includesvg incompatible with setkeys{Gin}

[ChrisJefferson]

The following latex file looks weirdly corrupted. The problem is the use of Gin I think?

\documentclass{article}
\usepackage{svg}

\usepackage{graphicx}
\setkeys{Gin}{height=3cm,keepaspectratio}

\begin{document}

\includesvg{bubbleup.svg}

\end{document}

[ChrisJefferson]

My svg

[mrpiggi]

The problem is the use of Gin I think?

Exactly. This is not part of the interface. I could implement it once I will find some time but this won't happen in the near future. And honestly, I am not keen to do this as this potentially increases the need for maintenance without any real benefit as there is a working interface.

Using global settings for graphics dimensions seems odd to me anyway. Nevertheless, you could achieve this by using \svgsetup accordingly (although for the particular image, height=3cm is way to small):

\documentclass{article}
\usepackage{svg}

\begin{document}

\svgsetup{height=3cm,keepaspectratio}
\includesvg{bubbleup}

\end{document}

[ChrisJefferson]

Hi, thank you for your quick reply.

If you don't mind, I'll explain the background of this problem a bit more.

I am using pandoc, a common program for transforming between various file formats. I was getting some broken output.

Looking at pandoc, it uses the following latex template ( https://github.com/jgm/pandoc/blob/main/data/templates/default.latex ) , which contains the following (it's quite long, and the $ are handled before the code is given to latex). This template is used for all files generated, so I guess this Gin business is to handle all types of images.

$if(graphics)$
\usepackage{graphicx}
\makeatletter
\def\maxwidth{\ifdim\Gin@nat@width>\linewidth\linewidth\else\Gin@nat@width\fi}
\def\maxheight{\ifdim\Gin@nat@height>\textheight\textheight\else\Gin@nat@height\fi}
\makeatother
% Scale images if necessary, so that they will not overflow the page
% margins by default, and it is still possible to overwrite the defaults
% using explicit options in \includegraphics[width, height, ...]{}
\setkeys{Gin}{width=\maxwidth,height=\maxheight,keepaspectratio}
% Set default figure placement to htbp
\makeatletter
\def\fps@figure{htbp}
\makeatother
$endif$
$if(svg)$
\usepackage{svg}
$endif$

I realise it is not your job to fix this, but is there a suggested fix I can give to pandoc?

[mrpiggi]

I realise it is not your job to fix this, but is there a suggested fix I can give to pandoc?

I already saw the linked issue and had a brief look. That's why showed the way you could achieve the desired behavior with \svgsetup. So, regarding to the given snippet of the pandoc setup, it would just be \svgsetup{width=\maxwidth,height=\maxheight,keepaspectratio}.

An additional note: the conditional $if(svg)$ should probably be nested into the previous one as package svg loads graphicx anyway and with the current setup, the latter could be loaded without the desired setup.

[ChrisJefferson]

Thanks!

Unfortunately, that doesn't seem to work (everything just gets rendered on top of each other). I guess this might be because the \maxwidth and \maxheight are themselves full of references to \Gin? This is far beyond my latex ability!

[mrpiggi]

The pandoc setup should IMHO look like this

$if(graphics)$
\usepackage{graphicx}
\makeatletter
\def\maxwidth{\ifdim\Gin@nat@width>\linewidth\linewidth\else\Gin@nat@width\fi}
\def\maxheight{\ifdim\Gin@nat@height>\textheight\textheight\else\Gin@nat@height\fi}
\makeatother
% Scale images if necessary, so that they will not overflow the page
% margins by default, and it is still possible to overwrite the defaults
% using explicit options in \includegraphics[width, height, ...]{}
\setkeys{Gin}{width=\maxwidth,height=\maxheight,keepaspectratio}
% Set default figure placement to htbp
\makeatletter
\def\fps@figure{htbp}
\makeatother
$if(svg)$
\usepackage{svg}
\svgsetup{width=\maxwidth,height=\maxheight,keepaspectratio}
$endif$
$endif$

whereas it needs to be ensured, that $if(graphics)$ is set in case $if(svg)$ is required or the very first conditional would be something like $if(graphics) or (svg)$ (not quite sure if this is valid for pandoc). This change would have to be applied to the pandoc setup.

The problem here is, that pandoc relies on the internals of package graphicx/graphics by using \Gin@nat@width and \Gin@nat@height which are set, when \includegraphics is invoked. But package svg needs no know the desired size of the file to be included beforehand, which is why this approach fails as well.

So, there is currently no short-term workaround I can think of besides just explicitly specifying the desired size of the image via \includesvg[width=..., height=...]{<svg-file>}.

[ChrisJefferson]

Thank you very much for looking into this, we will see how pandoc wants to clean things up!

[jgm]

it needs to be ensured, that $if(graphics)$ is set in case $if(svg)$ is required

That is already ensured.

Question: why can't the svg package use the SVG size information encoded in the SVG's attributes

<svg width="597.89pt" height="1075pt" version="1.1" viewBox="0 0 597.89 1075.2" xmlns="http://www.w3.org/2000/svg">

when no [width=_,height=_] option is provided?

[mrpiggi]

Package svg is nothing but a wrapper for the (latex) export functionality provided by Inkscape. It does not touch the SVG file itself.

[mrpiggi]

Just to be clear, the native image size is used by default. It only fails with pandoc because of the provided settings via \setkeys{Gin}

[jgm]

OK, I see. The Gin business is supposed to scale images that extend beyond textwidth to textwidth, but somehow with the svg it scales it down to tiny.

I don't think removing the Gin stuff is a good option for us; it was added for a reason. Is there any other way to ensure that images that would overflow textwidth are resized appropriately?

[mrpiggi]

OK, I see. The Gin business is supposed to scale images that extend beyond textwidth to textwidth, but somehow with the svg it scales it down to tiny.

That's because \Gin@nat@width and \Gin@nat@height are set during the invocation of \includegraphics internally but package svg needs to know the desired output size beforehand. This relates to the format of *.pdf_tex files exported via Inkscape. In particular, those files are using lines like \includegraphics[width=\unitlength,...]{...} and in order to provide capability for scaling the resulting output, package svg has to adapt \unitlength accordingly.

I don't think removing the Gin stuff is a good option for us; it was added for a reason. Is there any other way to ensure that images that would overflow textwidth are resized appropriately?

Well, a similar but different approach would be, not to modify the default settings of package graphicx but to scale the output provided by both \includegraphics and \includesvg in a generic way. The sample provided below defines a command \pandocbounded{...} which can be used as a generic wrapper for any output content which should not extend both \textheight and \linewidth by:

1. Store the desired output in a box
2. Determine horizontal and vertical scaling factors regarding \textheight and \linewidth by evaluating the box size
3. Choose the smaller factor
4. Scale the content of the box if factor is smaller than 1, otherwise use the content as it is

\documentclass{article}
\usepackage{graphicx}
\usepackage{svg}

\makeatletter
\newsavebox\pandoc@box
\newcommand*\pandocbounded[1]{%
  \sbox\pandoc@box{#1}%
  % scaling factors for width and height
  \Gscale@div\@tempa\textheight{\dimexpr\ht\pandoc@box+\dp\pandoc@box\relax}%
  \Gscale@div\@tempb\linewidth{\wd\pandoc@box}%
  % select the smaller of both
  \ifdim\@tempb\p@<\@tempa\p@
    \let\@tempa\@tempb
  \fi
  % scaling accordingly (\@tempa < 1)
  \ifdim\@tempa\p@<\p@
    \scalebox{\@tempa}{\usebox\pandoc@box}%
  % scaling not needed, use as it is
  \else
    \usebox{\pandoc@box}%
  \fi
}
\makeatother

\begin{document}
\pandocbounded{\includegraphics{<graphic-file>}}
\pandocbounded{\includesvg{<svg-file>}}
\end{document}

I am not familiar how pandoc is actually generating LaTeX source files. But \pandocbounded{...} should obviously only be used, if no setting regarding the graphic size is given. But this is something, you are probably aware of.

Don't hesitate to ask for more, if needed ;)