Lua filter to insert image with caption

Lua filter to insert image with caption

[Thorsten Sommer]

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Dear community,

I worked on the PlantUML filter (cf. 
https://github.com/pandoc/lua-filters/blob/master/plantuml/plantuml.lua) to 
give the generated graphics a caption. 

It looked simple at first. All I want is to get a figure with caption, so 
in Markdown:

![This is my caption.](img.jpg)

As long as this stands alone in a paragraph, it gets transformed into a 
figure with caption. Now, I want to do the same from a Lua filter. My 
attempt was this:

local imgObj = pandoc.Image({pandoc.Str("Test caption.")}, fname)
local para = pandoc.Para({imgObj})

Thus, it generates one paragraph which contains only the generated PlantUML 
graphics. Unfortunately, it generates the image only, without the caption. 
What is wrong?

Second question: How can I pass the individual captions from markdown? 
Right now, the PlantUML filter needs a code block of the type 'plantuml', 
e.g.:

```plantuml
@startuml
A - B 
@enduml
```

I would need something like:

```plantuml[My individual caption is this...]
@startuml
A - B 
@enduml
```

Is it possible to read these additional text inside the Lua filter?


Thanks for all answers.


Best
Thorsten

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Re: Lua filter to insert image with caption

[John MacFarlane]

There's a little hackish trick we use internally to distinguish
figures from regular images in paragraphs in the AST.
(This will go away when we get a proper Figure type.)

The hack is to add `fig:` to the front of the image
title.

   local imgObj = pandoc.Image({pandoc.Str("Test caption.")}, fname, 'fig:')

Try that.

Thorsten Sommer <vektoren-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:

> Dear community,
>
> I worked on the PlantUML filter (cf. 
> https://github.com/pandoc/lua-filters/blob/master/plantuml/plantuml.lua) to 
> give the generated graphics a caption. 
>
> It looked simple at first. All I want is to get a figure with caption, so 
> in Markdown:
>
> ![This is my caption.](img.jpg)
>
> As long as this stands alone in a paragraph, it gets transformed into a 
> figure with caption. Now, I want to do the same from a Lua filter. My 
> attempt was this:
>
> local imgObj = pandoc.Image({pandoc.Str("Test caption.")}, fname)
> local para = pandoc.Para({imgObj})
>
> Thus, it generates one paragraph which contains only the generated PlantUML 
> graphics. Unfortunately, it generates the image only, without the caption. 
> What is wrong?
>
> Second question: How can I pass the individual captions from markdown? 
> Right now, the PlantUML filter needs a code block of the type 'plantuml', 
> e.g.:
>
> ```plantuml
> @startuml
> A - B 
> @enduml
> ```
>
> I would need something like:
>
> ```plantuml[My individual caption is this...]
> @startuml
> A - B 
> @enduml
> ```
>
> Is it possible to read these additional text inside the Lua filter?
>
>
> Thanks for all answers.
>
>
> Best
> Thorsten
>
> -- 
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> For more options, visit https://groups.google.com/d/optout.

Re: Lua filter to insert image with caption

[Thorsten Sommer]

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Thanks John. It works just fine. I also figured out, how to solve my second 
issue. Just in case anyone else had the question as well:

Let's say, this is the markdown document:

# Test Section



```{.plantuml caption="This is a test caption."}
@startuml
skinparam dpi 300
A - B
@enduml
```


In this case, `.plantuml` is the class and `caption="..."` is an attribute 
of this code block. Now, we can change the PlantUML lua filter 
(https://github.com/pandoc/lua-filters/blob/master/plantuml/plantuml.lua) 
like this:

-- search for class "plantuml" and replace with image
function CodeBlock(block)
    if block.classes[1] == "plantuml" then
        local img = plantuml(block.text, filetype, plantumlPath)
        local fname = pandoc.sha1(img) .. "." .. filetype
        pandoc.mediabag.insert(fname, mimetype, img)
        return pandoc.Para{ pandoc.Image({pandoc.Str(block.attributes[
"caption"])}, fname, "fig:") }
    end
end

Here, `block.attributes["caption"]` reads the desired attribute's content 
which gets a caption of the image.

At the weekend, I will create a fork + pull request of 
https://github.com/pandoc/lua-filters in order to provide this solution to 
everyone.


Best
Thorsten

Am Donnerstag, 3. Januar 2019 21:43:57 UTC+1 schrieb John MacFarlane:
>
>
> There's a little hackish trick we use internally to distinguish 
> figures from regular images in paragraphs in the AST. 
> (This will go away when we get a proper Figure type.) 
>
> The hack is to add `fig:` to the front of the image 
> title. 
>
>    local imgObj = pandoc.Image({pandoc.Str("Test caption.")}, fname, 
> 'fig:') 
>
> Try that. 
>
> Thorsten Sommer <vekt...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org <javascript:>> writes: 
>
> > Dear community, 
> > 
> > I worked on the PlantUML filter (cf. 
> > https://github.com/pandoc/lua-filters/blob/master/plantuml/plantuml.lua) 
> to 
> > give the generated graphics a caption. 
> > 
> > It looked simple at first. All I want is to get a figure with caption, 
> so 
> > in Markdown: 
> > 
> > ![This is my caption.](img.jpg) 
> > 
> > As long as this stands alone in a paragraph, it gets transformed into a 
> > figure with caption. Now, I want to do the same from a Lua filter. My 
> > attempt was this: 
> > 
> > local imgObj = pandoc.Image({pandoc.Str("Test caption.")}, fname) 
> > local para = pandoc.Para({imgObj}) 
> > 
> > Thus, it generates one paragraph which contains only the generated 
> PlantUML 
> > graphics. Unfortunately, it generates the image only, without the 
> caption. 
> > What is wrong? 
> > 
> > Second question: How can I pass the individual captions from markdown? 
> > Right now, the PlantUML filter needs a code block of the type 
> 'plantuml', 
> > e.g.: 
> > 
> > ```plantuml 
> > @startuml 
> > A - B 
> > @enduml 
> > ``` 
> > 
> > I would need something like: 
> > 
> > ```plantuml[My individual caption is this...] 
> > @startuml 
> > A - B 
> > @enduml 
> > ``` 
> > 
> > Is it possible to read these additional text inside the Lua filter? 
> > 
> > 
> > Thanks for all answers. 
> > 
> > 
> > Best 
> > Thorsten 
> > 
> > -- 
> > You received this message because you are subscribed to the Google 
> Groups "pandoc-discuss" group. 
> > To unsubscribe from this group and stop receiving emails from it, send 
> an email to pandoc-discus...-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org <javascript:>. 
> > To post to this group, send email to pandoc-...-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org 
> <javascript:>. 
> > To view this discussion on the web visit 
> https://groups.google.com/d/msgid/pandoc-discuss/463cce3d-8746-4ebd-b047-ddfb3ddf2467%40googlegroups.com. 
>
> > For more options, visit https://groups.google.com/d/optout. 
>

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