Don't output \caption in LaTeX when image alt text is empty

[Adri2000]

Tested with .md as input, LaTeX/Beamer as output.
![](image.png) will generate \caption{}.

This is a regression according to https://groups.google.com/forum/#!topic/pandoc-discuss/9H_3h20ILj0. Maybe in commit d81b435.

Proposed patch on master:

diff --git a/src/Text/Pandoc/Writers/LaTeX.hs b/src/Text/Pandoc/Writers/LaTeX.hs
index 9526333..4fac59a 100644
--- a/src/Text/Pandoc/Writers/LaTeX.hs
+++ b/src/Text/Pandoc/Writers/LaTeX.hs
@@ -417,7 +417,9 @@ blockToLaTeX (Para [Image attr@(ident, _, _) txt (src,'f':'i':'g':':':tit)]) = d
   img <- inlineToLaTeX (Image attr txt (src,tit))
   let footnotes = notesToLaTeX notes
   lab <- labelFor ident
-  let caption = "\\caption" <> captForLof <> braces capt <> lab
+  let caption = if null text
+                   then empty
+                   else "\\caption" <> captForLof <> braces capt <> lab
   figure <- hypertarget ident (cr <>
             "\\begin{figure}[htbp]" $$ "\\centering" $$ img $$
             caption $$ "\\end{figure}" <> cr)

Not tested, but I successfully tested a similar patch for the pandoc version that's running on my laptop.

[jgm]

The change you suggest would mean that uncaptioned images don't get labels, even if an ID is specified.

[Adri2000]

Sorry, not sure I understand exactly what you mean. Do you have an example?

[jgm]

![](img.jpg){#myimage}

With the proposed change, you won't get \label{myimage} anywhere in the figure.

[Adri2000]

Does the following look better? If not please don't hesitate to just fix it and commit, as I'm really not familiar with Haskell, and not much with Pandoc either :)

Thanks!

diff --git a/src/Text/Pandoc/Writers/LaTeX.hs b/src/Text/Pandoc/Writers/LaTeX.hs
index 9526333..683d737 100644
--- a/src/Text/Pandoc/Writers/LaTeX.hs
+++ b/src/Text/Pandoc/Writers/LaTeX.hs
@@ -417,7 +417,9 @@ blockToLaTeX (Para [Image attr@(ident, _, _) txt (src,'f':'i':'g':':':tit)]) = d
   img <- inlineToLaTeX (Image attr txt (src,tit))
   let footnotes = notesToLaTeX notes
   lab <- labelFor ident
-  let caption = "\\caption" <> captForLof <> braces capt <> lab
+  let caption = if null text
+                   then lab
+                   else "\\caption" <> captForLof <> braces capt <> lab
   figure <- hypertarget ident (cr <>
             "\\begin{figure}[htbp]" $$ "\\centering" $$ img $$
             caption $$ "\\end{figure}" <> cr)

[jgm]

On reflection, I guess that without \caption, it probably
doesn't make sense to have \label, since there will be no
figure number to refer to.

But that raises the question what behavior would be better.
Some might expect that a figure with empty caption would
still get a figure number and be labelable.

+++ Adrien Cunin [Apr 20 16 06:28 ]:

Does the following look better? If not please don't hesitate to just
fix it and commit, as I'm really not familiar with Haskell, and not
much with Pandoc either :)

Thanks!
diff --git a/src/Text/Pandoc/Writers/LaTeX.hs b/src/Text/Pandoc/Writers/LaTeX.hs
index 9526333..683d737 100644
--- a/src/Text/Pandoc/Writers/LaTeX.hs
+++ b/src/Text/Pandoc/Writers/LaTeX.hs
@@ -417,7 +417,9 @@ blockToLaTeX (Para [Image attr@(ident, _, _) txt (src,'f':'i
':'g':':':tit)]) = d
img <- inlineToLaTeX (Image attr txt (src,tit))
let footnotes = notesToLaTeX notes
lab <- labelFor ident

• let caption = "\caption" <> captForLof <> braces capt <> lab

• let caption = if null text

•               then lab
  

•               else "\\caption" <> captForLof <> braces capt <> lab
  

  figure <- hypertarget ident (cr <>
  "\begin{figure}[htbp]" $$ "\centering" $$ img $$
  caption $$ "\end{figure}" <> cr)

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References

1. Don't output \caption in LaTeX when image alt text is empty #2844 (comment)

[Adri2000]

Hi,
What's the best way to move forward on this issue?

[jgm]

Fixing this by requiring a non-empty caption for implicit_figures.

[jgm]

Note: you'll now get no figure at all (not just a figure without a \caption) if you have empty alt text.