontdim\lowerfontdim
            \fontdim.5\fontdim
        \else
            \ifnum\maxbad>10000
                \moreiterationstrue
                \upperfontdim\fontdim
                \advance\fontdim\lowerfontdim
                \fontdim.5\fontdim
            \else
                \advance\dimen@-#2
                \ifdim\dimen@<10pt
                    \lowerfontdim\fontdim
                    \advance\fontdim\upperfontdim
                    \fontdim.5\fontdim
                    \dimen@\upperfontdim
                    \advance\dimen@-\lowerfontdim
                    \ifdim\dimen@<.2pt
                        \moreiterationsfalse
                    \else
                        \moreiterationstrue
                    \fi
                \else
                    \moreiterationsfalse
                \fi
            \fi
        \fi
    \ifmoreiterations \repeat
    \message{Selected font: \the\fontdim\space^^J}%
    \vbox to #2{\box0\hbox{}}% Typeset content
}%
\makeatother

\usepackage{parskip}

\setlength\fboxsep{0pt}
\begin{document}

\begin{fitbox}{600px}{200px}%
\center{I am curious about area-filling text rendering options}
\end{fitbox}

\end{document}

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