Draw on your slides

You can draw on a slide while you present, or ahead of time: circle a number, underline a line of code, sketch an arrow. It works with a mouse, a finger, and best with an iPad and its pencil. What you draw is kept with the presentation and shows again the next time you present it, in the reader view and in PDFs.

Start drawing#

Press D in standalone slides or in the presenter view, or use the pen button (Draw in the presenter view). A toolbar appears on the slide:

Tool	What it does
Pen	Thin to thick with the pencil's pressure. Kept.
Highlighter	A wide, see-through stroke in its own colours, always below the pen's strokes. Kept.
Select and move	Draw a loop around strokes, or tap one, to select it; a finger's tap on a stroke selects it with any tool. Drag inside the dashed box with the pen to move it; a straight line shows handles at its ends, which the pen moves. Delete, the bin beside the selection, or the toolbar's bin removes the selection.
Laser pointer	A red dot with a white core and a trail that stays as long as the pen or finger is down and disappears by itself once it is lifted, for pointing at something or circling it. With a pencil that can hover, the dot follows it without touching. Never kept.
Eraser	Removes whole strokes you touch.

Zoom: two fingers zoom into the slide and move around it, one finger moves a zoomed slide, and Ctrl + scroll (a trackpad pinch) zooms on a laptop. Only the slide grows; the bars and the toolbar keep their size. The audience window shows the same part of the slide. 1:1 at the top left shows the whole slide again, as does the next slide. To zoom straight to a picture or a table with a number key, see hotspots.

On a touch screen such as an iPad, drawing is on as soon as the presenter view opens, with the toolbar open, and in the deck as soon as the pencil touches it, with the toolbar folded into its button in the bottom right corner (↘ folds it, the button opens it again). In the presenter view there, neither the bar on top nor the open toolbar covers the slide: the slide sits between them, as large as fits, and takes the toolbar's strip back while it is folded. Both bars are a little smaller than on a computer. Until then, a tap on the right third of the screen goes forward, on the left third back, and a swipe does the same. Drawing starts with the laser pointer; choose the pen or the highlighter to write. The pen and the highlighter each have colours and three sizes, and each keeps its own; one pen colour is Accent, the accent colour of the theme and palette: a drawing in it changes with them. The other pen colours follow light and dark: on dark slides red, blue and green are lighter, and the text colour is white instead of black. The toolbar also has undo and redo (also Cmd/Ctrl+Z and Cmd/Ctrl+Shift+Z), Clear this slide, and × to stop drawing; D and Escape do the same. While you draw, the pencil and the mouse draw; fingers keep working: a swipe to the left goes forward, to the right back, a tap on a stroke selects it, and buttons and polls on the slide still respond. Turn slides with the arrow keys or the presenter view's arrows, as always. Holding the pen still for half a second at the end of a stroke makes it a straight line; near a multiple of 15° (horizontal, vertical, 45° …) it snaps to that angle.

I hides and shows what was drawn before, for example when a slide should look clean again. The toolbar has the same switch.

The audience window, and any other deck window in the same browser, shows every stroke as you draw it.

Where drawings are kept#

Drawings live in a file next to your slides: my-talk.drawings.json for my-talk.md. Keep the two together, and send or check in both.

With mdeck run, each stroke is saved in that file as soon as you lift the pen. Nothing reloads, and the talk goes on. A stroke the server cannot take (the deck changed under the page) is dropped and a short notice over the slide says so.
A slide that gets its first drawing receives an id: in its settings, made from its heading, for example id: the-important-part. The drawing stays with that slide when you add or move slides. If you change the id: in the editor, the drawing moves with it.
A slide from an included file (:::include) keeps its drawings by its place in that file; give it an id: there, and they stay with it when you insert slides before it.
A deck in several languages (talk.en.md beside talk.de.md) keeps its drawings with the file you started mdeck run with, under that file's slide ids; drawing in the other language goes to the same file, slide by slide. Build, send or print from that file to include them.
If you delete a slide that has drawings, they stay in the file. mdeck check tells you about them; bring the slide back, or delete them from the file.
The first save of a session keeps a copy of the previous file in .mdeck-backups, next to your slides.
Opened from a built folder or a single file, the page has nowhere to save. Drawings are kept in that browser, and the toolbar's download button saves them as the drawings file, to put next to your slides. Safari may clear such browser data after a week without use, so download it after drawing.

Builds and PDFs include the drawings. In the reader view, which a file from mdeck send opens in, a Drawings button hides and shows them, also for Save as PDF; the browser remembers the choice. To leave them out of a build altogether, add --no-drawings:

In your terminal

mdeck pdf my-talk.md --no-drawings

Present from an iPad#

There are two ways.

The iPad on its own. Connect it to the projector, which usually shows the same picture as the iPad, and open standalone slides with Present from the reader view. Swipe left or right to go forward or back, also while drawing. This keeps notes off the wall.

The iPad next to your laptop. The laptop shows the slides on the projector; you draw and go through the slides on the iPad, with your notes on it.

Start mdeck run my-talk.md --network, so the iPad in the same network can reach your laptop.
In the presenter view on the laptop, click the connection icons at its top, choose iPad, and scan the code with the iPad's camera. The presenter view opens on the iPad, paired with your laptop, so it may save drawings and steer the phones of a poll. It is the same presenter view as on the laptop; pairing only gives it these rights. Once it is open, the launch page says so.
On the laptop, open the audience window from the same place and move it to the projector. It follows the iPad: slides, revealed points, drawings as you draw them, and videos. Navigation in the audience window also updates the iPad's slide, notes and next-slide preview.

Videos. A video file on a slide (<videoplayer src="…" />) plays, pauses and jumps on the projector as you tap it on the iPad. The sound comes from the projector: while the audience window is open, the iPad's copy plays silently. Browsers start sound only on a page someone has clicked, so click the audience window once before the talk (going full screen counts); otherwise the video plays there without sound and shows Click for sound.

Online videos (<videoplayer url="…" /> from YouTube, Vimeo or SwitchTube) do not follow the iPad. They run inside the video service's own player, which mdeck cannot start or stop, so they play only on the screen where you start them. For a talk from the iPad, start them in the audience window on the laptop, or download the video and use a video file.

A pairing code works once, for ten minutes. It leads to the laptop's address in the network it is in when the code is shown; the panel says which, and says so when the laptop is in no network the iPad could reach. Unpair on the launch page ends every pairing; so does stopping mdeck run. The iPad then says over the slide that it is no longer paired, since what you do on it stays on it; scan a new code.

The iPad on another network. Some networks, often big Wi-Fi networks at universities, do not let devices reach each other, and a laptop's firewall may not let the iPad in. With a server of your own (see Ask your audience) the iPad does not need to reach your laptop at all: your laptop connects out to the server, and the server passes the iPad's requests to it. The slides are not uploaded or stored anywhere.

Tell mdeck where your server is: server: https://rooms.example.org in the deck's settings, or MDECK_SERVER in your shell, or the address after the option in the next step.
Start MDECK_SERVER_KEY=your-key mdeck run my-talk.md --server. The key is the one the server was started with. With MDECK_SERVER and MDECK_SERVER_KEY both set in your shell, plain mdeck run my-talk.md is enough: it uses the server whenever it answers.
In the presenter view on the laptop, click the connection icons, choose iPad and scan the code. The address in the code is on your server and contains a long random name, so treat it like a private link.
Open the audience window on the laptop as before. It follows the iPad through the server.

Everything else works as with --network: drawings are saved in the drawings file beside the deck, and the iPad may steer polls. Editing the slides on the laptop reloads the iPad too. The server only passes on what the presenter and audience pages need; the launch page, the editor and the other files in your folder are not reachable through it. Stopping mdeck run ends the connection, and a pairing code stops working when you unpair or stop.

On the iPad the presenter view shows only the slide, with one bar at the top: the slide number, the timer, previous and next, drawing, black screen, freeze (the projector keeps its slide), all slides, hotspots, the slide's own controls, the notes drawer (with the next slide, also N), who is connected and the settings. The settings switch the layout; each device remembers its choice.

With a server of your own (the server setting, see Ask your audience), the same also works with a hosted deck: open the presenter view on the iPad with your key (?serverkey=…), and the audience window anywhere else follows it. With the deck opened through mdeck run and the server's key set (MDECK_SERVER_KEY), the paired iPad and the audience window talk over your own network, and only the polls go through the server. Drawings are then kept on the iPad; download the drawings file after the talk.

Tips for the iPad#

Full screen: the full-screen button (four corners) or F, where the browser allows it. Safari on an iPhone does not. Alternatively, use Share → Add to Home Screen: the deck then opens without Safari's bars. Such a Home Screen app keeps its own browser data, apart from Safari's.
Fingers and the pencil: the pencil draws, fingers operate the slides, also while drawing. Swipe left to go forward, right to go back; tap a stroke to select it. To draw with a finger (on a device without a pencil), switch on the hand button on the toolbar; fingers then draw instead.
Networks: many large Wi-Fi networks do not let devices reach each other. If the iPad cannot open the pairing code, connect both to a phone hotspot.