In theory https://github.com/matplotlib/matplotlib/blob/master/lib/matplotlib/backends/backend_pgf.py#L714 should actually measure the sizes correctly for the pgf backend.

I guess the problem is that the settings of the pgf backend may change between when matplotlib generates the pgf and when the file is actually compiled.

I feel that the proper solution is to have a way for the pgf backend to just tell matplotlib "just pass me the full string, not one line at a time, I (i.e. tex) have a layout manager myself".

That'd be nice. You can do multiline in pgf if you use the tabular environment, so thats doable. Though I'm not sure what happens to the line spacing if you do that.

But I think PGF is the only backend to handle this sort of thing. So you'd need to have special logic in draw_text() just to handle that one backend (because the other renderers get fed the string one line at a time).

But I'm open to this not being a good solution. Are there other backends that use the text object like PGF does? If its just PGF, I'm not convinced its used often enough to justify changing the rest of the infrastructure to make it work, and this hack looks fine.

Can't you just do multiline in pgf by using '\' (a normal latex newline) (haven't used pgf for a while but wouldn't be surprised if you could)?

In fact if that works I'd suggest just documenting this as the preferred approach for pgf... that'll also get better linespacing (consistent with what tex would do).

I don't think so. I tried that:

\pgftext[x=2in,y=4in,left,base]{First \ Second}%

doesn't do anything.

\pgftext[x=2in,y=4in,left,base]{First \\ Second}%

gives:

! LaTeX Error: Something's wrong--perhaps a missing \item.

\pgftext[x=2in,y=4in,left,base]{\begin{tabular}{c} First \\ Second \end{tabular}}

Works fine.

https://tex.stackexchange.com/questions/123671/manual-automatic-line-breaks-and-text-alignment-in-tikz-nodes See "Use \\ and align." (and others)

Yeah, but I don't think that works for PGF. Those are TikZ objects. But I could be doing something else wrong or misunderstanding.

Sort of hijacking the thread at that point but looks like my pgf install is broken: compiling

\documentclass[article]
\usepackage{pgf}
\begin{document}
\end{document}

(nothing even with matplotlib) gives

This is pdfTeX, Version 3.14159265-2.6-1.40.17 (TeX Live 2016) (preloaded format=pdflatex)
 restricted \write18 enabled.
entering extended mode
(./foo.tex
LaTeX2e <2016/03/31> patch level 3
Babel <3.9r> and hyphenation patterns for 4 language(s) loaded.
! TeX capacity exceeded, sorry [parameter stack size=10000].
\@fileswithoptions #1->
                       \@ifnextchar [{\@fileswith@ptions #1}{\@fileswith@pti...
l.2 \usepackage{
                pgf}
!  ==> Fatal error occurred, no output PDF file produced!
Transcript written on foo.log.

any hint?

I just used the example in #9747 that uses \usepackage{pgfplots} I use TexLive...

Ah, I don't know how to write a latex preamble anymore. My bad.

https://tex.stackexchange.com/questions/53704/can-i-put-a-line-break-in-pgftext should work though (modulo whatever fixes are needed in the pgf backend)...

But again, we pass to renderer.draw_text() by line. Is it worth putting a separate logic in here just for PGF?

Even worse, I only know that its a matplotlib.backends.backend_mixed.MixedModeRenderer at this point of the code, so I can't even put logic in based on whether we are outputting PGF or not...

OK, I'm going to close this. The OP found that properly specifying the fonts in their rcParams did the trick of lining up the characters properly.