Enhance fold labels on folded beamer frames #1830

bk90 · 2020-10-15T08:18:30Z

Hello,

this PR enhances (IMHO) the labels on folded frames in LaTeX beamer documents.

The first commit changes the regex parsing comments on the \begin{frame} line. So far the comments where only found if they were separated from the \begin{frame} only by whitespace. Now optional [...] are allowed, as in \begin{frame}[noframenumbering] % Title page.
The second commit extends the search for \frametitle() by looking for \framesubtitle() on the following line and, if both are found, displaying them on the fold as frametitle: framesubtitle.
The third commit to me is optional due to commit (1). It changes the regex looking for frametitle, so that commented out frametitles are found as well. This originally was a workaround for the first commit, but still could be useful.

lervag · 2020-10-15T16:55:23Z

Thanks. Could you provide a couple of complete examples for the various cases?

bk90 · 2020-10-23T19:58:39Z

Sure. Given this code

\begin{frame}[noframenumbering]  % Title page                                    
  \titlepage                                                                     
\end{frame}

\begin{frame}
  \frametitle{Title}
  \framesubtitle{Subtitle}
\end{frame}

\begin{frame}
  % \frametitle{Title}
\end{frame}

I get this folding:

\begin{frame}       Title page·····················································

\begin{frame}       Title: Subtitle·················································

\begin{frame}       Title··························································

Without the changes the folding is

\begin{frame}       ·······························································

\begin{frame}       Title···························································

\begin{frame}       ·······························································

The first example changes, because the regex now allows for [.*] in between \begin{frame} and the comment.

The second example changes, because the code now searches and extracts a \framesubtitle{Subtitle} in the line following \framtitle{Title}. This could be improved by searching not only the following line but all following lines. Do you think that's necessary?

The third example changes, because commented out \frametitle{Title} commands are parsed as well. I don't know if this is desired, what do you think?

lervag · 2020-10-30T19:04:45Z

Sure. Given this code ...

Thanks for the good examples and before vs after explanations.

The second example changes, because the code now searches and extracts a \framesubtitle{Subtitle} in the line following \framtitle{Title}. This could be improved by searching not only the following line but all following lines. Do you think that's necessary?

It seems possible, but I think this should already suffice for a useful improvement. If you want to look into even more advanced parsing, I'll be glad to consider an updated PR or a future PR for that!

The third example changes, because commented out \frametitle{Title} commands are parsed as well. I don't know if this is desired, what do you think?

I'm not sure. In a way, I think we should ignore the commented out title. It does not feel light the right way to control the fold text. Do you have a strong opinion about this?

lervag · 2020-10-30T19:06:59Z

autoload/vimtex/fold/envs.vim

+      if i+1 <= v:foldend && getline(i+1) =~# '^.*\\framesubtitle'
+        let framesubtitle = matchstr(getline(i+1),
+              \ '^.*\\framesubtitle\(\[.*\]\)\?{\zs.\{-1,}\ze\(}\s*\)\?$')
+        return printf('%S: %S', frametitle, framesubtitle)


I would simplify this to:

let frametitle .= ': ' . matchstr(getline(i+1), \ '^.*\\framesubtitle$\[.*\]$\?{\zs.\{-1,}\ze$}\s*$\?$')

I tried this and as far as I can tell this adds : 0 to the fold text if no subtitle is available, so the if condition seems necessary. But I could remove the extra variable and return statement, if you prefer.

lervag

I've looked through the code, and I think it is decent. I have two comments, and we'll have to decide about the commented out frametitles. I also want to add tests, but I can do that myself. If you want to try, look into test/tests/test-folding for examples of how to do it.

lervag · 2020-10-30T19:09:03Z

autoload/vimtex/fold/envs.vim


  " If no caption found, check for a caption comment
-  return matchstr(a:line,'\\begin\*\?{.*}\s*%\s*\zs.*')
+  return matchstr(a:line,'\\begin\*\?{.*}\(\[.*\]\)\?\s*%\s*\zs.*')


I would change $\[.*\]$\? to $\[[^\]]*\]$\?.

I can't get it to work with the suggestion. What would be the improvement? I copied the regex for detecting the brackets from the \frametitle regex a few lines above this.

bk90 · 2021-02-08T00:03:08Z

The third example changes, because commented out \frametitle{Title} commands are parsed as well. I don't know if this is desired, what do you think?

I'm not sure. In a way, I think we should ignore the commented out title. It does not feel light the right way to control the fold text. Do you have a strong opinion about this?

I removed the code for the commented frame titles. I guess if someone comments the frame title its for a good reason, so we should respect this and not show it on the fold. If the title should be shown it can be added as a comment to the\begin{frame} line.

I also want to add tests, but I can do that myself. If you want to try, look into test/tests/test-folding for examples of how to do it.

I added a test, but have some trouble with it. The way it's currently set up the test breaks on recognizing the title comment on line 204. If I switch the order of the two added beamer frames and update the test accordingly (line 204 -> 211, 208 -> 204) the test works. Do you have any idea why? As far as I can tell the order of the frames should not have any effect. When I open the latex file in vim the fold texts are shown as expected either way.

lervag · 2021-02-08T23:16:10Z

I removed the code for the commented frame titles. I guess if someone comments the frame title its for a good reason, so we should respect this and not show it on the fold. If the title should be shown it can be added as a comment to the\begin{frame} line.

Great!

I also want to add tests, but I can do that myself. If you want to try, look into test/tests/test-folding for examples of how to do it.

I added a test, but have some trouble with it. The way it's currently set up the test breaks on recognizing the title comment on line 204. If I switch the order of the two added beamer frames and update the test accordingly (line 204 -> 211, 208 -> 204) the test works. Do you have any idea why? As far as I can tell the order of the frames should not have any effect. When I open the latex file in vim the fold texts are shown as expected either way.

Huh, this is very strange. For some reason, the v:foldend and v:foldlevel variables are not correct when we call foldtextresult(xxx). I looked into this a bit now and could not find anything wrong with your code, and I suspect it might actually be a bug in Vim. Not fully sure, though. The behaviour is consistent between Vim and neovim.

But I'll accept this regardless; let's just swap the tests to make them pass and add a comment (e.g. refer to the issue tread).

Nice work, thanks! If you are happy with this, then I can probably merge this in a day or two.

bk90 · 2021-02-09T22:22:14Z

The test is updated and I think the PR is ready to be merged. Thank you for the great plugin, it has made my life easier for several years now. I'm glad I could make a small contribution :)

lervag · 2021-02-11T21:28:09Z

The test is updated and I think the PR is ready to be merged.

Merging now.

Thank you for the great plugin, it has made my life easier for several years now. I'm glad I could make a small contribution :)

I'm happy to hear it is useful to you! And thanks for your contribution, it is appreciated!

refer: #1830

lervag reviewed Oct 30, 2020

View reviewed changes

bk90 added 2 commits February 7, 2021 23:51

find comments after optional [.*] at \begin{frame}

28787da

show frametitle and framesubtitle on folds

52c2cdc

bk90 force-pushed the enhance-frame-fold-labels branch from 35e438c to 17c25ed Compare February 7, 2021 23:43

add a test for beamer frame folding

b51ea21

bk90 force-pushed the enhance-frame-fold-labels branch from 17c25ed to b51ea21 Compare February 9, 2021 22:06

lervag added a commit that referenced this pull request Feb 11, 2021

merge: improve foldtext on beamer frames

e629115

refer: #1830

lervag closed this Feb 11, 2021

Enhance fold labels on folded beamer frames #1830

Enhance fold labels on folded beamer frames #1830

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