Lamourio / decktape

PDF exporter for HTML presentations

DeckTape

DeckTape is a high-quality PDF exporter for HTML presentation frameworks.

DeckTape is built on top of Puppeteer which relies on Google Chrome for laying out and rendering Web pages and provides a headless Chrome instance scriptable with a JavaScript API.

DeckTape currently supports the following presentation frameworks out of the box:

Bespoke.js •  deck.js •  DZSlides •  Flowtime.js •  impress.js •  Inspire.js •  NueDeck •  remark •  reveal.js •  RISE •  Shower •  Slidy •  WebSlides

DeckTape also provides a generic command that works by emulating the end-user interaction, allowing it to be used to convert presentations from virtually any kind of framework. The generic mode is particularly useful for supporting HTML presentation frameworks that don’t expose an API or accessible state.

DeckTape’s plugin-based architecture exposes an extension API, making it possible to add support for other frameworks or to tailor existing plugins to your specific needs.

DeckTape can optionally be used to capture screenshots of your slide decks in various resolutions (similar to pageres). That can be useful to make sure your presentations are responsive or to create handouts for them.

You can browse some slide deck examples below that have been exported with DeckTape.

Install

NPM

Install DeckTape globally and run it:

$ npm install -g decktape
$ decktape

Or locally:

$ npm install decktape
$ `npm bin`/decktape

See the FAQ for troubleshooting / alternatives.

Usage

$ decktape -h

Usage: decktape [options] [command] <url> <filename>
       decktape version

command      one of: automatic, bespoke, deck, dzslides, flowtime, generic, impress, inspire,
             nuedeck, remark, reveal, shower, slidy, webslides
url          URL of the slides deck
filename     Filename of the output PDF file

Options:
   -s <size>, --size <size>        Size of the slides deck viewport: <width>x<height> (e.g. '1280x720')
   -p <ms>, --pause <ms>           Duration in milliseconds before each slide is exported  [1000]
   --load-pause <ms>               Duration in milliseconds between the page has loaded
                                   and starting to export slides  [0]
   --screenshots                   Capture each slide as an image  [false]
   --screenshots-directory <dir>   Screenshots output directory  [screenshots]
   --screenshots-size <size>       Screenshots resolution, can be repeated  [--size]
   --screenshots-format <format>   Screenshots image format, one of [jpg, png]  [png]
   --slides <range>                Range of slides to be exported, a combination of slide indexes
                                   and ranges (e.g. '1-3,5,8')
   --chrome-path <path>            Path to the Chromium or Chrome executable to run instead of the
                                   bundled Chromium
   --chrome-arg <arg>              Additional argument to pass to the Chrome instance, can be repeated

Defaults to the automatic command.
Iterates over the available plugins, picks the compatible one for presentation at the
specified <url> and uses it to export and write the PDF into the specified <filename>.

In addition to the general options listed above, command specific options can be displayed the following way:

$ decktape <command> -h

Commands

automatic

Iterates over the available plugins, picks the compatible one for presentation at the specified url and uses it to export and write the PDF into the specified filename.

generic

Emulates the end-user interaction by pressing the key with the specified --key option and iterates over the presentation as long as:

1. Any change to the DOM is detected by observing mutation events targeting the body element and its subtree nor

2. the number of slides exported has reached the specified --max-slides option.

The --key value must be one of the UI events KeyboardEvent key values and defaults to ArrowRight, e.g.:

$ decktape generic --key=ArrowDown

Options

--screenshots

Captures each slide as an image at the --screenshots-size resolution, exports it to the --screenshots-format image format and writes the output into the --screenshots-directory directory.

The --screenshots-size option can be set multiple times. For example:

$ decktape --screenshots --screenshots-size=400x300 --screenshots-size=800x600

--slides

Exports only the slides specified as a series of slides indexes and ranges, e.g.:

# Capture a single slide
$ decktape --slides 1
# Capture a series of slides
$ decktape --slides 1,3,5
# Capture a range of slides
$ decktape --slides 1-10
# Capture a combination of slides and ranges
$ decktape --slides 1,2,5-10

The rendering stops and the file written out after the largest numbered slide is exported.

Examples

The following slide deck examples have been exported using DeckTape:

HTML5 Presentation	Framework	Exported PDF
Reveal.js Demo	reveal.js	reveal-js-demo.pdf (2.0MB)
ES6+ maintenant !	reveal.js	devoxx-es6-maintenant.pdf (2.3MB)
reveal.js MathJax example	reveal.js	reveal-js-mathjax.pdf (0.3MB)
Getting Involved in Open Source	reveal.js	opensource-getting-involved.pdf (0.6MB)
Going Further with CDI	Asciidoctor + DZSlides	going-further-with-cdi.pdf (2.4MB)
Deck.js Modern HTML Presentations	deck.js	deck-js-presentation.pdf (0.5MB)
The Official Remark Slideshow	remark	remark-js-slideshow.pdf (0.15MB)
Coloured Terminal Listings in Remark	remark	remark-js-coloured-terminal.pdf (0.12MB)
HTML Slidy: Slide Shows in HTML and XHTML	Slidy	html-slidy-presentation.pdf (0.5MB)
Inspire.js: Lean, hackable, extensible slide deck framework	Inspire.js	inspirejs-sample-slideshow.pdf (1.9MB)
Shower Presentation Engine	Shower	shower-presentation-engine.pdf (0.6MB)
Welcome our new ES5 Overloards	Bespoke.js	new-es5-overloards.pdf (0.2MB)
Spectacle: A ReactJS Presentation Library	Spectacle	spectacle-reactjs-presentation.pdf (1.2MB)

Docker

DeckTape can be executed within a Docker container from the command-line using the astefanutti/decktape Docker image available on Docker Hub:

$ docker run astefanutti/decktape -h

For example:

• To convert an online HTML presentation and have it exported into the working directory under the slides.pdf filename:

  $ docker run --rm -t -v `pwd`:/slides astefanutti/decktape https://revealjs.com/demo/ slides.pdf

• Or, to convert an HTML presentation that’s stored on the local file system in the home directory:

  $ docker run --rm -t -v `pwd`:/slides -v ~:/home/user astefanutti/decktape /home/user/slides.html slides.pdf

• Or, to convert an HTML presentation that’s deployed on the local host:

  $ docker run --rm -t --net=host -v `pwd`:/slides astefanutti/decktape http://localhost:8000 slides.pdf

  You may have to use host.docker.internal instead of localhost on macOS and Windows.

You may want to specify a tag corresponding to a released version of DeckTape for the Docker image, e.g. astefanutti/decktape:3.0.0.

Besides, it is recommended to use the following options from the docker run command:

--rm

DeckTape is meant to be run as a short-term foreground process so that it’s not necessary to have the container’s file system persisted after DeckTape exits,

-v

to mount a data volume so that DeckTape can directly write to the local file system.

Alternatively, you can use the docker cp command, e.g.:

# Run docker run without the --rm option
$ docker run astefanutti/decktape https://revealjs.com slides.pdf
# Copy the exported PDF from the latest used container to the local file system
$ docker cp `docker ps -lq`:slides/slides.pdf .
# Finally remove the latest used container
$ docker rm `docker ps -lq`

If your presentation relies on fonts installed on the host system, but not in the base Docker container, you can mount your fonts directory as a volume, e.g. for macOS:

$ docker run -v "${HOME}/Library/Fonts:/home/node/.local/share/fonts" ...

FAQ

Install

• I’m using Arch Linux, is there an AUR package?

  Yes, it is available at https://aur.archlinux.org/packages/nodejs-decktape/.

Usage

• Is it possible to pass arguments to Chrome?

  Yes, you can use the --chrome-arg option, e.g.:

  $ decktape ... \
    --chrome-arg=--proxy-server="proxy:8080" \
    --chrome-arg=--allow-file-access-from-files

  The list of Chromium flags can be found here.

Troubleshooting

• No usable sandbox!

  Arch Linux, among other Linux distributions may have the user namespace in the kernel disabled by default. You can verify this by accessing chrome://sandbox in your chrom[e|ium] browser. You can find more about sandboxing, here. As a temporary work-around, you can pass --chrome-arg=--no-sandbox as a CLI option.

• Failed to read the 'rules' property from 'CSSStyleSheet': Cannot access rules

  Starting Chromium 64, accessing CSS rules in a stylesheet loaded from the local filesystem or an external location violates CORS policies. As some Decktape plugins tweak the CSS rules for better PDF printing, you need to allow access to local files or external stylesheets by setting the --disable-web-security flag option, e.g.:

  $ decktape ... --chrome-arg=--disable-web-security

• Layout inconsistencies

  Decktape relies on Pupeteer to convert each slide in PDF format. Slight layout inconsistencies can result as part of this transformation. One workaround is to set a specific slide size using the -s option. The value of -s 1024x768 has generally worked well in such situations.

• Reveal.js slide generation never finishes

  Decktape does not use the built-in PDF support of reveal.js, and instead captures each slide individually. Therefore you must not append ?print-pdf or load the print stylesheets in any other way when using Decktape.

Plugin API

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